Crucible structure and preparation method of tantalum carbide coating adopting crucible structure

Abstract

The invention provides a crucible structure and a preparation method of a tantalum carbide coating adopting the crucible structure. An inner crucible of the crucible structure is arranged in the middle of the inner bottom of an outer crucible, and a turbine fan assembly is arranged on a crucible cover in a penetrating mode; a first graphite ring and a second graphite ring are arranged in the outer crucible and above the inner crucible at intervals, and the inner diameter of the first graphite ring, the inner diameter of the graphite ring to be plated on the first graphite ring, the inner diameter of the second graphite ring and the inner diameter of the graphite ring to be plated on the second graphite ring are gradually reduced in the direction away from the inner crucible; one end of the turbine fan assembly is arranged between the first graphite ring and the second graphite ring. A chimney-like airflow channel with a wide lower part and a narrow upper part is formed in the crucible structure, the turbine fan assembly is designed, the airflow direction is guided, the airflow is driven to continuously react with the to-be-plated graphite ring on the side wall, the tantalum-containing atmosphere and the to-be-plated graphite ring are fully reacted, and the compactness and uniformity of a tantalum oxide coating on the surface of a graphite piece are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors and relates to a crucible structure and a method for preparing a tantalum carbide coating using the crucible structure. Background Art

[0002] Silicon carbide is currently the most mature material among the third-generation semiconductor materials. It has been widely used in many fields such as new energy vehicles, high-speed rail locomotives, aerospace, and wireless communications. It can be said that "everything can be silicon carbide". The current mainstream production method is physical vapor transport (PVT). At the same time, graphite materials have the advantages of high melting point, high purity, stable chemical properties, and low price. They have certain structural strength at high temperatures and are commonly used reaction vessels in the semiconductor field. Therefore, the silicon carbide raw material is placed in a graphite crucible, with a graphite cover with seed crystals on the top, and silicon carbide crystals are grown on the surface of the seed crystals by sublimation of silicon carbide powder.

[0003] During the decomposition and sublimation of silicon carbide raw materials, the silicon-rich atmosphere produced can easily corrode graphite crucibles and graphite parts, greatly reducing the service life of graphite parts. On the other hand, during the crystal growth process, the corroded graphite dust can float into the crystal through the airflow to form carbon wrapping, thus affecting the quality of the crystal.

[0004] Tantalum carbide is a high-temperature resistant coating material. The preparation of a tantalum carbide coating on the surface of graphite parts can effectively improve its corrosion resistance, increase the service life of graphite parts, and improve the crystal quality. There are many methods for preparing tantalum carbide coatings. The main method is chemical vapor deposition, but its process is more complicated and the equipment is expensive, which greatly increases the production cost. The spraying and dipping methods are simple to operate, but the density of the prepared coating is poor. Compared with other preparation methods, the high-temperature evaporation method has many advantages, the operation process is simple, and it can effectively prepare a dense tantalum oxide film, but the surface quality of the evaporated graphite parts is crucial to the control of the airflow during the reaction process. Therefore, it is crucial to design a crucible structure that rationally utilizes the airflow. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a crucible structure and a method for preparing a tantalum carbide coating using the same. In the present invention, a "chimney-like" airflow channel that is wide at the bottom and narrow at the top is constructed inside the crucible structure, and a turbofan assembly is designed to guide the airflow direction, drive the airflow to continuously react with the graphite ring to be plated on the side wall, so that the tantalum-containing atmosphere and the graphite ring to be plated fully react to form a dense and uniform tantalum carbide film on the surface of the graphite ring to be plated, thereby improving the density and uniformity of the tantalum oxide coating on the surface of the graphite part, greatly improving the efficiency of the coating and the utilization rate of the raw materials, and at the same time the corrosion resistance of the graphite part is also guaranteed, further improving the quality of the silicon carbide crystal.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a crucible structure, the crucible structure comprising an outer crucible, an inner crucible and a turbofan assembly, the inner crucible being centrally arranged at the inner bottom of the outer crucible, a crucible cover being arranged at one end of the outer crucible away from the inner crucible, and the turbofan assembly being penetrated through the crucible cover;

[0008] A first graphite ring and a second graphite ring are arranged above the inner crucible in the outer crucible, and the first graphite ring and the second graphite ring are both used to place the graphite ring to be plated, and the inner diameter of the first graphite ring, the inner diameter of the graphite ring to be plated on the first graphite ring, the inner diameter of the second graphite ring, and the inner diameter of the graphite ring to be plated on the second graphite ring gradually decrease in a direction away from the inner crucible;

[0009] One end of the turbofan assembly is arranged between the first graphite ring and the second graphite ring.

[0010] In the present invention, a "chimney-like" airflow channel that is wide at the bottom and narrow at the top is constructed inside the crucible structure, and a turbofan assembly is designed to guide the airflow direction, drive the airflow to continuously react with the graphite ring to be plated on the side wall, so that the tantalum-containing atmosphere and the graphite ring to be plated fully react, and form a dense and uniform tantalum carbide film on the surface of the graphite ring to be plated, thereby improving the density and uniformity of the tantalum oxide coating on the surface of the graphite part, greatly improving the efficiency of the coating and the utilization rate of the raw materials, and at the same time the corrosion resistance of the graphite part is also guaranteed, further improving the quality of the silicon carbide crystal.

[0011] It should be noted that in the present invention, the first graphite ring, the second graphite ring and several graphite rings to be plated are arranged in sequence along the axial direction inside the outer crucible. As the vertical height increases, the inner diameter gradually decreases, so as to achieve the purpose of expanding the longitudinal space. The through hole on the crucible cover and the design of narrow top and wide bottom are to increase the airflow above, so that the steam at the lower end can further flow upward and continuously react with the graphite rings to be plated; at the same time, high-temperature steam usually flows to the low-temperature area, and the edge temperature is higher than the middle temperature. The wide top and narrow bottom can make the graphite rings to be plated exposed in the middle area as much as possible to increase the sufficient contact reaction with the source steam.

[0012] It should be noted that the inner crucible in the present invention is used to place Ta 2 O 5 With TaCl 5 The specific ratio and concentration of the mixture are not particularly limited, and can be Ta 2 O 5 With TaCl 5The ratio is 1:1.5-2; when the overall crucible structure reaches a certain temperature, the mixture is dissolved and gasified to react with the graphite ring to be plated, thereby leaving a tantalum carbide coating on the graphite ring to be plated.

[0013] It should be noted that the inner diameter of the inner crucible in the present invention is slightly smaller than the inner diameter of the outer crucible, and is centrally placed in the outer crucible. There is no special limitation on the specific sizes of the outer crucible and the inner crucible, and those skilled in the art can make adaptive adjustments according to actual conditions.

[0014] It should be noted that the outer crucible and the crucible cover in the present invention can be detachably connected by threaded connection, and those skilled in the art can make adaptive adjustments to the specific connection method according to actual conditions.

[0015] It should be noted that the first graphite ring in the present invention can be arranged at the first step inside the outer crucible, and the second graphite ring can be arranged at the second step inside the outer crucible. The step can specifically be on the stepped plane inside the outer crucible, and the graphite rings to be plated can be placed in multiple layers on the first graphite ring and / or the second graphite ring to increase the contact surface with the reactants.

[0016] As a preferred technical solution of the present invention, the distance between the first graphite ring and the second graphite ring is 50mm-60mm, for example, it can be 50mm, 51mm, 52mm, 53mm, 54mm, 55mm, 56mm, 57mm, 58mm, 59mm, 60mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, the distance between the first graphite ring and the inner bottom of the outer crucible is 70 mm to 80 mm, for example, it can be 70 mm, 71 mm, 72 mm, 73 mm, 74 mm, 75 mm, 76 mm, 77 mm, 78 mm, 79 mm, 800 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] In the present invention, the distance between the first graphite ring and the second graphite ring is 50 mm to 60 mm because within this range, the tantalum-containing gas flow that is evaporated can fully react with the graphite part to be plated under the drive of the turbine fan. If it is not within this range, the tantalum carbide coating on the surface of the graphite part may be uneven, because the graphite parts that are not within the range cannot react with the gas flow driven by the turbine fan.

[0019] In the present invention, the distance between the first graphite ring and the inner bottom of the outer crucible is 70 mm to 80 mm because a suitable deposition rate can be obtained within this range. If it is not within this range, the deposition rate may be too fast or too slow. This is because the closer the distance, the shorter the path for the evaporated material to reach the workpiece to be plated, and the deposition rate is usually faster; conversely, as the distance increases, the deposition rate decreases.

[0020] As a preferred technical solution of the present invention, the minimum linear distance between the side of the first graphite ring facing the inner crucible and the open end of the inner crucible is 50 mm to 60 mm, for example, it can be 50 mm, 51 mm, 52 mm, 53 mm, 54 mm, 55 mm, 56 mm, 57 mm, 58 mm, 59 mm, 60 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] In the present invention, the minimum linear distance between the side of the first graphite ring facing the inner crucible and the open end of the inner crucible is 50 mm to 60 mm, because within this range, a uniform airflow can react with the graphite part. If it is not within this range, uneven coating may occur on the bottom of the graphite part. This is because if the distance is too close, it is easy to cause excessive reaction at the bottom of the graphite part to form uneven deposition spots, and if it is too far, it is easy to cause insufficient reaction of the upper graphite part, resulting in less coating and affecting the coating quality of the graphite part.

[0022] As a preferred technical solution of the present invention, through holes are evenly distributed on the side wall of the crucible cover.

[0023] It should be noted that the specific shape of the through hole is not particularly limited in the present invention, and those skilled in the art can make adaptive adjustments according to actual conditions. The shape of the through hole can be circular, square, or other regular or irregular shapes, and the through hole can be symmetrically designed so that the upper airflow inside the outer crucible is increased, and the steam at the lower end can further flow upward to continuously react with the graphite ring to be plated.

[0024] Preferably, the number of the through holes is 3 to 6, for example, 3, 4, 5, 6, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] As a preferred technical solution of the present invention, the distance between the side of the first graphite ring away from the inner crucible and the center of the through hole is 120mm to 140mm, for example, it can be 120mm, 122mm, 124mm, 126mm, 128mm, 130mm, 132mm, 134mm, 136mm, 138mm, 140mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] In the present invention, the distance between the side of the first graphite ring away from the inner crucible and the center of the through hole is 120 mm to 140 mm, because within this range, the evaporated material can be better distributed in the space, thereby improving the uniformity of the deposition layer; in addition, the deposition area of ​​the material can be increased, thereby improving production efficiency. If it is not within this range, uneven deposition may occur on the surface of the graphite part, because too small or too large a reaction space may cause uneven distribution of the evaporated material.

[0027] As a preferred technical solution of the present invention, the turbofan assembly includes a rotating rod, a turbofan and a driving motor. The turbofan is provided at one end of the rotating rod and extends into the interior of the outer crucible. The other end of the rotating rod is electrically connected to the driving motor.

[0028] Preferably, at least one turbofan is provided at one end of the rotating rod, for example, there may be 1, 2, 3, 4, etc., but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] It should be noted that the turbofan assembly designed in the present invention can drive the airflow to continuously react with the graphite ring to be plated on the side wall. At the same time, the design of the through hole can further guide the airflow direction, greatly increasing the reaction time between the tantalum-containing atmosphere and the graphite ring to be plated during the process, thereby forming a dense and uniform tantalum carbide film on the surface of the graphite ring to be plated.

[0030] As a preferred technical solution of the present invention, the inner crucible is a tungsten crucible.

[0031] Preferably, the outer crucible is a graphite crucible.

[0032] Preferably, the turbofan is a tungsten turbofan.

[0033] It should be noted that the inner crucible in the present invention is a tungsten crucible because, compared with other materials, tungsten does not react with tantalum oxide and tantalum chloride, has strong corrosion resistance, and can be combined with the outer graphite crucible to make the overall reaction more complete while saving the use of raw materials; the turbine fan is a tungsten turbine fan because it has high temperature corrosion resistance compared with other materials.

[0034] As a preferred technical solution of the present invention, a pressure detection component is provided on the outer crucible near the inner crucible, and the pressure detection component is used to detect the pressure value inside the outer crucible.

[0035] It should be noted that the present invention does not impose any special limitation on the specific shape, structure and quantity of the pressure detection assembly, and those skilled in the art may make adaptive adjustments according to actual conditions.

[0036] In a second aspect, the present invention provides a method for preparing a tantalum carbide coating, the preparation method being carried out using the crucible structure described in the first aspect, the preparation method comprising:

[0037] The graphite ring to be plated is pre-sintered, placed in the crucible structure, and evacuated, and then introduced with argon gas;

[0038] While the treated crucible structure is being heated, the turbofan is turned on, and the temperature is maintained after continuing to be heated to a certain temperature. After vacuuming again, an annular graphite part coated with tantalum carbide coating is obtained.

[0039] It should be noted that the present invention controls the pressure difference between the inside and outside of the graphite crucible by adopting a specific crucible structure to control the airflow in the graphite crucible, thereby forming a dense and uniform tantalum carbide film on the surface of the graphite ring to be plated.

[0040] It should be noted that the pre-sintering treatment of the graphite ring to be plated in the present invention is to remove impurities on its surface, and the graphite part can also achieve the effect of surface roughening during the pre-sintering process.

[0041] It should be noted that the pressure of the argon gas introduced in the present invention may be 100 mbar, which is mainly used to maintain the protective atmosphere and reaction atmosphere inside the crucible structure.

[0042] As a preferred technical solution of the present invention, the temperature of the pre-calcining treatment is 2000°C to 2200°C, for example, it can be 2000°C, 2020°C, 2040°C, 2060°C, 2080°C, 2100°C, 2120°C, 2140°C, 2160°C, 2180°C, 2200°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] The temperature of the pre-sintering treatment in the present invention is 2000°C to 2200°C because the impurity elements can be evaporated within this range. If the graphite contains other element impurities, such as metal elements (such as iron, nickel, titanium, etc.), these elements may evaporate at high temperatures. The gas impurities (such as hydrogen, nitrogen, oxygen, sulfur, etc.) that may be contained in the graphite may be released at high temperatures. If it is not within this range, it may cause the surface coating of the graphite part to have poor density and uniformity. This is because the impurities released during the reaction will cause the graphite part to be unable to fully react with the tantalum-containing gas flow, thereby affecting the coating quality.

[0044] Preferably, in the step of heat-treating the treated crucible structure, the heating temperature is 600°C to 800°C, for example, it can be 600°C, 620°C, 640°C, 660°C, 680°C, 700°C, 720°C, 740°C, 760°C, 780°C, 800°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0045] Preferably, after the treated crucible structure is heated, the temperature is maintained for 30 to 40 minutes, for example, 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes, 40 minutes, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] Preferably, the rotation speed of the turbofan is 500 r / min to 550 r / min, for example, it can be 500 r / min, 510 r / min, 520 r / min, 530 r / min, 540 r / min, 550 r / min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] The rotation speed of the turbofan in the present invention is 500r / min~550r / min, because within this range, the turbofan can fully drive the tantalum-containing airflow on the evaporation to flow evenly around. If it is not within this range, it may cause uneven airflow and the raw material cannot fully react with the graphite part. This is because the turbofan speed is too fast, the airflow flows upward too fast, and the raw material is lost before the reaction; if the speed is too slow, it cannot play the role of driving the airflow to flow upward.

[0048] It should be noted that in the present invention, the treated crucible structure is heated, and tantalum chloride will decompose. At this time, the external pressure of the outer crucible is controlled to be higher than the internal pressure. At this time, the turbofan is turned on at a speed of 500r / min to 550r / min. Under the drive of the tungsten turbofan in the graphite crucible driven by an external hardware mechanism, the tantalum molecules are fully reacted with the surface of the graphite ring to be plated to form a tantalum carbide film, which is the first coating.

[0049] Preferably, the certain temperature is 2000℃~2100℃, for example, it can be 2000℃, 2010℃, 2020℃, 2030℃, 2040℃, 2050℃, 2060℃, 2070℃, 2080℃, 2090℃, 2100℃, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] Preferably, the temperature is maintained for 30 to 40 minutes, for example, 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes, 40 minutes, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] It should be noted that in the present invention, the temperature is maintained after heating to a certain temperature. On the one hand, the tantalum carbide coating formed in the early stage is stabilized, and on the other hand, the tantalum oxide is sublimated to perform a secondary coating on the surface of the graphite ring to be plated. In this process, the reaction between oxygen molecules and chlorine molecules can further prevent the oxidation corrosion of the coating by oxygen molecules. This is the second coating.

[0052] It should be noted that, after the crucible structure in the present invention is vacuumed again, the external pressure of the graphite crucible is controlled to be less than the internal pressure, and the remaining tantalum-containing atmosphere in the graphite crucible will further flow into the graphite ring to be plated along the direction of the gas flow, so that it further reacts with the graphite ring to be plated, achieving the effect of the third coating of the graphite ring to be plated. After the graphite ring to be plated is plated three times, the exposed carbon surface of the graphite ring to be plated and the tantalum atmosphere are fully reacted, the density and uniformity are further greatly improved, a firm tantalum carbide film is formed, and the decomposition of the coating is prevented from being affected by the impurity atmosphere.

[0053] It should be noted that, in the present invention, by using a reaction precursor, i.e., a tantalum compound, which decomposes at high temperature to generate metallic tantalum, which is driven by the atmosphere to react with the carbon on the surface of the graphite ring to be plated to form tantalum carbide, the longitudinal reaction space is structurally expanded, and a method of exhausting gas from the upper side of the outer crucible is adopted to achieve continuous reaction of the high-temperature evaporated gas flow on the surface of the graphite ring to be plated, thereby preparing a tantalum carbide coating with a dense and uniform surface, which not only effectively improves the corrosion resistance of the graphite ring to be plated and meets the use requirements under high temperature conditions, but also reduces its manufacturing difficulty and production cost. The overall crucible structure is simple in design, easy to implement, and has obvious beneficial effects, which effectively solves the problems of small amount of surface coating on carbon graphite parts, poor density, and uneven coating.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] In the present invention, a "chimney-like" airflow channel that is wide at the bottom and narrow at the top is constructed inside the crucible structure, a turbofan assembly is designed, and a hole is opened on the upper crucible cover to guide the airflow direction, so that the airflow is driven to continuously react with the graphite ring to be plated on the side wall, so that the tantalum-containing atmosphere and the graphite ring to be plated fully react, and a dense and uniform tantalum carbide film is formed on the surface of the graphite ring to be plated, thereby improving the density and uniformity of the tantalum oxide coating on the surface of the graphite part, greatly improving the efficiency of the coating and the utilization rate of the raw materials, and at the same time, the corrosion resistance of the graphite part is also guaranteed, further improving the quality of the silicon carbide crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 A schematic diagram of a crucible structure provided for a specific embodiment of the present invention;

[0057] Among them, 1-turbofan assembly; 2-crucible cover; 3-outer crucible; 4-second graphite ring; 5-first graphite ring; 6-inner crucible; 7-pressure detection assembly; 8-graphite ring to be plated. DETAILED DESCRIPTION

[0058] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0059] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0060] Those skilled in the art should understand that the present invention necessarily includes necessary pipelines, conventional valves and general pump equipment for realizing a complete process, but the above content does not belong to the main inventive point of the present invention. Those skilled in the art can add layouts on their own based on the process flow and equipment structure selection, and the present invention does not make special requirements and specific limitations on this.

[0061] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0062] In one embodiment, the present invention provides a crucible structure such as Figure 1As shown, the crucible structure includes an outer crucible 3, an inner crucible 6 and a turbofan assembly 1, wherein the inner crucible 6 is centrally arranged at the inner bottom of the outer crucible 3, a crucible cover 2 is arranged at one end of the outer crucible 3 away from the inner crucible 6, and the turbofan assembly 1 is penetrated through the crucible cover 2;

[0063] A first graphite ring 5 and a second graphite ring 4 are arranged above the inner crucible 6 in the outer crucible 3. The first graphite ring 5 and the second graphite ring 4 are both used to place the graphite ring 8 to be plated. In the direction away from the inner crucible 6, the inner diameter of the first graphite ring 5, the inner diameter of the graphite ring 8 to be plated on the first graphite ring 5, the inner diameter of the second graphite ring 4, and the inner diameter of the graphite ring 8 to be plated on the second graphite ring 4 gradually decrease.

[0064] One end of the turbofan assembly 1 is arranged between the first graphite ring 5 and the second graphite ring 4 .

[0065] It should be noted that in the present invention, the first graphite ring 5, the second graphite ring 4 and several graphite rings to be plated 8 are arranged in sequence along the axial direction inside the outer crucible 3. As the vertical height increases, the inner diameter gradually decreases, so as to achieve the purpose of expanding the longitudinal space. The through hole on the crucible cover 2 is designed to be narrow at the top and wide at the bottom to increase the airflow at the top, so that the steam at the lower end can further flow upward and continuously react with the graphite rings 8 to be plated; at the same time, high-temperature steam usually flows to the low-temperature area, and the edge temperature is higher than the middle temperature. The wide top and narrow bottom can make the graphite rings 8 to be plated exposed in the middle area as much as possible to increase the sufficient contact reaction with the source steam.

[0066] It should be noted that the inner diameter of the inner crucible 6 in the present invention is slightly smaller than the inner diameter of the outer crucible 3, and is centrally placed in the outer crucible 3. There is no special limitation on the specific dimensions of the outer crucible 3 and the inner crucible 6, and those skilled in the art can make adaptive adjustments according to actual conditions.

[0067] It should be noted that, in the present invention, the outer crucible 3 and the crucible cover 2 can be connected by threaded connection to achieve the purpose of detachability, and those skilled in the art can make adaptive adjustments to the specific connection method according to actual conditions.

[0068] It should be noted that the first graphite ring 5 in the present invention can be arranged at the first step inside the outer crucible 3, and the second graphite ring 4 can be arranged at the second step inside the outer crucible 3. The step can specifically be on the stepped plane inside the outer crucible 3, and the graphite ring 8 to be plated can be placed in multiple layers on the first graphite ring 5 and / or the second graphite ring 4 to increase the contact surface with the reactants.

[0069] In one embodiment, the distance between the first graphite ring 5 and the second graphite ring 4 is 50 mm to 60 mm, for example, it can be 50 mm, 51 mm, 52 mm, 53 mm, 54 mm, 55 mm, 56 mm, 57 mm, 58 mm, 59 mm, 60 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0070] In one embodiment, the distance between the first graphite ring 5 and the inner bottom of the outer crucible 3 is 70 mm to 80 mm, for example, it can be 70 mm, 71 mm, 72 mm, 73 mm, 74 mm, 75 mm, 76 mm, 77 mm, 78 mm, 79 mm, 800 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0071] In one embodiment, the minimum linear distance between the side of the first graphite ring 5 facing the inner crucible 6 and the open end of the inner crucible 6 is 50 mm to 60 mm, for example, it can be 50 mm, 51 mm, 52 mm, 53 mm, 54 mm, 55 mm, 56 mm, 57 mm, 58 mm, 59 mm, 60 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0072] In one embodiment, through holes are evenly distributed on the side wall of the crucible cover 2 .

[0073] It should be noted that the specific shape of the through hole is not particularly limited in the present invention, and those skilled in the art can make adaptive adjustments according to actual conditions. The shape of the through hole can be circular, square, or other regular or irregular shapes, and the through hole is designed to increase the upper airflow inside the outer crucible 3, so that the steam at the lower end can further flow upward and continuously react with the graphite ring 8 to be plated.

[0074] In one embodiment, the number of through holes is 3 to 6, for example, 3, 4, 5, 6, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0075] In one embodiment, the distance between the side of the first graphite ring 5 away from the inner crucible 6 and the center of the through hole is 120 mm to 140 mm, for example, it can be 120 mm, 122 mm, 124 mm, 126 mm, 128 mm, 130 mm, 132 mm, 134 mm, 136 mm, 138 mm, 140 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0076] In one embodiment, the turbofan assembly 1 includes a rotating rod, a turbofan and a driving motor. The turbofan is disposed at one end of the rotating rod and extends into the outer crucible 3. The other end of the rotating rod is electrically connected to the driving motor.

[0077] In one embodiment, at least one turbofan is provided at one end of the rotating rod, for example, there may be 1, 2, 3, 4, etc., but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0078] It should be noted that the turbofan assembly 1 designed in the present invention can drive the airflow to continuously react with the graphite ring 8 to be plated on the side wall. At the same time, the design of the through hole can further guide the airflow direction, greatly increasing the reaction time between the tantalum-containing atmosphere and the graphite ring 8 to be plated during the process, thereby forming a dense and uniform tantalum carbide film on the surface of the graphite ring 8 to be plated.

[0079] In one embodiment, the inner crucible 6 is a tungsten crucible.

[0080] In one embodiment, the outer crucible 3 is a graphite crucible.

[0081] In one embodiment, the turbofan is a tungsten turbofan.

[0082] In one embodiment, a pressure detection assembly 7 is disposed on the outer crucible 3 near the inner crucible 6 , and the pressure detection assembly 7 is used to detect the pressure value inside the outer crucible 3 .

[0083] It should be noted that the present invention does not impose any special limitation on the specific shape, structure and quantity of the pressure detection assembly 7, and those skilled in the art may make adaptive adjustments according to actual conditions.

[0084] In another specific embodiment, the present invention provides a method for preparing a tantalum carbide coating, wherein the preparation method is performed using the above-mentioned crucible structure, comprising:

[0085] After the graphite ring 8 to be plated is pre-sintered, it is placed in a crucible structure, and after vacuuming, argon gas is introduced;

[0086] While the treated crucible structure is being heated, the turbofan is turned on, and the temperature is maintained after continuing to be heated to a certain temperature. After vacuuming again, an annular graphite part coated with tantalum carbide coating is obtained.

[0087] It should be noted that the present invention controls the pressure difference between the inside and outside of the graphite crucible by adopting a specific crucible structure to control the airflow in the graphite crucible, thereby forming a dense and uniform tantalum carbide film on the surface of the graphite ring 8 to be plated.

[0088] It should be noted that the pre-sintering treatment of the graphite ring 8 to be plated in the present invention is to remove impurities on its surface, and the graphite part can also achieve the effect of surface roughening during the pre-sintering process.

[0089] It should be noted that the pressure of the argon gas introduced in the present invention may be 100 mbar, which is mainly used to maintain the protective atmosphere and reaction atmosphere inside the crucible structure.

[0090] In one embodiment, the temperature of the pre-calcination treatment is 2000°C to 2200°C, for example, it can be 2000°C, 2020°C, 2040°C, 2060°C, 2080°C, 2100°C, 2120°C, 2140°C, 2160°C, 2180°C, 2200°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0091] In one embodiment, in the step of heat-treating the treated crucible structure, the heating temperature is 600°C to 800°C, for example, it can be 600°C, 620°C, 640°C, 660°C, 680°C, 700°C, 720°C, 740°C, 760°C, 780°C, 800°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0092] In one embodiment, after the treated crucible structure is heated, the temperature is maintained for 30 to 40 minutes, for example, 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes, 40 minutes, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0093] In one embodiment, the speed of the turbofan is 500 r / min to 550 r / min, for example, it can be 500 r / min, 510 r / min, 520 r / min, 530 r / min, 540 r / min, 550 r / min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0094] It should be noted that in the present invention, the treated crucible structure is heated and tantalum chloride will decompose. At this time, the external pressure of the outer crucible 3 is controlled to be higher than the internal pressure. At this time, the turbofan is turned on at a speed of 500r / min to 550r / min. Under the drive of the tungsten turbofan in the graphite crucible driven by the external hardware mechanism, the tantalum molecules are fully reacted with the surface of the graphite ring 8 to be plated to form a tantalum carbide film, which is the first coating.

[0095] In one embodiment, the certain temperature is 2000°C to 2100°C, for example, it can be 2000°C, 2010°C, 2020°C, 2030°C, 2040°C, 2050°C, 2060°C, 2070°C, 2080°C, 2090°C, 2100°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0096] In one embodiment, the temperature is maintained for 30 to 40 minutes, for example, 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes, 40 minutes, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0097] It should be noted that in the present invention, the temperature is maintained after heating to a certain temperature. On the one hand, the tantalum carbide coating formed in the early stage is stabilized, and on the other hand, the tantalum oxide is sublimated to perform a secondary coating on the surface of the graphite ring 8 to be plated. In this process, the reaction between oxygen molecules and chlorine molecules can further prevent the oxidation corrosion of the coating by oxygen molecules. This is the second coating.

[0098] It should be noted that, after the crucible structure in the present invention is vacuumed again, the external pressure of the graphite crucible is controlled to be less than the internal pressure, and the remaining tantalum-containing atmosphere in the graphite crucible will further flow into the graphite ring 8 to be plated along the direction of the gas flow, so that it further reacts with the graphite ring 8 to be plated, thereby achieving the effect of the third coating of the graphite ring 8 to be plated. After the graphite ring 8 to be plated is plated three times, the exposed carbon surface of the graphite ring 8 to be plated fully reacts with the tantalum atmosphere, and the density and uniformity are further greatly improved, forming a firm tantalum carbide film, and preventing the decomposition of the coating by the impurity atmosphere.

[0099] Example 1

[0100] This embodiment provides a crucible structure, wherein:

[0101] The crucible structure includes an outer crucible 3, an inner crucible 6 and a turbofan assembly 1, the inner crucible 6 is centrally arranged at the inner bottom of the outer crucible 3, a crucible cover 2 is arranged at one end of the outer crucible 3 away from the inner crucible 6, and the turbofan assembly 1 is penetrated by the crucible cover 2; the interior of the outer crucible 3 is provided with a first graphite ring 5 and a second graphite ring 4 above the inner crucible 6, and the first graphite ring 5 and the second graphite ring 4 are both used to place the graphite ring 8 to be plated, and along the direction away from the inner crucible 6, the inner diameter of the first graphite ring 5, the inner diameter of the graphite ring 8 to be plated on the first graphite ring 5, the inner diameter of the second graphite ring 4 and the inner diameter of the graphite ring 8 to be plated on the second graphite ring 4 gradually decrease; one end of the turbofan assembly 1 is arranged between the first graphite ring 5 and the second graphite ring 4.

[0102] The distance between the first graphite ring 5 and the second graphite ring 4 is 55 mm. The distance between the first graphite ring 5 and the inner bottom of the outer crucible 3 is 76 mm. The minimum linear distance between the side of the first graphite ring 5 facing the inner crucible 6 and the open end of the inner crucible 6 is 50 mm. Six through holes are evenly arranged on the side wall of the crucible cover 2, and the distance between the side of the first graphite ring 5 away from the inner crucible 6 and the center of the through hole is 130 mm.

[0103] The turbofan assembly 1 includes a rotating rod, a turbofan and a driving motor. Two turbofans are arranged at one end of the rotating rod and extend into the outer crucible 3. The other end of the rotating rod is electrically connected to one end of the rotating rod of the driving motor.

[0104] The inner crucible 6 is a tungsten crucible, the outer crucible 3 is a graphite crucible, the turbofan is a tungsten turbofan, and a pressure detection assembly 7 is provided on the outer crucible 3 near the inner crucible 6 . The pressure detection assembly 7 is used to detect the pressure value inside the outer crucible 3 .

[0105] This embodiment provides a method for preparing a tantalum carbide coating using the crucible structure of embodiment 1, comprising:

[0106] The graphite ring 8 to be plated is pre-sintered at a temperature of 2100° C., placed in a crucible structure, and then evacuated and introduced with argon gas.

[0107] While the treated crucible structure is heated, the heating temperature is 700°C, the temperature is maintained for 30 minutes, the turbofan is turned on, the speed of the turbofan is 500r / min, and the temperature is continued to be heated to a certain temperature of 2100°C and maintained for 40 minutes. After vacuum treatment again, an annular graphite part coated with tantalum carbide coating is obtained.

[0108] Comparative Example 1

[0109] This comparative example provides a crucible structure, which is different from Example 1 in that, along the direction away from the inner crucible 6, the inner diameter of the first graphite ring 5, the inner diameter of the graphite ring 8 to be plated on the first graphite ring 5, the inner diameter of the second graphite ring 4, and the inner diameter of the graphite ring 8 to be plated on the second graphite ring 4 gradually increase, and the formed air flow channel is in the form of wide at the top and narrow at the bottom. Other structures and parameters are the same as those in Example 1.

[0110] By testing the film thickness of the tantalum carbide coating prepared by the crucible structure adopted in Example 1 and Comparative Example 1, it is found that the density and uniformity of the tantalum carbide coating in Example 1 are significantly better than those of the tantalum carbide coating in Comparative Example 1. This is because the air flow channel of the present invention is limited to a form of narrow at the top and wide at the bottom, which is more in line with the phenomenon that high-temperature steam usually flows to the low-temperature area and the edge temperature is higher than the middle temperature, compared with the form of wide at the top and narrow at the bottom in Comparative Example 1. By laterally enlarging the space, the graphite-plated ring 8 is exposed in the middle area as much as possible to increase the sufficient contact reaction with the source steam, thereby obtaining a uniform and dense tantalum carbide coating.

[0111] The present invention designs a turbofan assembly 1 by constructing an airflow channel similar to a "chimney" which is wide at the bottom and narrow at the top inside the crucible structure, guides the airflow direction, and drives the airflow to continuously react with the graphite ring 8 to be plated on the side wall, so that the tantalum-containing atmosphere and the graphite ring 8 to be plated fully react, and a dense and uniform tantalum carbide film is formed on the surface of the graphite ring 8 to be plated, thereby improving the density and uniformity of the tantalum oxide coating on the surface of the graphite part, greatly improving the efficiency of the coating and the utilization rate of the raw materials, and at the same time, the corrosion resistance of the graphite part is also guaranteed, further improving the quality of the silicon carbide crystal.

[0112] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A crucible structure, characterized in that: The crucible structure comprises an outer crucible, an inner crucible and a turbofan assembly, wherein the inner crucible is centrally arranged at the inner bottom of the outer crucible, a crucible cover is arranged at one end of the outer crucible away from the inner crucible, and the turbofan assembly is penetrated through the crucible cover; A first graphite ring and a second graphite ring are arranged above the inner crucible in the outer crucible, and the first graphite ring and the second graphite ring are both used to place the graphite ring to be plated, and the inner diameter of the first graphite ring, the inner diameter of the graphite ring to be plated on the first graphite ring, the inner diameter of the second graphite ring, and the inner diameter of the graphite ring to be plated on the second graphite ring gradually decrease in a direction away from the inner crucible; One end of the turbofan assembly is arranged between the first graphite ring and the second graphite ring.

2. The crucible structure according to claim 1, characterized in that: The distance between the first graphite ring and the second graphite ring is 50 mm to 60 mm; Preferably, the distance between the first graphite ring and the inner bottom of the outer crucible is 70 mm to 80 mm.

3. The crucible structure according to claim 1 or 2, characterized in that: The minimum linear distance between the side of the first graphite ring facing the inner crucible and the opening end of the inner crucible is 50 mm to 60 mm.

4. The crucible structure according to any one of claims 1 to 3, characterized in that: The side wall of the crucible cover is evenly provided with through holes; Preferably, the number of the through holes is 3 to 6.

5. The crucible structure according to claim 4, characterized in that: The distance between the side of the first graphite ring away from the inner crucible and the center of the through hole is 120 mm to 140 mm.

6. The crucible structure according to any one of claims 1 to 5, characterized in that: The turbofan assembly comprises a rotating rod, a turbofan and a driving motor, wherein the turbofan is arranged at one end of the rotating rod and extends into the interior of the outer crucible, and the other end of the rotating rod is electrically connected to the driving motor; Preferably, at least one turbofan is provided at one end of the rotating rod.

7. The crucible structure according to claim 6, characterized in that: The inner crucible is a tungsten crucible; Preferably, the outer crucible is a graphite crucible; Preferably, the turbofan is a tungsten turbofan.

8. The crucible structure according to any one of claims 1 to 7, characterized in that: A pressure detection component is arranged on the outer crucible near the inner crucible, and the pressure detection component is used to detect the pressure value inside the outer crucible.

9. A method for preparing a tantalum carbide coating, characterized in that: The preparation method is carried out using the crucible structure according to any one of claims 1 to 8, and the preparation method comprises: The graphite ring to be plated is pre-sintered, placed in the crucible structure, and evacuated, and then introduced with argon gas; While the treated crucible structure is being heated, the turbofan is turned on, and the temperature is maintained after continuing to be heated to a certain temperature. After vacuuming again, an annular graphite part coated with tantalum carbide coating is obtained.

10. The preparation method according to claim 9, characterized in that: The temperature of the pre-sintering treatment is 2000°C to 2200°C; Preferably, in the step of heating the treated crucible structure, the heating temperature is 600° C. to 800° C.; Preferably, after the treated crucible structure is heated, the temperature is maintained for 30 to 40 minutes; Preferably, the speed of the turbofan is 500r / min to 550r / min; Preferably, the certain temperature is 2000°C to 2100°C; Preferably, the temperature is maintained for 30 to 40 minutes.

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