Member for plasma treatment apparatus and method for manufacturing same

Abstract

According to the present invention, a coating 53 is formed on a base material 52 of a member for a plasma treatment apparatus using a suspension plasma spray method. A suspension 63 used for the suspension plasma spray contains a fluorine-containing solvent 61, a plurality of yttrium fluoride particles, and a plurality of yttrium oxyfluoride particles.

Description

Plasma processing apparatus member and method for manufacturing the same

[0001] The present invention relates to a member for a plasma processing apparatus and a method for manufacturing the same, and more particularly to a member that is placed in a processing chamber of a plasma processing apparatus and exposed to plasma, and a method for manufacturing the same.

[0002] Plasma etching is used for microfabrication in the manufacture of semiconductor devices such as electronic devices and magnetic memories. The inner walls of the processing chamber of a plasma processing apparatus that performs plasma etching are exposed to high-frequency plasma and etching gas during the etching process. For this reason, the inner wall surfaces of the processing chamber are protected by forming a coating with excellent plasma resistance. The following are known conventional technologies related to materials for such plasma-resistant coatings.

[0003] Japanese Patent Laid-Open Publication No. 2004-197181 (Patent Document 1) describes a coating containing a Group IIIA element and elemental fluorine, which is used to cover the surface of a grounding part disposed inside a plasma etching apparatus. The coating contains a Group IIIA fluoride phase, and the fluoride phase is orthorhombic and contains 50% or more of a crystalline phase belonging to the space group Pnma.

[0004] In Japanese Patent Laid-Open No. 2009-176787 (Patent Document 2), a coating on the surface of a grounding part arranged inside a plasma etching apparatus is formed using Al ２ O ３ , YAG, Y ２ O ３ , Gd ２ O ３ , Yb ２ O ３ , Y.F. ３ In Japanese Patent Publication No. 2016-539250 (Patent Document 3), it is described that the material of the coating on the surface of the earth part arranged inside the plasma etching apparatus is Y. ３ Al ５ O １２ , Y ４ Al ２ O ９ , Er ２ O ３ , Gd ２ O３ , Y ２ O ３ , Er ３ Al ５ O １２ , Gd ３ Al ５ O １２ , Y.F. ３ , Nd ２ O ３ Either or Y ４ Al ２ O ９ and Y ２ O ３ -ZrO ２ It is described as including a solid solution.

[0005] Japanese Patent Laid-Open Publication No. 2013-140950 (Patent Document 4) describes that the material of the coating on the surface of the earth part of a plasma etching apparatus contains yttrium fluoride and yttrium oxyfluoride.

[0006] Japanese Patent Laid-Open No. 2014-141390 (Patent Document 5), Japanese Patent Laid-Open No. 2016-27624 (Patent Document 6), and Japanese Patent Laid-Open No. 2018-82154 (Patent Document 7) describe the use of yttrium oxide, yttrium fluoride, or yttrium oxyfluoride having an average crystallite size of less than 100 nm as a coating material for a grounding portion disposed inside a plasma etching apparatus, and the formation of a coating by an aerosol deposition method. The aerosol deposition method is also known to have the advantage of being able to reduce the surface irregularities of the formed film compared to atmospheric plasma spraying.

[0007] Meanwhile, Kazuhiro Ueda et al., in Advances in X-ray Analysis 50 (April 1, 2019), edited by the X-ray Analysis Research Forum of the Japan Society for Analytical Chemistry (published on pp. 197-205) (Non-Patent Document 1), disclose that increasing the average crystallite size increases the amount of foreign matter that is generated.

[0008] Japanese Patent Laid-Open Publication No. 2019-192701 (Patent Document 8) discloses that by setting the crystallite size of the coating of the grounding part disposed inside the plasma processing apparatus to 50 nm or less, the occurrence of foreign matter on the semiconductor wafers processed inside can be reduced. Furthermore, it also discloses that by setting the temperature of the base material of the grounding part within a predetermined range when forming the coating, the low-temperature phase ratio can be set to 60% or more and the crystallite size can be set to 50 nm or less.

[0009] Japanese Patent Laid-Open Publication No. 2017-190475 (Patent Document 9) discloses a specific range of mixing ratios of yttrium fluoride granulated powder and yttrium oxide granulated powder as a thermal spray material capable of obtaining a thermal spray coating of an yttrium-based fluoride compound. The thermal spray coating of an yttrium-based fluoride compound has sufficient corrosion resistance to plasma and can effectively prevent damage to the base material due to acid penetration during acid cleaning.

[0010] Japanese Patent Laid-Open Publication No. 2017-150085 (Patent Document 10) describes a process for producing a thermal spray coating made of yttrium fluoride that can suppress particle generation. The process uses a high-velocity flame spraying method or an atmospheric plasma spraying method, and discloses supplying a slurry containing yttrium fluoride particles having an average particle size within a specific range to a position downstream from the nozzle of a thermal spray gun or to the tip of the nozzle.

[0011] Japanese Patent Laid-Open Publication No. 2020-172702 (Patent Document 11) describes a method for forming a thermal spray coating on parts and components in a plasma etching apparatus. ４ Al ２ O ９ It has been disclosed that a thermal spray coating is formed by a suspension plasma spraying method in which a slurry of a compound (C1) dispersed in a solvent is sprayed. Suspension plasma spraying is also called SPS (Suspension Plasma Spraying), suspension plasma spraying, or suspension plasma spraying.

[0012] JP 2004-197181 A JP 2009-176787 A JP 2016-539250 A JP 2013-140950 A JP 2014-141390 A JP 2016-27624 A JP 2018-82154 A JP 2019-192701 A JP 2017-190475 A JP 2017-150085 A JP 2020-172702 A

[0013] Kazuhiro Ueda, Kazuyuki Ikenaga, Tomoyuki Tamura, Masahiro Kadoya, "Study on the Crystal Structure and Mechanism of Foreign Matter Generation of Yttrium-Based Materials for Plasma Etching Equipment," X-Ray Analysis Research Roundtable (ed.), Advances in X-Ray Analysis 50, Agne Technology Center, April 1, 2019, pp. 197-205

[0014] However, the inventors have found through their investigations that the above-mentioned prior art techniques using atmospheric plasma spraying have problems due to insufficient consideration of the following points.

[0015] That is, even if the raw materials used to form the coating are micronized to reduce the crystal size of the resulting coating, friction between the carrier gas, such as dry nitrogen, and the raw material powder causes the raw material powder to become charged and agglomerate, which does not fully achieve the effect of micronizing the raw materials. Furthermore, even if a carrier gas containing moisture is used to reduce the charge of the raw material powder, the raw material powder agglomerates due to the adsorption of water on the surface of the raw material powder, which does not fully achieve the effect of micronizing the raw materials. Furthermore, due to the agglomeration of the raw material powder, some of the raw material powder does not completely melt, but accumulates in a semi-molten state, making it difficult to form a thick microcrystalline layer. That is, the above-mentioned conventional techniques using atmospheric plasma spraying did not fully consider the agglomeration of the raw material.

[0016] To prevent the aggregation of raw material powder, a suspension plasma spraying method using a suspension in which the raw material is dispersed in a solvent is effective.

[0017] Patent Document 11 discloses a suspension plasma spraying method in which an oxide raw material is suspended in a solvent. In the suspension plasma spraying method, which uses a suspension in which the raw material is dispersed in an organic solvent such as water or ethanol, the solvent in the suspension functions as a thermally activated solution that reacts with the raw material powder, generating more energy than in air plasma spraying. Therefore, in suspension plasma spraying, the raw material powder is completely melted and deposited, allowing for the formation of a thicker microcrystalline layer than in air plasma spraying.

[0018] However, the inventors have found through their investigations that the following problems arise when fluorides or oxyfluorides are used as raw materials in a suspension plasma spraying method that uses a suspension in which raw materials are dispersed in a solvent.

[0019] Specifically, during the coating formation process using the suspension plasma spraying method, raw material powders consisting of fluorides or oxyfluorides undergo thermal decomposition and react with oxygen generated from the solvent or oxygen in the atmosphere to generate oxides. As a result, yttrium oxide is mixed into the formed coating. When such a coating is used in a plasma etching device, the coating is exposed to the fluorine plasma used during the etching process, and the yttrium oxide portion in the coating reacts with the fluorine plasma and converts to fluoride. This causes the volume of the yttrium oxide portion to expand, resulting in cracks on the surface of the coating. As a result, microparticles are scattered from the coating as foreign matter. If the scattered microparticles adhere to a workpiece, such as a semiconductor wafer, the plasma processing of the workpiece cannot be performed normally. As a result, the yield of the plasma processing of the workpiece decreases. The above-mentioned prior art did not fully consider the conditions for forming a sprayed coating that can sufficiently suppress the generation of such microparticles.

[0020] A primary object of the present invention is to reduce the generation of foreign matter from components for a plasma processing apparatus. Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

[0021] A brief summary of a representative embodiment of the present invention will be given below.

[0022] In one embodiment, a method for manufacturing a plasma processing apparatus member includes forming a coating on a substrate of the plasma processing apparatus member by a suspension plasma spraying method, the suspension used in the suspension plasma spraying including a fluorine-containing solvent, a plurality of yttrium fluoride particles, and a plurality of yttrium oxyfluoride particles.

[0023] According to one embodiment, it is possible to reduce the generation of foreign matter from the coating on the surface of a component placed in the processing chamber of a plasma processing apparatus, and to extend the life of the coating.

[0024] It is a longitudinal sectional view showing a schematic configuration of a plasma processing apparatus in one embodiment. It is an explanatory view of a method for forming a coating in one embodiment. It is an SEM image of a cross section of a coating. It is an SEM image of a cross section of a coating. It is an SEM image of a cross section of a coating.

[0025] Hereinafter, embodiments will be described in detail with reference to the drawings. In all drawings for explaining the embodiments, components having the same functions are designated by the same reference numerals, and repeated explanations thereof will be omitted. In the following embodiments, explanations of the same or similar parts will not be repeated unless particularly necessary.

[0026] (First Embodiment) <Configuration of Plasma Processing Apparatus> A plasma processing apparatus 1 according to this embodiment will be described below with reference to Fig. 1. Fig. 1 is a vertical cross-sectional view showing a schematic configuration of a plasma processing apparatus 1 according to this embodiment.

[0027] 1, the plasma processing apparatus 1 includes a vacuum vessel 2. A processing chamber 3 is the space inside the vacuum vessel 2. The processing chamber 3 is surrounded by the inner wall of the vacuum vessel 2. The upper part of the processing chamber 3 is a space surrounded by a cylindrical inner wall, and forms a discharge chamber (plasma generation chamber) where plasma 4 is generated.

[0028] A stage 5, which serves as a sample holder, is disposed within the processing chamber 3 below the discharge chamber where plasma 4 is generated. A wafer 6, which is an object to be processed, is placed 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 coaxial or positioned so close that they can be considered to be coaxial.

[0029] An exhaust port 7 is formed at the bottom of the vacuum vessel 2. The upper surface of the bottom of the vacuum vessel 2 forms the bottom surface of the processing chamber 3. The exhaust port 7 is located below the stage 5. The vertical central axis of the exhaust port 7 and the vertical central axis of the stage 5 are coaxial or located at positions that are close enough to be considered coaxial.

[0030] 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. The stage 5 is held at a midpoint between the upper and lower surfaces of the processing chamber 3 in the vertical direction of the processing chamber 3. A ring-shaped exhaust plate 9 is disposed within the processing chamber 3, surrounding the stage 5. Multiple through-holes (not shown) are formed in the exhaust plate 9. These multiple through-holes connect the space above the exhaust plate 9 in the processing chamber 3 to the space 8 below the exhaust plate 9. The space 8 below the stage 5 is connected to the discharge chamber via the multiple through-holes in the exhaust plate 9 and a gap between the side wall of the stage 5 and the cylindrical inner wall of the processing chamber 3. During processing of the wafer 6 on the stage 5, products generated on the upper surface of the wafer 6 and in the discharge chamber, as well as plasma and gas particles within the discharge chamber, pass through the space 8 and are exhausted to the outside of the processing chamber 3 through the exhaust port 7. Therefore, the space 8 constitutes an exhaust path.

[0031] Although the detailed configuration of the stage 5 is not shown in the figure, the stage 5 includes a base material, which is a cylindrical metal member, a dielectric film arranged to cover the upper surface of the base material, a heater arranged inside the dielectric film, and a coolant flow path arranged inside the base material. Within the stage 5, the coolant flow paths are arranged concentrically or spirally in multiple locations around the central axis of the stage 5. Furthermore, with a wafer 6 placed on the upper surface of the dielectric film of the stage 5, a heat-conductive gas, 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. For this purpose, piping through which the heat-conductive gas flows is arranged inside the base material and the dielectric film of the stage 5.

[0032] A high frequency power supply 11 is connected to the substrate of the stage 5 via an impedance matcher 12 and a coaxial cable. The high frequency power supply 11 supplies high frequency power to the substrate of the stage 5 while the wafer 6 is being processed by the plasma 4. This high frequency power forms an electric field above the top surface of the wafer 6 to attract charged particles in the plasma 4.

[0033] Furthermore, an electrode for electrostatic attraction is disposed above the heater in the dielectric film on the substrate of the stage 5. When DC power is supplied to this electrode, an electrostatic force is generated inside the dielectric film and the wafer 6 to attract and hold the wafer 6 to the upper surface of the dielectric film.

[0034] A window member 13 is disposed above the upper surface of the stage 5 so as to face the stage 5. The window member 13 is made of a dielectric material such as quartz or ceramics and has a disk shape. The window member 13 forms the upper part of the vacuum vessel 2 and airtightly seals the processing chamber 3. Furthermore, a shower plate 14 is disposed below the window member 13 at a position that forms the ceiling surface of the processing chamber 3. The shower plate 14 is made of a dielectric material such as quartz and has a disk shape. A plurality of through holes 15 are formed in the center of the shower plate 14. The shower plate 14 is disposed so 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 ceiling of the processing chamber 3.

[0035] The process gas supply pipe 17 is connected to the vacuum vessel 2 so as to communicate with the gap 16. A valve 18 that opens or closes the interior of the process gas supply pipe 17 is disposed at a predetermined location on the process gas supply pipe 17. The process gas (process gas) to be supplied into the process chamber 3 flows into the gap 16 through the process gas supply pipe 17 with the valve 18 open, then diffuses within the gap 16, and is supplied into the process chamber 3 through the multiple through-holes 15 in the shower plate 14. Therefore, the process gas is supplied into the process chamber 3 from above. The flow rate or speed of the process gas is adjusted by a gas flow rate controller (not shown) connected to one end of the process gas supply pipe 17.

[0036] A vacuum exhaust unit is disposed below the vacuum vessel 2 for exhausting gases and particles from the processing chamber 3 through the exhaust port 7. The vacuum exhaust unit includes a pressure adjustment plate 21 and a turbomolecular pump 22, which is 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 and decrease the area of ​​the flow path through which gas flows into the exhaust port 7. Furthermore, in the vacuum exhaust unit, the outlet of the turbomolecular pump 22 is connected via an exhaust pipe to a dry pump 23, which is a roughing pump. A valve 24 is disposed on the exhaust pipe.

[0037] The pressure adjustment plate 21 also functions as a valve that opens and closes the exhaust port 7. The vacuum vessel 2 is provided with a pressure detector 25, which is a sensor for detecting the pressure inside the processing chamber 3. A signal output from the pressure detector 25 is sent to a control unit (not shown), which detects the pressure value. The pressure adjustment plate 21 is driven based on a command signal output from the control unit in accordance with the detected pressure value. This changes the vertical position of the pressure adjustment plate 21, thereby increasing or decreasing the area of ​​the flow path through which gas flows into the exhaust port 7.

[0038] 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 for slowly exhausting the processing chamber 3 from atmospheric pressure to vacuum using the dry pump 23. The valve 29 is a main exhaust valve for quickly exhausting the processing chamber 3 using the dry pump 23.

[0039] A plasma generating unit is disposed above the upper cylindrical portion of the vacuum vessel 2 and around the sidewall of the cylindrical portion. This plasma generating unit is configured to generate an electric field or a magnetic field that is supplied to the processing chamber 3 to generate plasma 4. The plasma generating unit includes a waveguide 31, a magnetron oscillator 32, a solenoid coil 33, and a solenoid coil 34.

[0040] That is, a 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 conduit through which the microwave electric field output by the magnetron oscillator 32 propagates. The microwave electric field propagated within the waveguide 31 is supplied into the processing chamber 3. The waveguide 31 includes a rectangular waveguide section 31a extending horizontally and a circular waveguide section 31b extending vertically. The vertical cross section of the rectangular waveguide section 31a is rectangular. The magnetron oscillator 32 is disposed at one end of the rectangular waveguide section 31a. The circular waveguide section 31b is connected to the other end of the rectangular waveguide section 31a. The horizontal cross section of the circular waveguide section 31b is circular, and the central axis extends vertically. A cylindrical cavity 31c having a diameter expanded is disposed at the bottom end of the circular waveguide 31b. A specific mode of electric field is strengthened inside the cavity 31c. Multi-stage solenoid coils 33 and 34, which serve as magnetic field generators, are disposed above and around the cavity 31c and around the sides of the processing chamber 3.

[0041] <Operation of Plasma Processing Apparatus> Next, the operation of the plasma processing apparatus 1 will be described.

[0042] The wafer 6, which is the object to be processed, is transferred within a transfer chamber inside a vacuum transfer vessel (not shown) connected to the side wall of the vacuum vessel 2, and is carried into the processing chamber 3 of the vacuum vessel 2 of the plasma processing apparatus 1. Specifically, the wafer 6 is placed on the tip of an arm of a vacuum transfer device (not shown), such as a robot arm, arranged in the transfer chamber, and is transferred into the processing chamber 3 of the vacuum vessel 2 and placed on the upper surface of the stage 5.

[0043] When the arm of the vacuum transfer device leaves the processing chamber 3, the interior of the processing chamber 3 is sealed, and a DC voltage is applied to the electrostatic attraction electrode in the dielectric film of the stage 5. The resulting electrostatic force holds the wafer 6 on the dielectric film of the stage 5. In this state, a heat-conductive gas such as He is supplied through piping inside the stage 5 into the gap between the wafer 6 and the upper surface of the dielectric film of the stage 5. A coolant whose temperature is adjusted by a coolant temperature adjuster is supplied to the coolant flow path inside the stage 5. This promotes heat transfer between the temperature-adjusted substrate of the stage 5 and the wafer 6, and the temperature of the wafer 6 is adjusted to within a temperature range appropriate for plasma processing.

[0044] The process gas, the flow rate or velocity of which is adjusted by the gas flow rate control unit, passes through the process gas supply pipe 17, the gap 16, and the multiple through-holes 15 in the shower plate 14, and is supplied into the process chamber 3. The turbomolecular pump 22 also operates to exhaust the interior of the process chamber 3 through the exhaust port 7. The pressure within the process chamber 3 is adjusted to within a pressure range suitable for plasma processing by balancing the supply of the process gas into the process chamber 3 and the exhaust from the exhaust port 7. In this state, the electric field of microwaves generated by the magnetron oscillator 32 propagates through the waveguide 31, passes through the window member 13 and the shower plate 14, and is radiated into the process chamber 3. Furthermore, a magnetic field generated by the solenoid coils 33 and 34 is supplied to the process chamber 3, and electron cyclotron resonance (ECR) is generated by the interaction between the magnetic field and the electric field of the microwaves. As a result, atoms or molecules of the process gas are excited, ionized, and dissociated, thereby generating plasma 4 within the process chamber 3.

[0045] When the plasma 4 is generated, high-frequency power is supplied from the high-frequency power supply 11 to the substrate on the stage 5, forming a bias potential above the upper surface of the wafer 6. This attracts charged particles, such as ions, in the plasma 4 to 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 on the upper surface of the wafer 6. As a result, the film to be processed on the upper surface of the wafer 6 is etched. Because the film to be processed exposed from the mask layer is selectively etched, the etching of the film to be processed progresses along the shape of the mask layer. When a detector (not shown) detects that the etching of the film to be processed has reached its endpoint, 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. This stops the etching process.

[0046] When the control unit determines that there is no need to further proceed with the etching process on the wafer 6, the processing chamber 3 is evacuated to a high vacuum. Furthermore, static electricity is removed from the stage 5, and the wafer 6 is released from suction. Thereafter, the arm of the vacuum transfer device enters the processing chamber 3, and after the processed wafer 6 is handed over onto the arm, the arm retracts and the wafer 6 is transferred out of the processing chamber 3 to a vacuum transfer chamber.

[0047] <Earth electrode> The inner wall (inner wall surface) of the processing chamber 3 of the plasma processing apparatus 1 faces the plasma 4 and is exposed to particles in the plasma 4. On the other hand, in order to stabilize the potential of the plasma 4, which is a dielectric, it is necessary to dispose a member that functions as a ground electrode facing the plasma 4 and in contact with the plasma 4 within the processing chamber 3.

[0048] In the plasma processing apparatus 1 of this embodiment, an earth electrode 41 is disposed in the processing chamber 3. The earth electrode 41 functions as an electrode for earthing. The earth electrode 41 is a ring-shaped member. The earth electrode 41 covers the surface of a portion of the inner wall of the processing chamber 3 that surrounds the discharge chamber. The earth electrode 41 is disposed so as to surround the periphery (lateral periphery) of the space above the upper surface of the stage 5. In the vertical direction, at least a portion of the earth electrode 41 is located higher than the upper surface of the stage 5.

[0049] The earth electrode 41 includes a substrate (base material) 42 made of a conductive material and a coating 43 covering the surface of the substrate 42. In this embodiment, the substrate 42 of the earth electrode 41 is made of a metal such as a stainless steel alloy or an aluminum alloy. The earth electrode 41 is grounded.

[0050] When the plasma processing apparatus 1 is in operation, plasma 4 is generated in the processing chamber 3, and the earth electrode 41 is exposed to the plasma 4. Since the earth electrode 41 has a coating 43, the coating 43 of the earth electrode 41 is exposed to the plasma 4.

[0051] Unlike the present embodiment, if the earth electrode 41 does not have a coating on the surface of the substrate 42, the substrate 42 of the earth electrode 41 may be exposed to the plasma 4, which may cause corrosion of the substrate 42 of the earth electrode 41 or generation of foreign matter from the substrate 42. As a result, contamination of the wafer 6 may occur.

[0052] For this reason, in this embodiment, a coating 43 made of a highly plasma-resistant material is formed so as to cover the surface of the substrate 42 of the earth electrode 41. By forming the coating 43 covering the substrate 42, damage to the substrate 42 of the earth electrode 41 caused by the plasma 4 can be suppressed while maintaining the function of the earth electrode 41 as an electrode. As a result, corrosion of the earth electrode 41 and the earth electrode 41 being a source of foreign matter can be prevented, and contamination of the wafer 6 can be suppressed. The coating 43 may be a laminated film.

[0053] In this embodiment, the coating 43 of the earth electrode 41 contains yttrium fluoride and yttrium oxyfluoride. Yttrium fluoride and yttrium oxyfluoride are excellent coating materials with high plasma resistance. Therefore, the coating 43 containing yttrium fluoride and yttrium oxyfluoride has high resistance to plasma.

[0054] In this embodiment, the coating 43 of the earth electrode 41 is formed using a suspension plasma spraying method. Compared to the atmospheric plasma spraying method, the suspension plasma spraying method has the advantage that the raw material particles used for spraying are less likely to aggregate. In this embodiment, the coating 43 containing yttrium fluoride and yttrium oxyfluoride is formed by the suspension plasma spraying method, so the suspension used to form the coating 43 contains yttrium fluoride particles and yttrium oxyfluoride particles.

[0055] However, according to the inventor's investigations, it has been found that when a coating is formed by a suspension plasma spraying method using a suspension containing yttrium fluoride particles and yttrium oxyfluoride particles, yttrium oxide is likely to be mixed into the formed coating. In a coating containing yttrium fluoride, yttrium oxyfluoride, and yttrium oxide, if the ratio of yttrium oxide is large, foreign matter is likely to be generated from the coating when the coating is exposed to plasma in the processing chamber of a plasma processing apparatus. For this reason, it is desirable to suppress the ratio of yttrium oxide in the coating.

[0056] Therefore, in this embodiment, a fluorine-containing solvent is used as the solvent for the suspension used in forming the coating 43. That is, when forming the coating 43 by suspension plasma spraying, a fluorine-containing solvent and a suspension containing yttrium fluoride particles and yttrium oxyfluoride particles are used. This makes it possible to prevent yttrium oxide from being mixed into the coating 43 and to reduce the yttrium oxide content in the coating 43. This will be described in more detail later.

[0057] On the other hand, the base material 44 of the vacuum vessel 2, which does not function as an earth, is also made of a metal such as a stainless steel alloy or an aluminum alloy. The surface of the base material 44 of the vacuum vessel 2 is also subjected to a passivation treatment, thermal spraying, PVD, CVD, or other treatment to improve corrosion resistance against plasma and reduce wear. This makes it possible to suppress corrosion, metal contamination, or the generation of foreign matter that would occur when the base material 44 of the vacuum vessel 2 is exposed to the plasma 4.

[0058] It should be noted that a cylindrical cover member (not shown) made of a ceramic such as yttrium oxide or quartz may be disposed inside the inner wall surface of the cylindrical substrate 44, between the discharge chamber and the substrate 44. By disposing such a cover member between the substrate 44 and the plasma 4, contact between the substrate 44 and highly reactive particles in the plasma 4 and collisions between the substrate 44 and charged particles are blocked or reduced, thereby suppressing wear of the substrate 44.

[0059] <Method of Forming Coating> The method of forming the coating in this embodiment will be described below with reference to Fig. 2. Fig. 2 is an explanatory diagram of the method of forming the coating in this embodiment.

[0060] An earth electrode 41 is prepared without the coating 43. At this stage, the coating 43 is not formed on the surface of the base material 42 of the earth electrode 41, and the surface of the base material 42 of the earth electrode 41 is exposed.

[0061] Next, in order to improve the adhesion between the surface of the substrate 42 of the earth electrode 41 and the coating 43 formed thereon, the surface of the substrate 42 is roughened by sandblasting. The surface roughness Ra of the substrate 42 is preferably 1 μm or more (Ra≧1 μm).

[0062] Next, the surface of the base material 42 of the earth 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 degreased and cleaned surface of the base material 42 of the earth electrode 41 becomes the surface of the base material 52 shown in Figure 2. In other words, the base material 52 shown in Figure 2 corresponds to the base material 42 of the earth electrode 41.

[0063] Next, a step of forming a coating 53 on the surface of the substrate 52 by suspension plasma spraying is carried out. This step will be described below. The coating 53 corresponds to the coating 43 of the earth electrode 41 described above.

[0064] A thermal spray material (material for thermal spraying) 61 and a solvent (dispersion solvent) 62 are placed in a mixer (not shown) and stirred to produce (prepare) a suspension (liquid suspension) 63 in which the thermal spray material 61 is dispersed in the solvent 62.

[0065] The spray material 61 used in this embodiment contains a plurality of yttrium fluoride particles and a plurality of yttrium oxyfluoride particles. Here, the spray material 61 made of a plurality of yttrium fluoride particles and a plurality of yttrium oxyfluoride particles is used. It is desirable that the spray material 61 does not contain yttrium oxide particles. The solvent 62 is a solvent (dispersion solvent) in which the spray material 61 is dispersed. The particles that make up the spray material 61 are dispersed in the solvent 62. The solvent 62 used in this embodiment contains fluorine. Here, a fluorocarbon liquid made of CFC (chlorofluorocarbon) is used as the solvent 62.

[0066] Therefore, the suspension 61 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.

[0067] The average crystallite size of the yttrium fluoride particles constituting the thermal spray material 61 and the average crystallite size of the yttrium oxyfluoride particles are each preferably 50 nm or less. The average particle size of the yttrium fluoride particles constituting the thermal spray material 61 and the average particle size of the yttrium oxyfluoride particles are each preferably 0.05 μm or more. If the average particle size is smaller than 0.05 μm, the particles become charged due to friction between the solvent and the particles, and the particles aggregate within the suspension 63. The average particle size of the yttrium fluoride particles constituting the thermal spray material 61 and the average particle size of the yttrium oxyfluoride particles are each preferably 50 μm or less. If the average particle size is larger than 50 μm, the particles will precipitate within the solvent, and the suspension 63 will no longer function properly. The total content of the yttrium fluoride particles and yttrium oxyfluoride particles in the suspension 63 is preferably 10 wt % or more and 70 wt % or less.

[0068] A high voltage 72 is applied to a nozzle 71 of the thermal spraying device, and a plasma gas 73 is passed through the nozzle 71 to generate an arc discharge, thereby generating a thermal spray flame (plasma jet) 74. The plasma gas 73 is a gas for generating plasma, and may be, for example, argon gas alone, nitrogen gas alone, or a mixed gas of two or more selected from argon gas, hydrogen gas, helium gas, and nitrogen gas, but is not particularly limited thereto. The thermal spray flame 74 is a plasma-converted gas jet ejected from the nozzle 71.

[0069] The suspension 63 prepared as described above is introduced into a suspension supply pipe 75, passed through the suspension supply pipe 75, and introduced into a thermal spray flame 74. The suspension 63 introduced into the thermal spray flame 74 is heated by the thermal spray flame 74. As a result, the solvent 62 contained in the suspension 63 volatilizes, and the yttrium fluoride particles and yttrium oxyfluoride particles, which are the thermal spray material 61 contained in the suspension 63, are melted. At this time, some of the yttrium fluoride and some of the yttrium oxyfluoride are thermally decomposed into yttrium ions, fluorine ions, and oxygen ions. Then, when the thermally decomposed yttrium fluoride and yttrium oxyfluoride recombine, yttrium fluoride, yttrium oxyfluoride, and yttrium oxide are formed, which are then thermally sprayed onto the substrate 52.

[0070] In the prior art suspension plasma spraying method, water (H ２ O) or ethanol (C ２ H ５ In this case, yttrium oxide is easily formed when yttrium fluoride and yttrium oxyfluoride thermally decomposed in the thermal spray flame are recombined. This is because the environment during recombination is rich in oxygen due to the presence of oxygen in the atmosphere and oxygen generated by decomposition of the solvent (water or organic solvent).

[0071] 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 in this case, a fluorocarbon liquid consisting of a CFC is used. Therefore, in the spray 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) are present around the material melt (melt of the spray material 61). The electronegativity of fluorine is greater than the electronegativity of oxygen. Therefore, when yttrium fluoride and yttrium oxyfluoride thermally decomposed in the spray flame 74 recombine, the probability of yttrium oxyfluoride reforming is higher than the probability of yttrium oxide forming. As a result, the probability of yttrium oxide forming when yttrium fluoride and yttrium oxyfluoride thermally decomposed in the spray flame 74 recombine can be reduced. Therefore, compared to when water or an organic solvent is used as the solvent 62, when a solvent containing fluorine (here, CFC) is used as the solvent 62 as in this embodiment, the formation of yttrium oxide in the thermal spray flame 74 can be suppressed.

[0072] Molten yttrium fluoride, molten yttrium oxyfluoride, and molten yttrium oxide are sprayed onto and adhere 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. This process is repeated to stack the mixed films, thereby forming a coating 53 having a thickness of, for example, about 100 μm. The coating 53 is made of a mixture of yttrium fluoride, yttrium oxyfluoride, and yttrium oxide.

[0073] The ratio of the crystalline phase contained in the coating 53 formed by the suspension plasma spraying method of this embodiment is cubic crystalline YF ３ phase is 3 wt%, hexagonal YF ３ Phase is 3% by weight, rectangular crystal Y ５ O ４ F ７ phase 56 wt%, hexagonal Y-O-F phase 36 wt%, monoclinic Y ２O ３ The crystalline phase ratio was determined by semi-quantitative analysis using the RIR (Reference Intensity Ratio) method for X-ray diffraction intensity.

[0074] On the other hand, when the coating 53 is formed by a suspension plasma spraying method using water or an organic solvent as the solvent 62, the ratio of the crystalline phase contained in the coating 53 is cubic crystalline YF ３ phase is 3 wt%, hexagonal YF ３ Phase is 3% by weight, rectangular crystal Y ５ O ４ F ７ phase 41% by weight, hexagonal Y—O—F phase 41% by weight, monoclinic Y ２ O ３ phase is 6 wt%, cubic Y ２ O ３ According to the investigations of the present inventors, it was not possible to reduce the yttrium oxide phase content in the formed coating 53 to 5% by weight or less by the suspension plasma spraying method using water or an organic solvent as the solvent 62.

[0075] Therefore, it was confirmed that the proportion of yttrium oxide phase in coating 53 can be reduced when coating 53 is formed by suspension plasma spraying using a chlorofluorocarbon (CFC) liquid as solvent 62, as in the present embodiment, compared to when coating 53 is formed by suspension plasma spraying using water or an organic solvent as solvent 62.

[0076] In order to prevent foreign matter from being generated from coating 53 when coating 53 is exposed to plasma 4 in processing chamber 3 of plasma processing apparatus 1, the content of yttrium oxide in coating 53 is preferably 9 wt % or less, and more preferably 5 wt % or less. Such a content of yttrium oxide can be achieved by the method for forming coating 53 of the present embodiment.

[0077] Furthermore, the coating 53 may contain zero yttrium oxide, that is, the coating 53 may not contain yttrium oxide.

[0078] FIG. 3 is an SEM image of a cross section of a coating 53 formed on a substrate 52 by a suspension plasma spraying method using a chlorofluorocarbon (CFC) liquid as a solvent 62, as in this embodiment.

[0079] In the SEM image of FIG. 3 , the pitch-black regions represent the substrate 52 and pores 210. The results of the SEM-EDX analysis confirmed that the brighter (whiter) the contrast in the SEM image, the higher the oxygen concentration, and the darker (blacker) the contrast, the higher the fluorine concentration. The bright region (white region) 209 is a region with a high oxygen concentration and is thought to be composed primarily of yttrium oxide. The dark region (black region) 208 is a region with a high fluorine concentration and is thought to be composed primarily of yttrium fluoride. Judging from the oxygen concentration and fluorine concentration, the region 207, which has a brightness (color) intermediate between regions 208 and 209, is thought to be composed primarily of yttrium oxyfluoride. Furthermore, XRD analysis of the coating 53 confirmed that the crystallite size on the surface of the coating 53 was 30 nm or less. Furthermore, cross-sectional STEM observation confirmed that a microcrystalline layer was formed in the coating 53 of this embodiment in a region from the surface of the coating 53 to a depth of 10 μm. In addition, taking this into consideration together with the results of XRD analysis, it was estimated that the thickness of the microcrystalline layer having a crystallite size of 30 nm or less was 10 μm or more.

[0080] In order to prevent foreign matter from being generated from coating 53 when coating 53 is exposed to plasma 4 in processing chamber 3 of plasma processing apparatus 1, it is preferable that the average size of the crystallites in the yttrium fluoride phase in coating 53 and the average size of the crystallites in the yttrium oxyfluoride phase in coating 53 are each 50 nm or less. Such an average crystallite size can be achieved by the method for forming coating 53 of the present embodiment.

[0081] Figure 4 is an SEM image of a cross section of a coating 53 formed on a substrate 52 by a suspension plasma spraying method using water or an organic solvent as the solvent 62. Compared to the SEM image of Figure 3, the SEM image of Figure 4 clearly shows that there are many bright regions (white regions) 209 made of yttrium oxide. Furthermore, compared to the SEM image of Figure 3, the SEM image of Figure 4 shows that even within the intermediate color region 207, near-white regions and near-black regions are dispersed over a wide range.

[0082] Therefore, it was also confirmed from the SEM image that the proportion of the yttrium oxide phase in the coating 53 can be reduced when the coating 53 is formed by the suspension plasma spraying method using a chlorofluorocarbon (CFC) liquid as the solvent 62, as in the present embodiment, compared to when the coating 53 is formed by the suspension plasma spraying method using water or an organic solvent as the solvent 62.

[0083] FIG. 5 is an SEM image of a cross section of a coating 53 formed on a substrate 52 by atmospheric plasma spraying without using a suspension.

[0084] 3 and 4, the SEM image of FIG. 5 shows that almost no regions with high oxygen concentrations (white regions) are formed in the coating 53. This suggests that almost no yttrium oxide is produced. However, in the SEM image of FIG. 5, residual particle portions 211 are also observed near the surface of the coating 53. Here, the residual particle portions 211 are formed by the raw material particles being layered in a semi-molten state.

[0085] When forming the coating 53 using atmospheric plasma spraying, it is difficult to achieve a crystallite size of 30 nm or less near the surface of the coating 53 due to the influence of cohesion of raw material particles. It is also known that atmospheric plasma spraying deposits semi-molten raw material particles during coating formation. Because the residual particle portion 211 is heated during spraying, it contains coarse crystals that have grown inside the particles. In the atmosphere, air resistance causes the speed of solids to be higher than that of liquids, so the semi-molten particles reach the substrate 52 before the molten raw material. As a result, the residual particle portion 211 deposits first on the substrate 52, and the molten raw material deposits on top of it, forming microcrystals. Therefore, the coating 53 formed by atmospheric plasma spraying has a layered structure in which a microcrystalline layer exists on its surface and the residual particle portion 211 exists within it.

[0086] When a plasma etching apparatus is operated, the coating 53 disposed inside the processing chamber is gradually thinned due to the effects of reaction with the plasma gas, ion collisions, and the like. When the microcrystalline layer on the surface of the coating 53 disappears and the remaining particle portions 211 containing large crystallites are exposed on the surface of the coating 53, foreign matter is generated due to the remaining particle portions 211. This point is determined to be the end of the life of the coating 53. Therefore, reducing the remaining particle portions 211 in the coating 53 and thickening the microcrystalline layer on the surface of the coating 53 leads to an extension of the life of the coating 53.

[0087] In this embodiment, the coating 53 is formed by suspension plasma spraying instead of atmospheric plasma spraying, which can suppress or prevent the generation of residual particle portions 211 in the coating 53. In addition, the microcrystalline layer on the surface of the coating 53 can be made thicker. As a result, the life of the coating 53 can be extended.

[0088] Furthermore, there is a small amount of yttrium oxide near the surface of the coating 53 in Figure 3. It is conceivable that this small amount of yttrium oxide may affect the generation of foreign matter, but statistically speaking, the effect is negligible. The reason for this is as follows.

[0089] During operation of a plasma etching apparatus, an event in which a foreign particle originating from the inner wall of the processing chamber falls onto a wafer occurs when, among the many crystals on the surface of the inner wall, a crystal larger than the size detected as a foreign particle cracks, scattering fragments, and the scattered fragments accidentally fall onto the wafer. The probability of this event occurring is roughly estimated to be 10 based on the area of ​​the inner wall, the crystallite size of the inner wall material, the number of crystals, the wafer diameter, and the inner diameter of the processing chamber. －１２ ~10 －１３ In other words, in order to detect the generation of foreign matter from the surface of the coating 53, the Y ２ O ３ The crystals must be exposed in a group, and for this reason, it is believed that the yttrium oxide observed in the SEM image of Figure 3 has almost no effect on the generation of foreign matter.

[0090] As described above, according to this embodiment, it is possible to form coating 53 having a low content of yttrium oxide phase. Furthermore, it is possible to form coating 53 having a thick surface microcrystalline layer with an average crystallite size of 30 nm or less on the surface. In the processing chamber 3 of the plasma processing apparatus 1 in which a member having this coating 53 (here, earth electrode 41) is disposed, generation of foreign matter from coating 53 is reduced, and the life of coating 53 can be extended.

[0091] In this embodiment, CFC (chlorofluorocarbon) is used as the solvent 62. However, any one of FC (fluorocarbon), HCFC (hydrochlorofluorocarbon), and HFC (hydrofluorocarbon) can also be used as the solvent 62. Alternatively, a mixture of two or more of CFC, FC, HCFC, and HFC can be used as the solvent 62. Therefore, a fluorocarbon-based liquid can be used as the solvent 62. In these cases, substantially the same effects as when a CFC is used as the solvent 62 can be obtained.

[0092] In this embodiment, the coating 53 and its formation method have been described as being applied to the coating 43 of the earth electrode 41, which is a member for a plasma processing apparatus. The coating 53 and its formation method of this embodiment can also be applied to coatings of members for a plasma processing apparatus other than the earth electrode 41. The member for a plasma processing apparatus to which the coating 53 and its formation method of this embodiment are applied is placed in the processing chamber 3 of the plasma processing apparatus 1, and the coating of the member for the plasma processing apparatus is exposed to plasma 4 when the plasma processing apparatus is in operation.

[0093] (Embodiment 2) In this embodiment 2, the coating 53 is formed by the suspension plasma spraying method, as in the above-described embodiment 1, but the solvent 62 contained in the suspension 63 is different from that in the above-described embodiment 1. In this embodiment 2, ammonium fluoride (NH ４ F) An aqueous solution is used. The fact that the solvent 62 contains fluorine is common to both the first and second embodiments. The process of forming the coating 53 using the suspension plasma spraying method in the second embodiment will be described below with reference to FIG. 2.

[0094] The spray material 61 and the solvent 62 are placed in a mixer (not shown) and stirred to prepare a suspension 63. The spray material 61 used in the second embodiment is the same as that in the first embodiment.

[0095] The solvent 62 used in the second embodiment is ammonium fluoride (NH ４ 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 becomes difficult to prepare an appropriate suspension 63, and the NH ４ This is because F precipitates. Also, if the concentration of the ammonium fluoride aqueous solution is less than 5 wt %, the fluorine content of the solvent 62 becomes low, and the effect of suppressing the proportion of yttrium oxide in the coating 53 formed by the suspension plasma spraying method decreases.

[0096] In the second embodiment, a suspension 63 prepared using the same spray material 61 as in the first embodiment and a solvent 62 consisting of an aqueous ammonium fluoride solution is introduced into a suspension supply pipe 75, passed through the suspension supply pipe 75, and introduced into a spray flame 74, as in the first embodiment. The suspension 63 introduced into the spray flame 74 is heated by the spray flame 74. As a result, the solvent 62 contained in the suspension 63 volatilizes, and the yttrium fluoride particles and yttrium oxyfluoride particles contained in the suspension 63 become molten. At this time, some of the yttrium fluoride and some of the yttrium oxyfluoride are thermally decomposed into yttrium ions, fluorine ions, and oxygen ions. When the thermally decomposed yttrium fluoride and yttrium oxyfluoride recombine, yttrium fluoride, yttrium oxyfluoride, and yttrium oxide are formed, and these are sprayed onto the substrate 52.

[0097] 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 spray flame 74, oxygen in the atmosphere, oxygen generated from the yttrium oxyfluoride, and oxygen generated from the solvent 62 are present around the material melt (melt of the spray material 61). However, fluorine generated from the yttrium fluoride, fluorine generated from the yttrium oxyfluoride, and fluorine generated from the ammonium fluoride constituting the solvent 62 are also present around the material melt. The electronegativity of fluorine is greater than the electronegativity of oxygen. Therefore, when yttrium fluoride and yttrium oxyfluoride thermally decomposed in the spray flame 74 recombine, the probability of yttrium oxyfluoride reforming is higher than the probability of yttrium oxide forming. As a result, the probability of yttrium oxide forming when yttrium fluoride and yttrium oxyfluoride thermally decomposed in the spray flame 74 recombine can be reduced. Therefore, compared to when water or an organic solvent is used as the solvent 62, when a solvent containing fluorine (here, an aqueous ammonium fluoride solution) is used as the solvent 62 as in the present embodiment 2, the formation of yttrium oxide in the thermal spray flame 74 can be suppressed.

[0098] Molten yttrium fluoride, molten yttrium oxyfluoride, and molten yttrium oxide are sprayed onto and adhere 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. This process is repeated to stack the mixed films, thereby forming a coating 53 having a thickness of, for example, about 100 μm. The coating 53 is made of a mixture of yttrium fluoride, yttrium oxyfluoride, and yttrium oxide.

[0099] The ratio of the crystalline phase contained in the coating 53 formed by the suspension plasma spraying method of the second embodiment is ３ phase is 2 wt%, hexagonal YF ３ Phase is 3% by weight, rectangular crystal Y ５ O ４ F ７phase is 53% by weight, hexagonal Y—O—F phase is 39% by weight, and monoclinic Y ２ O ３ The crystalline phase ratio was determined by the same method as in the first embodiment.

[0100] Therefore, it was confirmed that the proportion of yttrium oxide phase in coating 53 can be reduced when coating 53 is formed by suspension plasma spraying using an ammonium fluoride aqueous solution as solvent 62, as in the present embodiment 2, compared to when coating 53 is formed by suspension plasma spraying using water or an organic solvent as solvent 62.

[0101] Furthermore, when the coating 53 was formed by the suspension plasma spraying method using an ammonium fluoride aqueous solution as the solvent 62, as in the second embodiment, the SEM image of the cross section of the coating 53 was similar to the SEM image of FIG. 3 above. That is, in the SEM image of the coating 53 of the second embodiment, it was confirmed that the amount of the bright regions (white regions) 209 consisting of yttrium oxide was clearly reduced compared to the SEM image of FIG. 4 above. Furthermore, XRD analysis of the coating 53 also confirmed that the crystallite size on the surface of the coating 53 of the second embodiment was 30 nm or less. Furthermore, cross-sectional STEM observation confirmed that a microcrystalline layer was formed in the coating 53 of the second embodiment in a region extending from the surface of the coating 53 to a depth of 10 μm. Furthermore, taking into account the results of the XRD analysis, it was estimated that the thickness of the microcrystalline layer having a crystallite size of 30 nm or less was 10 μm or more.

[0102] As explained in the first embodiment, reducing the remaining particle portions 211 in the coating 53 and thickening the microcrystalline layer on the surface of the coating 53 leads to extending the life of the coating 53. In the second embodiment as well, it is possible to suppress or prevent the remaining particle portions 211 from being generated in the coating 53. It is also possible to thicken the microcrystalline layer on the surface of the coating 53. As a result, it is possible to extend the life of the coating 53.

[0103] As described above, according to the second embodiment, it is possible to form a coating 53 having a low content of yttrium oxide phase. Furthermore, it is possible to form a coating 53 having a thick surface microcrystalline layer with an average crystallite size of 30 nm or less on the surface. In the processing chamber 3 of the plasma processing apparatus 1 in which a member having this coating 53 (here, the earth electrode 41) is disposed, generation of foreign matter from the surface of the coating 53 is reduced, and the life of the coating 53 can be extended.

[0104] In the second embodiment, an aqueous ammonium fluoride solution is used as the solvent 62. Instead of an aqueous ammonium fluoride solution, an aqueous potassium fluoride (KF) solution can also be used as the solvent 62. When an aqueous potassium fluoride solution is used as the solvent 62, substantially the same effect as when an aqueous ammonium fluoride solution is used as the solvent 62 can be obtained. When an aqueous potassium fluoride solution is used as the solvent 62, the concentration of the aqueous potassium fluoride solution is preferably 5 wt % or more and 50 wt % or less, similar to the concentration range of the aqueous ammonium fluoride solution described above.

[0105] In the second embodiment, the solvent 62 is sodium fluoride (NaF ２ If it is necessary to use an aqueous solution with a concentration of less than 5% by weight, sodium fluoride (NaF ２ When a sodium fluoride aqueous solution is used, a high effect can be obtained due to the high fluorine concentration in the solvent. However, the concentration of the sodium fluoride aqueous solution is preferably 4% by weight or less. This is because if the concentration of the sodium fluoride aqueous solution is greater than 4% by weight, sodium fluoride will precipitate in the suspension 63 with the spray material 61 as a nucleus.

[0106] Therefore, in this embodiment 2, the solvent 62 can be any of an ammonium fluoride aqueous solution, a potassium fluoride aqueous solution, and a sodium fluoride aqueous solution, or a mixture of two or more of an ammonium fluoride aqueous solution, a potassium fluoride aqueous solution, and a sodium fluoride aqueous solution.

[0107] The present invention has been specifically described above based on the above embodiment, but the present invention is not limited to the above embodiment and can be modified in various ways without departing from the spirit of the present invention.

[0108] REFERENCE SIGNS LIST 1 Plasma processing apparatus 2 Vacuum vessel 3 Processing chamber 4 Plasma 5 Stage 6 Wafer 7 Exhaust port 8 Space 9 Exhaust plate 11 High frequency power supply 12 Impedance matching box 13 Window member 14 Shower plate 15 Through hole 16 Gap 17 Processing gas supply pipe 18 Valve 21 Pressure adjustment plate 22 Turbo molecular pump 23 Dry pump 24 Valve 25 Pressure detector 27 Exhaust pipe 28, 29 Valve 31 Waveguide 31a Rectangular waveguide section 31b Circular waveguide section 31c Cavity section 32 Magnetron oscillator 33, 34 Solenoid coil 41 Earth electrode 42 Substrate 43 Coating 52 Substrate 53 Coating 61 Thermal spray material 62 Solvent 63 Suspension 71 Nozzle 72 High voltage 73 Plasma gas 74 Thermal spray flame

Claims

1. A method for manufacturing a member for a plasma processing apparatus, comprising: (a) a step of preparing a substrate to be used in the member for the plasma processing apparatus; (b) a step of preparing a first suspension containing a fluorine-containing solvent, a plurality of yttrium fluoride particles, and a plurality of yttrium oxyfluoride particles; and (c) a step of forming a coating on the substrate by a suspension plasma spraying method using the first suspension.

2. The method for manufacturing a member for a plasma processing apparatus according to claim 1, wherein the solvent is a fluorocarbon-based liquid.

3. A method for manufacturing a member for a plasma processing apparatus according to claim 1, wherein the solvent is any one of CFC, FC, HCFC and HFC, or a mixture of two or more of CFC, FC, HCFC and HFC.

4. A method for manufacturing a member for a plasma processing apparatus according to claim 1, wherein the solvent is one of an aqueous ammonium fluoride solution, an aqueous potassium fluoride solution, and an aqueous sodium fluoride solution, or a mixture of two or more of an aqueous ammonium fluoride solution, an aqueous potassium fluoride solution, and an aqueous sodium fluoride solution.

5. A method for manufacturing a member for a plasma processing apparatus according to claim 4, wherein the concentrations of the aqueous ammonium fluoride solution and the aqueous potassium fluoride solution are 5% by weight or more and 50% by weight or less.

6. A method for producing a member for a plasma processing apparatus according to claim 4, wherein the concentration of the aqueous sodium fluoride solution is 4% by weight or less.

7. A method for manufacturing a member for a plasma processing apparatus as described in claim 1, wherein the average particle diameter of the plurality of yttrium fluoride particles and the average particle diameter 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 member for a plasma processing apparatus according to claim 1, wherein the member for a plasma processing apparatus is placed in a processing chamber of the plasma processing apparatus, and the coating is exposed to plasma when the plasma processing apparatus is in operation.

9. The method for producing a member for a plasma processing apparatus according to claim 1, wherein the content of yttrium oxide in the coating is 9% by weight or less.

10. A method for producing a member for a plasma processing apparatus according to claim 1, wherein the content of yttrium oxide in the coating is 5% by weight or less.

11. A method for manufacturing a member for a plasma processing apparatus according to claim 1, wherein the coating contains an yttrium fluoride phase and an yttrium oxyfluoride phase, and the average size of the crystallites in the yttrium fluoride phase and the average size of the crystallites in the yttrium oxyfluoride phase are each 50 nm or less.

12. A member for a plasma processing apparatus having a substrate and a coating formed on the substrate, wherein the coating contains an yttrium fluoride phase and an yttrium oxyfluoride phase, the average size of crystallites in the yttrium fluoride phase and the average size of crystallites in the yttrium oxyfluoride phase are each 50 nm or less, and the yttrium oxide content in the coating is 5 wt % or less.

13. A member for a plasma processing apparatus according to claim 12, wherein the coating is formed by a suspension plasma spraying method.

14. A member for a plasma processing apparatus according to claim 12, wherein the member for a plasma processing apparatus is disposed in a processing chamber of the plasma processing apparatus and is exposed to plasma when the plasma processing apparatus is in operation.

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