JP2006265619A - Corrosion resistant member and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems with members used for a CVD system, plasma treatment system, etc., such as consumption of the members by reaction with corrosive gases or etching with plasma, contamination of products due to particle generation, and degradation in a yield and productivity, and also, a high cost of glass having resistance to the corrosive gases and plasma. <P>SOLUTION: The corrosion resistant member comprises a base material and a sprayed coating formed thereon. The corrosion resistant member comprising the sprayed coating composed of Si, O, N and group 2a element, and at least one element selected from the group consisting of B, Zr and Ti has high corrosion resistance to corrosive gas and plasma and heat resistant strength, and has reduced generation of particles. The corrosion resistant member can be produced, e.g., by thermally spraying a powdery mixture of silicon nitride, silica, group 2a element oxide powder and zirconia powder on a base material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a member used for a CVD (Chemical Vapor Deposition) apparatus, a plasma processing apparatus (plasma etching apparatus), etc. in the manufacture of semiconductors and the like, and in particular, a corrosion-resistant member comprising a sprayed film having high corrosion resistance against corrosive gas or plasma. It is about.

Corrosive gas is frequently used for plasma etching in the manufacturing process of semiconductors and the like and for cleaning of CVD apparatuses. For these corrosive gases, fluorine-based or chlorine-based gases are used. CF ₄ , C ₂ F ₆ , C ₃ F ₈ , CHF ₃ / CF ₄ , SF _6, etc. are used for the fluorine-based gas, and Cl ₂ , BCl ₃ , CCl _4, etc. are used for the chlorine-based gas. Yes. It has also been proposed to use HF, F ₂ , NF ₃ .

  Quartz, alumina, ceramics such as aluminum nitride, and metals such as aluminum and stainless steel are used for the parts that come into contact with the gas or plasma containing the gas, such as containers, inner walls, and components of such corrosive gases. Has been. However, these members have a problem that they are consumed in a short time and cause generation of particles in the apparatus.

For example, a quartz member reacts with fluorine gas to produce SiF ₄ and sublimates and wears out. Also, in ceramic members such as alumina and aluminum nitride, aluminum fluoride AlF ₃ is difficult to sublimate, but wear due to physical sputtering occurs, and at the same time, it is selectively corroded at grain boundaries and pores of members such as plasma. Proceeds, and particles are generated by dropping the crystal particles.

  As a method for solving such a problem, glass composed of Si—Al—O—N element is used as a method for improving the corrosion resistance by eliminating the grain boundaries and simultaneously introducing nitrogen while eliminating the grain boundaries. Has been proposed (see, for example, Patent Document 1). However, since a reducing atmosphere or an inert atmosphere is necessary to produce these corrosion-resistant glasses, the apparatus becomes large-scale, and as a result, the corrosion-resistant members tend to be expensive. In addition, this composition does not always have sufficient corrosion resistance.

  On the other hand, a technique for forming a sprayed film on the surface of the base material in order to protect the base material is known, and it is conceivable to spray and coat the above-mentioned corrosion-resistant glass on the base material. However, with the conventional spraying technique, it is difficult to form a dense nitrogen-containing sprayed film, and the formation of a protective film by conventional spraying has mainly used metal or oxide ceramics.

As a prior art for producing a sprayed film containing nitrogen, for example, a mixed powder of AlN, SiO ₂ and MgO is sprayed on Si ₃ N ₄ , Al ₂ O ₃ and Y ₂ O ₃ by explosion spraying to form an amorphous layer And YAG layer forming technology (for example, see Non-Patent Document 1) and explosive spraying of β sialon and χ sialon powder obtained by heat treatment of mixed powder of Si ₃ N ₄ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ A silicon nitride sprayed film formed by the method described above and a mixed powder of Si ₃ N ₄ , Al ₂ O ₃ , Y ₂ O ₃ formed by α spraying silicon nitride by plasma spraying have been reported. However, since these sprayed films have a high melting point, the sprayed powder does not melt well and adheres to the substrate, resulting in weak bonds between the individual particles of the sprayed film, increasing the number of pores, and low density. During plasma etching, corrosion progresses selectively at the grain boundaries and pores of the sprayed film, and particles are likely to be generated due to dropping of crystal grains. Further, the corrosion resistance of the sprayed film to the corrosive gas and plasma was not sufficient. Furthermore, the apparatus used for explosive spraying is expensive, the deposition efficiency of the sprayed film is poor, and the metal substrate such as aluminum may be deformed by the wind pressure at the time of the explosion.

  In other words, there is a need for further improvement in the technology for producing a sprayed film having a very high corrosion resistance, in which individual particles are well bonded with a dense nitrogen-containing material using a general spraying method. Therefore, there has been a demand for a corrosion-resistant member that does not generate particles due to falling off of crystal particles during plasma etching and has good corrosion resistance against corrosive gas or plasma.

JP-A-11-228172 R. B. Heimann, S .; Thiele, L.M. M.M. Berger, M.M. Herrmann, M.M. Nebelung, B.M. Wielage, T.W. M.M. Schnick, P.A. Vuoristo, “Thermally Sprayed Silicon Nitride-Based Coatings on Steel for Application in Severe Operation Environments: Preliminary Results Vs. 26,389 (1998)

As described above, in the process using a corrosive gas or plasma in the semiconductor manufacturing process, there are problems such as generation of particles due to corrosion of members, product contamination associated therewith, and yield reduction. Further, there is a problem that the life of the member is reduced due to the low corrosion resistance of the member. A vitreous corrosion-resistant member composed of a Si—Al—O—N element that suppresses such problems has been proposed, but the corrosion resistance is not always sufficient. On the other hand, although spraying with the Si ₃ N ₄ —Al ₂ O ₃ —Y ₂ O ₃ system is possible, the density of the sprayed film is low, and it is necessary to solve the problem of particles.

  The object of the present invention is to provide a corrosion-resistant member comprising a glassy sprayed film having high corrosion resistance, few particles, easy production and containing nitrogen.

  As a result of intensive studies in view of the current situation as described above, the present inventors have been composed of at least one element selected from the group consisting of Si, O, N and 2a group elements and B, Zr and Ti. The material is suitable for thermal spraying, and by spraying this material on the base material, the bonding between particles is good and a dense thermal sprayed film can be formed. And the present invention has been completed.

Hereinafter, the corrosion-resistant member of the present invention will be described in detail.
(First invention)
Of the present invention, the first invention is a corrosion-resistant member comprising a base material and a sprayed film formed thereon, and the part exposed to plasma or corrosive gas is Si, O, N and 2a group And a sprayed coating composed of at least one element selected from the group consisting of B, Zr and Ti.

  The group 2a element in the present invention is a group 2a element of the periodic table of elements, and specifically, Be, Mg, Ca, Sr, and Ba. Since the sprayed coating constituting the corrosion-resistant member of the present invention is mainly composed of glass, the reactivity with the corrosive gas or its plasma is low, and even if it reacts with fluorine in the corrosive gas, the reaction is generated. The substance is a high boiling point compound that is difficult to be etched by plasma, has an effect of suppressing etching by plasma or corrosive gas, and a particularly preferable group 2a element is Mg.

  In the first aspect of the present invention, the composition of the corrosion-resistant member is such that when Zr is used, the atomic ratio of Zr: Si ranges from 5:95 to 70:30, and the atomic ratio of O: N is 99.9. Is in the range of 0.1 to 60:40, and the atomic ratio of the Zr + Si: 2a group element is preferably 75:25 to 40:60.

  When Ti is used, the atomic ratio of Ti: Si is in the range of 5:95 to 80:20, the atomic ratio of O: N is in the range of 99.9: 0.1 to 60:40, and Ti + Si : The atomic ratio of the group 2a element is preferably 85:15 to 40:60.

  When B is used, the atomic ratio of B: Si is in the range of 5:95 to 70:30, the atomic ratio of O: N is in the range of 99.9: 0.1 to 60:40, and B + Si : The atomic ratio of the group 2a element is preferably 85:15 to 40:60.

  When using Zr, Ti, or B described above, oxygen contained in the oxide is not included when the group 2a element is introduced as an oxide.

  Further, the corrosion-resistant member of the present invention is characterized in that the main component of the sprayed film composed of Si, O, N and 2a groups and at least one element selected from the group consisting of B, Zr and Ti is glass. It is what. The glass phase composed of Si, O, N and 2a group elements is excellent in corrosion resistance, and at the same time, there is no crystal grain boundary because it is glass. Generation of particles due to dropping of the crystal particles due to corrosion of the steel is suppressed. And this glass phase is vitrified by adding N, and further the corrosion resistance is increased.

  Furthermore, the corrosion-resistant member of the present invention is composed of a glass phase composed of at least Si, O, N and 2a group elements and a crystal phase containing at least one element selected from the group consisting of B, Zr and Ti. It is a sprayed film. The characteristics of the glass phase composed of Si, O, N, and Group 2a elements are as described above. However, since this composition is a eutectic composition, the melting point of the sprayed powder is lowered, and the deposited sprayed film is dense. It becomes. Further, the crystal phase containing Zr and / or Ti is excellent in corrosion resistance because the boiling point of the reactant with the corrosive gas or the plasma containing the corrosive gas is high.

  As this eutectic composition, a sprayed film in which the crystal phase containing Zr is cubic zirconium oxide in which a group 2a oxide is dissolved can be exemplified. Both the group 2a element and Zr in the cubic zirconium oxide crystal phase are excellent in corrosion resistance since the boiling point of the reaction product with the corrosive gas or plasma is high. Examples of the sprayed film of cubic zirconium oxide in which Group 2a is dissolved include cubic zirconium oxide in which magnesium oxide is dissolved.

  An example of the crystal phase containing B is boron nitride. The boron nitride and the glass phase composed of Si, O, N, and 2a group elements have a eutectic composition, so that the melting point of the sprayed powder is lowered and the deposited sprayed film becomes dense.

  The substrate used in the present invention is not particularly limited, and examples thereof include heat-resistant glass such as quartz glass, metals such as aluminum and stainless steel, ceramics such as alumina and mullite, resins such as polyimide and polycarbonate.

  The surface of the substrate used preferably has a surface roughness Ra of 1 to 50 μm. Among these, in order to maintain good adhesion between the sprayed film and the substrate, the thickness is preferably 1 to 15 μm. If the surface roughness Ra is less than 1 μm, the substrate and the sprayed coating may be easily peeled off, and it may be difficult to uniformly coat the corrosion-resistant glass sprayed coating on the substrate. On the other hand, when the surface roughness Ra exceeds 50 μm, it is difficult to smooth the surface of the sprayed film, and it may be difficult to suppress etching by plasma or corrosive gas. As a method of setting the surface roughness Ra of the substrate surface to 1 to 50 μm, a method of spraying a sprayed film having such a surface roughness on the substrate in advance, a method of blasting the substrate itself, or a blasting treatment and hydrofluoric acid The method etc. which perform the chemical etching by etc. collectively can be illustrated.

  Although there is no limitation in the sprayed film thickness of the corrosion-resistant member of this invention, it is preferable that it is 0.01-3 mm, especially 0.01-0.5 mm. If the sprayed coating thickness of the corrosion-resistant member exceeds 3 mm, the sprayed coating may be easily cracked or peeled off due to the difference in thermal expansion coefficient with the base material. May be sufficient. The sprayed film thickness of the corrosion-resistant member can be confirmed by observing the cross section of the member with a microscope or by analyzing the composition of constituent elements using an EPMA (X-ray microanalyzer).

  The surface roughness Ra of the sprayed coating of the corrosion-resistant member of the present invention is preferably 0.01 to 10 μm, particularly preferably 8 μm or less. If the surface smoothness of the sprayed film is poor and rough, the protrusions formed on the surface of the sprayed film, particularly the edge portions, are selectively etched by plasma or corrosive gas, and particles are likely to be generated.

Particles are likely to be generated if the surface is rough, but this evaluation method is to measure the surface roughness Ra before and after plasma etching after polishing the surface of the sprayed film and plasma etching the polished surface. Can be evaluated. If the difference in Ra before and after plasma etching is large, the surface is roughened by etching, and it is expected that many particles are generated.
(Second invention)
Next, as a second invention, a method for producing a corrosion-resistant member according to the first invention will be described.

  The corrosion-resistant member of the present invention can be produced by forming a corrosion-resistant sprayed film by thermal spraying.

  The thermal spraying method used in the present invention is preferably plasma spraying. FIG. 1 shows a general plasma spraying apparatus. The plasma spraying apparatus melts the sprayed powder 13 by using a plasma jet formed by the plasma gas 12 flowing between the anode 11 and the cathode 10 as arc discharge as a heat source, and the melted sprayed powder has a flow velocity of the plasma gas. In this case, the bumps are deposited on the substrate 15.

In the plasma spraying apparatus, an inert gas such as N ₂ or Ar, a reducing gas such as H _2, or a mixed gas thereof can be used as the plasma gas. In thermal spraying of nitrogen-containing materials, if oxygen is contained in the plasma gas, it decomposes during thermal spraying, and the corrosion resistance decreases due to the disappearance of nitrogen from the sprayed film. Therefore, an inert gas or a reducing gas is used as the plasma gas. A plasma spraying method that can be used is preferable. The spray gas flow rate is preferably 50 SLM (Standard Litter Per Minutes) or more. Regarding the nitrogen content in the sprayed film, the surface of the sprayed film is subjected to fluorescent X-ray analysis or EPMA analysis, or the thermal conductivity of nitrogen gas generated after thermally decomposing a small amount of the sprayed film is measured. Analyze by using a nitrogen analyzer to measure.

  In addition to the plasma spraying method, the sprayed film of the present invention can also be manufactured by flame spraying or high-speed flame spraying as a general spraying method. In this case, it can be created under normal flame spraying conditions, but it is preferable to spray in a flame in a reducing atmosphere in which the fuel is excessive with respect to oxygen or the like.

  In the thermal spraying of the present invention, the thermal spraying power to be applied when spraying the thermal spraying frame onto the base material varies depending on the apparatus used. For example, in the case of a plasma thermal spraying apparatus as shown in FIG. Conditions can be exemplified.

  When manufacturing the corrosion-resistant member of the present invention, the spraying distance, which is the distance between the tip of the spray gun and the substrate under normal pressure, is preferably 40 to 150 mm. If the spraying distance exceeds 150 mm, the sprayed material will cool down before adhering to the substrate, and the sprayed film may not be deposited on the substrate. If the spraying distance is shorter than 40 mm, the temperature of both the substrate and the sprayed film will rise. As a result, the disappearance of nitrogen may occur due to the decomposition of the nitride, which is the thermal spray material, and the corrosion resistance may decrease.

  The thermal spraying raw material used in the present invention is a raw material having a composition containing Si, O, N and Group 2a elements and at least one element selected from the group consisting of B, Zr and Ti. preferable. Examples of such raw materials include, for example, zirconia, a mixture of powder granules composed of at least silica, silicon nitride, group 2a oxide and zirconia, and powder composed of at least silica, silicon nitride, group 2a oxide and zirconia. Can be prepared by mixing in a predetermined ratio, preparing an ingot sintered or melted under a reducing atmosphere under pressure or normal pressure, and then pulverizing. It is also possible to obtain a mixed powder comprising at least silica, silicon nitride, group 2a oxide, and zirconia, and then granulating the mixed slurry by a spray-drying method, followed by sintering the granule. . In each method described above, an acrylic binder or the like may be added as necessary.

  Although there is no limitation on the particle size of the raw material powder used for thermal spraying, the average particle size (secondary particle size) is preferably 10 to 100 μm. If the average particle size is less than 10 μm, the raw material powder itself does not have sufficient fluidity, and it may be difficult to uniformly supply the raw material into the thermal spray frame. On the other hand, if the average particle size exceeds 100 μm, the sprayed particles may not be melted uniformly, and the adhesion of the resulting sprayed film to the substrate may be likely to deteriorate.

  In the present invention, it is preferable to perform thermal spraying by preheating the surface of the base material in advance when forming the sprayed coating. Preheating the substrate surface in advance is effective for preventing cracking of the substrate due to heat shock and obtaining a corrosion-resistant member having high adhesion during thermal spraying. The preheating temperature varies depending on the type of substrate used, but for example, a range of 100 to 800 ° C. for a quartz glass substrate, 50 to 500 ° C. for an aluminum substrate, and 50 to 200 ° C. for a resin substrate is preferable.

  If the preheating temperature is increased too much, nitrogen in the sprayed film is decomposed, which is not preferable. Preheating may be performed by heating the substrate with an external heater, or irradiating the substrate with a thermal spray frame without supplying raw materials. The preheating temperature can be measured with a thermocouple from the back surface of the substrate or with a non-contact radiation thermometer.

  In the production of the corrosion-resistant member of the present invention, in the case of plasma spraying using an inert gas or a reducing gas under atmospheric pressure, the substrate temperature is preferably 100 to 800 ° C., although depending on the type of substrate. In the case of glass or ceramics, 50 to 800 ° C. is preferable. If the substrate temperature is lower than 50 ° C., the sprayed material is cooled when adhering to the substrate, and the film quality of the sprayed film on the substrate may be deteriorated. If the substrate temperature is higher than 800 ° C., the sprayed material is Decomposition of the nitride may cause disappearance of nitrogen and decrease corrosion resistance. In the case of a resin base material, although it depends on the type of resin, the base material temperature is preferably 50 to 300 ° C.

  The corrosion-resistant member of the present invention can be used for a container or a part of a film forming apparatus or a plasma processing apparatus. As a method of using the corrosion-resistant member, it can be used in a part that comes into contact with corrosive gas or plasma in these apparatuses, and more specifically, it can be used as a ring-shaped member or a bell jar.

  The film forming apparatus here is, for example, a CVD apparatus or a PVD (Physical Vapor Deposition) apparatus. The reaction tubes and bell jars of these devices are cleaned with fluorine-based gas for cleaning after use, and corrosion due to the cleaning and the generation of particles due to the cleaning have been a problem. Those problems are solved by using.

  The plasma processing apparatus here is, for example, a plasma etching apparatus or a plasma cleaning apparatus, and refers to an apparatus that irradiates a product placed in the apparatus with plasma and peels or cleans the surface of the product. Since the ring-shaped focus ring or bell jar of these apparatuses is also etched by fluorine-based plasma, the generation of particles is a problem in the parts in the apparatus that come into contact with corrosive gas or plasma. Similarly, in this case, if the corrosion-resistant member of the present invention is used, it is difficult to corrode and the generation of particles is small.

  The corrosion-resistant member of the present invention has high corrosion resistance and less particle generation when used in an apparatus using a corrosive gas or plasma, such as a CVD apparatus or a plasma processing apparatus. Can be operated continuously.

The present invention will be described in detail based on examples, but the present invention is not limited only to these examples.
Example 1) Preparation of Thermal Sprayed Substrate A quartz glass substrate having a surface roughness Ra of 10 μm was prepared by blasting quartz glass having a surface roughness Ra of 6 μm for 1 hour with 24% hydrofluoric acid.

2) Preparation of thermal spraying raw material powder A compound selected from the group consisting of Group 2a oxide, zirconia, titania and boric acid shown in Table 1, silica, silicon nitride or boron nitride has the composition shown in Table 1. Then, after mixing the binder with these powders, a granulated powder having an average particle size of 50 μm was obtained by spray drying. The granulated powder was degreased at 500 ° C. for 2 hours and then sintered at 1200 ° C. for 2 hours to obtain a sintered powder having an average particle size of 50 μm.

3) Formation of sprayed film Using the base material prepared in 1) and using the plasma spraying apparatus shown in FIG. 1 at normal pressure, nitrogen 40 SLM and hydrogen 12 SLM are flowed as plasma gases, the spraying distance is 60 mm, While moving the spray gun at a speed of 400 mm / sec, plasma was generated at a power of 30 kW, and the base material was preheated without supplying raw material powder.

  Next, the spraying raw material powder prepared in 2) was supplied at a feed rate of 7 g / min, sprayed 15 times while moving the spray gun at a speed of 400 mm / second, a pitch of 4 mm, and a spray distance of 60 mm to form a sprayed film.

4) Performance evaluation For sprayed coatings of various compositions obtained in 3), measurement of surface roughness Ra with a contact surface roughness meter, confirmation of constituent phases and glass phases by X-ray diffraction method, and SEM observation of cross section Measurement of porosity, measurement of nitrogen content by measuring thermal conductivity of nitrogen gas generated after cracked sprayed film is decomposed by furnace, measurement of etching rate and amount of particles when exposed to plasma containing fluorine gas A test was conducted.

As etching conditions, plasma was generated by applying a high-frequency power of 300 W between the electrode plates using a pressure of 1 torr in the reaction processing chamber, CF ₄ gas as the reaction gas. The surface of the thermal sprayed film to be etched was made to have a Ra of 0.1 μm or less by polishing. Etching thickness was measured using a step measurement method, and particle generation was performed by observing the surface of quartz glass placed next to the test sample during etching.

The results of the surface roughness Ra, the constituent phase, the porosity, the nitrogen content, the etching rate and the particle amount are shown in Table 1. All of the corrosion-resistant members were dense and the etching rate was as small as 0.1 μm / hr or less, excellent in corrosion resistance, and generating less particles.
Comparative Example A thermal spray film was formed by the same method as in 1) to 3) from the raw material powder for thermal spraying having the composition shown in Table 1 as a comparative example, and performance evaluation was performed in the same manner as in 4).

The quartz glass member of Comparative Example 1 was confirmed to be glassy, but the etching rate was larger than that of the corrosion resistant member, and the corrosion resistance was poor. In the Al ₂ O ₃ sprayed film of Comparative Example 102, the etching rate was low, but more particles were generated than the glassy corrosion-resistant member of the Example. In the member of Comparative Example 103 using the granulated magnesium oxide powder, the etching rate was higher than that of the corrosion-resistant member of the present invention, and many particles were generated. In the member of Comparative Example 104 using a commercially available partially stabilized zirconia powder for thermal spraying, the etching rate was higher than that of the corrosion-resistant member of the present invention, and many particles were generated. In the member of Comparative Example 105 using the thermal spraying raw material powder prepared with the composition of Table 1, silica, zirconia, and magnesia powder, the etching rate is higher than that of the corrosion-resistant member of the present invention, and more particles are generated. did.

It is a figure which shows an example of a plasma spraying apparatus.

Explanation of symbols

10: Cathode 11: Anode 12: Plasma gas 13: Thermal spray powder (supply port)
14: Thermal spray distance 15: Base material 16: Thermal spray film 17: Power supply

Claims (9)

A corrosion-resistant member comprising a base material and a sprayed film formed thereon, wherein the portion exposed to plasma or corrosive gas is from the group consisting of Si, O, N and 2a group, and B, Zr and Ti A corrosion-resistant member, characterized by being a sprayed coating composed of at least one element selected. The corrosion-resistant member according to claim 1, wherein the main component of the sprayed film is glass. The thermal spray film is characterized by being composed of a glass phase composed of at least Si, O, N and 2a group elements and a crystal phase comprising at least one element selected from the group consisting of B, Zr and Ti. The corrosion-resistant member according to claim 1. The corrosion-resistant member according to claim 3, wherein the crystal phase of the sprayed film is cubic zirconium oxide in which a group 2a oxide is solid-dissolved. The composition of the corrosion-resistant member has a Zr: Si atomic ratio in the range of 5:95 to 70:30, an O: N atomic ratio in the range of 99.9: 0.1 to 60:40, and Zr + Si: The corrosion-resistant member according to claim 1, wherein the atomic ratio of the Group 2a element is 75:25 to 40:60. The composition of the corrosion-resistant member has a Ti: Si atomic ratio ranging from 5:95 to 80:20, an O: N atomic ratio ranging from 99.9: 0.1 to 60:40, and Ti + Si: The corrosion-resistant member according to claim 1, wherein the atomic ratio of the group 2a element is 85:15 to 40:60. The composition of the corrosion resistant member has a B: Si atomic ratio in the range of 5:95 to 70:30, an O: N atomic ratio in the range of 99.9: 0.1 to 60:40, and B + Si: The corrosion-resistant member according to claim 1, wherein the atomic ratio of the group 2a element is 85:15 to 40:60. The corrosion-resistant member according to claim 3, wherein the crystal phase is boron nitride. A base material and a thermal spray formed thereon, characterized by using atmospheric pressure plasma spraying using an inert gas or a mixed gas of an inert gas and a reducing gas, and having a total flow rate of the sprayed gas of 50 SLM or more A corrosion-resistant member made of a film, wherein the portion exposed to plasma or corrosive gas is composed of Si, O, N and 2a groups and at least one element selected from the group consisting of B, Zr and Ti A method for producing a corrosion-resistant member which is a sprayed film.

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