JP5521184B2 - Method for producing fluoride spray coating coated member - Google Patents

Description

The present invention relates to a method of manufacturing a fluoride spray coating covering member, in particular, the fluoride spray coating covering member even when exposed to the atmosphere such as corrosive halogen gas exhibiting excellent corrosion resistance and resistance to plasma erosion resistance We propose a manufacturing method.

The thermal spraying method uses a gas plasma flame such as Ar or H ₂ or a hydrocarbon combustion flame to soften or melt particles of metal (hereinafter referred to as metal, including alloys), ceramics, cermet, etc. This is one of the surface treatment techniques for spraying onto the surface of the object to be treated (base material) and depositing them to form a film. In this technology, as long as it is a material that softens or melts by heat, not only glass and plastic, but also metals such as tungsten (melting point 3,387 ° C.) and tantalum (melting point 2,996 ° C.) having a high melting point, Al ₂ Oxide ceramics such as O ₃ (melting point: 2,015 ° C.) and MgO (melting point: 2,800 ° C.) can be formed, and there is an advantage that the degree of freedom in selecting the kind of coating material is very large. For this reason, the application using the characteristic of a thermal spray coating has expanded to many industrial fields.

  In addition, the quality of sprayed coatings and spray guns greatly affect the quality of the sprayed coating, and therefore, further improvements and developments are energetically performed along with improvements in quality and productivity. For example, in Patent Document 1, since the metal film particles sprayed in the atmosphere contain a large amount of oxides, air is used as a cause of a decrease in mutual bonding force between particles constituting the film and adhesion with a substrate. A method and apparatus for plasma spraying (reduced pressure plasma spraying) in an excluded low pressure argon gas atmosphere of 50 hPa to 200 hPa are proposed.

  In Patent Document 2, the phenomenon of carbide decomposition or oxidation in a high-temperature heat source, such as carbide cermet particles, is minimized and the kinetic energy of the heat source is used to maximize the flight speed of the carbide particles. A high-speed flame spraying method that shortens the exposure time (temperature) of the particles to the limit is proposed.

  As described above, the quality of the thermal spray coating and the thermal spraying apparatus have been sufficiently studied. However, the examination of the film deposition process of the thermal spray coating is still insufficient. For example, some of the spray particles introduced into the thermal spray heat source completely melt, while others remain unmelted. When these particles are deposited on the surface of the substrate, mutual fusion occurs. Since it becomes incomplete or uneven, there is a problem that voids (pores) are inevitably generated and become apparent as pores of the film.

For example, according to Patent Document 3, it is clarified that Al ₂ O ₃ or Y ₂ O ₃ sprayed coating formed by the low pressure plasma spraying method has pores of about 0.2 to 7%. ing. That is, most of these pores exist as penetrating pores (pores extending from the outside of the coating to the surface of the substrate), and therefore provide a corrosive gas or fluid infiltration path in the environment of use. As a result, the corrosion of the surface of the base material proceeds, causing a decrease in the bonding force between the film and the base material, which causes peeling.

  As described above, since the sprayed coating inevitably has pores, it is encouraged to perform a sealing treatment after the film formation. For example, JIS H 9302 ceramic spraying work standard describes a method in which after a ceramic spray coating is formed, an inorganic or organic polymer sealing agent is applied or sprayed on the surface to fill the pores. ing.

  By the way, the above-mentioned sprayed coating member is subjected to plasma processing in an environment where there is a halogen or halogen compound, and particularly semiconductor processing in which fine particles generated by the plasma processing need to be cleaned and removed. When used in the field of equipment, it is necessary to consider the following surface treatment, and there are some proposals for the prior art for that purpose.

  That is, in processing equipment such as dry etcher, CVD, PVD, etc. used in semiconductor processing and liquid crystal manufacturing processes, processing is required due to the need for microfabrication and higher accuracy associated with higher integration of substrate circuits such as silicon and glass. Higher cleanliness has been demanded as an environment. On the other hand, for various processes for microfabrication, highly corrosive harmful gases such as fluorides and chlorides or aqueous solutions are used. Therefore, the members disposed in these processes have a high corrosion wear rate, and as a result, there is a concern about the generation of corrosion products and secondary environmental contamination due to their scattering.

Semiconductor devices are mainly composed of compound semiconductors composed of Si, Ga, As, P, etc., and many of the manufacturing processes belong to so-called dry processes that are processed in vacuum or reduced pressure. In these environments, various processes such as film formation, impurity implantation, etching, ashing, and cleaning are repeatedly performed. As an apparatus belonging to such a dry process, an oxidation furnace, a CVD apparatus, a PVD apparatus, an epitaxial growth apparatus, an ion implantation apparatus, a diffusion furnace, a reactive ion etching apparatus, piping attached to these apparatuses, a supply / exhaust fan, There are parts and parts such as vacuum pumps and valves. In these devices, the use of highly corrosive chemicals and gases as shown below is known. Basically, fluorides such as BF ₃ , PF ₃ , PF ₆ , NF ₃ , WF ₃ , HF, BCl ₃ , PCl ₃ , PCl ₅ , POCl ₃ , AsCl ₃ , SnCl ₄ , TiCl ₄ , SiH ₂ Cl ₂ , Chloride such as SiCl ₄ , HCl and Cl ₂ , bromide such as HBr, NH ₃ , Cl ₃ F and the like are also frequently used.

In the above-described dry process using a halide, plasma (low temperature plasma) is often used to activate the reaction and improve processing accuracy. In the plasma usage environment, various halides become highly corrosive atomic or ionized F, Cl, Br, and I, and have a great effect on fine processing of semiconductor materials. On the other hand, fine particles of SiO ₂ , Si ₃ N ₄ , Si, W, and the like that are removed by the etching process float from the surface of the semiconductor material subjected to the plasma process (particularly plasma etching process) in the environment. There is a problem in that they adhere to the surface of the device during or after processing, and the quality of the device is significantly reduced.

One of these countermeasures has conventionally been surface treatment with aluminum anodic oxide (alumite). In addition, oxides such as Al ₂ O ₃ , Al ₂ O ₃ .TiO ₂ , Y ₂ O _3, etc., and oxides of Group IIIa metals of the periodic table are sprayed, vapor deposition (CVD, PVD), etc. There are techniques for coating the surface of a device member or using it as a sintered material (Patent Documents 4 to 8).

More recently, plasma erosion resistance is improved by irradiating the surface of the sprayed coating of Y ₂ O ₃ or Y ₂ O ₃ —Al ₂ O ₃ with a laser beam or an electron beam to remelt the surface of the sprayed coating. Techniques for improvement are also disclosed (Patent Documents 9 to 12).

For example, YF ₃ (yttrium fluoride) is used as a material that surpasses the plasma erosion resistance of conventional Y ₂ O ₃ coatings as a means to raise the cleanliness of the manufacturing environment of high-performance semiconductor processing to the limit. The method to apply in is proposed. Specifically, a YF ₃ film is coated on the surface of a sintered body such as YAG or an oxide of a group IIIa element of the periodic table (Patent Documents 13 and 14), Y ₂ O ₃ , Yb ₂ O ₃ , YF A method using a mixture such as ₃ as a film forming material (Patent Documents 15 and 16), and a method using YF ₃ as a film forming material by a thermal spraying method (Patent Documents 17 and 18) can be seen.

Japanese Patent Laid-Open No. 1-139749 Japanese Patent Laid-Open No. 9-67661 JP 2001-164354 A Japanese Patent Publication No. 6-36583 Japanese Patent Laid-Open No. 9-69554 JP 2001-164354 A Japanese Patent Laid-Open No. 11-80925 JP 2007-107100 A Japanese Patent Laid-Open No. 2005-256093 JP 2005-256098 A JP 2006-118053 A JP 2007-217779 A JP 2002-293630 A JP 2002-252209 A JP 2008-98660 A Japanese Patent Laid-Open No. 2005-243988 JP 2004-197181 A JP 2002-037683 A

Regarding fluoride sprayed coatings, in particular, it is required to solve the following technical problems of the prior art.
(1) A film of a fluoride layer such as CeF ₃ or YF ₃ formed by a thermal spraying method is used for each oxide (A1 ₂ O ₃ , Y) in a corrosive action by a halogen gas or a plasma etching environment in a halogen-based gas. ₂ 0 ₃ ) Compared to a film, it shows remarkable durability and has the effect of significantly reducing contamination of the semiconductor processing environment. On the other hand, a common problem with coatings formed by thermal spraying is the presence of through pores.

  For example, in the case of semiconductor processing equipment, through-holes in a sprayed coating are fine particles that are cut out by etching as processing progresses, even if they are dedicated to dry processes such as plasma etching processing. May accumulate in the apparatus, which may make it difficult to produce high quality semiconductor processed products. Therefore, it is necessary to clean the apparatus using acid, alkali, pure water or the like. At the time of such a cleaning operation, these aqueous solutions penetrate into the inside of the coating surface through the through pores, chemically corrode the surface of the base material and the undercoat, and deteriorate the durability of the covering member. There is.

(2) After a ceramic sprayed coating such as Y ₂ O ₃ is formed, the surface of the coating is fluorinated to produce a thin film such as YF _{3 on} the surface of Y ₂ O ₃ particles. The through pores remain in the state at the time of film formation. As a result, although the halogen corrosion resistance is improved, it is easy to enter the inside of cleaning water, etc., so there is a problem that the service life is short due to the occurrence of corrosion inside the coating and the early peeling phenomenon of the sprayed coating resulting from the corrosion. is there.

(3) In the process of spraying fluoride particles such as YF ₃ , CeF ₃ , and MgF ₂ , these particles melt and decompose in a heat source such as a gas plasma or a fossil fuel combustion flame and gasify. Many. Therefore, many voids exist in the particles deposited on the substrate surface due to poor bonding due to the influence of low surface energy peculiar to fluoride in the ejection holes of the decomposition gas and the mutual coupling part between the particles. Therefore, the entire fluoride sprayed coating is a coating with many through pores.

(4) With regard to this point, conventionally, the surface of the oxide ceramic sprayed coating is irradiated with high energy such as an electron beam or a laser beam to melt and fuse the constituent components constituting the sprayed coating. A method for eliminating the through pores has been proposed. This remelting technique of the oxide ceramic sprayed coating can completely eliminate the open pores (including through-holes) on the coating surface and improve the plasma erosion resistance. However, on the high energy irradiated surface, the cracking phenomenon occurs in the coating surface due to the volume shrinkage phenomenon in the cooling process after remelting of the sprayed particles, and this plays a role of a new through-hole. In some cases, there is a problem in that it is impossible to prevent the various chemicals and cleaning water used in the cleaning operation for maintaining the cleanness of the processing environment from entering the coating. In spraying heat source, with respect to the thermal spray coating an aggregate of fluoride particles such as components of high YF _3, AlF ₃ to vaporize or decompose, to the effects and its film quality when subjected to the high-energy irradiation treatment The impact has not been clarified so far.

An object of the present invention is to prior art, particularly to solve the aforementioned problems fluoride sprayed coating are having such YF _3. That is, the surface portion of the fluoride spray coating, and nonporous by remelting treatment by thermal energy irradiation, to propose an advantageous production method of a fluoride spray coating covering member having both good corrosion resistance and resistance to plasma erosion resistance There is.

To achieve the above object, the result of intensive studies, the inventors selected directly on the surface of the substrate, or Al, Al-Ni, Al- Zn, Ni-Cr, from among Ni-Cr-Al Form a porous fluoride sprayed coating composed of fluoride of group IIIa element of the periodic table of elements through an undercoat composed of one or more metallic sprayed coatings , and then coat the surface of the fluoride sprayed coating 120 to 250 and the high-energy irradiation treatment after preheated to ° C., then a fluoride spray coating covering member, characterized in that the densified layer by the cooling to room temperature at a cooling rate of 1 ℃ less per minute We propose a manufacturing method.

In the present invention,
(1) The fluoride sprayed coating has a porosity of 0.2 to 20% and an overall thickness of 30 to 500 μm, and the electron beam is within a range of 0.5 to 8 μm from the surface of the sprayed coating. A densified layer by irradiation or laser beam irradiation treatment,
(2) The undercoat has a thickness of 30 to 150 μm formed of one or more metallic sprayed films selected from Al, Al—Ni, Al—Zn, Ni—Cr, and Ni—Cr—Al. That
(3) The fluoride sprayed coating is one or more fluorides selected from Y and lanthanoid elements having atomic numbers of 57 to 71 ,
However , it is considered to be a more preferable problem solving means.

According to the present invention, the following effects can be expected.
(1) According to the present invention relating to the above-described configuration, the surface layer portion of the sprayed coating is remelted by subjecting the fluoride sprayed coating to electron beam or laser beam irradiation treatment. In addition to the open pores, all the through pores connected through the voids inside the coating can be blocked by the fusion phenomenon, so that the above-described corrosion problem induced by the presence of the pores can be reliably solved.
(2) In particular, according to the present invention, regarding the remelted layer when the fluoride sprayed coating is subjected to the high energy irradiation treatment, the “crack” generated on the irradiated surface of the sprayed coating when this is rapidly cooled is The material is almost completely extinguished by preheating and slow cooling of the material, making it non-porous, further improving the corrosion resistance of the material and further improving the plasma erosion resistance when applied to semiconductor and liquid crystal manufacturing and processing equipment. Can be improved.

It is the figure which showed typically the treatment process for demonstrating this invention. For YF ₃ spray coating, it shows a SEM photograph of the laser beam irradiation surface of the case of changing the preheating and cooling rate. In the figure, (a) is an SEM photograph immediately after the formation of the sprayed coating, (b) is an EM photograph when preheating and slow cooling are not performed in a room temperature environment, and (c) is a high energy irradiation after preheating to 200 ° C. It is a surface SEM photograph at the time of cooling at a rate of 1 ° C per minute.

Hereinafter, preferred embodiments of the present invention will be described. FIG. 1 shows a process flow for carrying out the method of the present invention. Details of the configuration of the present invention will be described below in the order of the steps.
(1) Substrate and pretreatment The substrate applicable to the present invention is Al and its alloys, Ti and its alloys, stainless steel, other alloy steels and carbon steels, metals such as Ni and its alloys, quartz and oxides A sintered body of an inorganic compound made of carbide, boride, silicide, nitride, and a mixture thereof is preferable. Moreover, as a base material used for this invention, what carried out metal plating (electroplating, CVD, PVD) on the surface can also be used.

(2) Method for forming fluoride spray coating on substrate surface As described above, in forming a fluoride spray coating on the substrate surface, it is necessary to comply with the ceramic spraying work standard specified in JIS H9302. It is preferable to perform processing. For example, after removing rust and oils and fats on the surface of the substrate, and then roughening by spraying grinding particles such as Al ₂ O ₃ and SiC, and directly applying a metallic undercoat on the surface, A top coat is formed thereon to form a fluoride spray coating. As a method for coating the fluoride spray coating on the substrate surface, an atmospheric plasma spraying method, a low pressure plasma spraying method, a high-speed flame spraying method, or the like is preferably used, but is not particularly limited.

  The formation of the fluoride spray coating on the substrate is performed directly on the surface or indirectly through an undercoat. As the undercoat, it is preferable to apply a metallic material such as Al, Al—Ni alloy, Al—Zn alloy, Ni—Cr alloy, Ni—Cr—Al alloy to a thickness of 30 to 150 μm.

  These undercoats can be formed by flame spraying, electric arc spraying, high-speed flame spraying, various plasma spraying methods, etc., but other film forming methods may be used.

(3) Fluoride spray material As the spray material for forming a fluoride spray coating used in the present invention, fluoride particles of lanthanoid elements belonging to Y in the periodic table IIIa of elements and atomic numbers 57 to 71 are used. . That is, as the metal elements having atomic numbers 57 to 71, lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium ( Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), and the like.

  As the fluoride spray material made of these metals, a material adjusted to a particle size of 5 to 80 μm is used. The reason for limiting to this particle size is that fine particles of less than 5 μm are decomposed when heated in a thermal spraying heat source, and the particle size is further reduced, so that more particles are scattered than film formation. On the other hand, when the particle size exceeds 80 μm, the feed rate to the spray gun becomes unstable and the pores of the formed film tend to increase.

  The thermal spray coating obtained by thermal spraying the fluoride thermal spray material is preferably applied to a thickness of 30 to 500 μm. The range of 50 to 200 μm is particularly suitable. The reason is that with a film thinner than 30 μm, it is difficult to obtain a film with a uniform film thickness. On the other hand, when it is formed thicker than 500 μm, the residual stress at the time of forming the fluoride film increases, and it is easy to peel off from the substrate. Because.

(4) Features of fluoride spray coating The following are common physicochemical properties of fluoride. That is, this fluoride spray coating has chemical stability against halogen-based gas as compared with metal coatings and ceramic coatings, but the surface energy is small, so the mutual bonding force of fluoride particles constituting the coating and the substrate There is a problem that the adhesion strength of is weak. In addition, since this film has various phenomena such as decomposition (oxidation), vaporization (vaporization), melting, and softening in a thermal spray heat source, it proceeds in an extremely short time (1/100 to 1/1000 seconds). Since it is porous (area ratio 0.2 to 20%) and a large residual stress is generated in the film, the film often peels even if the substrate is slightly deformed. In addition, since the fluoride itself has poor ductility, the film easily “cracks” and, together with the pores generated during the film formation, leads to internal penetration of acid and alkaline cleaning liquids, which causes the corrosion of the substrate. It is easy to become. Therefore, although the corrosion resistance of the fluoride itself is good, there is a problem that the property cannot be effectively used.

(5) High energy irradiation treatment on the surface of the fluoride spray coating In the present invention, the prevention of “cracking” caused by through pores and residual stress existing in the fluoride spray coating coated on the substrate surface. It is important that the surface of the film is subjected to high energy irradiation treatment such as electron beam or laser beam to be remelted to form a dense film. For example, as the high energy irradiation treatment of the present invention, electron beam irradiation or laser beam irradiation under the following conditions is suitable.

(A) Irradiation atmosphere of electron beam irradiation treatment: 1 × 10 ^{−1 to} 5 × 10 ⁻³ MPa inert gas atmosphere irradiation output: 10 to 30 KeV
Irradiation speed: 1-50mm / s
Number of irradiations: 1 to 30 times (continuous or discontinuous)

(B) Laser beam irradiation treatment The surface of the fluoride coating is irradiated with a laser heat source such as a CO ₂ laser, YAG laser, semiconductor laser, or excimer laser to melt the surface of the spray coating. The atmosphere of the laser beam irradiation treatment can be freely selected in the air, in an inert gas, or in a reduced pressure (vacuum). As the laser beam irradiation conditions, the following are recommended.
Laser power: 1-10kW
Beam area: ^{2 to 10} mm ²
Beam scanning speed: 2 to 20 mm / s
Number of irradiation: 1 to 100 times (continuous or discontinuous)

  The surface layer of the thermal spray coating is melted by a high energy irradiation process such as an electron beam or a laser beam. As a result, a dense layer is formed on the surface of the sprayed coating. This dense layer determines the irradiation conditions so that the depth from the surface is about 0.5 to 8 μm. The reason is that a dense layer thinner than 0.5 μm has a small effect on the irradiation treatment, while on the other hand, even if it is thicker than 8 μm, the irradiation effect is saturated and “cracking” tends to occur in the cooling process after remelting. It is.

  Next, when the fluoride sprayed coating is subjected to the above-mentioned high energy irradiation treatment, it is preferable to preheat the substrate to be treated and to cool it slowly after the irradiation. preferable. Specifically, before the high energy irradiation treatment, preheating is performed at a temperature of 120 to 250 ° C., high energy irradiation is performed while maintaining the temperature, and the surface of the fluoride spray coating is remelted. Thereafter, the sprayed coating is preferably slowly cooled at a cooling rate of 1 ° C./min or less. The reason for this is that the thermal conductivity of the fluoride spray coating is small and its ductility is poor. Therefore, after high-energy spraying without preheating, and then naturally cooling down to room temperature (15-30 ° C), the ceramic surface is exposed to the ceramic surface. This is because a “cracking” phenomenon similar to that after remelting of the sprayed coating surface occurs. For this reason, it is desirable to implement each operation of actual preheating-irradiation process-slow cooling in 0.1-10 hPa pressure reduction. This is because, in a reduced pressure atmosphere, irradiation can be performed using the preheating temperature, and the surface of the fluoride sprayed coating can be smoothed and cracking can be prevented without being rapidly cooled even if left as it is. In addition, the high energy irradiation process of the fluoride sprayed coating which concerns on this invention in the Example mentioned later is processed in all the pressure reductions.

FIG. 2 shows SEM photographs of the surface of the fluoride sprayed coating and the high-energy irradiation treatment of the sample immediately after plasma spraying, the one treated with laser at room temperature, and the one subjected to preheating and slow cooling. . FIG. 2A shows the surface state of the YF ₃ plasma sprayed coating formed on the surface of the stainless steel substrate immediately after the plasma spraying treatment. On the surface of this sprayed coating, smooth portions of YF ₃ particles melted by the plasma heat source are seen, while there are many portions where unmelted particles exist in a rough state, and fine cracks are generated. Is observed.

  FIG. 2B shows a state of “cracking” generated when a laser beam is irradiated in a room temperature environment without preheating and gradually cooling the sprayed surface. The laser-irradiated surface has become smooth due to the remelting phenomenon, but “cracking” that appears to have occurred during the cooling and solidification process was observed.

  On the other hand, FIG. 2 (c) shows the surface state when the sprayed coating is preheated to 200 ° C., irradiated with a laser beam, and then cooled at a rate of 1 ° C. per minute. The surface is smooth and “cracking” is not observed. Further, it can be seen that the unmelted particles are also remelted and changed to a shape that is rounded and small, has a smooth surface, and is less susceptible to plasma erosion.

Example 1
In this example, fluoride of YF ₃ , CeF ₃ , ErF ₃ was directly applied to the surface of an SS400 steel test piece (size: width 50 mm × length 70 mm × thickness 3.2 mm) corresponding to the base material by atmospheric plasma spraying. Each sprayed coating was formed to a thickness of 100 μm, and then the surface of the sprayed coating was re-melted by irradiation with high energy, and the presence or absence of through pores in the coating was examined by a ferroxyl test method. As a comparative example, the fluoride spray coating without high energy irradiation treatment and the Y ₂ O ₃ spray coating known as a plasma erosion-resistant spray coating were also subjected to the ferroxyl test using the presence or absence of high energy irradiation as a variable factor. did.

(1) Feroxyl test (base spray test)
In this ferroxyl test, 10 g of potassium hexacyanoferrate (III) and 15 g of sodium chloride were dissolved in 1 liter of distilled water, and this was sufficiently impregnated into a filter paper for analysis, and then this filter paper was affixed to the surface of the test piece. After leaving still for 30 minutes, the filter paper was peeled off, and the presence or absence of blue spots on the filter paper surface was visually judged. According to this method, if there are through-pores in the amorphous membrane, the ferroxyl test solution penetrates, reaches the iron base interface and generates iron ions, and this reacts with potassium hexacyano (III) acid, and filter paper. Can be determined by generating blue spots on the surface of the surface.

(2) Test results The test results are shown in Table 1. As is apparent from the results shown in this table, there are many blue spots because both the fluoride spray coating and the oxide spray coating (Y ₂ O ₃ ) have many through-pores in the coating state. (No. 1, 4, 7, 10). In addition, in oxide sprayed coatings (Nos. 11 and 12), even when high-energy irradiation treatment is performed and the coating surface is re-melted, “cracking” occurs in the coating in the cooling process of the melted part. Although the score was reduced, it was not a complete dense film.
On the other hand, when the fluoride sprayed coating is treated with high energy, the through-pores at the time of film formation disappear due to the remelting phenomenon of the coating, and blue spots are hardly observed, and the inside of acid, alkali, washing water, etc. It was confirmed that there was an intrusion prevention effect.

(Example 2)
In this example, fluoride (YF ₃ , DyF ₃ , CeF ₃ ) was sprayed to a thickness of 80 μm on the surface of an Al base (size: width 50 mm × length 50 mm × thickness 3 mm) by atmospheric plasma irradiation. Thereafter, a re-melting treatment by irradiating the surface with an electron beam or a laser beam was used as a test film, and this was subjected to a plasma etching process to evaluate the erosion resistance of each film. In addition, as a film of the comparative example, Y ₂ O ₃ , Dy ₂ O ₃ , CeO ₂ 12 mass% Y ₂ O ₃ -88 mass% ZrO ₂ sprayed film were also subjected to a plasma etching treatment under the same conditions for comparison.

The plasma etching atmosphere gas composition and conditions are shown below.
(1) Atmospheric gas and flow rate conditions (a) F-containing gas: CHF ₃ / O ₂ / Ar = 80/100/160 (flow rate cm ³ per minute)
(B) CH-containing gas: C ₂ H ₂ / Ar = 80/100 (flow rate cm ³ per minute)
(2) Plasma irradiation output high frequency power: 1300W
Pressure: 4Pa
Temperature: 60 ° C
(3) Plasma etching test atmosphere (a) Conducted in an F-containing gas atmosphere (b) Implemented in a CH-containing gas atmosphere (C) Implemented in an atmosphere in which an F-containing gas atmosphere 1h and a CH-containing gas atmosphere 1h are alternately repeated (Evaluation)
In the evaluation of the plasma erosion resistance test, the plasma erosion resistance and the environmental pollution resistance were investigated by measuring the number of particles of the film component scattered from the test film by the etching process. The particles were measured by measuring the time required for the number of particles having a particle size of 0.2 μm or more attached to the surface of an 8-inch diameter silicon wafer disposed in the test container to reach 30 particles.

(5) Test results The test results are shown in Table 2. As is clear from the results shown in this table, the thermal spray coating of the comparative example (No. 1, 3, 5, 7) shows the time until the particle generation amount exceeds the allowable value. There is little particle generation, and there is a situation in which the amount of F is slightly increased in the F-containing gas and the time to reach the allowable value is shortened. However, it has been found that the number of particles generated in an atmosphere in which F-containing gas and CH-containing gas are alternately repeated is further increased. This is considered to be because the oxide film on the surface of the oxide ceramic film is always in an unstable state and scattered due to the repetition of the oxidizing action of the fluorinated gas and the reducing action of the CH gas in the F-containing gas. On the other hand, the fluoride spray coating (No. 2, 4, 6) maintains a chemically stable state in F-containing gas, CH-containing gas, and these gas alternating atmospheres, and generates particles. It is thought that this was suppressed. In addition, the size of the particles scraped off from the fluoride spray coating by erosion is often about 1/5 to 1/10 smaller than that of oxide ceramic, which also improves the environmental pollution resistance. It is thought that there is.

(Example 3)
In this example, the effect of high energy irradiation treatment to YF ₃ fluoride sprayed coating was examined immersion test and resistance to plasma erosion resistance in an alkaline solution.
(1) Test film Using an Al alloy (A13003) (dimensions: width 50 mm × length 50 mm × thickness 5 mm) as a base material, after blast roughening treatment, YF ₃ was deposited to a thickness of 100 μm by low pressure plasma spraying. After being molded, the surface was irradiated with an electron beam and a laser beam, and remelted.

(2) Corrosion / Damage Test Method In this example, as a corrosion resistance test for chemicals, the test film was immersed in a 5% NaOH aqueous solution for 1 hour at 40 ° C., and hydrogen gas bubbles were generated from the surface of the film. The film was examined for the denseness of the film by visual observation. In this test, a chemical resistant paint was applied to the exposed portion of the base material, and an aqueous NaOH solution was prepared so as to enter the inside from the surface of the coating. If the NaOH aqueous solution enters inside from the pores of the film, this reacts with the base material (Al alloy) as shown in the following formula (1) to generate hydrogen gas. Because.
Al + NaOH + H ₂ O → NaAlO ₂ + 3 / 2H ₂ (1)
The plasma erosion resistance test was evaluated under the same conditions as in the F-containing gas of Example 2. As a comparative film of this example, Y ₂ O ₃ was deposited by low-pressure plasma spraying, and then the surface was irradiated with an electron beam and a laser beam, and subjected to NaOH immersion and plasma erosion tests under the same conditions. did.

(3) Test results Table 3 shows the test results. As is clear from the results shown in this table, when the YF ₃ coating (No. 1, 4) of the comparative example is immersed in 5% NaOH solution, the Al alloy of the base material passes through the pores of the coating after about 5 minutes. A small hydrogen gas bubble was generated by erosion by the NaOH solution that had entered through. On the other hand, in the test films (No. 2, ₃ , 5, 6) in which the surface of the YF ₃ sprayed coating was subjected to high energy irradiation treatment, generation of hydrogen gas was not observed and the coating surface was densified. Was confirmed. On the other hand, in the Y ₂ O ₃ film of the comparative example, generation of hydrogen gas was confirmed not only in the film formation state but also in all the high energy irradiated (Nos. 7 to 12), and it was found that the density was poor. .
On the other hand, in the loss amount by the plasma erosion test, the Y ₂ O ₃ film (No. 7, 10) of the comparative example shows an erosion amount of about 6.1 to 6.3 μm. It is reduced to about 2.2 μm and exhibits a great effect in improving plasma erosion resistance. On the other hand, the fluoride sprayed coating according to the present invention exhibits even higher plasma erosion resistance regardless of the presence or absence of the high energy irradiation treatment, and particularly the test coating (No. 2, 3, 5 and 6) show that the amount of loss is much smaller and the contamination in the semiconductor processing apparatus can be greatly reduced.

Example 4
In this example, the plasma erosion resistance of the fluoride sprayed coating according to the present invention was investigated.
(1) Test coating A3003 (dimensions: width 50 mm × length 50 mm × thickness 5 mm) defined by JIS H4000 is used as a base material, and the surface is YF ₃ by atmospheric plasma spraying and EuF ₃ by 80 μm by low pressure plasma spraying. In the case where an undercoat (Ni-20 mass% Cr) was applied to a thickness of 30 μm prior to the formation of the fluoride spray coating, the presence or absence of the influence was investigated.
The surface of the above-mentioned fluoride sprayed coating was remelted by irradiating an electron beam and a laser beam. In addition, the fluoride sprayed coating which does not implement high energy irradiation was prepared as a film of a comparative example.

(2) Plasma erosion resistance test method The plasma erosion resistance test was performed under the same conditions in the F-containing gas atmosphere of Example 2, and the test method was evaluated using the same method as in Example 3.

(3) Test results Table 4 shows the test results. As is apparent from the results shown in this table, the comparative example fluoride spray coating (No. 1, 4, 7, 10) has a large plasma erosion loss amount regardless of the presence or absence of the undercoat. It reached 2.7 μm. On the other hand, in the coating (No. 2, 3, 5, 6, 8, 9, 11, 12) in which the surface of the fluoride spray coating is subjected to high energy irradiation treatment, the loss amount is about 0.6 to 0.8 μm. As a result, excellent plasma erosion resistance was confirmed.
In addition, the amount of erosion loss is slightly higher in the porous fluoride spray coating (No. 1, 4) formed by the atmospheric plasma spraying method than in the low-pressure plasma spray coating with a low porosity. From this, it can be seen that the porosity of the fluoride sprayed coating has an effect on this kind of plasma erosion resistance, and it is recognized that the irradiated surface is smooth and the irradiated surface is not the target of concentrated impact of plasma particles. It is done.

  The technology according to the present invention can be applied to a member for a precision processing apparatus of a semiconductor that requires high halogen corrosion resistance and plasma erosion resistance. Specifically, using a processing gas containing halogen and its compound, in addition to the Teppo shield, baffle plate, focus ring, insulator ring, sill ring, bellows cover, electrode, etc., which are disposed in the plasma-treated apparatus, It can be used as a corrosion-resistant film for chemical plant equipment members having similar gas atmospheres.

Claims (3)

Directly on the surface of the substrate, or Al, Al-Ni, Al- Zn, Ni-Cr, via an undercoat consisting of one or more metallic thermal spray coating selected from among Ni-Cr-Al, element A porous fluoride sprayed coating composed of a fluoride of a group IIIa element of the periodic table is formed, and then the surface of the fluoride sprayed coating is preheated to 120 to 250 ° C. , followed by high energy irradiation treatment, and then 1 method for producing a fluoride spray coating covering member, characterized in that the densified layer by the cooling to room temperature at 1 ℃ less cooling rate per minute. The fluoride sprayed coating has a porosity of 0.2 to 20% and an overall thickness of 30 to 500 μm. Of these, the range from the sprayed coating surface to 0.5 to 8 μm is irradiated with an electron beam or method for producing a fluoride spray coating covering member according to claim 1, wherein the laser beam is densified layer produced by irradiation treatment. The said fluoride sprayed coating is 1 or more types of fluoride chosen from Y and the lanthanoid type | system | group element of atomic number 57-71, The manufacture of the fluoride sprayed coating coating member of Claim 1 or 2 characterized by the above-mentioned. Method.

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