Spraying material and preparation method, spraying slurry, spraying coating and formation method, and spraying component

Abstract

The present invention provides a spraying material and preparation method, a spraying slurry, a spraying coating and formation method, and a spraying component. The spraying material comprises rare earth (R), aluminum, and oxygen, the spraying material being in the form of a powder and comprising a monoclinic rare earth (R) aluminum (R4Al2O9) crystal phase and a rare earth oxide (R2O3) crystal phase. Regarding diffraction peaks detected by X-ray diffraction using characteristic X-rays of Cu–Kα at a diffraction angle 2θ range of 10° to 70°, the spraying material has a diffraction peak attributable to the rare earth oxide (R2O3) and a diffraction peak attributable to the monoclinic rare earth (R) aluminum (R4Al2O9), and an intensity ratio (I(R) / I(RAL)) of the integrated intensity I(R) of the maximum diffraction peak attributable to the rare earth oxide (R2O3) to the integrated intensity I(RAL) of the maximum diffraction peak attributable to the monoclinic rare earth aluminum (R4Al2O9) is at least 1.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This nonprovisional application claims priority under 35 U.S.C. § 119(a) to patent application No. 2019-076099 filed in Japan on April 12, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a spray coating suitable for use as a part or component in a plasma etching apparatus used in a semiconductor manufacturing process, a method for forming the spray coating, a spray material or spray slurry for forming the spray coating, and a method for preparing the spray material. The present invention also relates to a spray component suitable for use in a plasma etching apparatus used in a semiconductor manufacturing process. Background Art

[0004] In a plasma etching apparatus used in a semiconductor manufacturing process, a wafer to be processed is treated in a highly corrosive plasma atmosphere of a halogen-based gas such as a fluorine-based gas or a chlorine-based gas. Typically, fluorine-based gases such as SF6, CF4, CHF3, ClF3, HF, and NF3 and chlorine-based gases such as Cl2, BCl3, HCl, CCl4, and SiCl4 are used as the gas.

[0005] In the manufacture of parts and components of plasma etching equipment exposed to a highly corrosive gas plasma atmosphere, a corrosion-resistant spray coating is generally formed on the surface of a substrate by an atmospheric plasma spraying (APS) method (in which a source material such as a rare earth compound is supplied in powder form) or a suspension plasma spraying (SPS) method (in which a source material dispersed in a dispersion medium is supplied in slurry form). Examples of rare earth compounds include yttrium oxide, yttrium fluoride, yttrium oxyfluoride, and yttrium aluminum garnet.

[0006] Among spray coatings of rare earth compounds, yttrium oxide, which has good corrosion resistance to corrosive halogen-based gas plasmas, excels in plasma etching resistance. However, yttrium oxide spray coatings have a problem, as they contain a large amount of yttrium-based particles. Yttrium fluoride-based coatings are considered to be excellent in plasma resistance, but have relatively low coating hardness and poor plasma etching resistance. Yttrium aluminum garnet coatings, while advantageous in terms of a small amount of rare earth particles and high coating hardness, however, have insufficient corrosion resistance and poor plasma etching resistance.

[0007] Meanwhile, JP-A 2003-63883 (Patent Document 1) proposes a component comprising a substrate and a mixed phase laminated thereon, comprising a monoclinic rare earth aluminum phase as a main phase and at least one phase selected from rare earth aluminum perovskite, rare earth aluminum garnet, and rare earth oxide as a subphase. However, there is room for improvement, particularly from the perspective of corrosion resistance.

[0008] Citation List

[0009] Patent Document 1: JP-A 2003-63883 (US 2003 / 0049500A1) Summary of the Invention

[0010] For spray coatings used to resist corrosion on parts or components in plasma etching equipment, plasma-resistant coatings such as yttrium oxide spray coatings, yttrium fluoride spray coatings, and yttrium aluminum garnet coatings are generally used. However, the problem with conventional coatings is insufficient plasma etching resistance because conventional coatings generate a large amount of yttrium-based particles due to reaction with corrosive halogen-based gas plasma and have low hardness or low corrosion resistance.

[0011] An object of the present invention is to provide a spray coating having high corrosion resistance for parts or components used in plasma etching equipment and excellent plasma etching resistance with a reduced amount of particles generated by reaction with a halogen-based gas plasma, and a method for forming the spray coating. Another object of the present invention is to provide a spray material or spray slurry capable of forming such a spray coating, a method for preparing the same, and a spray component including such a spray coating.

[0012] The inventors have discovered a powdered spray material containing rare earth (R), aluminum, and oxygen, including a monoclinic rare earth (R) aluminum (R4Al2O9) crystalline phase and a rare earth oxide (R2O3) crystalline phase, and having a specified structure and specified properties. The spray material can form a spray coating having high corrosion resistance and excellent plasma etching resistance while reducing the amount of particles generated by the reaction with a halogen-based gas plasma. In addition, the inventors have discovered that the spray material or a spray slurry including the spray material can be suitably prepared by the following steps: dispersing aluminum oxide in an aqueous solution of a rare earth salt to form a slurry; adding a precipitant to the slurry to crystallize a precursor containing rare earth and aluminum into a precipitate; collecting the precipitate by solid-liquid separation; and firing the precursor containing rare earth and aluminum in an oxygen-containing gas atmosphere.

[0013] In addition, the inventors have found that a spray coating comprising a composite oxide containing rare earth and aluminum can be formed by thermal spraying, in particular plasma spraying, using a spray material or a spray slurry; in particular, the spray coating formed by using the spray material or the spray slurry contains rare earth (R), aluminum and oxygen and includes a crystalline phase of a composite oxide containing rare earth and aluminum, having a rare earth-rich composition compared to the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9) and having a structure in which the Al atomic sites in the monoclinic rare earth aluminum (R4Al2O9) are partially replaced by rare earth (R) atoms. The spray coating has high corrosion resistance and excellent plasma etching resistance under reduced amounts of particles generated by reaction with halogen-based gas plasma. In addition, the inventors have found that a spray component in which the spray coating is formed on a substrate directly or via an undercoat is excellent for parts and components in plasma etching equipment.

[0014] In a first aspect, the present invention provides a spraying (melting) material containing rare earth (R), aluminum and oxygen, wherein the spraying material is a powder and includes a monoclinic rare earth (R) aluminum (R4Al2O9) crystalline phase and a rare earth oxide (R2O3) crystalline phase, wherein

[0015] With respect to diffraction peaks detected by an X-ray diffraction method using characteristic X-rays of Cu–Kα within a diffraction angle 2θ range of 10° to 70°, the sprayed material has a diffraction peak attributable to rare earth oxide (R2O3) and a diffraction peak attributable to monoclinic rare earth (R) aluminum (R4Al2O9), and

[0016] The intensity ratio I(R) / I(RAL) of the integrated intensity I(R) of the maximum diffraction peak attributed to the rare earth oxide (R2O3) to the integrated intensity I(RAL) of the maximum diffraction peak attributed to the monoclinic rare earth aluminum (R4Al2O9) is at least 1.

[0017] Preferably, the spraying material has a 2 / g BET specific surface area S and up to 2g / cm 3 In particular, the spray material has an S / ρ value of 1 to 4, which is obtained by dividing the BET specific surface area S by the bulk density ρ.

[0018] Preferably, the spraying material has a composition corresponding to a relative rare earth oxide (R2O3) content of 75 to 99 weight % and a relative aluminum oxide (Al2O3) content of 1 to 25 weight % in the total content of rare earth oxide (R2O3) and aluminum oxide (Al2O3), and the rare earth oxide (R2O3) content and the aluminum oxide (Al2O3) content are calculated based on the rare earth (R) content and the aluminum content in the spraying material, respectively.

[0019] Preferably, the rare earth (R) in the spraying material is selected from yttrium (Y), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu).

[0020] Preferably, the spray material has an average particle size D50 of 1 to 50 μm.

[0021] In a second aspect, the present invention provides a spraying slurry comprising a spraying material and a dispersion medium, wherein the content of the spraying material in the spraying slurry is 10 to 70 wt %.

[0022] Preferably, the dispersion medium is an aqueous dispersion medium.

[0023] Preferably, the spray slurry includes a dispersant.

[0024] Preferably, the spray slurry has a viscosity of less than 15 mPa·s.

[0025] In a third aspect, the present invention provides a method for preparing a spray slurry, comprising the steps of:

[0026] A slurry is formed by dispersing alumina in an aqueous solution of a rare earth salt;

[0027] crystallizing a precursor containing rare earth and aluminum into a precipitate by adding a precipitant to the slurry;

[0028] collecting the precipitate by solid-liquid separation; and

[0029] The precursor containing rare earth and aluminum is fired in an oxygen-containing gas atmosphere.

[0030] In a fourth aspect, the present invention provides a method for forming a spray coating, comprising the steps of:

[0031] A spray coating including a composite oxide containing rare earth and aluminum is formed on a substrate directly or via an undercoat layer by plasma spraying using a spray material or a spray slurry.

[0032] In a fifth aspect, the present invention provides a spray coating containing rare earth (R), aluminum and oxygen, the spray coating comprising a crystalline phase of a composite oxide containing rare earth (R) and aluminum, wherein

[0033] The crystalline phase of the composite oxide includes a composition rich in rare earth compared to the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9) and a crystalline phase of the composite oxide having a structure in which the Al atomic sites in monoclinic rare earth aluminum (R4Al2O9) are partially substituted by rare earth (R) atoms.

[0034] Preferably, the sprayed coating comprises a rare earth oxide (R2O3) crystalline phase.

[0035] Preferably, the spray coating comprises a material selected from the group consisting of monoclinic rare earth aluminum (R4Al2O9), rare earth aluminum perovskite (RA1O3) and rare earth aluminum garnet (R3Al5O 12 ) at least one crystalline phase.

[0036] Preferably, the sprayed coating has a composition corresponding to a relative rare earth oxide (R2O3) content of 75 to 99 weight % and a relative aluminum oxide (Al2O3) content of 1 to 25 weight % in the total content of rare earth oxide (R2O3) and aluminum oxide (Al2O3), the rare earth oxide (R2O3) content and the aluminum oxide (Al2O3) content being calculated based on the rare earth (R) content and the aluminum content in the sprayed coating, respectively.

[0037] Preferably, the rare earth (R) in the spray coating is selected from yttrium (Y), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu).

[0038] Preferably, the sprayed coating has a surface roughness Ra of at most 8 μm, a thickness of 10 to 500 μm, a Vickers hardness HV 0.3 of at least 600 and / or a porosity of at most 5%.

[0039] In a sixth aspect, the present invention provides a sprayed component including a sprayed coating formed on a substrate directly or via a primer coating.

[0040] Beneficial effects of the present invention

[0041] According to the present invention, a spray coating can be formed that has excellent plasma etching resistance and high corrosion resistance while reducing the amount of particles generated by the reaction with the halogen-based gas plasma. The spray coating is excellent as a spray coating formed on parts or components of plasma etching equipment used in semiconductor manufacturing processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is the X-ray diffraction curve of the sprayed material obtained in Example 2.

[0043] Figure 2 is the X-ray diffraction curve of the spray coating obtained in Example 8. DETAILED DESCRIPTION

[0044] The spraying material of the present invention is suitable for forming (typically by thermal spraying such as plasma spraying) a spray coating (thermal spray coating) as a part or component in a plasma etching device for a semiconductor manufacturing process. The spraying material of the present invention preferably contains rare earth (R), aluminum and oxygen and includes a crystalline phase of a composite oxide containing rare earth (R) and aluminum, and more preferably includes a monoclinic rare earth (R) aluminum (R4Al2O9) crystalline phase and a rare earth oxide (R2O3) crystalline phase. The spraying material of the present invention is generally in a powdery (granular) form. The spraying material of the present invention can form a spray coating having excellent plasma etching resistance (corrosion resistance) under the condition of a reduced amount of rare earth particles caused by corrosive halogen-based gas plasma.

[0045] The spray coating material of the present invention may have a diffraction peak attributable to the rare earth oxide (R2O3) and a diffraction peak attributable to monoclinic rare earth (R) aluminum (R4Al2O9) as detected by X-ray diffraction using characteristic X-rays of Cu-Kα within a diffraction angle 2θ range of 10° to 70°. The intensity ratio I(R) / I(RAL) of the integrated intensity I(R) at the maximum diffraction peak attributable to the rare earth oxide (R2O3) to the integrated intensity I(RAL) at the maximum diffraction peak attributable to the monoclinic rare earth aluminum (R4Al2O9) is preferably at least 1, more preferably at least 1.1. The upper limit of the intensity ratio I(R) / I(RAL) is generally at most 45. The integrated intensity can be obtained by integrating the peak intensity (integrating over the peak area) from the obtained XRD curve (diffraction intensity curve). For example, when the monoclinic rare earth aluminum (R4Al2O9) is monoclinic yttrium aluminum (Y4Al2O9), the maximum peak is generally a diffraction peak attributable to the (-122) plane of the crystal lattice, but is not limited thereto. The diffraction peak is generally detected at approximately 2θ = 29.6°. For example, when the rare earth oxide (R2O3) is cubic yttrium oxide (Y2O3), the maximum peak is generally a diffraction peak attributable to the (222) plane of the crystal lattice, but is not limited thereto. The diffraction peak is generally detected at approximately 2θ = 29.2°.

[0046] The spray material of the present invention preferably has a 2 The specific surface area S is preferably at least 1.1 m 2 When the spraying material has a large specific surface area, the heat of the frame easily reaches the interior of the particles during plasma spraying. Therefore, when the molten particles collide with the substrate or the coating on the substrate and form splashes, the resulting coating tends to be dense and the splashes are tightly bound. The upper limit of the specific surface area S is preferably at most 3.5 m 2 / g, more preferably up to 3m 2A spray material having a small specific surface area can reduce fine particles that do not enter the thermal spray frame but adhere to the surface portion of the formed coating and cause particle contamination, and fine particles that evaporate due to excessive heat input through the thermal spray frame.

[0047] The spray material of the present invention preferably has a maximum of 2 g / cm 3 In the present invention, the aerated bulk density can be used as the bulk density ρ. The bulk density ρ is more preferably at most 1.8 g / cm 3 A spray material having a low bulk density can form a spray coating having a high hardness because the flame heat permeability per unit particle is improved when the spray material is used in plasma spraying. The lower limit of the bulk density ρ is preferably at least 0.4 g / cm 3 , more preferably at least 0.5 g / cm 3 , but not limited thereto. When the spraying material has a high density, it is easy for the spraying material to form splashes during plasma spraying and it is easy to form a dense coating. In addition, the risk of deterioration of the properties of the resulting spray coating can be reduced because the particles have fewer gas components contained in the particle gaps.

[0048] The spray material of the present invention preferably has an S / ρ value of 1 to 4. 2 / g) divided by the bulk density ρ (g / cm 3 ) to obtain the S / ρ value. A large S / ρ value means that the specific surface area S is too large and the bulk density is too small. Therefore, when the S / ρ value is greater than 4, there is a possibility that particles that will cause particle contamination and particles that will easily form splashes that can form a rough coating will increase. On the other hand, a small S / ρ value means that the specific surface area S is too small and the bulk density is too large. Therefore, when the S / ρ value is less than 1, there is a possibility that particles that will form a rough coating due to an increase in unmelted parts and particles that will reduce the hardness of the resulting coating due to poor thermal permeability will increase. The S / ρ value is more preferably at least 1.2, even more preferably at least 1.5, and more preferably at most 3.8, even more preferably at most 3.5.

[0049] When the rare earth oxide (R2O3) content and the aluminum oxide (Al2O3) content are calculated based on the rare earth (R) content and the aluminum content in the spraying material, respectively, the spraying material of the present invention preferably has a composition corresponding to a relative rare earth oxide (R2O3) content of 75 to 99% by weight and a relative aluminum oxide (Al2O3) content of 1 to 25% by weight in the total content of the rare earth oxide (R2O3) and aluminum oxide (Al2O3). The relative content calculated as the rare earth oxide (R2O3) content is more preferably at least 80% by weight, even more preferably at least 85% by weight, and more preferably at most 97% by weight, even more preferably at most 95% by weight. On the other hand, the relative content calculated as aluminum oxide (Al2O3) is more preferably at least 3% by weight, even more preferably at least 5% by weight, and more preferably at most 20% by weight, even more preferably at most 15% by weight.

[0050] In the spraying material of the present invention, the total weight of the main oxide components (composite oxides containing rare earth and aluminum, and rare earth oxides (in the case of two species), or composite oxides containing rare earth and aluminum, rare earth oxides, and aluminum oxide (in the case of three species including aluminum oxide)) is defined as the total weight of the relative content of rare earth oxides and the relative content of aluminum oxide. In addition, the weight of R2O3 as the basic composition of rare earth oxides converted from the rare earth content and aluminum content in the spraying material and the weight of Al2O3 as the basic composition of aluminum oxide are defined as the relative content of rare earth oxides and aluminum oxide, respectively. The total content of oxides other than the main oxide content is preferably at most 3% by weight in the spraying material, more preferably at most 1% by weight. Most preferably, the spraying material is substantially free of oxides other than the main oxide content, that is, the spraying material is substantially composed of the two or three species constituting the main oxide component, but is not limited thereto. The rare earth and aluminum contents in the spraying material can be measured by, for example, ICP emission spectroscopy, fluorescent X-ray analysis, etc. Fluorescent X-ray analysis is preferred because it allows selective measurement of rare earth and aluminum constituting the main oxide component.

[0051] The rare earth (R) in the spray material of the present invention includes at least one element selected from yttrium (Y) and lanthanide elements from lanthanum (La) to lutetium (Lu) having atomic numbers of 57 to 71. The rare earth (R) is preferably selected from yttrium (Y), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), and more preferably selected from yttrium (Y), gadolinium (Gd), dysprosium (Dy), erbium (Er), and ytterbium (Yb). The rare earth (R) can be used as a single element or in combination of two or more elements.

[0052] The spraying material of the present invention preferably has an average particle size D50 of at most 50 μm. The average particle size D50 indicates the cumulative 50% diameter (or median diameter) of the volume-based particle size distribution. When the particles collide with the substrate or the coating on the substrate, the particles of the spraying material with small particle size form splashes with a small diameter, so that the porosity of the spray coating formed becomes low, and the cracking generated in the splashes is controlled. The average particle diameter D50 is more preferably at most 45 μm, even more preferably at most 40 μm. On the other hand, the spraying material of the present invention preferably has an average particle size D50 of at least 1 μm. The particles of the spraying material with large particle size have large momentum, so that when the particles collide with the substrate or the coating on the substrate, the particles are easy to form splashes. The average particle diameter D50 is more preferably at least 1.2 μm, even more preferably at least 1.5 μm.

[0053] The particles of the spraying material of the present invention can be used as a spraying material in the form of a slurry (spraying slurry for thermal spraying) comprising particles of the spraying material dispersed in a dispersion medium. The content of the spraying material particles in the entire spraying slurry is preferably at most 70 wt %. If the content of the thermal spraying material exceeds 70 wt %, the slurry may clog in the supply equipment during thermal spraying, thus preventing the formation of a spray coating. When the content of the spraying material particles in the spraying slurry is low, the particles actively move in the flow of the slurry and improve dispersibility. In addition, when the content of the spraying material particles is low, the fluidity of the slurry is improved, which is preferred for the purpose of slurry supply. The content of the spraying material particles is more preferably at most 65 wt %, even more preferably at most 60 wt %, and most preferably at most 52 wt %. When high fluidity is required, a lower content of thermal spraying material can be used, in which case the content is preferably at most 45 wt %, more preferably at most 40 wt %, and even more preferably at most 35 wt %. On the other hand, the content of the spraying material particles in the entire spraying slurry is preferably at least 10 wt %. When the content of the spraying material particles in the spray slurry is high, the adhesion efficiency of the spray coating formed from the thermal spray slurry is improved, thereby reducing slurry consumption and improving thermal spraying yield. In addition, when the content of the spraying material particles is high, the spraying time can be shortened. The content of the spraying material particles is more preferably at least 15% by weight, and even more preferably at least 20% by weight.

[0054] The spraying slurry may include particles that are not the spraying material of the present invention, for example, particles of rare earth compounds containing composite oxides of rare earth and aluminum are not included, which do not affect the effect of the present invention in the case of a small amount. The particles that are not the spraying material of the present invention are preferably at most 10 weight percent of the spraying material of the present invention included in the spraying slurry, more preferably at most 5 weight percent, even more preferably 3 weight percent. Most preferably, the spraying slurry is substantially free of particles that are not the spraying material of the present invention. Examples of rare earth compounds that constitute particles that are not the spraying material include rare earth oxides, rare earth fluorides, rare earth oxyfluorides, rare earth hydroxides, rare earth carbonates, etc.

[0055] When the spraying material of the present invention is dispersed with a dispersion medium to form a spray slurry, it is preferred to use a dispersion medium selected from one or more types of aqueous dispersion mediums. For aqueous dispersion mediums, independent water or a mixture of water and an organic solvent can be used. The example of an organic medium includes, for example, alcohol, ether, ester, ketone, etc., but is not limited thereto. In particular, a more preferred example includes a monovalent or divalent alcohol with 2 to 6 carbon atoms, an ether with 3 to 8 carbon atoms, such as ethyl cellosolve, a glycol ether with 4 to 8 carbon atoms, such as dimethyl diglycol (DMDG), a glycol ester with 4 to 8 carbon atoms, such as ethyl cellosolve acetate and butyl cellosolve acetate, and a cyclic ketone with 6 to 9 carbon atoms, such as isophorone. A water-soluble organic solvent that can be mixed with water is more suitable for an organic solvent. The most preferred dispersion medium is a mixture of water or water and an alcohol. When a mixture of water and an organic solvent is used, as a mixing ratio of water to organic solvent, the water content is preferably at least 50% by weight, more preferably at least 70% by weight, and preferably less than 100% by weight, more preferably at most 99% by weight, and the organic solvent content is preferably greater than 0% by weight, more preferably at least 1% by weight, and preferably at most 50% by weight, more preferably at most 30% by weight.

[0056] When the spraying material of the present invention is dispersed with a dispersion medium to form a spray slurry, the spray slurry preferably includes a dispersant to effectively prevent particle aggregation. The content of the dispersant in the whole spray slurry is preferably at most 3 weight %. As dispersant, cationic dispersants, anionic dispersants, nonionic dispersants, etc. are used, but are not limited thereto. Examples of cationic dispersants include cationic dispersants based on polyalkylene imines, cationic dispersants based on polyalkylene polyamines, cationic dispersants based on quaternary ammoniums, and cationic dispersants based on alkylamines. Examples of anionic dispersants include anionic dispersants based on polycarboxylic acids, anionic dispersants based on polyacrylic acid, and anionic dispersants based on polysulfonic acid. Examples of nonionic dispersants include nonionic dispersants based on polyvinyl alcohol and nonionic dispersants based on polyacrylamide. The content of the dispersant in the spray slurry is more preferably at most 2 weight %, even more preferably at most 1 weight %.

[0057] The spraying slurry preferably has a viscosity of less than 15 mPa·s. Low viscosity provides for active movement of particles in the slurry and improved slurry fluidity. The slurry viscosity is more preferably at most 10 mPa·s, even more preferably at most 7 mPa·s. The lower limit of the viscosity is preferably at least 1 mPa·s, more preferably at least 1.5 mPa·s, even more preferably at least 2 mPa·s, but is not limited thereto.

[0058] The spray slurry preferably has a particle settling rate of at least 50 μm / s. A high settling rate means that the particles are mobile in the slurry, less affected by the drag of the surrounding environment. A high settling rate leads to improved flowability of the particles included in the slurry. More preferably, the settling rate is at least 55 μm / s, even more preferably at least 60 μm / s.

[0059] The spraying material of the present invention can be prepared by a method comprising the following steps:

[0060] (A) forming a slurry by dispersing aluminum oxide in an aqueous solution of a rare earth salt;

[0061] (B) crystallizing a precursor containing rare earth and aluminum into a precipitate by adding a precipitant to the slurry;

[0062] (C) collecting the precipitate by solid-liquid separation; and

[0063] (D) Firing a precursor containing rare earth and aluminum in an oxygen-containing gas atmosphere.

[0064] In this method, a precursor is initially provided to prepare a spray material. In step (A), a slurry is formed by dispersing aluminum oxide in an aqueous solution of a rare earth salt. At this point, the ratio of the rare earth salt to the aluminum oxide is preferably adjusted so that the ratio of rare earth to aluminum contained in the resulting spray material corresponds to a ratio within the relative content of rare earth oxide (R2O3) and aluminum oxide (Al2O3) in the spray material. Examples of rare earth salts include nitrates, hydrochlorides, and the like.

[0065] Next, in step (B), a precipitant is added to the slurry. The precipitant is added to an aqueous solution of a rare earth salt in which aluminum oxide is uniformly dispersed. Examples of precipitants include oxalic acid, urea, ammonium carbonate, ammonium bicarbonate, and the like. The amount of precipitant added is preferably 5 to 20 times the molar amount of the rare earth (R). When the precipitant is added to the slurry, the rare earth salt reacts with the precipitant, and the precursor containing the rare earth and aluminum crystallizes into a precipitate. The reaction temperature is typically 70 to 100°C, and the reaction time is typically 2 to 12 hours.

[0066] Next, in step (C), the precipitate as a precursor containing rare earth and aluminum is separated by solid-liquid separation such as filtration and optional washing, and the precursor containing rare earth and aluminum is collected in the form of a water-containing solid. If necessary, the collected precipitate can be pre-fired in an oxygen-containing gas atmosphere such as an air atmosphere. Pre-firing is performed, for example, at a temperature of 600 to 1,000°C for 1 to 8 hours. It should be noted that pre-firing is applied so that the reaction from the precursor to the spraying material of the present invention is not completed. If necessary, after pre-firing, the precipitate can be crushed by a crusher such as a hammer mill.

[0067] Next, in step (D), a precursor containing rare earth and aluminum is fired in an oxygen-containing gas atmosphere, such as air. Prior to firing the precursor, the precursor particles may be formed into pellets by granulation. Granulation is a method of forming particles of larger size by collecting and combining particles of smaller size, and typically results in particles with spaces between the combined particles of smaller size. The firing temperature is preferably 900 to 1,700°C. The firing temperature is more preferably at least 1,000°C, even more preferably at least 1,100°C, and most preferably at least 1,200°C. The firing time is typically 2 to 6 hours.

[0068] When a spraying material having an average particle diameter D50 of 1 to 10 μm is prepared, the particles tend to strongly aggregate after firing. Therefore, if necessary, the spraying material obtained after firing can be powdered by, for example, ball milling or jet milling, and can be sieved.

[0069] Granulation is effective for preparing a spray material having an average particle diameter D50 of 10 to 50 μm. In this case, the preparation method may include, for example, the following steps: firing the resulting precursor at 900 to 1,700°C; optionally pulverizing the precursor by, for example, ball milling or jet milling; optionally sieving the resulting powder; preparing a slurry; granulating the resulting powder using a spray dryer; and further firing the resulting spray material at 1,100 to 1,700°C. In this case, the resulting spray material may be sieved, if necessary.

[0070] According to the present invention, can for example form the spray coating (surface layer coating) that is applied aptly to the part for semiconductor manufacturing apparatus or the composite oxide that comprises rare earth and aluminium by using spraying material of the present invention directly or via bottom coating (lower layer coating) on ​​base material.In addition, can manufacture the spraying member that comprises the spray coating (surface layer coating) that forms on base material directly or via bottom coating (lower layer coating).

[0071] The example of the material of base material comprises inorganic compound (ceramic), such as stainless steel, aluminium, nickel, chromium, zinc and alloy thereof, aluminium oxide, zirconium oxide, aluminium nitride, silicon nitride, silicon carbide and quartz glass, and carbon etc., however, be not limited to this.According to the purposes (such as being used for semiconductor manufacturing equipment) of spraying component, select suitable material.For example, in the case of aluminium metal or aluminium alloy base material, preferably have the base material of the application of alumite (alumite) processing of acid resistance.The shape of base material can be for example flat plate shape or cylindrical shape, however, be not limited to this.

[0072] When forming a spray coating on a substrate, it is preferred that the surface of the substrate on which the spray coating is to be formed be degreased with acetone and subjected to a surface roughening treatment using an abrasive such as corundum to increase the surface roughness Ra. By roughening the surface of the substrate, peeling of the coating caused by the difference in thermal expansion coefficient between the spray coating and the substrate can be effectively suppressed. The degree of surface roughening can be appropriately adjusted according to the material of the substrate.

[0073] Before forming the spray coating, a preliminary lower coating is formed on the substrate, and the spray coating can be formed via a primer coating. The primer coating can be formed to a thickness of 50 to 300 μm. When the spray coating is formed on the lower coating, preferably in contact with the lower coating, the primer coating and the spray coating can be formed as a lower coating and a surface coating, respectively, thereby forming a coating having a multilayer structure.

[0074] Examples of materials for the primer layer include rare earth oxides, rare earth fluorides, and rare earth oxyfluorides. Examples of the rare earth constituting the primer layer include the same elements exemplified for the rare earth (R) in the spraying material, with yttrium (Y) being preferred. The primer layer can be formed under normal pressure by thermal spraying, such as atmospheric plasma spraying or suspension plasma spraying.

[0075] The base coating has a porosity of preferably at most 5%, more preferably at most 4%, and even more preferably at most 3%. The lower limit of the porosity is generally at least 0.1%, but is not limited thereto. The base coating has a surface roughness Ra of preferably at most 10 μm, more preferably at most 6 μm. A low surface roughness Ra is preferred, but the lower limit of the surface roughness Ra is generally at least 0.1 μm. When a spray coating is formed as a top coating on, preferably in contact with, a base coating having a low Ra, it is preferred because the surface roughness Ra of the top coating can also be reduced.

[0076] An undercoat layer having such low porosity and / or low surface roughness Ra can be formed by, for example, a method comprising the steps of providing a single particle powder or granulated spray powder as a source material having an average particle size D50 of at least 0.5 μm, preferably at least 1 μm and at most 50 μm, preferably at most 30 μm, and thermally spraying the molten particles sufficiently by plasma spraying or detonation spraying, but not limited thereto. This method can form a dense undercoat layer having low porosity and / or low surface roughness Ra. It should be noted that "single particle powder" is a powder composed of particles that are spherical particles, angular particles, or ground particles and have a solid-filled interior. When a single particle powder is used, even if the single particle powder has a smaller particle size than the granulated spray powder, the spatter diameter is small because the single particle powder is composed of particles with a solid-filled interior. Therefore, it can form an undercoat layer in which cracking is suppressed.

[0077] The surface roughness Ra of the lower coating can be reduced by surface processing, such as mechanical polishing (surface grinding, inner cylinder processing, mirror processing, etc.), sandblasting with fine beads, manual polishing with a diamond pad, etc.

[0078] The thermal spraying method of the present invention for forming a spray coating (surface layer coating) by using a spraying material is preferably plasma spraying, but is not limited thereto. The plasma spraying may be atmospheric plasma spraying or suspension plasma spraying.

[0079] The plasma gas used to form the plasma in atmospheric plasma spraying can include argon alone, nitrogen alone, and a mixed gas consisting of at least two types of gases selected from argon, hydrogen, helium, and nitrogen, but is not limited thereto. The spraying distance in atmospheric plasma spraying is preferably at most 150 mm. A shorter spraying distance improves the adhesion efficiency, increases the hardness, and reduces the porosity of the sprayed coating. The spraying distance is more preferably at most 140 mm, even more preferably at most 130 mm. The lower limit of the spraying distance is preferably at least 50 mm, more preferably at least 60 mm, even more preferably 70 mm, but is not limited thereto.

[0080] The plasma gas for forming the plasma in the suspension plasma spraying can include a mixed gas composed of at least two types of gases selected from argon, hydrogen, helium and nitrogen, preferably a three-type mixed gas composed of argon, hydrogen and nitrogen, more preferably a four-type mixed gas composed of argon, hydrogen, helium and nitrogen, but is not limited thereto. The spraying distance in the suspension plasma spraying is preferably at most 100 mm. A shorter spraying distance improves the bonding efficiency of the sprayed coating, increases hardness and reduces porosity. The spraying distance is more preferably at most 90 mm, even more preferably at most 80 mm. The lower limit of the spraying distance is preferably at least 50 mm, more preferably at least 55 mm, even more preferably 60 mm, but is not limited thereto.

[0081] When forming a spray coating on a substrate or on a coating (undercoating) formed on a substrate, thermal spraying is preferably performed while cooling the substrate and / or the coating (undercoating) formed on the substrate and further cooling the formed spray coating (surface coating). Cooling may be, for example, air cooling or water cooling.

[0082] In particular, during thermal spraying, the temperature of the substrate or the substrate and the coating formed on the substrate is preferably at least 100°C. When a higher temperature is applied, the bond between the substrate and the resulting sprayed coating, or between the coating formed on the substrate (undercoating) and the resulting sprayed coating becomes stronger, and a dense sprayed coating can be formed. In addition, when the temperature is high, quenching stress is generated, thereby improving the hardness of the resulting sprayed coating. During thermal spraying, the temperature of the substrate or the substrate and the coating formed on the substrate is more preferably at least 130°C, and even more preferably at least 150°C.

[0083] On the other hand, during thermal spraying, the temperature of the substrate or the substrate and the coating formed on the substrate is preferably at most 300°C. When a lower temperature is used, damage or deformation of the substrate or the substrate and the coating formed on the substrate due to heat can be prevented, thereby preventing delamination between the substrate and the resulting sprayed coating, or between the coating formed on the substrate (undercoating) and the resulting sprayed coating. During thermal spraying, the temperature of the substrate or the substrate and the coating formed on the substrate is more preferably at most 270°C, even more preferably at most 250°C. This temperature can be achieved by controlling the cooling capacity.

[0084] Other spraying conditions in plasma spraying, such as the supply rate of the spraying material (spraying slurry), the amount of gas supplied, and the applied power (current value and voltage value) are not particularly limited, and generally known conditions can be applied. They can be appropriately adjusted according to the substrate, the spraying material, the application of the resulting sprayed component, etc.

[0085] Especially, as mentioned above, when directly forming spray coating on base material, can form the harder and dense spray coating that is difficult to peel off by improving the surface roughness Ra of the substrate surface that forms spray coating thereon and further applying above-mentioned temperature.In such case, the surface roughness Ra of formed spray coating tends to be high.Therefore, when by mechanical polishing (surface grinding, inner barrel processing, mirror finish etc.), use fine bead sandblasting, use diamond pad manual polishing etc. to reduce surface roughness Ra, can form the spray coating of lubrication, it is difficult to peel off and is the harder and dense coating with low surface roughness Ra.

[0086] The spray coating of the present invention is suitable for use as a part or component in a plasma etching device used in a semiconductor manufacturing process. The spray coating of the present invention preferably includes a rare earth (R), aluminum, and oxygen, as well as a crystalline phase of a composite oxide containing a rare earth (R) and aluminum. The spray coating of the present invention has excellent resistance to plasma etching (corrosion resistance) with a reduced amount of particles generated by corrosive halogen-based gas plasma.

[0087] The spray coating of the present invention preferably includes a crystalline phase of a composite oxide containing rare earth and aluminum, which includes a crystalline phase having a rare earth-rich composition compared to the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9) and a crystalline phase having a structure in which the Al atomic sites in the monoclinic rare earth aluminum (R4Al2O9) are partially substituted by rare earth (R) atoms.

[0088] A spray coating comprising a crystalline phase of a composite oxide containing a crystalline phase having a composition rich in rare earths compared to the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9) can be formed, for example, by thermal spraying, in particular by plasma spraying, the spray material of the present invention. The crystalline phase of the composite oxide containing a crystalline phase having a composition rich in rare earths compared to the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9) can be confirmed by detecting an XRD diffraction peak at a diffraction angle that is 0.05 to 0.5° (by difference) lower than the diffraction angle of the maximum XRD diffraction peak attributable to monoclinic rare earth aluminum (R4Al2O9), in particular, lower than the diffraction angle of the maximum XRD diffraction peak attributable to monoclinic rare earth aluminum (R4Al2O9) in the spray material used to form the spray coating. The difference is preferably at least 0.1° and preferably at most 0.3°.

[0089] For example, when the monoclinic rare earth aluminum (R4Al2O9) is monoclinic yttrium aluminum (Y4Al2O9), the maximum peak is generally a diffraction peak attributable to the (-122) plane of the lattice, but is not limited thereto. The diffraction peak is generally detected at approximately 2θ = 29.6°. In addition, a peak of a crystalline phase having a rare earth-rich composition compared to the stoichiometric composition of the monoclinic rare earth aluminum (R4Al2O9) is generally detected at a portion or all of the diffraction angles that are not the maximum peak and at a lower diffraction angle than the peak of the XRD diffraction peak attributable to the monoclinic rare earth aluminum (R4Al2O9).

[0090] In the crystal phase of the composite oxide having a rare earth-rich composition compared to the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9), a portion of the Al sites (Al 3+ ions) are replaced by R sites (R 3+ ions) are replaced and the lattice spacing d is expanded. The diffraction peak of the composite oxide having a rare earth-rich composition compared to the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9) depends on the Bragg diffraction condition: 2dsinθ=nλ, where d is the lattice spacing, θ is the grazing angle, n is a positive integer, and λ is the wavelength of the X-ray. Therefore, it is believed that the peak appears at a lower angle than the diffraction angle of the diffraction peak attributed to monoclinic rare earth aluminum (R4Al2O9) because the grazing angle θ of the X-ray is reduced. In the case where the monoclinic rare earth aluminum (R4Al2O9) is monoclinic yttrium aluminum (Y4Al2O9), a portion of the Al in Y4Al2O9 is α-yttrium. 3+ Ion (in the case of hexacoordination, the ionic radius is ) is replaced by R with a larger ionic radius through isomorphous substitution 3+ Ion (in the case of hexacoordination, the ionic radius is ) is replaced, then the lattice spacing d is expanded.

[0091] The diffraction peak of the composite oxide having a composition richer in rare earth than the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9) is not listed in X-ray diffraction databases such as JCPDS. However, the detection of a peak shifted to a lower angle than the diffraction angle attributable to the diffraction peak of monoclinic rare earth aluminum (R4Al2O9) indicates the presence of a crystalline phase having a composition richer in rare earth than the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9).

[0092] From the perspective of corrosion resistance, rare earth oxide (R2O3) is superior to monoclinic rare earth aluminum (R4Al2O9). Therefore, it can be said that a composite oxide having a composition rich in rare earths compared to the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9) has advantages in terms of corrosion resistance. A spray coating comprising a mixed phase of a crystalline phase of monoclinic rare earth aluminum (R4Al2O9) and a crystalline phase of a rare earth oxide (R2O3) has never been obtained by plasma spraying. In particular, a spray coating comprising a crystalline phase of a composite oxide having a composition rich in rare earths compared to the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9) is not known. The spray coating of the present invention, which comprises a crystalline phase of a composite oxide having a composition rich in rare earths compared to the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9), has excellent resistance to plasma etching (corrosion resistance) even in the presence of extremely small amounts of particles generated by corrosive halogen-based gas plasma.

[0093] The spray coating of the present invention may include a crystalline phase of rare earth oxide (R2O3). The inclusion of rare earth oxide is advantageous in that the corrosion resistance of the thermal spray coating is improved.

[0094] The spray coating of the present invention may include a material selected from the group consisting of monoclinic rare earth aluminum (R4Al2O9), rare earth aluminum perovskite (RA1O3) and rare earth aluminum garnet (R3Al5O 12 ) at least one crystalline phase. Including R4Al2O9, RAlO3 or R3Al5O 12 The advantage is that the amount of particles generated by the spray coating is reduced.

[0095] When the rare earth oxide (RO) content and the aluminum oxide (AlO) content are calculated based on the rare earth (R) content and the aluminum content in the sprayed coating, respectively, the sprayed coating of the present invention preferably has a composition corresponding to a relative rare earth oxide (RO) content of 75 to 99% by weight and a relative aluminum oxide (AlO) content of 1 to 25% by weight in the total content of the rare earth oxide (RO) and aluminum oxide (AlO). The relative content calculated as the rare earth oxide (RO) content is more preferably at least 80% by weight, even more preferably at least 85% by weight, and more preferably at most 97% by weight, even more preferably at most 95% by weight. On the other hand, the relative content calculated as aluminum oxide (AlO) is more preferably at least 3% by weight, even more preferably at least 5% by weight, and more preferably at most 20% by weight, even more preferably at most 15% by weight.

[0096] In the spray coating of the present invention, the total weight of the main oxide components (composite oxides containing rare earth and aluminum, rare earth oxides and aluminum oxide) is set to the total weight of the relative content of rare earth oxides and the relative content of aluminum oxide. In addition, the weight of R2O3 as the basic composition of rare earth oxide converted from the rare earth content and aluminum content in the spray coating and the weight of Al2O3 as the basic composition of aluminum oxide are respectively set to the relative content of rare earth oxides and aluminum oxide. Preferably, the spray coating is substantially free of oxides other than the main oxide content, that is, the spray coating is substantially composed of one or more species constituting the main oxide components, but is not limited thereto. The content of rare earth and aluminum in the spray coating can be measured by, for example, ICP emission spectroscopy, fluorescent X-ray analysis, etc. Because the rare earth and aluminum constituting the main oxide components can be selectively measured, fluorescent X-ray analysis is preferred.

[0097] The rare earth (R) in the spray coating of the present invention includes at least one element selected from yttrium (Y) and lanthanide elements from lanthanum (La) to lutetium (Lu) having atomic numbers of 57 to 71. The rare earth (R) is preferably selected from yttrium (Y), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), and more preferably selected from yttrium (Y), gadolinium (Gd), dysprosium (Dy), erbium (Er), and ytterbium (Yb). The rare earth (R) can be used as a single element or in combination of two or more elements.

[0098] The spray coating has a surface roughness Ra of at most, preferably at most, 8 μm. When the spray coating has a surface roughness Ra of at most 8 μm, it is advantageous in that the generation of particles caused by the halogen-based gas plasma can be further suppressed. The surface roughness Ra is more preferably at most 7 μm, and even more preferably at most 6 μm. On the other hand, however, a low surface roughness Ra is preferred, and the lower limit of the surface roughness Ra is generally at least 0.1 μm. When the surface roughness Ra is at least 0.1 μm, the spray coating is less likely to be damaged by excessive processing during coating thickness adjustment, and is less likely to cause particle separation.

[0099] The spray coating of the present invention preferably has a thickness of at least 10 μm. When the thickness is at least 10 μm, corrosion resistance to halogen-based gas plasma is more effectively exerted. The thickness is more preferably at least 30 μm, and even more preferably at least 50 μm. On the other hand, the upper limit of the thickness is preferably at most 500 μm. When the thickness of the spray coating is at most 500 μm, it is difficult to peel the spray coating from the substrate or from the coating (undercoating) formed on the substrate. The upper limit of the thickness is more preferably at most 400 μm, and even more preferably at most 300 μm.

[0100] The spray coating of the present invention preferably has a Vickers hardness HV0.3 of at least 600. When the Vickers hardness HV0.3 is at least 600, it is difficult to etch the surface of the coating by plasma etching using a halogen-based gas plasma, and the corrosion resistance becomes higher. The Vickers hardness HV0.3 is more preferably at least 630, and even more preferably at least 650. On the other hand, however, a high Vickers hardness HV0.3 is preferred, and the upper limit of the Vickers hardness HV0.3 is generally at most 1,000. When the Vickers hardness HV0.3 is at most 1,000, it is difficult to peel the spray coating from the substrate or from the coating (undercoating) formed on the substrate.

[0101] The spray coating of the present invention preferably has a porosity of at most 5%. A porosity of at most 5% is advantageous in that the generation of particles caused by the halogen-based gas plasma can be further suppressed. Furthermore, it tends to improve corrosion resistance. The porosity is more preferably at most 4%, and even more preferably at most 3%. It should be noted that the lower limit of the porosity is generally at least 0.1%, but this is not limiting.

[0102] Example

[0103] Examples of the invention are given below by way of illustration and not by way of limitation.

[0104] Example 1

[0105] Yttrium nitrate (Y(NO3)3) and aluminum oxide (Al2O3) were provided in the ratios specified in Table 1 so that the relative content of yttrium oxide (Y2O3) and the relative content of aluminum oxide (Al2O3) in the total content of yttrium oxide (Y2O3) and aluminum oxide (Al2O3) matched the ratio in the resulting spray material. A slurry was then prepared by dispersing aluminum oxide (Al2O3) powder having an average particle size D50 of 0.5 μm into a 0.01 mol / L aqueous yttrium nitrate solution. Next, urea was added to the solution in an amount corresponding to 10 mol of urea per 1 mol of yttrium nitrate, the solution was stirred, and a precipitate was crystallized. The resulting precipitate, which was a precursor containing rare earth (yttrium) and aluminum, was then collected by solid-liquid separation.

[0106] The obtained precipitate (precursor) was then dispersed in water with carboxymethyl cellulose added as a binder to prepare a slurry. The obtained slurry was granulated using a spray dryer, and the obtained granulated particles were fired at 1,600° C. in an air atmosphere for 2 hours to obtain a spray material.

[0107] The crystalline phase of the obtained spraying material was identified by X-ray diffraction (XRD), the constituent crystals were analyzed, and the maximum peak was determined. The intensity ratio I(R) / I(RAL) of the integrated intensity I(R) of the maximum diffraction peak attributable to the rare earth oxide (R2O3) and the integrated intensity I(RAL) of the maximum diffraction peak attributable to the monoclinic rare earth aluminum (R4Al2O9) was then calculated. X-ray diffraction (XRD) was measured by an X'Pert PRO / MPD X-ray diffraction analyzer manufactured by Malvern Panalytical Ltd. and by HighScore Plus analysis software manufactured by Malvern Panalytical Ltd. to identify the crystalline phase and calculate the integrated intensity. The measurement conditions were as follows: characteristic X-ray: Cu-Kα (tube voltage: 45kV, tube current: 40mA), scanning range: 2θ: 5 to 70°, step length: 0.0167113°, time per step: 13.970 seconds, scanning rate: 0.151921° / sec. The BET specific surface area S and bulk density ρ were measured, and S / ρ was calculated. From the quantitative results of yttrium and aluminum by X-ray fluorescence analysis, the ratio of yttrium to aluminum was calculated as the relative content of yttrium oxide (Y2O3) and the relative content of aluminum oxide (Al2O3) in the sum of the contents. In addition, the particle size distribution (average particle diameter D50) was measured. The results are shown in Table 1. It should be noted that the diffraction angle (2θ(RAL)) attributable to the maximum peak of monoclinic rare earth aluminum (R4Al2O9) is shown in Table 3. The details of various measurements or analyses are described below.

[0108] Example 2

[0109] A precursor was obtained by the same method as in Example 1, fired at 1,600°C for 2 hours in an air atmosphere, and powdered by a jet mill to obtain a spray material. The obtained spray material was measured or analyzed by the same method as in Example 1. The results are shown in Tables 1 and 3. In addition, the XRD curve is shown in Figure 1 middle.

[0110] The obtained spraying material and dispersant were mixed with a dispersion medium, and the spraying material was dispersed in the dispersion medium to obtain a spraying material in the form of a slurry. The slurry concentration, the dispersion medium used, the dispersant used, and the concentration of the dispersant in the slurry are shown in Table 2. In addition, the viscosity of the obtained slurry was measured. The results are shown in Table 2. It should be noted that the detailed viscosity measurement is described below.

[0111] Example 3

[0112] A spraying material was obtained using the same method as in Example 2, except that the precursor firing temperature and firing time were set to 1,300°C and 4 hours, respectively. The obtained spraying material was measured or analyzed using the same method as in Example 1. The results are shown in Tables 1 and 3. Furthermore, a slurry-based spraying material was obtained using the same method as in Example 2, and its viscosity was measured. The slurry concentration, the dispersion medium used, the dispersant used, the dispersant concentration in the slurry, and the viscosity are shown in Table 2.

[0113] Example 4

[0114] A precursor was obtained by the same method as in Example 1, except that yttrium (Y) was changed to gadolinium (Gd) (yttrium nitrate: Y(NO3)3 as a source material was changed to gadolinium nitrate: Gd(NO3)3), and the obtained precursor was fired at 1,200°C for 2 hours in an air atmosphere and powdered by a jet mill to obtain a spraying material. The obtained spraying material was measured or analyzed by the same method as in Example 1. The results are shown in Tables 1 and 3. In addition, a spraying material in the form of a slurry was obtained by the same method as in Example 2, and the viscosity was measured. The slurry concentration, the dispersion medium used, the dispersant used, the concentration of the dispersant in the slurry, and the viscosity are shown in Table 2.

[0115] Example 5

[0116] A precursor was obtained by the same method as in Example 1, except that yttrium (Y) was changed to ytterbium (Yb) (yttrium nitrate: Y(NO3)3 as a source material was changed to ytterbium nitrate: Yb(NO3)3), and the obtained precursor was fired at 1,500°C for 2 hours in an air atmosphere and powdered by a jet mill to obtain a spraying material. The obtained spraying material was measured or analyzed by the same method as in Example 1. The results are shown in Tables 1 and 3. In addition, a spraying material in the form of a slurry was obtained by the same method as in Example 2, and the viscosity was measured. The slurry concentration, the dispersion medium used, the dispersant used, the concentration of the dispersant in the slurry, and the viscosity are shown in Table 2.

[0117] Example 6

[0118] The spray material obtained by the same method as in Example 2 was measured or analyzed by the same method as in Example 1. The results are shown in Tables 1 and 3. Furthermore, a slurry-form spray material was obtained by the same method as in Example 2, and the viscosity was measured. The slurry concentration, the dispersion medium used, and the viscosity are shown in Table 2.

[0119] Comparative Example 1

[0120] Yttrium oxide (Y2O3) powder with an average particle size D50 of 1.2 μm was dispersed in water with carboxymethyl cellulose added as a dispersant to prepare a slurry. The resulting slurry was granulated using a spray dryer to form granulated particles, which were then fired at 1,600°C for 2 hours in an air atmosphere to obtain a spray material. The resulting spray material was measured and analyzed using the same method as in Example 1. The results are shown in Table 1.

[0121] Comparative Example 2

[0122] Yttrium oxide (Y2O3) and aluminum oxide (Al2O3) are provided in the ratio specified in Table 1 so that the relative content of yttrium oxide (Y2O3) in the total content of yttrium oxide (Y2O3) and aluminum oxide (Al2O3) and the relative content of aluminum oxide (Al2O3) match the ratio in the resulting spray material. A slurry is then prepared by dispersing them in water with the addition of carboxymethyl cellulose as a dispersant. The obtained slurry is mixed and powdered for 24 hours in a tank made of aluminum oxide in a ball mill using balls made of aluminum oxide. Next, the obtained slurry after mixing and powdering is granulated by a spray dryer to form granulated particles, and the obtained granulated particles are fired at 1,400°C for 2 hours in an air atmosphere to obtain a spray material. The obtained spray material is measured or analyzed by the same method as in Example 1. The results are shown in Table 1.

[0123] Comparative Example 3

[0124] Yttrium oxide (Y2O3) was fired at 1,600°C for 2 hours in an air atmosphere, pulverized by a jet mill, and sieved to obtain a spray material. The obtained spray material was measured or analyzed by the same method as in Example 1. The results are shown in Table 1. In addition, a slurry-type spray material was obtained by the same method as in Example 2, and the viscosity was measured. The slurry concentration, the dispersion medium used, the dispersant used, the concentration of the dispersant in the slurry, and the viscosity are shown in Table 2.

[0125] Table 1

[0126]

[0127] Table 2

[0128]

[0129] Examples 7 to 12 and Comparative Examples 4 to 6

[0130] In the case of using the spraying materials of Examples 1 to 5 or Comparative Examples 1 to 3, a spray coating is obtained by forming a spray coating on a substrate by plasma spraying directly or via a bottom coating. The substrate is made of the materials shown in Table 3, and the surface of the substrate is subjected to surface roughening treatment by sandblasting polishing using a corundum abrasive with a particle size shown in Table 3. The spray coatings as the surface layer coatings shown in Table 3 are formed by using the spraying materials in the powder form in Examples 7 and Comparative Examples 4 and 5 and by using the spraying materials in the slurry form in Examples 8 to 12 and Comparative Example 6 by suspension plasma spraying (SPS). Directly on the substrate (except Example 8) or via the bottom coating (undercoat) (Example 8) formed on the substrate by atmospheric plasma spraying, a spray coating is formed as the surface layer coating shown in Table 3. The crystalline phase of the undercoat used in Example 8 is identified by X-ray diffraction (XRD) and the composition crystals are analyzed. Surface roughness Ra, thickness and porosity are measured. The results are shown in Table 3. The details of each measurement or analysis are described below.

[0131] Atmospheric plasma spraying was performed under atmospheric pressure at normal pressure by a thermal sprayer SG-100 manufactured by Praxair ST Technology, Inc., and suspension plasma spraying was performed under atmospheric suspension plasma spraying at normal pressure by a thermal sprayer 100HE manufactured by Progressive Co., Ltd. The conditions of the atmospheric plasma spraying and the suspension plasma spraying for forming the spray coating (surface layer coating) are shown in Table 4.

[0132] The crystal phase of the obtained spray coating (surface layer coating) was identified by X-ray diffraction (XRD), and the composition crystals were analyzed. The diffraction angle (2θ(R)) of the peak at a position 0.05 to 0.5° (by difference) lower than the diffraction angle of the maximum XRD diffraction peak attributable to monoclinic rare earth aluminum (R4Al2O9) in the spray material was used. + AL)). The ratio of yttrium to aluminum was calculated as the relative content of yttrium oxide (Y2O3) and aluminum oxide (Al2O3) in the sum of the contents from the results of quantification of yttrium and aluminum by X-ray fluorescence analysis. Surface roughness Ra, thickness, Vickers hardness HV0.3, and porosity were measured. In addition, the corrosion resistance of the spray coating and the amount of rare earth particles produced were evaluated by using the obtained sprayed components. The results are shown in Table 3. The XRD curve in Example 8 is shown in Figure 2 The results are shown in Table 3. Details of each measurement, analysis or evaluation are described below.

[0133] Table 3

[0134]

[0135] Table 4

[0136]

[0137] [X-ray diffraction (XRD)]

[0138] The characteristic X-ray is Cu-Kα, and a diffraction curve is obtained within a diffraction angle 2θ of 10° to 70°.

[0139] [BET specific surface area]

[0140] The BET specific surface area was measured by a fully automatic surface area analyzer Macsorb HM model-1280 manufactured by Mountech Co., Ltd.

[0141] [Bulk density]

[0142] The bulk density is measured by a powder tester PT-X manufactured by Hosokawa Micron Corporation.

[0143] [Ratio of rare earth oxide to aluminum oxide]

[0144] The contents of rare earth and aluminum were measured by X-ray fluorescence analysis, and their ratios were calculated as the ratio of the relative content of yttrium oxide (Y 2 O 3 ) to the relative content of aluminum oxide (Al 2 O 3 ) based on the measured values.

[0145] [Particle size distribution]

[0146] The volume-based particle size distribution was measured by laser diffraction and the average particle size D50 was evaluated.

[0147] [Viscosity of slurry]

[0148] The viscosity of the slurry was measured by a TVB-10 type viscometer manufactured by Toki Sangyo Co., Ltd. at a rotation speed of 60 rpm and a rotation time of 1 minute.

[0149] [Surface roughness Ra]

[0150] The surface roughness Ra was measured by a surface roughness measuring instrument HANDYSURF E-35A manufactured by Tokyo Seimitsu Co., Ltd.

[0151] [Coating thickness]

[0152] The coating thickness was measured by an eddy current coating thickness tester LH-300J manufactured by Kett Electric Laboratory.

[0153] [Vickers hardness HV0.3]

[0154] The surface of the spray coating of the test piece was machined to a mirror surface with a surface roughness Ra of 0.1 μm. The Vickers hardness HV0.3 was measured on the machined mirror surface of the test piece using a micro Vickers hardness tester HMV-G manufactured by Shimadzu Corporation at a load of 2.942 N and a holding time of 10 seconds. The result was evaluated as the average of five points.

[0155] [Porosity]

[0156] The test piece was embedded in resin and cut out at the cross section. The surface was processed into a mirror surface with a surface roughness Ra of 0.1 μm, and then a surface photograph was taken using an electron microscope (magnification: 1,000 times). After imaging in five fields of view (imaging area per field of view: 0.01 mm 2 ), and porosity was quantified using the image analysis software "ImageJ" (public software from the National Institutes of Health). Porosity was calculated as the percentage of pore area relative to the entire image area, and the results were evaluated as the average of five fields of view. Porosity was specifically measured according to the following procedure.

[0157] (1) A coating test piece cut into a size of 9 mm x 9 mm square and 5 mm thick (including the substrate) was embedded in a resin.

[0158] (2) The cross section was mirror-polished (surface roughness Ra = 0.1 μm).

[0159] (3) A cross-sectional photograph (backscattered electron image) was taken by SEM at a magnification of 1,000 times.

[0160] (4) By using the image analysis software "ImageJ", the image processing range of the cross-sectional photograph was specified and trimming processing was performed.

[0161] (5) Convert the processed image into a grayscale image.

[0162] (6) As the image threshold setting, the low-level threshold is set to 0, and the high-level threshold is set to a value that colors all gaps in red.

[0163] (7) Convert the processed image into a binary image.

[0164] (8) Calculate the total area of ​​the gap.

[0165] (9) The length unit is set to pixel, and the total area (pixel) of the gap portion is obtained.

[0166] (10) Set the image threshold so that the low-level threshold is 0 and the high-level threshold is 255, and then obtain the entire area (pixels) of the image.

[0167] (11) The porosity is calculated by dividing the total area (pixels) of the void portion by the entire area (pixels) of the image.

[0168] [Testing and evaluation of corrosion resistance]

[0169] The surface of the spray coating (surface layer coating) of the test piece (spraying component) is arranged into a mirror surface with a surface roughness Ra of 0.1 μm. After preparing the part covered with the masking tape and the exposed part of the coating, the test piece is placed in a device for reactive ion plasma testing and exposed to plasma under the conditions of a plasma output of 440W, a CF4+20 volume %O2 gas species, a flow rate of 20 sccm, a gas pressure of 5 Pa and a test time of 8 hours. To the test piece after plasma exposure, the contact surface profile measurement system Dektak3030 manufactured by Bruker Nano Inc. is used to measure the step height caused by corrosion between the part covered by the masking tape and the exposed part of the coating. The result of corrosion resistance is evaluated by calculating the average value of four points. In the evaluation by this test, the average value of the height of the step (the average height of the step) is preferably at most 3.5 μm. When the average step height in the step is greater than 3.5 μm, it may not be possible to fully demonstrate plasma etching resistance for use in a plasma etching device. The average step height among the steps is more preferably at most 3.2 μm, even more preferably at most 3 μm.

[0170] [Testing and evaluation of the amount of rare earth particles produced]

[0171] The test piece (sprayed component) was subjected to ultrasonic cleaning (output: 200W, cleaning time: 30 minutes), dried, and then immersed in 20mL of ultrapure water and subjected to ultrasonic cleaning for another 5 minutes. After ultrasonic cleaning, the test piece was taken out, and 2mL of 5.3N nitric acid aqueous solution was added to the ultrapure water after ultrasonic cleaning to dissolve the rare earth particles contained in the ultrapure water. The amount of rare earth in the collected rare earth particles was measured by ICP emission spectroscopy and evaluated as the amount of rare earth per unit surface area of ​​the spray coating of the test piece. In the evaluation of this test, the amount of rare earth particles is preferably at most 3μg / cm 2 When the amount of rare earth particles is greater than 3μg / cm 2 When the amount of rare earth particles is less than 2.5 μg / cm, the particles generated are too many and the sprayed component may not be able to withstand use in a plasma etching device. The amount of rare earth particles is more preferably at most 2.5 μg / cm 2, and even more preferably at most 2 μg / cm 2 .

[0172] The spray coatings (surface layer coatings) obtained in Examples 7 to 12 exhibit excellent plasma etching resistance (corrosion resistance) despite the reduced amount of rare earth particles generated by the reaction with the corrosive halogen-based gas plasma. The generation of rare earth particles relates to the phenomenon that when the surface of the spray coating is halogenated by the halogen-based gas plasma, the aluminum halide evaporates and no longer remains as particles, whereas the generated rare earth halide remains as particles without evaporation. On the other hand, with regard to plasma etching resistance, the rare earth-rich case is superior to the aluminum-rich case. In addition, the generation of rare earth particles relates to the fact that, compared with the aluminum-rich spray material, the rare earth-rich spray material has fewer particles that cause particle contamination and form a rough coating.

[0173] The sprayed materials obtained in Examples 1 to 6 have an intensity ratio I(R) / I(RAL) of at least 1. The sprayed materials can suitably form a composite oxide (R4Al2O9) having a composition rich in rare earths compared to the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9). + The results show that the sprayed material contains a relatively small amount of particles that cause particle contamination and form a rough coating (with a rare earth oxide content of 75 to 99% by weight and an aluminum oxide content of 1 to 25% by weight as the relative content of rare earth oxide and aluminum oxide (Al2O3)). In particular, since the S / ρ value obtained by dividing the surface area S by the bulk density p is within the range of 1 to 4, the sprayed material has a relatively small amount of particles that cause particle contamination and form a rough coating. Therefore, from these results, it can be understood that rare earth particles are less generated in such a sprayed material and that the sprayed material is advantageous for forming a sprayed coating having excellent plasma etching resistance (corrosion resistance).

[0174] In addition, in the spray coatings (surface layer coatings) obtained in Examples 7 to 12, the spraying material used had an XRD diffraction peak detected at a diffraction angle lower than the diffraction angle of the maximum XRD diffraction peak attributable to monoclinic rare earth aluminum (R4Al2O9) by 0.05 to 0.5° (by difference). Based on the presence of this peak, it was confirmed that the spray coating included a composite oxide (R4Al2O9) having a rare earth-rich composition compared to the stoichiometric composition of monoclinic rare earth aluminum (R4Al2O9) and a structure in which the Al atomic sites in the monoclinic rare earth aluminum (R4Al2O9) were partially substituted with rare earth (R) atoms. + AL). In addition, it has been recognized that by including a composite oxide (R + AL), the sprayed materials obtained in Examples 7 to 12 have excellent plasma etching resistance (corrosion resistance) with a reduced amount of particles generated due to the corrosive halogen-based gas plasma.

Claims

1. A spraying material comprising rare earth R, aluminum and oxygen, wherein the spraying material is a powder made of particles and the particles include a mixed phase comprising a monoclinic rare earth aluminum R4Al2O9 crystalline phase and a rare earth oxide R2O3 crystalline phase, wherein The spraying material has a diffraction peak attributable to rare earth oxide R2O3 and a diffraction peak attributable to monoclinic rare earth aluminum R4Al2O9, as for diffraction peaks detected within a diffraction angle 2θ range of 10° to 70° by an X-ray diffraction method using characteristic X-rays of Cu-Kα, and The intensity ratio I(R) / I(RAL) of the integrated intensity I(R) of the maximum diffraction peak attributable to the rare earth oxide R2O3 to the integrated intensity I(RAL) of the maximum diffraction peak attributable to the monoclinic rare earth aluminum R4Al2O9 is at least 2, The spraying material has 1 m 2 / g-3.5m 2 / g BET specific surface area S and up to 2 g / cm 3 Bulk density , The spraying material has an S / value, where the S / The value is obtained by dividing the value of the BET specific surface area S by the bulk density The value of , and The spraying material has a composition corresponding to a relative rare earth oxide R2O3 content of 75 to 99 weight % and a relative aluminum oxide Al2O3 content of 1 to 25 weight % in the total content of rare earth oxide R2O3 and aluminum oxide Al2O3, wherein the rare earth oxide R2O3 content and the aluminum oxide Al2O3 content are calculated based on the rare earth R content and the aluminum content in the spraying material, respectively.

2. The spraying material according to claim 1, wherein the rare earth R is selected from yttrium (Y), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu). The spray material according to claim 1 , which has an average particle size D50 of 1 to 50 μm.

4. A spraying slurry comprising the spraying material according to claim 1 and a dispersion medium, wherein a content of the spraying material in the spraying slurry is 10 to 70 wt%. The spray slurry according to claim 4 , wherein the dispersion medium is an aqueous dispersion medium. The spraying slurry according to claim 4 , further comprising a dispersant. The spray slurry according to claim 4 , having a viscosity of less than 15 mPa·s.

8. A method for preparing the spray slurry according to claim 4, comprising the following steps: A slurry is formed by dispersing alumina in an aqueous solution of a rare earth salt; crystallizing a precursor containing rare earth and aluminum into a precipitate by adding a precipitant to the slurry; collecting the precipitate by solid-liquid separation; and The precursor containing rare earth and aluminum is fired in an oxygen-containing gas atmosphere.

9. A method for forming a spray coating, comprising the steps of: A spray coating is formed on a substrate by plasma spraying using the spray material according to claim 1 directly or via an undercoat layer, the spray coating comprising a composite oxide containing rare earth and aluminum.

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