Method for forming thermal spraying film and method for producing thermal spraying material

Abstract

The present invention provides a technology for forming a thermal spraying film that achieves both suppression of particles and plasma resistance.　This method for forming a thermal spraying film comprises: a step for preparing a powder of an Si / SiC composite material; and a step for thermally spraying the powder onto a base material through plasma spraying.

Description

Method for forming thermal spray coating and method for preparing thermal spray material

[0001] This disclosure relates to a method for forming a thermal spray film and a method for preparing a thermal spray material.

[0002] Patent Document 1 discloses a technique for coating components inside a chamber with thermal spray ceramics in a plasma etching apparatus.

[0003] Special Publication No. 2022-542655

[0004] In one aspect, this disclosure provides a technology for forming a thermal spray coating that achieves both particle suppression and plasma resistance.

[0005] To solve the above problems, according to one embodiment, a method for forming a thermal spray film is provided, comprising the steps of preparing a powder of a Si / SiC composite material and thermal spraying the powder onto a substrate by plasma spraying.

[0006] From one perspective, this technology can provide a method for forming a thermal spray coating that achieves both particle suppression and plasma resistance.

[0007] An example of a diagram illustrating the configuration of a plasma spraying apparatus. An example of a flowchart showing the spray film formation method according to this embodiment. A schematic diagram illustrating the spray film formation method according to this embodiment. An example of a graph showing the relationship between the distance from the nozzle tip of the spray gun and the powder temperature. An example of a graph showing the relationship between the distance from the nozzle tip of the spray gun and the powder velocity.

[0008] Various exemplary embodiments will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts will be denoted by the same reference numerals.

[0009] [Plasma spraying apparatus 100] First, the plasma spraying apparatus 100 that forms a sprayed film 320 (see Figure 3(c) described later) on the substrate 200 will be explained using Figure 1. Figure 1 is an example of a diagram illustrating the configuration of the plasma spraying apparatus 100.

[0010] The plasma spraying apparatus 100 comprises a chamber 10, a support section 11, a pressure gauge 12, a spray plasma generation section 20, an exhaust section 30, and a control section 40. The plasma spraying apparatus 100 is a film deposition apparatus that forms a sprayed film (a Si / SiC composite sprayed film 320, described later) on a substrate 200.

[0011] The chamber 10 is an airtight container. The support 11 is provided inside the chamber 10. The support 11 supports the base material 200. The support 11 may also be configured to be movable. The movement of the support 11 is controlled by the control unit 40. The pressure gauge 12 detects the pressure inside the chamber 10. The detected pressure is transmitted to the control unit 40.

[0012] The thermal spray plasma generation unit 20 includes a gas supply unit 21, a feeder 22, a thermal spray gun 23, and a power supply 24.

[0013] The gas supply unit 21 supplies plasma ignition gas and raw material powder transport gas to the feeder 22. The plasma ignition gas and raw material powder transport gas are Ar, He, H ２ , N ２ Any of the following gases can be used. The feeder 22 contains the raw material powder. The feeder 22 supplies the raw material powder to the thermal spray gun 23 along with the gas supplied from the gas supply unit 21. The power supply 24 supplies power for plasma generation to the thermal spray gun 23.

[0014] The thermal spray gun 23 ignites the plasma using plasma ignition gas supplied from the feeder 22 and electricity for plasma generation supplied from the power supply 24. The thermal spray gun 23 also melts or semi-melts the raw material powder supplied with the transport gas using the heat of the plasma, and imparts kinetic energy to release the thermal spray plasma P, which contains molten droplets flying at high speed, into the chamber 10. By spraying the molten raw material droplets onto the substrate 200, a thermal spray film is formed on the surface of the substrate 200.

[0015] The exhaust section 30 is connected to the exhaust port 10e of the chamber 10 and exhausts the gas inside the chamber 10. The exhaust section 30 includes a vacuum pump 31, a pressure control valve 32, and an exhaust pipe 33. The exhaust pipe 33 connects the exhaust port 10e and the vacuum pump 31. Also, the pressure control valve 32 is provided in the exhaust pipe 33.

[0016] The control section 40 controls the entire plasma spraying apparatus 100. Specifically, the control section 40 controls the gas supply section 21, the feeder 22, and the power source 24 to generate the spraying plasma P. Also, the control section 40 controls the support section 11 to control the position irradiated with the spraying plasma P. Further, the control section 40 controls the vacuum pump 31 and the pressure control valve 32 based on the pressure detected by the pressure gauge 12, thereby controlling the atmosphere and pressure inside the chamber 10.

[0017] [Sprayed film] In a plasma etching apparatus that generates plasma of an etching gas and performs an etching process on a substrate, components (base material 200) inside the plasma processing chamber are coated with a protective film for protecting the components (base material 200) from the plasma. As the protective film, for example, a sprayed film having plasma resistance is used. As the sprayed film having plasma resistance, generally, Al ２ O ３ , Y ２ O ３ and the like sprayed films are used.

[0018] By the way, when using a sprayed film such as Al ２ O ３ , Y ２ O ３ and the like as the protective film for coating the components (base material 200), there is a possibility that particles containing metal atoms such as aluminum (Al) and yttrium (Y) are generated due to ion sputtering or the like from the plasma to the components (base material 200). Also, there is a problem that particles containing metal atoms such as aluminum (Al) and yttrium (Y) may adhere to the substrate processed in the plasma etching apparatus.

[0019] As a protective film that does not contain metal atoms, it is conceivable to use a Si thermal spray film. When a Si thermal spray film is used as a protective film to cover a component (substrate 200), even if particles are generated by ion sputtering from the plasma onto the component (substrate 200), the particles can be vaporized with a fluorine (F)-containing gas (xF: x represents an unspecified atom, etc.) (Si + xF → SiF ｙ ↑: y indicates the number of unspecified atoms. ) This makes it possible to suppress the influence of particles on the substrate processed in the plasma etching apparatus. On the other hand, the Si thermal spray film is Al ２ O ３ , Y ２ O ３ Compared to other thermal spray coatings, it has the drawbacks of low plasma resistance and a high wear rate.

[0020] SiC, for example, is a suitable material for forming protective films that achieve both particle suppression and plasma resistance.

[0021] For example, as an etching gas, CF ４ When an etching gas plasma is generated using a gas, if the silicon film (Si) consumption rate is normalized to 1, for example, silicon oxide film (SiO ２ The wear rate of the ) is approximately 5, while the wear rate of the silicon carbide film (SiC) is approximately 0.75.

[0022] Also, as an etching gas, CF ４ Ar, O ２ When an etching gas plasma is generated using a mixed gas, if the silicon film (Si) consumption rate is normalized to 1, for example, silicon oxide film (SiO ２ The wear rate of ) is approximately 3, while the wear rate of silicon carbide film (SiC) is approximately 0.6.

[0023] Furthermore, when an etching gas plasma is generated under the etching conditions for a polysilicon film, if the silicon film (Si) consumption rate is normalized to 1, for example, the silicon oxide film (SiO ２ The wear rate of ) is approximately 0.45, and the wear rate of silicon carbide film (SiC) is approximately 0.46.

[0024] Thus, under each etching condition, the consumption rate of the silicon carbide film (SiC) is lower than that of the silicon film (Si). In other words, silicon carbide film (SiC) has higher plasma resistance than silicon film (Si). Furthermore, by using a silicon carbide film (SiC) that does not contain metal atoms as a protective film, the influence of particles on the substrate can be suppressed.

[0025] Incidentally, in plasma spraying using the plasma spraying apparatus 100 shown in Figure 1, a sprayed film is formed by partially melting the raw material powder and spraying it onto a component (substrate 200). Here, if SiC is used as the raw material powder for the sprayed film, it remains solid SiC up to about 2830°C, and then decomposes into droplets of liquefied silicon (Si) and solid graphite (C) at about 2830°C. The sprayed film formed from these droplets is a film in which graphite (C) is embedded in the silicon (Si) sprayed film. For this reason, it is difficult to form a sprayed film with materials that decompose or sublimate without melting at high temperatures, such as SiC.

[0026] Furthermore, in the case of plasma spraying under an atmospheric environment, SiC is in the atmosphere of O ２ It may react with other substances and become oxidized.

[0027] Furthermore, a method of forming a SiC protective film on the component (substrate 200) using CVD (chemical vapor deposition) is also conceivable. However, compared to the method of forming a protective film by thermal spraying, the CVD method has several drawbacks, including increased construction costs, a lower film deposition rate (longer construction time), and difficulty in achieving thicker films.

[0028] [Method for Forming Thermal Spray Film] Next, a method for forming a thermal spray film that achieves both particle suppression and plasma resistance will be explained using Figures 2 and 3. Figure 2 is an example of a flowchart showing the thermal spray film formation method according to this embodiment.

[0029] In step S101, a powder made of a Si and SiC composite material (hereinafter referred to as "Si / SiC composite material") is prepared.

[0030] Here, a powder of the Si / SiC composite material is supplied to the feeder 22 as the raw material powder.

[0031] Here, an example of a method for producing a powder of the Si / SiC composite material will be described. The Si / SiC composite material is composed of a plurality of Si phases made of Si crystals and a plurality of SiC phases made of SiC crystals. For example, it can be formed by impregnating a SiC ceramic porous body with metallic silicon. By pulverizing the Si / SiC composite material to form a powder, a powder of the Si / SiC composite material can be produced.

[0032] The powder of the Si / SiC composite material is preferably a powder having a particle size of, for example, 1 μm or more and 100 μm or less. In order to make the distribution of the SiC phase in the Si / SiC composite sprayed film formed by spraying uniform, it is preferable that the ratio of the Si phase to the SiC phase in each powder is somewhat equal. Further, since the Si / SiC composite sprayed film formed by spraying preferably contains more SiC phases having higher plasma resistance than Si, the ratio of the SiC phase in one powder particle is preferably larger than the ratio of the Si phase. For example, the ratio of SiC in one powder particle is preferably in the range of 75% or more and 95% or less. Also, in the Si / SiC composite material obtained by impregnating a SiC ceramic porous body serving as the base powder with metallic silicon, the size of the SiC phase needs to be smaller than the particle size of the powder to be produced.

[0033] When a sprayed film is formed using a mixed powder of Si powder and SiC powder, only Si melts without SiC melting, and thus a sprayed film of Si is formed. Also, when a sprayed film is formed using a powder of a composite material of Si and C (Si / C composite material), a film in which C rather than SiC enters the sprayed film is formed. Therefore, in the present embodiment, a sprayed film is formed from a powder made of the Si / SiC composite material.

[0034] The Si / SiC composite material is composed of a plurality of Si phases made of Si crystals and a plurality of SiC phases made of SiC crystals. These plurality of Si phases and plurality of SiC phases have different sizes and are randomly arranged. That is, in any cross-section, there are a plurality of Si phases with different sizes (areas) and a plurality of SiC phases with different sizes (areas). The average size of the Si phase or SiC phase can be adjusted by the method of manufacturing the Si / SiC composite material or the like. For example, by adjusting the porosity of the SiC ceramic porous body or the like, the average size of the Si phase or SiC phase can be adjusted. Thereby, the average size of the Si phase or SiC phase can be, for example, about 10 μm.

[0035] When the size of the SiC phase is generally 10 μm or less, if it is processed into a powder with a particle size larger than the size of the phase, for example, about several tens of μm, the ratio of Si to SiC in each powder can be made somewhat uniform.

[0036] In other words, the Si / SiC composite material before pulverization contains a Si phase and a SiC phase with an average particle size being the first particle size. Let the average particle size in the powder of the Si / SiC composite material after pulverization be the second particle size. In this case, it is preferable that the second particle size is larger than the first particle size.

[0037] Further, it is preferable that the second particle size is 2 times or more and 100 times or less of the first particle size. Thereby, the ratio of Si to SiC in each powder can be made somewhat uniform.

[0038] In step S102, the powder is sprayed by the plasma spraying method.

[0039] Here, a base material 200 (a component used in a plasma etching apparatus and arranged in a plasma processing chamber) is set on a support portion 11 in the chamber 10. Further, the control unit 40 controls the vacuum pump 31 to exhaust the gas in the chamber 10. Further, the control unit 40 detects the pressure in the chamber 10 with the pressure gauge 12 and controls the pressure control valve 32 based on the detected pressure in the chamber 10 so that the pressure in the chamber 10 becomes a predetermined pressure.

[0040] Furthermore, the control unit 40 controls the gas supply unit 21 to supply plasma ignition gas and raw material powder transport gas to the thermal spray gun 23 via the feeder 22. As a result, the thermal spray gun 23 is supplied with plasma ignition gas, transport gas, and raw material powder (Si / SiC composite material powder). The control unit 40 also controls the power supply 24 to supply power for plasma generation to the thermal spray gun 23. As a result, thermal spray plasma P is released from the thermal spray gun 23 into the chamber 10.

[0041] Here, the plasma spraying apparatus 100 generates spray plasma P from the spraying gun 23 with the chamber 10 as a deoxygenated atmosphere. For example, in the chamber 10 ２ The concentration is preferably 100 ppm or less.

[0042] Furthermore, the temperature of the raw material powder (Si / SiC composite material powder) in the thermal spray plasma P is higher than the melting point of Si (1404°C) (1404°C + α). Also, the temperature of the raw material powder (Si / SiC composite material powder) in the thermal spray plasma P is sufficiently lower than the temperature at which SiC decomposes (2830°C).

[0043] Furthermore, the pressure inside the chamber 10 may be atmospheric pressure, reduced to less than atmospheric pressure, or increased to more than atmospheric pressure. In other words, the plasma spraying apparatus 100 may form a sprayed film on the substrate 200 using any of the following methods: atmospheric pressure plasma spraying, reduced pressure plasma spraying, or pressurized plasma spraying.

[0044] Furthermore, in order to densely form a non-melting SiC film, it is preferable to spray the thermal spray plasma P onto the surface of the substrate 200 at high speed. For this reason, it is preferable that the plasma spraying apparatus 100 is a reduced-pressure plasma spraying apparatus that reduces the pressure inside the chamber 10 to below atmospheric pressure.

[0045] In step S103, a Si / SiC composite thermal spray film is formed.

[0046] Here, the control unit 40 moves the support portion 11 that supports the substrate 200 to form a thermal spray film on a desired surface of the substrate 200. Although this has been described as moving the support portion 11 relative to the thermal spray gun 23, it is not limited to this configuration, and the thermal spray gun 23 may be moved relative to the support portion 11.

[0047] Figure 3 is a schematic diagram illustrating the thermal spray coating method according to this embodiment.

[0048] Figure 3(a) schematically shows the Si / SiC composite material powder 300 prepared in step S101. As described above, the Si / SiC composite material powder 300 has a Si phase and a SiC phase.

[0049] Figure 3(b) schematically shows the Si / SiC composite material droplet 310 in the thermal spray plasma P generated in step S102. The powder 300 is heated by the thermal spray plasma P. This forms a Si / SiC composite material droplet 310 having molten Si 311 and solid SiC 312.

[0050] Figure 3(c) schematically shows the Si / SiC composite thermal spray film 320 formed on the surface of the substrate 200 in step S103. The Si / SiC composite thermal spray film 320 is formed on the surface of the substrate 200 by spraying droplets 310 of the Si / SiC composite material, which has molten Si 311 and solid SiC 312, onto the surface of the substrate 200 at high speed. The Si / SiC composite thermal spray film 320 has a Si phase 321 and a SiC phase 322.

[0051] Figure 4 is an example of a graph showing the relationship between the distance from the nozzle tip of the thermal spray gun 23 and the powder temperature. The horizontal axis represents the distance from the nozzle tip of the thermal spray gun 23 [cm]. The vertical axis represents the temperature of the raw material powder [K]. Profile 411 in reduced-pressure plasma spraying is shown as a solid line, and profile 412 in atmospheric pressure plasma spraying is shown as a dashed line.

[0052] In atmospheric pressure plasma spraying, the powder temperature is high near the nozzle of the spray gun 23, and decreases as it moves away from the nozzle. In contrast, in reduced pressure plasma spraying, the temperature remains relatively constant compared to atmospheric pressure plasma spraying.

[0053] By using reduced-pressure plasma spraying, the Si phase can be melted from the Si / SiC composite material, while the SiC layer can be solidified. Furthermore, the decomposition of the SiC phase into silicon (Si) and graphite (C) can be suppressed.

[0054] Figure 5 is an example of a graph showing the relationship between the distance from the nozzle tip of the thermal spray gun 23 and the powder velocity. The horizontal axis represents the distance from the nozzle tip of the thermal spray gun 23 [cm]. The vertical axis represents the velocity of the raw material powder [m / s]. Profile 421 in reduced-pressure plasma spraying is shown as a solid line, and profile 422 in atmospheric pressure plasma spraying is shown as a dashed line.

[0055] In reduced-pressure plasma spraying, the powder velocity can be increased compared to atmospheric pressure plasma spraying. By increasing the powder velocity, a dense Si / SiC composite sprayed film 320 can be formed.

[0056] As described above, according to the thermal spray film formation method of this embodiment, a Si / SiC composite thermal spray film 320 having a Si phase 321 and a SiC phase 322 can be formed on a substrate 200 (a component used in a plasma etching apparatus and placed in a plasma processing chamber).

[0057] The Si / SiC composite thermal spray coating 320 is made of Al ２ O ３ , Y ２ O ３ Compared to other thermal spray coatings, it can suppress particles. Even if Si particles are generated, they can be vaporized with a fluorine (F)-containing gas. Even if C particles are generated, they can be vaporized with a fluorine (F)-containing gas or an oxygen (O)-containing gas. This makes it possible to suppress the influence of particles on the substrate processed in a plasma etching apparatus. In other words, by using a Si / SiC composite thermal spray coating 320 that does not contain metal atoms such as aluminum (Al) or yttrium (Y) as a protective film, the influence of particles on the substrate can be suppressed.

[0058] Furthermore, the Si / SiC composite thermal spray film 320 exhibits improved plasma resistance compared to the Si thermal spray film. As mentioned above, under various etching conditions, the silicon carbide film (SiC) has higher plasma resistance than the silicon film (Si). Therefore, the Si / SiC composite thermal spray film 320, which has a Si phase 321 and a SiC phase 322, exhibits improved plasma resistance compared to the Si thermal spray film.

[0059] Therefore, the Si / SiC composite thermal spray film 320 can achieve both particle suppression and plasma resistance.

[0060] It should be noted that the present invention is not limited to the configurations shown in the above embodiments, including combinations with other elements. These aspects can be modified without departing from the spirit of the present invention and can be appropriately determined according to their application.

[0061] The embodiments disclosed above include, for example, the following aspects: (Note 1) A method for forming a thermal spray film, comprising the steps of: preparing a powder of a Si / SiC composite material; and thermal spraying the powder onto a substrate by plasma spraying. (Note 2) The method for forming a thermal spray film according to Note 1, wherein the particle size of the powder is 1 μm or more and 100 μm or less. (Note 3) The method for forming a thermal spray film according to Note 1 or Note 2, wherein the thermal spraying is performed in a reduced pressure atmosphere. (Note 4) The thermal spraying is O ２A method for forming a thermal spray film according to any one of Appendix 1 to Appendix 3, wherein the method is carried out in a deoxygenated atmosphere with a concentration of 100 ppm or less. (Appendix 5) A method for forming a thermal spray film according to any one of Appendix 1 to Appendix 4, wherein the powder is heated by the plasma spray to form droplets having molten Si and solid SiC. (Appendix 6) A method for preparing a thermal spray material, comprising the steps of: preparing a Si / SiC composite material containing a Si phase and a SiC phase having an average particle size of a first particle; and pulverizing the Si / SiC composite material to produce a powder having an average particle size of a second particle, wherein the second particle size is larger than the first particle size. (Appendix 7) A method for preparing a thermal spray material according to Appendix 6, wherein the second particle size is twice or more the size of the first particle size. (Note 8) The step of preparing the Si / SiC composite material is the method for preparing a thermal spray material according to Note 6 or Note 7, wherein the step of preparing the Si / SiC composite material is to impregnate a porous SiC ceramic body with metallic silicon to form the Si / SiC composite material.

[0062] Furthermore, this application claims priority based on U.S. Patent Application No. 63 / 700,808, filed on September 30, 2024, and the entire contents of these Japanese patent applications are incorporated herein by reference.

[0063] 10 Chamber 11 Support section 20 Thermal spray plasma generation section 21 Gas supply section 22 Feeder 23 Thermal spray gun 24 Power supply 30 Exhaust section 31 Vacuum pump 32 Pressure control valve 40 Control section 100 Plasma spraying apparatus 200 Substrate 300 Powder 310 Droplets 320 Si / SiC composite thermal spray film 321 Si phase 322 SiC phase P Thermal spray plasma

Claims

1. A method for forming a thermal spray film, comprising the steps of: preparing a powder of a Si / SiC composite material; and thermal spraying the powder onto a substrate by plasma spraying.

2. The method for forming a thermal spray film according to claim 1, wherein the particle size of the powder is 1 μm or more and 100 μm or less.

3. The thermal spraying method according to claim 1, wherein the thermal spraying is performed in a reduced-pressure atmosphere.

4. The thermal spraying is O ２ The method for forming a thermal spray film according to claim 1, which is carried out in a deoxygenated atmosphere with a concentration of 100 ppm or less.

5. The method for forming a thermal spray film according to claim 1, wherein the powder is heated by the plasma spray to form droplets having molten Si and solid SiC.

6. A method for producing a thermal spray material, comprising the steps of: preparing a Si / SiC composite material containing a Si phase and a SiC phase having an average particle size of a first particle; and pulverizing the Si / SiC composite material to produce a powder having an average particle size of a second particle, wherein the second particle size is larger than the first particle size.

7. The method for preparing a thermal spray material according to claim 6, wherein the second particle size is at least twice the first particle size.

8. The method for preparing a thermal spray material according to claim 6, wherein the step of preparing the Si / SiC composite material is to impregnate a porous SiC ceramic body with metallic silicon to form the Si / SiC composite material.

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