A silicon carbide particle and its preparation method

Abstract

This invention discloses silicon carbide particles and their preparation method, relating to the field of semiconductor technology. Silicon carbide particles with controllable particle size are prepared using a reaction system including a fluidized bed, with an average particle size of 3mm-11mm. The fluidized bed includes nozzles on the inner side of a cone wall, and the focusing point and flow rate of the fluid ejected from the nozzles are set. By controlling the flow rate of the fluid ejected from the nozzles, the particle size of the finished product is precisely controlled, reducing the defect rate caused by substandard particle size and achieving a high particle size yield. The product has controllable particle size and high purity, avoiding the risks introduced by crushing and screening. Furthermore, the production process does not require the disassembly and assembly of a single furnace, enabling continuous production, simplifying the production process, reducing input costs, ensuring product quality, and improving production efficiency, providing a new approach for future industrialization.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically, to a silicon carbide particle and a method for preparing the same. Background Technology

[0002] With the rapid development of semiconductor technology and the new energy industry, high-purity silicon carbide materials, as one of the key basic materials, are widely used in power devices, optoelectronic devices, and high-temperature, high-frequency, high-power electronic devices. However, as the market demand for high-purity silicon carbide continues to grow, higher requirements are being placed on the purity, particle size consistency, and production capacity of raw materials.

[0003] Currently, industrial methods for synthesizing silicon carbide raw materials mainly include self-propagating high-temperature synthesis, direct synthesis, chemical vapor deposition (CVD), and batch powder synthesis processes using traditional resistance furnaces or induction furnaces. The silicon carbide products produced by these processes are prone to severe agglomeration and sintering, forming large agglomerates with initial particle sizes far exceeding the particle size range required by downstream processes. Therefore, subsequent mechanical crushing and sieving are necessary to obtain particle sizes that meet specifications. However, due to the high Mohs hardness of silicon carbide, conventional crushing methods easily introduce metallic impurities during the application of external force, affecting the electrical performance and reliability of the final devices. To reduce or remove the negative impact of metallic impurities, acid pickling is often used to ensure product purity. However, acid pickling involves multiple pickling processes, making wastewater treatment and chemical management difficult, and increasing overall operating costs.

[0004] In addition, induction furnaces in traditional processes suffer from uneven temperature distribution, which affects the consistency of products. While resistance furnaces have more stable temperature control, they have high energy consumption, low heating efficiency, and complex furnace body disassembly and assembly, making maintenance difficult and seriously affecting the efficiency of continuous production.

[0005] Therefore, the synthesis of silicon carbide raw materials still faces severe challenges in terms of energy efficiency, production continuity, product controllability, and environmental friendliness.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide silicon carbide particles and a method for preparing the same, so as to solve or improve the above-mentioned technical problems.

[0008] This invention is implemented as follows:

[0009] In a first aspect, the present invention provides a method for preparing silicon carbide particles, wherein silicon carbide particles with controllable particle size are obtained by using a reaction system including a fluidized bed, and the average particle size of the silicon carbide particles is 3mm-11mm.

[0010] The fluidized bed includes nozzles on the inner side of the cone wall. The fluid ejected from the nozzles has the same deflection point as the central axis of the fluidized bed reaction chamber. The fluid velocity ejected from the nozzles is 8.35 m / s to 22.86 m / s.

[0011] In an optional embodiment, silicon carbide particles with controllable particle size are obtained, and the fluid flow rate ejected from the nozzle has at least one of the following characteristics:

[0012] Feature 1: When the average particle size of silicon carbide particles is 3.8mm-4.5mm, the fluid velocity ejected from the nozzle is 8.35m / s-14.46m / s, and the required time is 201h-262h.

[0013] Feature 2: When the average particle size of silicon carbide particles is 5.5mm-6.5mm, the fluid velocity ejected from the nozzle is 10.22m / s-17.70m / s, and the required time is 301h-380h.

[0014] Feature 3: When the average particle size of silicon carbide particles is 7.5mm-8.5mm, the fluid velocity ejected from the nozzle is 11.80m / s-20.45m / s, and the required time is 418h-497h.

[0015] Feature 4: When the average particle size of silicon carbide particles is 9.5mm-10.5mm, the fluid velocity ejected from the nozzle is 13.20m / s-22.86m / s, and the required time is 536h-615h.

[0016] In an optional implementation, the nozzles are arranged on the same horizontal plane inside the cone wall, and the number of nozzles is 1 to 10 groups.

[0017] Using a vertical line perpendicular to the ground as a reference, the vertical direction deflection angle α, the direction of the same group of directions α all point to the same point on the central axis of the reaction chamber, and the deflection angle α is 30°-60°;

[0018] And / or, in the axial direction of the reaction chamber, let X be the vertical distance from the nozzle to the central axis, and Y be the distance from the deflection point of the nozzle group to the bottom of the reaction chamber, Y = L1 + L2, where L1 is the distance from the nozzle to the bottom of the reaction chamber, L1 is 0.4m-0.6m; L2 = X / tanα;

[0019] And / or, the distance between the deflection point of this group of nozzles and the top of the reaction chamber is 1m-2m.

[0020] In an optional embodiment, when the nozzle deflection angle is constant, the fluid velocity ejected from the nozzle has at least one of the following characteristics:

[0021] Feature 1: When the nozzle deflection angle α is 30°, the fluid velocity ejected from the nozzle is 8.35 m / s - 13.20 m / s;

[0022] Feature 2: When the nozzle deflection angle α is 45°, the fluid velocity ejected from the nozzle is 10.22 m / s - 16.16 m / s;

[0023] Feature 3: When the nozzle deflection angle α is 60°, the fluid velocity ejected from the nozzle is 14.46 m / s-22.86 m / s.

[0024] In an optional embodiment, the raw materials for preparing silicon carbide particles include any one of the following components:

[0025] Component 1, with raw materials consisting of independent carbon and silicon sources;

[0026] The component consists of two parts, with the raw materials being a single precursor including a carbon source and a silicon source.

[0027] In an optional embodiment, when the raw material for preparing silicon carbide particles is component one, the carbon source includes at least one of methane, ethane, ethylene, acetylene, propylene, propane, and carbon monoxide.

[0028] The silicon source includes at least one of silane, dichlorosilane, trichlorosilane, and silicon tetrachloride.

[0029] In an optional embodiment, when the raw material for preparing silicon carbide particles is component two, the single precursor includes at least one of methyltrichlorosilane, tetramethylsilane, hexamethyldisilane and methylsilane.

[0030] And / or, also includes a carrier gas, wherein the molar ratio of the carrier gas to the single precursor is (5-20):1.

[0031] In an optional embodiment, the reaction system further includes an evaporation device, a preheating device, a heating device, a seed crystal feeding device, a tail gas treatment device, and a storage device.

[0032] The evaporation unit is connected to the preheating unit; the preheated raw material gas enters the reaction chamber of the fluidized bed for reaction.

[0033] The outlet of the reaction chamber is connected to the inlet of the exhaust gas treatment device, and the outlet of the exhaust gas treatment device is connected to the preheating device.

[0034] The heating device is located outside the reaction chamber and is used to heat the raw material gas; the seed crystal feeding device is located at the top of the reaction chamber, and the storage device is located at the bottom of the reaction chamber.

[0035] In an optional embodiment, the reaction chamber includes a constant-diameter section and an inverted conical section, wherein the inverted conical section is located at the bottom of the reaction chamber and is detachably connected to the material storage device; the constant-diameter section is located at the top of the reaction chamber and is detachably connected to the seed crystal feeding device.

[0036] And / or, a nozzle is provided on the inner side of the cone wall of the inverted cone section, and the nozzle is connected to the outlet of the preheating device;

[0037] And / or, the length of the nozzle is 0.05m-0.2m, and the diameter of the nozzle is 5mm-20mm.

[0038] In a second aspect, the present invention provides silicon carbide particles, which are prepared by any of the preparation methods described in the foregoing embodiments;

[0039] The purity of silicon carbide particles is ≥6N.

[0040] The present invention has the following beneficial effects:

[0041] This invention precisely controls the average particle size of the produced silicon carbide particles by controlling the fluid flow rate ejected from the nozzle, reducing the defect rate caused by substandard particle size and achieving a high particle size yield. The resulting product has controllable particle size and high purity, avoiding the risks introduced by crushing, screening, and acid washing processes. Furthermore, the production process does not require the disassembly and assembly of individual furnaces, enabling continuous production, simplifying the production process, reducing input costs, ensuring product quality, and improving production efficiency, providing a new approach for future industrialization. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 A schematic diagram of the reaction system for preparing silicon carbide particles;

[0044] Figure 2 A schematic diagram of the structure used for calculating the nozzle position relationship;

[0045] Figure 3 The particle size distribution of silicon carbide particles prepared with 6 mm as the standard is shown.

[0046] Figure 4 The XRD analysis results are for the silicon carbide particles obtained in Example 1.

[0047] Figure 5 The results are Raman analysis of the silicon carbide particles obtained in Example 1.

[0048] Icons: 10 - Schematic diagram of the reaction system; 100 - Reaction chamber; 1001 - Top of reaction chamber; 1002 - Bottom of reaction chamber; 1003 - Central axis; 101 - Heating device; 102 - Reaction chamber inlet; 103 - Inverted conical section; 104 - Nozzle plane; 105 - Nozzle; 106 - Nozzle deflection angle; 107 - Constant diameter section; 108 - Tail gas outlet; 109 - Tail gas pipe; 110 - Seed crystal feeding device; 111 - Tail gas treatment device; 112 - Inlet of tail gas treatment device; 113 - Outlet of tail gas treatment device; 120 - Storage device; 130 - Preheating device; 131 - Preheating device; 200 - Deflection point. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0050] In a first aspect, the present invention provides a method for preparing silicon carbide particles, wherein silicon carbide particles with controllable particle size are obtained by using a reaction system including a fluidized bed, and the average particle size of the silicon carbide particles is 3mm-11mm.

[0051] The fluidized bed includes nozzles 105 on the inner side of the cone wall. The fluid ejected from the nozzles 105 has the same deflection point 200 as the central axis 1003 of the fluidized bed reaction chamber 100. The flow velocity of the fluid ejected from the nozzles 105 is 8.35m / s-22.86m / s.

[0052] It should be noted that the embodiments of the present invention precisely control the particle size of the finished product by controlling the fluid flow rate ejected from the nozzle 105, thereby reducing the defect rate caused by substandard particle size and achieving a yield rate of up to 97% for particle size. The product particle size is controllable, with high purity, avoiding the risks introduced by crushing, screening, and pickling processes. Furthermore, the production process does not require the disassembly and reassembly of individual furnaces, enabling continuous production, simplifying the production process, reducing input costs, ensuring product quality, and improving production efficiency, thus providing a new approach for future industrialization.

[0053] In an optional embodiment, silicon carbide particles with controllable particle size are obtained, and the fluid flow rate ejected from nozzle 105 has at least one of the following characteristics:

[0054] Feature 1: When the average particle size of silicon carbide particles is 3.8mm-4.5mm, the fluid velocity ejected from nozzle 105 is 8.35m / s-14.46m / s, and the required time is 201h-262h.

[0055] Feature 2: When the average particle size of silicon carbide particles is 5.5mm-6.5mm, the fluid velocity ejected from nozzle 105 is 10.22m / s-17.70m / s, and the required time is 301h-380h.

[0056] Feature 3: When the average particle size of silicon carbide particles is 7.5mm-8.5mm, the fluid velocity ejected from nozzle 105 is 11.80m / s-20.45m / s, and the required time is 418h-497h.

[0057] Feature 4: When the average particle size of silicon carbide particles is 9.5mm-10.5mm, the fluid velocity ejected from nozzle 105 is 13.20m / s-22.86m / s, and the required time is 536h-615h.

[0058] It should be noted that the flow rate of nozzle 105 can be adjusted reasonably according to the actual required particle size of silicon carbide particles. After determining the particle size of silicon carbide particles, the seed crystals tumble in the reaction chamber 100 under the action of the gas flow rate according to the corresponding specified flow rate.

[0059] Under constant pressure and a fixed temperature, silicon carbide gradually deposits and adheres to the seed crystal surface, growing larger over time. Due to crystal growth, particles approaching or exceeding the set product particle size are difficult to maintain axial balance under gravity and thus accumulate at the bottom 1002 of the reaction chamber, while those below the size limit continue to react. Therefore, the particle size of the product can be controlled within a very small range. For example, if the obtained silicon carbide particles are based on a 6mm product, the final particle size of the silicon carbide particles prepared using the method of this invention is mainly concentrated around 6.1mm.

[0060] It should be noted that, in an optional embodiment of the present invention, an air extraction pump may be installed on the exhaust pipe 109 that connects the reaction chamber 100 and the exhaust gas treatment device 111, such as by installing an exhaust gas back pressure valve to regulate the pressure inside the reaction chamber 100; the air extraction pump is used to regulate the pressure inside the reaction chamber 100, and the reaction pressure is usually controlled at 0.1MPa-0.5MPa.

[0061] In other embodiments of the present invention, it is also necessary to control the gas pumping speed in the reaction chamber 100, control the pressure to <0.1MPa, and maintain a negative pressure state in the reaction chamber 100 to promote the discharge of HCl, promote the forward reaction, and improve the reaction efficiency.

[0062] In an optional embodiment, the nozzles 105 are arranged on the same horizontal plane inside the cone wall, and the number of nozzles 105 is 1 to 10 groups.

[0063] Using a vertical line perpendicular to the ground as a reference, the vertical deflection angle α, and the directions of the same group of directions α all point to the same point on the central axis 1003 of the reaction chamber 100, with the deflection angle α being 30°-60°.

[0064] It should be noted that the nozzles 105 on the same horizontal plane form a group, and the fluid ejected by each group of nozzles 105 will have the same deflection point 200 with the same point on the central axis 1003 of the reaction chamber 100. Each group of horizontal nozzles 105 forms a 360° airflow surface on the horizontal airflow. The number of nozzle groups 105 can be designed to be 1-10.

[0065] And / or, in the axial direction of the reaction chamber 100, let X be the vertical distance from nozzle 105 to the central axis 1003, and Y be the distance from the point of the nozzle deflection angle 106 to the bottom 1002 of the reaction chamber. Y = L1 + L2, where L1 is the distance from nozzle 105 to the bottom 1002 of the reaction chamber, and L1 is 0.4m-0.6m; L2 = X / tanα. The units of Y, X, L1, and L2 are all meters (m). A schematic diagram of the nozzle position relationship calculation is shown below. Figure 2 .

[0066] And / or, the distance between the nozzle deflection angle 106 point and the top 1001 of the reaction chamber is 1m-2m.

[0067] It should be noted that the space between the nozzle deflection angle 106 and the top of the reaction chamber 1001 is the main deposition reaction space. If the distance is too small, the deposition reaction space is small, and the total reaction volume is too small; if the distance is too large, the deposition reaction space is too large, which will lead to excessive load on the equipment. The distance between the nozzle deflection angle 106 and the top of the reaction chamber 1001 is related to the number of nozzle groups 105 and the specifications of the reaction furnace body, and should be adjusted reasonably according to the actual situation.

[0068] In an optional embodiment, when the nozzle deflection angle 106 is a constant value, the fluid velocity ejected from the nozzle 105 has at least one of the following characteristics:

[0069] Feature 1: When the nozzle deflection angle 106 is 30°, the fluid velocity ejected from nozzle 105 is 8.35 m / s - 13.20 m / s;

[0070] Feature 2: When the nozzle deflection angle 106 is 45°, the fluid velocity ejected from nozzle 105 is 10.22 m / s - 16.16 m / s;

[0071] Feature 3: When the nozzle deflection angle 106 is 60°, the fluid velocity ejected from nozzle 105 is 14.46 m / s-22.86 m / s.

[0072] It should be noted that, in actual production, the nozzle deflection angle 106 is fixed for each batch. In other embodiments of the present invention, the nozzle deflection angle 106 can be adjusted to other values ​​within the range of 30°-60° as needed.

[0073] To prepare silicon carbide particles of the required particle size, with the particle size of nozzle 105 fixed, the fluid flow rate ejected from nozzle 105 can be adjusted as needed. If the fluid flow rate ejected from nozzle 105 cannot meet the particle size requirements, the nozzle deflection angle 106 is adjusted to a suitable angle before preparation, based on previous calculations, and then the fluid flow rate ejected from nozzle 105 is adjusted.

[0074] In an optional embodiment, the raw materials for preparing silicon carbide particles include any one of the following components:

[0075] Component 1, with raw materials consisting of independent carbon and silicon sources;

[0076] The component consists of two parts, with the raw materials being a single precursor including a carbon source and a silicon source.

[0077] In an optional embodiment, when the raw material for preparing silicon carbide particles is component one, the carbon source includes at least one of methane, ethane, ethylene, acetylene, propylene, propane, and carbon monoxide.

[0078] The silicon source includes at least one of silane, dichlorosilane, trichlorosilane, and silicon tetrachloride.

[0079] It should be noted that if component one is selected for the reaction, the design of nozzle 105 can be adjusted through different preparation schemes, wherein the nozzle deflection angle 106 and the fluid velocity ejected from nozzle 105 are consistent with the design of component two, specifically including at least one of the following scheme types:

[0080] Option 1 allows the carbon and silicon sources to be mixed and processed first, and then transported by carrier gas to the nozzle 105 of the example scheme for ejection, eliminating the need to design two nozzles 105.

[0081] Option 2: Design nozzles 105 that independently spray carbon or silicon sources, as shown in the example. The nozzles 105 spray carbon and silicon sources in each layer or alternately.

[0082] Option 3: Design two nozzles 105. The silicon source is positioned as in the example scheme. The carbon source nozzle 105 is located between the nozzle deflection angle 106 and the top of the reaction chamber 1001. The nozzle is set horizontally. The flow rate of the fluid ejected from the carbon source nozzle 105 and the number of nozzles 105 are in a carbon:silicon ratio of 1:1 (the effect of adding materials).

[0083] In an optional embodiment, when the raw material for preparing silicon carbide particles is component two, the single precursor includes at least one of methyltrichlorosilane, tetramethylsilane, hexamethyldisilane, and methylsilane.

[0084] For example, the mechanism of preparing silicon carbide particles using methyltrichlorosilane (CH3SiCl3, abbreviated as MTS) is illustrated below:

[0085] The main reaction mechanism is: CH3SiCl3(g) → SiC(s) + 3HCl(g) (reaction conditions: H2, 1000℃-1400℃); during this process, C-Si bond breaking and free radical generation also occur: CH3SiCl3(g) →·SiCl3(g) +·CH3(g), which also means that intermediate products such as·SiCl2 will be generated during the reaction.

[0086] The fluidized bed reaction of this invention has a simple processing technology. Only simple cleaning and drying are required to obtain the final silicon carbide particles. It has low power consumption, the product does not require crushing and acid washing, and continuous production can be achieved.

[0087] If the self-propagating high-temperature synthesis method is used, the reaction mechanism is Si(s) + C(s) → SiC(s) (reaction conditions: 1800℃-2500℃). After this reaction, the silicon carbide produced exhibits agglomeration and clumping. The product needs to be crushed, sieved to obtain particles of the required size, washed to remove impurities, and dried to remove the cleaning agent in sequence before the desired silicon carbide particles can be finally obtained. The process is cumbersome and may also involve the introduction of contaminants, increasing the cost.

[0088] And / or, also includes a carrier gas, wherein the molar ratio of the carrier gas to the single precursor is (5-20):1.

[0089] The carrier gas is introduced to suppress side reactions. If H2 is in excess and carbon is not effectively inserted, free silicon is generated: ·SiCl2(g) + H2(g) → Si(s) + 2HCl(g); if H2 is insufficient, free carbon is generated: 2·CH3(g) → C2H6(g) → (high temperature pyrolysis) 2C(s) + 3H2(g).

[0090] In an optional embodiment, the reaction system further includes an evaporation device, a preheating device 130, a heating device 101, a seed crystal feeding device 110, a tail gas treatment device 111, and a storage device 120; a schematic diagram of the reaction system for preparing silicon carbide particles is shown in Figure 10. Figure 1 .

[0091] The evaporation device (not shown in the figure) is connected to the preheating device 130; the preheated raw material gas enters the reaction chamber 100 of the fluidized bed for reaction; specifically, the outlet of the preheating device 130 is connected to the inlet 102 of the reaction chamber, specifically to the nozzle plane 104 of the cone wall of the reaction chamber 100, for conveying the reaction raw materials.

[0092] Specifically, the raw material is placed in a constant temperature evaporator at 80℃-150℃ to turn it into a gaseous state. After the carrier gas is introduced (the carrier gas / single precursor is mixed at a molar ratio of 5:1-20:1), the carrier gas carries the raw material gas into the preheating device 130 for preheating. The preheating temperature is 500℃-800℃ to ensure that the mixed gas reaches the active temperature of the reaction when it enters the fluidized bed reaction chamber 100. The temperature of the reaction chamber 100 is 1000℃-1400℃.

[0093] The outlet of the reaction chamber 100 is connected to the inlet 112 of the exhaust gas treatment device, and the outlet 113 of the exhaust gas treatment device is connected to the preheating device 130.

[0094] Heating device 101 is located outside reaction chamber 100 and is used to heat the raw material gas; seed crystal feeding device 110 is located at the top of reaction chamber 100, and storage device 120 is located at the bottom of reaction chamber 100. The heating device 101 is positioned outside the equal-diameter portion 107 of reaction chamber 100 to facilitate uniform heating of the reaction materials within reaction chamber 100, ensuring a more complete and thorough reaction. When the sensor connected to storage device 120 at the bottom 1002 of the reaction chamber detects that storage device 120 is about to be full, the bottom valve (not shown in the figure) is closed, and the discharge device is disassembled and replaced. After replacing storage device 120, vacuuming and gas exchange are completed, and the valve is reopened to continue collecting. Similarly, by opening and closing the valve connected to seed crystal feeding device 110, seed crystals are added, thereby achieving uninterrupted continuous production, which is expected to improve production efficiency by approximately 16.67%.

[0095] In an optional embodiment, the seed silicon carbide has a particle size of 50 μm-380 μm.

[0096] The exhaust gas introduced into the reaction chamber 100 and the exhaust gas produced by the reaction are extracted by a pump connected to the exhaust gas pipe 109. After being treated by the exhaust gas treatment device 111, the raw material gas is returned to the furnace to participate in the reaction through the preheating device 130, thereby achieving the effect of recycling and greatly reducing production costs.

[0097] In an optional embodiment, the reaction chamber 100 includes a constant diameter portion 107 and an inverted conical portion 103, wherein the inverted conical portion 103 is located at the bottom of the reaction chamber 100 and is detachably connected to the storage device 120; the constant diameter portion 107 is located at the top of the reaction chamber 100 and is detachably connected to the seed crystal feeding device 110; in this embodiment of the invention, the exhaust gas outlet 108 of the reaction chamber 100 is located at the top of the constant diameter portion 107 for connecting to the inlet of the exhaust gas treatment device 111; in other embodiments of the invention, the position of the exhaust gas outlet 108 can be reasonably adjusted according to the spatial position of the reaction chamber 100, such as being located on the side wall of the constant diameter portion 107.

[0098] In an optional embodiment, the exhaust outlet 108 is connected to the exhaust treatment device 111 via an exhaust pipe 109, and an air pump is connected to the exhaust pipe 109.

[0099] And / or, a nozzle 105 is provided on the inner side of the cone wall of the inverted cone portion 103, and the nozzle 105 is connected to the outlet of the preheating device 130;

[0100] And / or, the length of the nozzle 105 is 0.05m-0.2m, and the diameter of the nozzle 105 is 5mm-20mm.

[0101] It should be noted that the present invention does not specify the shape of the nozzle 105, which may include any one of the following: straight tube shape, bird beak shape (from large to small diameter), trumpet shape (from small to large diameter), and arc shape. The appropriate shape can be selected according to actual needs.

[0102] In an optional embodiment, the prepared silicon carbide particles are further subjected to cleaning and drying processes.

[0103] The cleaning process is mainly used to remove unreacted raw materials (residual chlorosilane compounds), byproducts (HCl), and impurities from the surface of the particles during the preparation process, thus avoiding corrosion of the reaction equipment. Specifically, in the embodiments of the present invention, acid washing or alkaline washing can be used for cleaning. If acid washing is used, such as dilute hydrochloric acid, nitric acid, or hydrofluoric acid, it is beneficial to dissolve metal oxides and some chlorides. If alkaline washing is used, such as sodium hydroxide solution, it is beneficial to neutralize acidic residues and remove free carbon and organic impurities.

[0104] Then, wash the product multiple times with water (such as deionized water, purified water, ultrapure water, etc.) until it reaches neutrality (the conductivity meets the standard). Finally, perform a drying process. The drying process is not particularly limited in this invention. Its main purpose is to remove moisture from the surface of the silicon carbide particles. The drying temperature is 60℃-100℃, and the drying time is adjusted reasonably according to the actual amount of material being processed.

[0105] In summary, the embodiments of the present invention provide a method for preparing silicon carbide particles, which includes the following steps: wherein, a schematic diagram of the reaction system for preparing silicon carbide particles is shown in Figure 10. Figure 1 As shown.

[0106] A single precursor is placed in an evaporator at 80℃-150℃, and a carrier gas (H2) is introduced to mix it with MTS at a molar ratio of (5-20):1. The mixture is then introduced into a preheating device 130; after preheating to 500℃-800℃, it is introduced into a fluidized bed reaction chamber 100 for reaction. Inside the reaction chamber 100, the nozzle deflection angle 106 on the inner side of the cone wall is 30°-60°, and the number of nozzles 105 is 1-10 groups, evenly distributed on the same horizontal plane. The fluid ejected from the nozzle 105 will have the same deflection point 200 as the central axis 1003 of the reaction chamber 100. Each set of horizontal nozzles 105 forms a 360° airflow surface on the horizontal airflow. After reacting for 201h-615h, silicon carbide particles with an average particle size of 3mm-11mm are obtained. The particle size of the seed silicon carbide is 50μm-380μm. The pressure in the reaction chamber 100 is 0.1MPa-0.5MPa, and the temperature is 1000℃-1400℃.

[0107] The obtained silicon carbide particles are subjected to cleaning and drying treatments. The cleaning reagents are acid (such as dilute hydrochloric acid, nitric acid, or hydrofluoric acid), sodium hydroxide solution, and water. After washing with water until neutral, the particles are dried at a temperature of 60℃-100℃. The concentrations of the acid and sodium hydroxide solution are those of conventional cleaning reagents.

[0108] In a second aspect, the present invention provides silicon carbide particles, which are prepared by any of the preparation methods described in the foregoing embodiments;

[0109] The purity of silicon carbide particles is ≥6N.

[0110] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0111] Example 1

[0112] This embodiment provides a method for preparing silicon carbide particles, which includes the following steps: A schematic diagram of the reaction system for preparing silicon carbide particles is shown in Figure 10. Figure 1 As shown.

[0113] A single precursor (methyltrichlorosilane, CH3SiCl3, abbreviated as MTS) is placed in an evaporator at 100°C, and a carrier gas (H2) is introduced to mix it with MTS at a molar ratio of 15:1. The mixture is then introduced into a preheating device 130 and preheated to 800°C. The mixture is then introduced into a fluidized bed reaction chamber 100 for reaction. Inside the reaction chamber 100, the nozzles on the inner side of the cone wall have a deflection angle of 30° (106), and there are four groups of nozzles (105) evenly distributed on the same horizontal plane. The fluid ejected from each group of nozzles 105 will have the same deflection point 200 as the central axis 1003 of the reaction chamber 100. Each group of horizontal nozzles 105 forms a 360° airflow surface on the horizontal airflow. The fluid velocity ejected from the nozzles 105 is 10.22 m / s. After reacting for 231.5 ± 3 h, silicon carbide particles with an average particle size of 6 mm are obtained. The particle size of the seed silicon carbide is 180 μm. The pressure inside the reaction chamber 100 is 0.3 MPa and the temperature is 1100 °C.

[0114] The nozzle 105 is a straight tube with a length of 0.1m and a diameter of 10mm. In the axial direction of the reaction chamber, the vertical distance from the nozzle to the central axis is X=0.6m. The distance Y from the deflection point of this group of nozzles to the bottom of the reaction chamber is Y=L1+L2, where L1 is the distance from the nozzle to the bottom of the reaction chamber, and L1 is 0.5m; L2=X / tan30°, that is, Y=0.5m+0.6m / tan30°.

[0115] The obtained silicon carbide particles are cleaned and dried. The cleaning reagents are dilute hydrochloric acid solution and sodium hydroxide solution. The drying temperature after washing is 60℃-100℃.

[0116] Experimental Example 1

[0117] This experiment was conducted to investigate the particle size of silicon carbide particles obtained when the nozzle deflection angle 106 was fixed at 30°, the number of nozzles 105 was 4, the distance between the nozzle deflection angle 106 and the top of the reaction chamber 1001 was 1m-2m, and the fluid flow rate ejected from the nozzles 105 was different. The preparation steps were the same as in Example 1, the only difference being the fluid flow rate ejected from the nozzles 105. The relevant data are summarized in Table 1.

[0118] Table 1. Silicon carbide particles obtained with a nozzle deflection angle of 30°

[0119]

[0120] Experiment Example 2

[0121] This experiment was conducted to investigate the particle size of silicon carbide particles obtained when the nozzle deflection angle 106 was fixed at 45°, the number of nozzles 105 was 4, the distance between the nozzle deflection angle 106 and the top of the reaction chamber 100 was 1m-2m, and the fluid flow rate ejected from the nozzles 105 was different. The preparation steps were the same as in Example 1, the only difference being the fluid flow rate ejected from the nozzles 105. The relevant data are summarized in Table 2.

[0122] Table 2. Silicon carbide particles obtained with a nozzle deflection angle of 45°

[0123]

[0124] Experimental Example 3

[0125] This experiment was conducted to investigate the particle size of silicon carbide particles obtained when the nozzle deflection angle 106 was fixed at 60°, the number of nozzles 105 was 4, the distance between the nozzle deflection angle 106 and the top of the reaction chamber 1001 was 1m-2m, and the fluid flow rate ejected from the nozzles 105 was different. The preparation steps were the same as in Example 1, the only difference being the fluid flow rate ejected from the nozzles 105. The relevant data are summarized in Table 3.

[0126] Table 3. Silicon carbide particles obtained with a nozzle deflection angle of 60°

[0127]

[0128] The results from Experiments 1-3 show that the particle size fluctuation range is not large, basically around ±0.6 mm. At different α angles, the particle size can be precisely controlled by controlling the flow rate.

[0129] Experiment Example 4

[0130] This experiment was used to investigate the particle size of silicon carbide particles with an average particle size of 4 mm when the nozzle deflection angle 106 was fixed at 30°. The particle size of silicon carbide particles obtained with different numbers of nozzles 105 were investigated. The preparation steps were the same as in Example 1, except that the fluid flow rate ejected from the nozzle 105 was different. The relevant data are summarized in Table 4.

[0131] Table 4. Silicon carbide particles obtained with different numbers of nozzle groups

[0132]

[0133] As can be seen from the data in Table 4, with the increase of the number of groups, the particle size fluctuation range becomes smaller and the particle size distribution becomes more precise. It can be seen that increasing the number of nozzle 105 groups is beneficial to the precise control of particle size.

[0134] Experimental Example 5

[0135] This experiment investigates the effect of different molar ratios of carrier gas and single precursor on the yield of silicon carbide particles. The carrier gas is H2, and the single precursor is methyltrichlorosilane (CH3SiCl3, abbreviated as MTS).

[0136] Table 5. Yield of silicon carbide particles prepared with different molar ratios of carrier gas to single precursor

[0137]

[0138] Test Example 1

[0139] This test example uses 6mm standard silicon carbide particles. With the nozzle deflection angle fixed at 30° (106), and four nozzle groups (105), particle size analysis was performed on the final product, and a normal distribution of particle size was plotted. The relevant results are shown in [link to results]. Figure 3 .

[0140] from Figure 3 It can be seen that, using 6mm silicon carbide particles as the standard, the particle size of the final product is mainly concentrated around 6.1±0.6mm. The particle size can be precisely controlled, and the precision can be further improved by adjusting the number of groups.

[0141] Test Example 2

[0142] This test example uses the product prepared in Example 1 as an example to measure the purity. The relevant data are shown in Table 6.

[0143] Table 6 Purity Test Data

[0144]

[0145] As can be seen from the data in Table 6, the purity of the produced silicon carbide particles can reach 7N, close to 8N, and the content of metal elements that have a great impact on semiconductor performance is lower than the detection limit, which can meet the purity requirements of semiconductor silicon carbide.

[0146] Test Example 3

[0147] This test case uses the product prepared in Example 1 as an example for XRD analysis. The relevant results are shown below. Figure 4 .

[0148] from Figure 4 The results show that by comparing the characteristic peaks (111) 35.6°, (200) 41.4°, (220) 60°, and (311) 71.8°, it can be known that the silicon carbide deposited on the seed surface is 3C-SiC.

[0149] Test Example 4

[0150] This test case uses the product prepared in Example 1 as an example for Raman analysis. The relevant results are shown below. Figure 5 .

[0151] from Figure 5 The results show that the characteristic peak value is 794 cm⁻¹. -1 970cm -1 The presence of sharp peaks on both sides is also strong evidence for the existence of 3C-SiC.

[0152] In summary, this invention precisely controls the average particle size of the produced silicon carbide particles by controlling the fluid flow rate ejected from nozzle 105, reducing the defect rate caused by substandard particle size and achieving a high particle size yield. The resulting product has controllable particle size and high purity, avoiding the risks introduced by crushing and screening. Furthermore, the production process does not require disassembly and reassembly of individual furnaces, enabling continuous production, simplifying the production process, reducing input costs, ensuring product quality, and improving production efficiency, thus providing a new approach for future industrialization.

[0153] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing silicon carbide particles, characterized in that, Silicon carbide particles with controllable particle size are prepared by using a reaction system including a fluidized bed, wherein the average particle size of the silicon carbide particles is 3 mm-11 mm. The fluidized bed includes nozzles on the inner side of the cone wall, and the fluid ejected from the nozzles has the same deflection point as the central axis of the fluidized bed reaction chamber; the fluid velocity ejected from the nozzles is 8.35 m / s-22.86 m / s. The nozzles are arranged on the same horizontal plane inside the cone wall, and a circle of nozzles on the same horizontal plane constitutes a group; Using a vertical line perpendicular to the ground as a reference, the vertical direction deflection angle α, the direction of the same group of directions α all point to the same point on the central axis of the reaction chamber, and the deflection angle α is 30°-60°; In the axial direction of the reaction chamber, let X be the vertical distance from the nozzle to the central axis, and Y be the distance from the deflection point of the nozzle group to the bottom of the reaction chamber. Y = L1 + L2, where L1 is the distance from the nozzle to the bottom of the reaction chamber, and L1 is 0.4m-0.6m; L2 = X / tanα.

2. The preparation method according to claim 1, characterized in that, Silicon carbide particles with controllable particle size are obtained, and the fluid flow rate ejected from the nozzle has at least one of the following characteristics: Feature 1: When the average particle size of silicon carbide particles is 3.8mm-4.5mm, the fluid velocity ejected from the nozzle is 8.35m / s-14.46m / s, and the required time is 201h-262h. Feature 2: When the average particle size of silicon carbide particles is 5.5mm-6.5mm, the fluid velocity ejected from the nozzle is 10.22m / s-17.70m / s, and the required time is 301h-380h. Feature 3: When the average particle size of silicon carbide particles is 7.5mm-8.5mm, the fluid velocity ejected from the nozzle is 11.80m / s-20.45m / s, and the required time is 418h-497h. Feature 4: When the average particle size of silicon carbide particles is 9.5mm-10.5mm, the fluid velocity ejected from the nozzle is 13.20m / s-22.86m / s, and the required time is 536h-615h.

3. The preparation method according to claim 1, characterized in that, The number of nozzles is 1 to 10 groups; And / or, the distance between the deflection point of this group of nozzles and the top of the reaction chamber is 1m-2m.

4. The preparation method according to claim 3, characterized in that, When the nozzle deflection angle is constant, the fluid velocity ejected from the nozzle has at least one of the following characteristics: Feature 1: When the nozzle deflection angle α is 30°, the fluid velocity ejected from the nozzle is 8.35 m / s - 13.20 m / s; Feature 2: When the nozzle deflection angle α is 45°, the fluid velocity ejected from the nozzle is 10.22 m / s - 16.16 m / s; Feature 3: When the nozzle deflection angle α is 60°, the fluid velocity ejected from the nozzle is 14.46 m / s-22.86 m / s.

5. The preparation method according to claim 1, characterized in that, The raw materials for preparing silicon carbide particles include any one of the following components: Component 1, with raw materials consisting of independent carbon and silicon sources; The component consists of two parts, with the raw materials being a single precursor including a carbon source and a silicon source.

6. The preparation method according to claim 5, characterized in that, When the raw material for preparing silicon carbide particles is component one, the carbon source includes at least one of methane, ethane, ethylene, acetylene, propylene, propane, and carbon monoxide. The silicon source includes at least one of silane, dichlorosilane, trichlorosilane, and silicon tetrachloride.

7. The preparation method according to claim 5, characterized in that, When the raw material for preparing silicon carbide particles is component two, the single precursor includes at least one of methyltrichlorosilane, tetramethylsilane, hexamethyldisilane and methylsilane; And / or, it also includes a carrier gas, wherein the molar ratio of the carrier gas to the single precursor is (5-20):

1.

8. The preparation method according to claim 1, characterized in that, The reaction system also includes an evaporation device, a preheating device, a heating device, a seed crystal feeding device, a tail gas treatment device, and a storage device; The evaporation device is connected to the preheating device; the preheated raw material gas enters the reaction chamber of the fluidized bed for reaction; The outlet of the reaction chamber is connected to the inlet of the exhaust gas treatment device, and the outlet of the exhaust gas treatment device is connected to the preheating device. The heating device is located outside the reaction chamber and is used to heat the raw material gas; the seed crystal feeding device is located at the top of the reaction chamber, and the storage device is located at the bottom of the reaction chamber.

9. The preparation method according to claim 8, characterized in that, The reaction chamber includes a constant-diameter section and an inverted conical section, wherein the inverted conical section is located at the bottom of the reaction chamber and is detachably connected to the material storage device; the constant-diameter section is located at the top of the reaction chamber and is detachably connected to the seed crystal feeding device. And / or, a nozzle is provided on the inner side of the cone wall of the inverted cone portion, and the nozzle is connected to the outlet of the preheating device; And / or, the length of the nozzle is 0.05m-0.2m, and the diameter of the nozzle is 5mm-20mm.

10. A silicon carbide particle, characterized in that, Prepared by the preparation method according to any one of claims 1-9; The purity of the silicon carbide particles is ≥6N.

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