Thermal spraying material, thermal spray coating, method for forming thermal spray coating, component for plasma etching apparatus

Abstract

To provide a flame spray coating with an excellent plasma erosion resistance, capable of protecting a component of a plasma etching apparatus from a plasma erosion for a long period of time and contributing to a stable production of a device and a long life of the component.SOLUTION: A flame spray material according to an aspect of the invention comprises a composite compound including 40 mol% or more and 80 mol% or less of a rare-earth fluoride, 10 mol% or more and 40 mol% or less of magnesium fluoride, and 0 mol% or more and 40 mol% or less of calcium fluoride.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a spraying material, a sprayed film, a method for forming a sprayed film, and a component for a plasma etching apparatus.

Background Art

[0002] In the field of manufacturing semiconductor devices, generally, dry etching using plasma of halogen-based gases such as fluorine, chlorine, and bromine is performed inside a vacuum chamber to perform microfabrication on the surface of a semiconductor substrate. Further, after dry etching, the inside of the chamber after taking out the semiconductor substrate is cleaned using oxygen gas plasma. Along with this, erosion occurs in the members exposed to the reactive plasma in the chamber, and there is a possibility that the corroded parts may fall off in the form of particles and become particles. When these particles adhere to the semiconductor substrate, it may cause defects in the circuit.

[0003] Therefore, conventionally, for the purpose of reducing the generation of particles, a sprayed film with high plasma erosion resistance is provided on the members exposed to the reactive plasma in the chamber to protect the members from plasma erosion. For example, Patent Document 1 describes providing a layer composed of dense fluoride ceramics mainly containing at least one selected from CaF2, MgF2, YF3, AlF3, and CeF3 and having a porosity of 2% or less as a sprayed film with high plasma erosion resistance.

[0004] Patent Document 2 describes spraying a powder for spraying containing a rare earth element and a Group 2 element of the periodic table onto a member exposed to reactive plasma to form an oxide film in order to form a film that is less likely to generate large-sized particles when subjected to plasma erosion. Patent Document 3 describes a thermal spraying material capable of forming a thermal spray coating with improved plasma erosion resistance, which includes composite particles formed by integrating a plurality of ytterbium fluoride fine particles, and the thermal spraying material has a lightness L of 91 or less in the Lab color space.

[0005] Patent Document 4 describes a coated substrate having a thermal spray coating with high plasma resistance, difficult to peel off, excellent acid resistance, and a high surface resistance value on the surface of a substrate, which satisfies the following configurations (1) to (4). (1) The thickness of the coating is 10 to 1000 μm. (2) The coating contains a fluoride and an oxide of a rare earth element (Ln) as main components. (3) On the surface of the coating, a particulate portion [α1] with a monoclinic crystal structure, having a diameter of 10 nm to 1 μm and mainly composed of an oxide of a rare earth element (Ln), and a particulate portion [β1] with an orthorhombic crystal structure, having a diameter of 10 nm to 1 μm and mainly composed of a fluoride of a rare earth element (Ln) are dispersed in an amorphous matrix mainly composed of a fluoride of a rare earth element (Ln). (4) When observed at 200 times magnification using an optical microscope on the surface of the coating, a white stain-like portion with a maximum diameter of 50 to 1000 μm is confirmed, and the area ratio occupied by this stain-like portion in the observation field of view is 0.01 to 2%.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, the thermal spray coatings described in Patent Documents 1 to 4 have room for improvement in terms of excellent plasma erosion resistance and protecting the members of the plasma etching apparatus from plasma erosion over a long period of time. An object of the present invention is to provide a thermal spray coating that is excellent in plasma erosion resistance, can protect the members of a plasma etching apparatus from plasma erosion over a long period of time, and can contribute to stable production of devices and extended service life of the members.

Means for Solving the Problems

[0008] In order to solve the above problems, a first aspect of the present invention provides a thermal spray material composed of a composite compound containing rare earth fluoride in a proportion of 40 mol% or more and 80 mol% or less, magnesium fluoride in a proportion of 10 mol% or more and 40 mol% or less, and calcium fluoride in a proportion of 0 mol% or more and 40 mol% or less. A second aspect of the present invention provides a thermal spray coating containing rare earth fluoride in a proportion of 40 mol% or more and 80 mol% or less, magnesium fluoride in a proportion of 10 mol% or more and 40 mol% or less, calcium fluoride in a proportion of 0 mol% or more and 40 mol% or less, including a crystalline phase and an amorphous phase, and having a crystallinity of 1% or more and 75% or less.

Advantages of the Invention

[0009] According to the thermal spray material of the first aspect of the present invention, it is possible to form a thermal spray coating that is excellent in plasma erosion resistance, can protect the members of the plasma etching apparatus from plasma erosion over a long period of time, and can contribute to stable production of devices and extended service life of the members. The thermal spray coating of the second aspect of the present invention is expected to be a thermal spray coating that is excellent in plasma erosion resistance, can protect the members of the plasma etching apparatus from plasma erosion over a long period of time, and can contribute to stable production of devices and extended service life of the members. According to the method for forming a sprayed coating using the sprayed material of the first aspect of the present invention, a sprayed coating excellent in plasma erosion resistance can be formed, which can protect the members of a plasma etching apparatus from plasma erosion over a long period of time and contribute to stable production of devices and long life of the members.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the embodiments shown below. In the embodiments shown below, technically preferable limitations are made in order to carry out the present invention, but these limitations are not essential requirements of the present invention. The sprayed material of this embodiment is composed of a composite containing a fluoride of a rare earth element in a proportion of 40 mol% or more and 80 mol% or less, magnesium fluoride in a proportion of 10 mol% or more and 40 mol% or less, and calcium fluoride in a proportion of 0 mol% or more and 40 mol% or less. The proportion of magnesium fluoride is preferably 20 mol% or more and 40 mol% or less.

[0011] The fluoride of the rare earth element is preferably yttrium fluoride. This composite is a granulated powder of yttrium fluoride primary particles, magnesium fluoride primary particles, and calcium fluoride primary particles having an average particle diameter of 10 μm or less, and the average particle diameter of this granulated powder is preferably 5 μm or more and 40 μm or less. This composite is preferably a granulated sintered powder obtained by sintering the granulated powder. The sprayed coating formed by spraying the sprayed material of this embodiment under general conditions contains a fluoride of a rare earth element in a proportion of 40 mol% or more and 80 mol% or less, magnesium fluoride in a proportion of 10 mol% or more and 40 mol% or less, and calcium fluoride in a proportion of 0 mol% or more and 40 mol% or less, contains a crystalline phase and an amorphous phase, and the crystallinity is 1% or more and 75% or less. The crystallinity of the sprayed coating can be calculated based on the diffraction pattern obtained by X-ray diffraction.

[0012] The fluoride of the rare earth element is preferably yttrium fluoride. The porosity of the sprayed coating is preferably 2.0 area% or less. The method for forming the sprayed coating of this embodiment uses a composite containing a fluoride of a rare earth element at a ratio of 40 mol% or more and 80 mol% or less, magnesium fluoride at a ratio of 10 mol% or more and 40 mol% or less, and calcium fluoride at a ratio of 0 mol% or more and 40 mol% or less. It is a method of forming a sprayed coating containing a crystalline phase and an amorphous phase, containing a fluoride of a rare earth element at a ratio of 40 mol% or more and 80 mol% or less, magnesium fluoride at a ratio of 10 mol% or more and 40 mol% or less, and calcium fluoride at a ratio of 0 mol% or more and 40 mol% or less.

[0013] The composite used in this method preferably contains a fluoride of a rare earth element at a ratio of 40 mol% or more and 80 mol% or less, magnesium fluoride at a ratio of 20 mol% or more and 40 mol% or less, and calcium fluoride at a ratio of 0 mol% or more and 40 mol% or less. The fluoride of the rare earth element constituting the composite used in this method is preferably yttrium fluoride. According to the method for forming the sprayed coating of this embodiment, a sprayed coating with a porosity of 2.0 area% or less can be formed.

[0014] According to the method for forming the sprayed coating of this embodiment, a sprayed coating with a crystallinity of 1% or more and 75% or less can be formed. The component for a plasma etching apparatus of this embodiment is a component for a plasma etching apparatus whose surface is coated with the above-mentioned sprayed coating. According to the sprayed material of this embodiment, it is possible to form a sprayed coating that is excellent in plasma erosion resistance, protects the members of the plasma etching apparatus from plasma erosion over a long period, and contributes to the stable production of the device and the long life of the members.

[0015] The sprayed coating of this embodiment is excellent in plasma erosion resistance, can protect the members of a plasma etching apparatus from plasma erosion over a long period, and is expected to be a sprayed coating that can contribute to stable production of devices and extended service life of the members. According to the method for forming the sprayed coating of this embodiment, it becomes possible to form a sprayed coating that is excellent in plasma erosion resistance, can protect the members of a plasma etching apparatus from plasma erosion over a long period, and can contribute to stable production of devices and extended service life of the members.

[0016] [Regarding the manufacturing method of the spraying material] The composite material constituting the spraying material of the first aspect of the present invention is formed of a material containing at least a fluoride of a rare earth element and a fluoride of a Group 2 element. This composite material can be manufactured by granulating, for example, into a spherical shape, primary particles composed of a fluoride of a rare earth element and primary particles composed of a fluoride of a Group 2 element. Also, this granulated powder can be manufactured by sintering while maintaining the composition of the primary particles.

[0017] The granulation method is not particularly limited, and various known granulation methods can be adopted. For example, specifically, one or more of methods such as tumbling granulation method, fluidized bed granulation method, stirring granulation method, compression granulation method, extrusion granulation method, crushing granulation method, spray drying method, etc. can be adopted. Preferably, it is the spray drying method. For firing the granulated powder, a general batch type firing furnace, a continuous type firing furnace, etc. can be used without particular limitation. In a general granulated powder, fine particles which are primary particles are simply integrally aggregated (bonded by a binder), for example, via a binder. Relatively large pores are interposed in the gaps between the fine particles in such a granulated powder. Thus, in a general granulated powder, the presence of relatively large pores between the pseudo-primary particles has the meaning of "granulation".

[0018] On the other hand, when the granulated powder is sintered, the binder disappears and the fine particles directly bond to reduce the surface energy. As a result, the composite particles integrally bonded as described above are realized. Note that as sintering progresses, the area of the bonding portion (interface) gradually increases, and the bonding strength is further enhanced. Also, due to the mass transfer in the sintered particles, the fine particles become rounded into a more stable spherical shape. At the same time, the pores existing inside the granulated powder are discharged, resulting in densification.

[0019] The firing conditions for sintering are not particularly limited as long as the composition of the primary particles does not change in a state where sintering has sufficiently progressed. The firing conditions can be roughly estimated, for example, by heating in a non-oxidizing atmosphere at a temperature of 600°C or higher and lower than the melting point (for example, lower than 1200°C). The firing atmosphere can be, for example, an inert atmosphere or a vacuum atmosphere so that the composition does not change. The inert atmosphere in this case is an oxygen-free atmosphere, and can be a noble gas atmosphere such as argon (Ar), neon (Ne), helium (He), or a non-oxidizing atmosphere such as nitrogen (N2). When using a batch-type firing furnace, for example, the atmosphere inside the furnace can be made a non-oxidizing atmosphere. When using a continuous firing furnace, for example, a non-oxidizing gas stream can be introduced into the region where heating is performed (the region where sintering progresses) inside the firing furnace to carry out sintering.

[0020] [Regarding the substrate] In the component for a plasma etching apparatus (substrate with a film having a film on the surface) whose surface is coated with the sprayed film according to the second aspect of the present invention, the substrate on which the sprayed film is formed is not particularly limited. For example, as long as it is a substrate made of a material that can be subjected to spraying of the spraying material and has desired resistance, its material, shape, etc. are not particularly limited. Examples of the material constituting the substrate include metal materials including various metals, semi-metals, and their alloys, and various inorganic materials.

[0021] Specifically, examples of the metal materials include metal materials such as aluminum, aluminum alloys, iron, steel, copper, copper alloys, nickel, nickel alloys, gold, silver, bismuth, manganese, zinc, zinc alloys, etc.; Group IV semiconductors such as silicon (Si) and germanium (Ge), Group II-VI compound semiconductors such as zinc selenide (ZnSe), cadmium sulfide (CdS), and zinc oxide (ZnO), Group III-V compound semiconductors such as gallium arsenide (GaAs), indium phosphide (InP), and gallium nitride (GaN), Group IV compound semiconductors such as silicon carbide (SiC) and silicon germanium (SiGe), and semimetal materials such as chalcopyrite-based semiconductors such as copper indium selenide (CuInSe2), etc. Examples of the inorganic materials include substrate materials such as calcium fluoride (CaF2) and quartz (SiO2), oxide ceramics such as alumina (Al2O3) and zirconia (ZrO2), nitride ceramics such as silicon nitride (Si3N4), boron nitride (BN), and titanium nitride (TiN), and carbide-based ceramics such as silicon carbide (SiC) and tungsten carbide (WC), etc.

[0022] Any one of these materials may constitute the base material, or two or more of them may be combined to form the base material. Among them, steel typified by various SUS materials (which may be so-called stainless steel), heat-resistant alloys typified by Inconel, low-expansion alloys typified by Invar and Kovar, corrosion-resistant alloys typified by Hastelloy, and aluminum alloys typified by 1000 series to 7000 series aluminum alloys, etc., which are general-purpose metal materials with a relatively large coefficient of thermal expansion, are preferred examples of the base material. Such a base material may be, for example, a member constituting a semiconductor device manufacturing apparatus and may be a member exposed to highly reactive oxygen gas plasma or halogen gas plasma. For example, silicon carbide (SiC), etc. mentioned above may be classified into different categories as compound semiconductors, inorganic materials, etc. for the convenience of use, etc., but they may be the same material.

[0023] [Regarding the method for forming a sprayed coating] The thermal spray coating of the second aspect can be formed by supplying the thermal spray material of the first aspect to a thermal spraying apparatus based on a known thermal spraying method. That is, a thermal spray coating made of such a material is formed by spraying a powdery thermal spray material in a softened or melted state by a heat source such as combustion or electric energy. The thermal spraying method for spraying this thermal spray material is not particularly limited. For example, preferably, a thermal spraying method such as a plasma spraying method, a high-velocity flame spraying method, a flame spraying method, or an explosion spraying method is exemplified.

[0024] The characteristics of the thermal spray coating may depend to some extent on the thermal spraying method and its thermal spraying conditions. However, no matter which thermal spraying method and thermal spraying conditions are adopted, by using the thermal spray material disclosed herein, it is possible to form a thermal spray coating with improved plasma erosion resistance as compared with the case of using other thermal spray materials. The plasma spraying method is a thermal spraying method that uses a plasma flame as a thermal spray heat source for softening or melting a thermal spray material. When an arc is generated between electrodes and an operating gas is turned into plasma by such an arc, such a plasma flow ejects from a nozzle as a high-temperature and high-velocity plasma jet. The plasma spraying method generally includes a coating technique for obtaining a thermal spray coating by injecting a thermal spray material into this plasma jet, heating and accelerating it, and depositing it on a substrate.

[0025] Note that the plasma spraying method can be in modes such as atmospheric plasma spraying (APS) performed in the atmosphere, low-pressure plasma spraying (LPS) in which spraying is performed at a pressure lower than atmospheric pressure, and high-pressure plasma spraying in which plasma spraying is performed in a pressure vessel at a pressure higher than atmospheric pressure. According to such plasma spraying, for example, as an example, by melting and accelerating a thermal spray material by a plasma jet of about 5000°C to 10000°C, the thermal spray material can be made to collide with and deposit on a substrate at a speed of about 300 m / s to 600 m / s.

Example

[0026] Hereinafter, examples of the present invention will be described. [Production of thermal spray material] <No.1> First, yttrium fluoride (YF3) powder with an average primary particle diameter of 3.0 μm, calcium fluoride (CaF2) powder with an average primary particle diameter of 1.0 μm, and magnesium fluoride (MgF2) powder with an average primary particle diameter of 4.0 μm were dispersed in a dispersion medium together with a resin binder at a ratio such that YF3 was 50 mol%, CaF2 was 20 mol%, and MgF2 was 30 mol% to obtain a raw material dispersion. The resin binder was used at a ratio of 1.0 part by mass with respect to 100 parts by mass of the total powder. Next, using a spray dryer, the raw material dispersion was sprayed into an air stream to evaporate the dispersion medium from the spray droplets to produce granulated powder. That is, granulation was performed by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace and fired at 800 °C in an Ar atmosphere for about 120 minutes to obtain granulated sintered powder. The composition of the obtained granulated sintered powder did not change, with YF3 being 50 mol%, CaF2 being 20 mol%, and MgF2 being 30 mol%, and the average particle diameter of the particles classified by a sieve or air flow was 30 μm. The granulated sintered powder thus obtained was used as the No. 1 thermal spray material.

[0027] <No.2> First, yttrium fluoride (YF3) powder with an average primary particle diameter of 1.0 μm and magnesium fluoride (MgF2) powder with an average primary particle diameter of 4.0 μm were dispersed in a dispersion medium together with a resin binder at a ratio such that YF3 was 64 mol% and MgF2 was 36 mol% to obtain a raw material dispersion. The resin binder was used at a ratio of 1.0 part by mass with respect to 100 parts by mass of the total powder. Next, using a spray dryer, the raw material dispersion was sprayed into an air stream, and the granulated powder was produced by evaporating the dispersion medium from the spray droplets. That is, granulation was performed by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace, and fired at 780 °C under a vacuum atmosphere for about 180 minutes to obtain a granulated sintered powder. The composition of the obtained granulated sintered powder did not change, with YF3 being 64 mol% and MgF2 being 36 mol%, and the average particle size of the particles classified by a sieve or an air stream was 25 μm. The granulated sintered powder thus obtained was used as the thermal spraying material No. 2.

[0028] <No.3> First, yttrium fluoride (YF3) powder with an average primary particle size of 0.5 μm, calcium fluoride (CaF2) powder with an average primary particle size of 1.0 μm, and magnesium fluoride (MgF2) powder with an average primary particle size of 5.0 μm were dispersed in a dispersion medium together with a resin binder at a ratio of YF3 being 50 mol%, CaF2 being 25 mol%, and MgF2 being 25 mol% to obtain a raw material dispersion. The resin binder was used at a ratio of 1.5 parts by mass per 100 parts by mass of the total powder. Next, using a spray dryer, the raw material dispersion was sprayed into an air stream, and the granulated powder was produced by evaporating the dispersion medium from the spray droplets. That is, granulation was performed by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace, and fired at 850 °C under an N2 atmosphere for about 120 minutes to obtain a granulated sintered powder. The composition of the obtained granulated sintered powder did not change, with YF3 being 50 mol%, CaF2 being 25 mol%, and MgF2 being 25 mol%, and the average particle size of the particles classified by a sieve or an air stream was 30 μm. The granulated sintered powder thus obtained was used as the thermal spraying material No. 3.

[0029] <No.4> First, yttrium fluoride (YF3) powder with an average primary particle size of 2.0 μm, calcium fluoride (CaF2) powder with an average primary particle size of 4.0 μm, and magnesium fluoride (MgF2) powder with an average primary particle size of 3.0 μm were dispersed in a dispersion medium together with a resin binder at a ratio of 64 mol% YF3, 12 mol% CaF2, and 24 mol% MgF2 to obtain a raw material dispersion. The resin binder was used at a ratio of 1.0 part by mass per 100 parts by mass of the total powder. Next, using a spray dryer, the raw material dispersion was sprayed into the air stream, and the dispersion medium was evaporated from the spray droplets to produce granulated powder. That is, granulation was carried out by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace and fired at 860 °C in an Ar atmosphere for about 150 minutes to obtain granulated sintered powder. The composition of the obtained granulated sintered powder did not change, with 64 mol% YF3, 12 mol% CaF2, and 24 mol% MgF2, and the average particle size of the particles classified by a sieve or air flow was 34 μm. The granulated sintered powder thus obtained was used as the No. 4 thermal spraying material.

[0030] <No.5> First, yttrium fluoride (YF3) powder with an average primary particle size of 3.0 μm, calcium fluoride (CaF2) powder with an average primary particle size of 1.0 μm, and magnesium fluoride (MgF2) powder with an average primary particle size of 8.0 μm were dispersed in a dispersion medium together with a resin binder at a ratio of 50 mol% YF3, 20 mol% CaF2, and 30 mol% MgF2 to obtain a raw material dispersion. The resin binder was used at a ratio of 1.5 parts by mass per 100 parts by mass of the total powder. Next, using a spray dryer, the raw material dispersion was sprayed into the air stream, and the dispersion medium was evaporated from the spray droplets to produce granulated powder. That is, granulation was carried out by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace and fired at 830 °C in a vacuum atmosphere for about 180 minutes to obtain granulated sintered powder. The composition of the obtained granulated sintered powder did not change, with 50 mol% YF3, 20 mol% CaF2, and 30 mol% MgF2, and the average particle size of the particles classified by a sieve or air flow was 22 μm. The granulated sintered powder thus obtained was used as the No. 5 thermal spraying material.

[0031] <No.6> The granulated powder obtained by granulating with the spray drying method in No.1 was used as the spraying material for No.6 without sintering. The average particle diameter of the particles classified by a sieve or air flow was 32 μm.

[0032] <No.7> The granulated powder obtained by granulating with the spray drying method in No.2 was introduced into a multi - atmosphere furnace and fired at 850 °C for about 120 minutes under an Ar atmosphere to obtain granulated sintered powder. The composition of the obtained granulated sintered powder was unchanged with YF3 being 64 mol% and MgF2 being 36 mol%, and the average particle diameter of the particles classified by a sieve or air flow was 46 μm. The granulated sintered powder thus obtained was used as the spraying material for No.7.

[0033] <No.8> The granulated powder obtained by granulating with the spray drying method in No.2 was introduced into a multi - atmosphere furnace and fired at 870 °C for about 120 minutes under an Ar atmosphere to obtain granulated sintered powder. The composition of the obtained granulated sintered powder was unchanged with YF3 being 64 mol% and MgF2 being 36 mol%, and the average particle diameter of the particles classified by a sieve or air flow was 52 μm. The granulated sintered powder thus obtained was used as the spraying material for No.8.

[0034] <No.9> The granulated powder obtained by granulating with the spray drying method in No.2 was introduced into a multi - atmosphere furnace and fired at 850 °C for about 120 minutes under a vacuum atmosphere to obtain granulated sintered powder. The composition of the obtained granulated sintered powder was unchanged with YF3 being 64 mol% and MgF2 being 36 mol%, and the average particle diameter of the particles classified by a sieve or air flow was 10 μm. The granulated sintered powder thus obtained was used as the spraying material for No.9.

[0035] <No.10> The granulated powder obtained by granulating with the spray drying method at No.2 was introduced into a multi-atmosphere furnace and fired at 860 °C for about 120 minutes under a vacuum atmosphere to obtain a granulated sintered powder. The composition of the obtained granulated sintered powder did not change, with YF3 being 64 mol% and MgF2 being 36 mol%, and the average particle size of the particles classified by a sieve or air flow was 8 μm. The granulated sintered powder thus obtained was used as the spraying material for No.10.

[0036] <No.11> First, yttrium fluoride (YF3) powder with an average primary particle size of 3.0 μm, calcium fluoride (CaF2) powder with an average primary particle size of 0.8 μm, and magnesium fluoride (MgF2) powder with an average primary particle size of 4.0 μm were dispersed in a dispersion medium together with a resin binder at a ratio of YF3 being 30 mol%, CaF2 being 20 mol%, and MgF2 being 50 mol% to obtain a raw material dispersion liquid. The resin binder was at a ratio of 2.0 parts by mass with respect to 100 parts by mass of the total powder. Next, using a spray dryer, the raw material dispersion liquid was sprayed into the air stream, and the dispersion medium was evaporated from the spray droplets to produce granulated powder. That is, granulation was carried out by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace and fired at 800 °C for about 120 minutes under an N2 atmosphere to obtain a granulated sintered powder. The composition of the obtained granulated sintered powder did not change, with YF3 being 30 mol%, CaF2 being 20 mol%, and MgF2 being 50 mol%, and the average particle size of the particles classified by a sieve or air flow was 25 μm. The granulated sintered powder thus obtained was used as the spraying material for No.11.

[0037] <No.12> First, yttrium fluoride (YF3) powder with an average primary particle size of 3.0 μm and calcium fluoride (CaF2) powder with an average primary particle size of 2.0 μm were dispersed in a dispersion medium together with a resin binder at a ratio of YF3 being 30 mol% and CaF2 being 70 mol% to obtain a raw material dispersion liquid. The resin binder was at a ratio of 1.0 part by mass with respect to 100 parts by mass of the total powder. Next, using a spray dryer, the raw material dispersion was sprayed into an air stream, and the dispersion medium was evaporated from the spray droplets to produce granulated powder. That is, granulation was performed by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace, and fired at 750 °C in an Ar atmosphere for about 180 minutes to obtain granulated sintered powder. The composition of the obtained granulated sintered powder did not change, with YF3 being 30 mol% and CaF2 being 70 mol%, and the average particle size of the particles classified by a sieve or air flow was 48 μm. The granulated sintered powder thus obtained was used as the spraying material No. 12.

[0038] <No.13> First, yttrium fluoride (YF3) powder with an average primary particle size of 1.0 μm and calcium fluoride (CaF2) powder with an average primary particle size of 1.0 μm were dispersed in a dispersion medium together with a resin binder at a ratio of 71 mol% YF3 and 29 mol% CaF2 to obtain a raw material dispersion. The resin binder was used at a ratio of 2.5 parts by mass per 100 parts by mass of the total powder. Next, using a spray dryer, the raw material dispersion was sprayed into an air stream, and the dispersion medium was evaporated from the spray droplets to produce granulated powder. That is, granulation was performed by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace, and fired at 900 °C in a vacuum atmosphere for about 30 minutes to obtain granulated sintered powder. The composition of the obtained granulated sintered powder did not change, with YF3 being 71 mol% and CaF2 being 29 mol%, and the average particle size of the particles classified by a sieve or air flow was 26 μm. The granulated sintered powder thus obtained was used as the spraying material No. 13.

[0039] <No.14> First, yttrium fluoride (YF3) powder with an average primary particle size of 2.0 μm and calcium fluoride (CaF2) powder with an average primary particle size of 2.0 μm were dispersed in a dispersion medium together with a resin binder at a ratio of 80 mol% YF3 and 20 mol% CaF2 to obtain a raw material dispersion. The resin binder was used at a ratio of 1.5 parts by mass per 100 parts by mass of the total powder. Next, using a spray dryer, the raw material dispersion was sprayed into an air stream, and granulated powder was produced by evaporating the dispersion medium from the spray droplets. That is, granulation was performed by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace, and fired at 800 °C under an Ar atmosphere for about 60 minutes to obtain granulated sintered powder. The composition of the obtained granulated sintered powder was unchanged with 80 mol% YF3 and 20 mol% CaF2, and the average particle size of the particles classified by a sieve or an air stream was 49 μm. The granulated sintered powder thus obtained was used as the spraying material No. 14.

[0040] <No.15> First, yttrium fluoride (YF3) powder with an average primary particle size of 5.0 μm and calcium fluoride (CaF2) powder with an average primary particle size of 1.0 μm were dispersed in a dispersion medium together with a resin binder at a ratio of 91 mol% YF3 and 9 mol% CaF2 to obtain a raw material dispersion. The resin binder was at a ratio of 1.0 part by mass per 100 parts by mass of the total powder. Next, using a spray dryer, the raw material dispersion was sprayed into an air stream, and granulated powder was produced by evaporating the dispersion medium from the spray droplets. That is, granulation was performed by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace, and fired at 700 °C under an N2 atmosphere for about 240 minutes to obtain granulated sintered powder. The composition of the obtained granulated sintered powder was unchanged with 91 mol% YF3 and 9 mol% CaF2, and the average particle size of the particles classified by a sieve or an air stream was 25 μm. The granulated sintered powder thus obtained was used as the spraying material No. 15.

[0041] <No.16> First, yttrium fluoride (YF3) powder with an average primary particle size of 5.0 μm was dispersed in a dispersion medium together with a resin binder to obtain a raw material dispersion. The resin binder was at a ratio of 1.0 part by mass per 100 parts by mass of the powder. Next, using a spray dryer, the raw material dispersion was sprayed into an air stream, and the dispersion medium was evaporated from the spray droplets to produce granulated powder. That is, granulation was performed by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace, and sintered at 1050 °C under a vacuum atmosphere for about 120 minutes to obtain granulated sintered powder. The composition of the obtained granulated sintered powder was 100 mol% YF3, and the average particle size of the particles classified by a sieve or an air stream was 25 μm. The granulated sintered powder thus obtained was used as the spraying material No. 16.

[0042] <No.17> First, calcium fluoride (CaF2) powder with an average primary particle size of 1.0 μm was dispersed in a dispersion medium together with a resin binder to obtain a raw material dispersion. The resin binder was used at a ratio of 1.5 parts by mass per 100 parts by mass of the powder. Next, using a spray dryer, the raw material dispersion was sprayed into an air stream, and the dispersion medium was evaporated from the spray droplets to produce granulated powder. That is, granulation was performed by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace, and sintered at 1200 °C under a vacuum atmosphere for about 120 minutes to obtain granulated sintered powder. The composition of the obtained granulated sintered powder was 100 mol% CaF2, and the average particle size of the particles classified by a sieve or an air stream was 25 μm. The granulated sintered powder thus obtained was used as the spraying material No. 17.

[0043] <No.18> First, magnesium fluoride (MgF2) powder with an average primary particle size of 4.0 μm was dispersed in a dispersion medium together with a resin binder to obtain a raw material dispersion. The resin binder was used at a ratio of 2.0 parts by mass per 100 parts by mass of the powder. Next, using a spray dryer, the raw material dispersion was sprayed into the air stream, and the granulated powder was produced by evaporating the dispersion medium from the spray droplets. That is, granulation was performed by the spray drying method. Next, the obtained granulated powder was introduced into a multi-atmosphere furnace and fired under the conditions of an Ar atmosphere and 1050 °C for about 60 minutes to obtain a granulated sintered powder. The composition of the obtained granulated sintered powder was 100 mol% of MgF3, and the average particle size of the particles classified by a sieve or an air stream was 25 μm. The granulated sintered powder thus obtained was used as the spraying material No. 18.

[0044] <No.19> First, yttrium fluoride (YF3) powder with an average primary particle size of 0.5 μm, calcium fluoride (CaF2) powder with an average primary particle size of 1.0 μm, and magnesium fluoride (MgF2) powder with an average primary particle size of 5.0 μm were mixed at a ratio of 50 mol% of YF3, 25 mol% of CaF2, and 25 mol% of MgF2 to obtain a mixture. Next, the obtained mixture was introduced into a multi-atmosphere furnace and melted under the conditions of an Ar atmosphere and 1150 °C for about 120 minutes of firing. Then, the melted mass was crushed with a roll jaw crusher or a grinder, and a powder with an average particle size of 30 μm of the particles classified by a sieve or an air stream was obtained. The composition of the obtained powder did not change, with 50 mol% of YF3, 25 mol% of CaF2, and 25 mol% of MgF2. The powder thus obtained was used as the spraying material No. 19.

[0045] <No.20> First, yttrium fluoride (YF3) powder with an average particle size of 30.0 μm, calcium fluoride (CaF2) powder with an average particle size of 30.0 μm, and magnesium fluoride (MgF2) powder with an average particle size of 30.0 μm were mixed at a ratio of 50 mol% of YF3, 25 mol% of CaF2, and 25 mol% of MgF2 to obtain a mixed powder with an average particle size of 30.0 μm. The mixed powder thus obtained was used as the spraying material No. 20.

[0046] <No.21> First, yttrium oxide (Y2O3) powder with an average primary particle diameter of 3.0 μm was dispersed in a dispersion medium together with a resin binder to obtain a raw material dispersion. The resin binder was used at a ratio of 1.0 part by mass with respect to 100 parts by mass of the powder. Next, using a spray dryer, the raw material dispersion was sprayed into an air stream to evaporate the dispersion medium from the spray droplets, thereby producing granulated powder. That is, granulation was performed by the spray drying method. Next, the obtained granulated powder was introduced into an atmospheric firing furnace and fired under atmospheric conditions at 1600 °C for about 300 minutes to obtain granulated sintered powder. The composition of the obtained granulated sintered powder was 100 mol% Y2O3, and the average particle diameter of the particles classified by a sieve or an air stream was 25 μm. The granulated sintered powder thus obtained was used as the thermal spray material No. 21.

[0047] [Formation of Thermal Spray Coating] Thermal spray materials Nos. 1 to 21 were thermally sprayed onto a substrate to form a thermal spray coating. The thermal spraying conditions were as follows. First, as a substrate to be thermally sprayed, a plate (20 mm × 20 mm × 2 mm) made of an aluminum alloy (A6061) was prepared. The thermally sprayed surface of the substrate was subjected to blasting treatment with an alumina abrasive. Thermal spraying was performed by the atmospheric plasma spraying method using a commercially available plasma spraying device (Metco (trademark) F4 Series manufactured by Oerlikon Metco). As the plasma operating gas, argon gas and hydrogen gas were used to generate plasma, and a thermal spray coating with a thickness of 200 μm was formed. For the thermal spray coatings Nos. 1 to 21 thus obtained, the porosity, crystallinity, and erosion rate were examined by the methods shown below. The results are shown in Table 1 together with the composition of each thermal spray material.

[0048] (Porosity) The porosity was calculated by the following method. First, the substrates with each sprayed coating of No. 1 to No. 21 were cut perpendicularly to the surface on which the sprayed coating was formed. After embedding this cut piece in resin and polishing the cross-section generated by the cutting, an image of this coating cross-section was taken using a scanning electron microscope (JSM-IT300LA manufactured by JEOL Ltd.). Next, by analyzing this coating cross-section image using image analysis software (WinROOF2018 manufactured by Mitani Shoko Co., Ltd.), the area of the pore part in the image of the coating cross-section was specified, and the ratio (area %) of the area of the pore part to the entire cross-section was calculated. This calculated value was taken as the porosity. The results are shown in the column of "Porosity" of "Sprayed Coating" in Table 1.

[0049] (Crystallinity) Each sprayed coating of No. 1 to No. 21 was placed on the sample holder of an X-ray diffractometer (SmartLab manufactured by Rigaku Corporation) to obtain a diffraction pattern. Then, based on the obtained diffraction pattern, the scattering integrated intensity of the amorphous phase and the scattering integrated intensity of the crystalline phase were defined, and the crystallinity was calculated from the calculation formula described below. Note that the scattering integrated intensity corresponds to the area of the diffraction peak. "Crystallinity = Scattering integrated intensity of crystalline phase / (Scattering integrated intensity of crystalline phase + Scattering integrated intensity of amorphous phase)" The results are shown in the column of "Crystallinity" of "Sprayed Coating" in Table 1.

[0050] (Erosion rate) After mirror-polishing each sprayed coating of No. 1 to No. 21, it was placed on a silicon wafer installed on the stage inside the chamber of an inductively coupled (ICP) type plasma etching apparatus (RIE-101iPH manufactured by Samco Inc.). Subsequently, plasma was generated using a mixed gas of fluorine-based (CF4), oxygen, and Ar (flow rate ratio 7:1:9) to etch the silicon wafer and the sprayed coating. The exposure time for each plasma was 45 minutes.

[0051] After conducting the plasma exposure test in this manner, the amount of thickness reduction of the silicon wafer and the sprayed coating due to the plasma was measured as the etching amount (erosion amount). The plasma erosion rate of each sprayed coating was converted to a value when the erosion rate of the silicon wafer was set to 100. The amount of thickness reduction of the silicon wafer and the sprayed coating was determined by measuring the step between the central portion of the masked sample and the plasma exposure surface using a laser microscope (manufactured by Keyence Corporation, VK-X250 / X260).

[0052]

Table 1

[0053] The following can be understood from the results in Table 1. In Examples No.1 to No.10, both the spraying material and the sprayed coating satisfy "containing a fluoride of a rare earth element in a proportion of 40 mol% or more and 80 mol% or less", "containing magnesium fluoride in a proportion of 10 mol% or more and 40 mol% or less", "containing calcium fluoride in a proportion of 0 mol% or more and 40 mol% or less", and "the fluoride of the rare earth element being yttrium fluoride".

[0054] Also, in Examples No.1 to No.10, the composite compound constituting the spraying material satisfies "being a granulated powder of yttrium fluoride primary particles, magnesium fluoride primary particles, and calcium fluoride primary particles having an average particle diameter of 5 μm or less, or being a granulated sintered powder obtained by sintering this granulated powder". Therefore, the sprayed coating formed by spraying the spraying materials of No.1 to No.10 under general conditions became a sprayed coating containing a crystalline phase and an amorphous phase, and the porosity of the sprayed coating could be made 2.1 area% or less, and the crystallinity of the sprayed coating could be made 32.7% or more and 71.5% or less. Also, the erosion rate of the formed sprayed coating could be made 15.0% or less. In particular, in No.1 to No.3, No.5, No.6, No.9, and No.10, the erosion rate of the formed sprayed coating could be made 13.0% or less.

[0055] Among the spraying materials of No.1 to No.10, the spraying materials of No.1 to No.6, No.9, and No.10 with an average particle diameter of 40 μm or less were able to reduce the porosity of the sprayed coating to 1.5 area% or less. On the other hand, the sprayed coating formed by spraying the spraying materials of No.11 to No.21 under general conditions had a high crystallinity of 92.7% or more, an erosion rate of 14.6% or more, and in particular, No.12 to No.18 had a high porosity of 2.8 area% or more.

Claims

1. A thermal spraying material comprising a composite compound containing rare earth fluoride in a proportion of 40 mol% or more and 80 mol% or less, magnesium fluoride in a proportion of 10 mol% or more and 40 mol% or less, and calcium fluoride as an essential component, wherein the content ratio of the calcium fluoride is 40 mol% or less.

2. A thermal spraying material comprising a composite compound containing yttrium fluoride in a proportion of 40 mol% or more and 80 mol% or less, magnesium fluoride in a proportion of 10 mol% or more and 40 mol% or less, and calcium fluoride as an essential component, wherein the content ratio of the calcium fluoride is 40 mol% or less.

3. The thermal spraying material according to Claim 1 or 2, wherein the content ratio of the calcium fluoride is 12 mol% or more and 25 mol% or less.

4. The thermal spraying material according to Claim 2 or 3, wherein the composite compound is a granulated powder of yttrium fluoride, magnesium fluoride, and calcium fluoride, the average particle diameter of the primary particles is 10 μm or less, and the average particle diameter of the granulated powder is 5 μm or more and 40 μm or less.

5. The thermal spraying material according to Claim 4, wherein the composite compound is a granulated sintered powder obtained by sintering the granulated powder.

6. A thermal spraying coating containing rare earth fluoride in a proportion of 40 mol% or more and 80 mol% or less, magnesium fluoride in a proportion of 10 mol% or more and 40 mol% or less, and calcium fluoride as an essential component, wherein the content ratio of the calcium fluoride is 40 mol% or less, and the coating contains a crystalline phase and an amorphous phase, and the crystallinity is 1% or more and 75% or less.

7. A thermal spraying coating containing yttrium fluoride in a proportion of 40 mol% or more and 80 mol% or less, magnesium fluoride in a proportion of 10 mol% or more and 40 mol% or less, and calcium fluoride as an essential component, wherein the content ratio of the calcium fluoride is 40 mol% or less, and the coating contains a crystalline phase and an amorphous phase, and the crystallinity is 1% or more and 75% or less.

8. The thermal spraying coating according to Claim 6 or 7, wherein the content ratio of the calcium fluoride is 12 mol% or more and 25 mol% or less.

9. The thermal spraying coating according to any one of Claims 6 to 8, wherein the porosity is 2.0 area% or less.

10. A method for forming a thermal spraying coating, which forms the thermal spraying coating according to any one of Claims 6 to 9 by using the thermal spraying material according to any one of Claims 1 to 5.

11. A component for a plasma etching apparatus, the surface of which is coated with a thermal spray coating according to any one of claims 6 to 9.

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