A synthesis device of semi-insulating powder

Abstract

The utility model relates to the technical fields of semiconductor material preparation devices, concretely to a kind of synthesis equipment of semi-insulating powder, including furnace body, heater located in furnace body, graphite crucible is arranged in the inner ring of heater;Still including the gas pipe fixed on furnace body;The gas pipe includes inlet pipe and outlet pipe, inlet pipe and outlet pipe are horizontally arranged at the space place above raw material area in graphite crucible, and inlet pipe and outlet pipe are all horizontally inserted into furnace body from furnace body outside;The heater is used to control the raw material area in graphite crucible and the raw material area upper space form positive temperature difference;The outer wall of the graphite crucible is symmetrically provided with porous graphite splicing piece, and the porous graphite splicing piece is oppositely arranged with inlet pipe and outlet pipe.The scheme can eliminate the block of raw material to inert gas stream, realize nitrogen rapid directional discharge, effectively avoid nitrogen element doping, and improve the preparation qualified rate of silicon carbide powder.

Description

Technical Field

[0001] This utility model relates to the technical field of semiconductor material preparation apparatus, specifically to a device for synthesizing semi-insulating powder. Background Technology

[0002] Silicon carbide (SiC), as a typical representative of third-generation semiconductor materials, is considered one of the ideal materials for manufacturing high-temperature, high-frequency, high-power, and high-voltage devices due to its advantages such as wide bandgap, high thermal conductivity, high breakdown electric field, and large electron migration rate. Among them, semi-insulating silicon carbide powder can be used as a raw material for conductive silicon carbide ingots as well as as a raw material for AR glasses and moissanite, and has extremely high industrial application potential.

[0003] The preparation of semi-insulating silicon carbide powder requires specialized equipment. This equipment creates a specific temperature field to heat the raw materials within a graphite crucible, causing the carbon and silicon powders in the raw materials to undergo a self-propagating reaction at high temperatures to synthesize silicon carbide powder. However, both the graphite crucible and the carbon powder adsorb nitrogen from the air, primarily based on the principle of physical adsorption, specifically through van der Waals forces between the adsorbate (nitrogen molecules) and the adsorbent (graphite material or carbon powder) molecules. This adsorption process is non-selective, reversible, and fast, which means that nitrogen can become doped into the silicon carbide lattice during the synthesis process, reducing the yield and purity of the silicon carbide powder.

[0004] To address this issue, the prior art, "A High-Purity Silicon Carbide Powder Synthesis Apparatus" (Publication No.: CN215139935U), discloses an apparatus structure including a crucible, a protective layer, and a ventilation component. The ventilation component comprises a first porous structure and a second porous structure. The first porous structure extends from the bottom center of the apparatus into a holding chamber for storing silicon-carbon mixed powder and is used to introduce hydrogen gas into the holding chamber. The second porous structure is located at the end of the crucible and communicates with the holding chamber. When hydrogen gas is introduced through the first porous structure, nitrogen gas in the holding chamber can escape through the second porous structure, thereby promoting nitrogen gas discharge and improving the purity of the silicon carbide powder. However, the prior art still has the following technical problems: In the prior art, the first porous structure used for introducing hydrogen is cylindrical, and its outer periphery is in direct contact with the carbon powder and silicon powder in the holding chamber. This causes the raw materials to obstruct the introduction of hydrogen, significantly reducing the speed at which hydrogen enters the holding chamber from the first porous structure. This reduces the efficiency of using hydrogen to expel nitrogen from the holding chamber. Furthermore, since hydrogen enters the holding chamber laterally from the first porous structure, while nitrogen needs to exit from the second porous structure located at the bottom of the device, the laterally entering hydrogen easily mixes with nitrogen, making it difficult to quickly expel nitrogen from the bottom of the device and reducing the nitrogen removal effect. In particular, the nitrogen removal from the top of the holding chamber is slower, which can easily cause nitrogen to be doped into the silicon carbide lattice during the reaction, reducing the yield of silicon carbide powder. Utility Model Content

[0005] This invention provides a device for synthesizing semi-insulating powder, which can solve the problem that existing devices are too slow in removing nitrogen when preparing silicon carbide powder, which easily leads to a decrease in the yield of silicon carbide powder due to nitrogen.

[0006] This application provides the following technical solution: a semi-insulating powder synthesis device, including a furnace body, a heater located inside the furnace body, and a graphite crucible disposed in the inner ring of the heater; It also includes a gas pipe fixed on the furnace body; the gas pipe includes an inlet pipe and an outlet pipe, which are horizontally arranged in the space above the raw material area inside the graphite crucible, and both the inlet pipe and the outlet pipe extend horizontally into the furnace body from the outside of the furnace body. The heater is used to control the formation of a positive temperature difference between the raw material zone inside the graphite crucible and the space above the raw material zone; The graphite crucible has porous graphite splicing parts symmetrically arranged on its crucible wall, and the porous graphite splicing parts are arranged opposite to the air inlet pipe and the air outlet pipe.

[0007] Beneficial effects: 1. Accelerate nitrogen removal, improve denitrification efficiency and powder synthesis yield. By controlling the temperature difference between the raw material area and the space above it within the graphite crucible using a heater, the temperature of the raw material area is higher than the temperature of the space above it. This allows the nitrogen adsorbed in the raw material to move and converge towards the cooler space above the raw material area. The inlet pipe is located above the raw material area. Inert gas is introduced into the inlet pipe, pushing the nitrogen gathered there towards the outlet pipe, thus quickly expelling the nitrogen and achieving rapid denitrification. Compared to existing devices, this solution first utilizes the temperature difference to concentrate nitrogen in the space above the raw material area, and then optimizes the inert gas path through the inlet pipe, allowing the nitrogen to be discharged from the crucible at a faster rate. This avoids slow nitrogen removal during synthesis, which could lead to nitrogen doping in the silicon carbide powder lattice, thereby effectively improving the yield of silicon carbide powder.

[0008] 2. The device structure has been optimized to reduce the obstruction of the incoming gas flow by the raw materials and improve nitrogen discharge efficiency. In the prior art, the outer periphery of the first porous structure is in direct contact with the raw materials, which can easily affect the speed at which hydrogen enters the holding space and reduce nitrogen discharge efficiency. In contrast, the porous graphite splice in this solution is positioned opposite the inlet and outlet pipes, so that the porous graphite splice is also located in the space above the raw material area. When the inert gas is introduced from the inlet pipe, it can quickly enter the crucible without being blocked by the raw materials, thereby accelerating the nitrogen discharge speed and promoting the improvement of the yield of silicon carbide powder synthesis.

[0009] Furthermore, both the air inlet pipe and the air outlet pipe have a flared shape at the end near the porous graphite splice.

[0010] Beneficial effects: Designing the inlet and outlet pipes with a funnel shape near the porous graphite splice significantly optimizes the flow and diffusion of airflow within the furnace, improving denitrification efficiency and powder synthesis quality. For the inlet pipe, the funnel shape increases the output cross-sectional area of ​​the inert gas, reduces airflow resistance, and allows the inert gas to diffuse quickly and evenly into the porous graphite splice after being ejected from the pipe, ensuring a stable and comprehensive gas curtain above the raw material area. For the outlet pipe, the flared design of the funnel shape increases the nitrogen intake range and improves the nitrogen discharge rate, while reducing nitrogen eddies and stagnation at the pipe inlet, preventing local nitrogen accumulation and promoting the stability and yield of powder synthesis.

[0011] Furthermore, the heater is an induction heater with a heating coil, and the graphite crucible is located at the center of the heating coil.

[0012] Beneficial effects: The heating coil does not obstruct the intake and exhaust of the air inlet and outlet pipes, improving the rationality of the device design. At the same time, induction heating allows heat to be transferred directly from the crucible to the raw materials, resulting in faster heating and higher thermal efficiency, which can quickly reach the high-temperature environment required for powder synthesis. Furthermore, induction heating can achieve precise temperature control by adjusting the current frequency, resulting in higher temperature control accuracy. This avoids the risk of nitrogen doping caused by temperature fluctuations and improves the yield of silicon carbide powder preparation. Furthermore, the heater controls the positive temperature difference between the raw material zone inside the graphite crucible and the space above the raw material zone to be within the range of 200℃-350℃.

[0013] Beneficial effects: Precisely limiting the positive temperature difference between the raw material zone controlled by the heater and the space above the raw material zone to the range of 200℃-350℃ provides the optimal temperature environment for efficient denitrification and high-quality semi-insulating powder synthesis. This temperature difference range avoids the problem that when the temperature difference is too small, the nitrogen molecules adsorbed in the raw material do not have enough thermal kinetic energy, making it difficult for them to quickly detach from the raw material and converge to the lower-temperature space above, resulting in low nitrogen discharge efficiency and easy residual doping. At the same time, it prevents the raw material zone from being heated when the temperature difference is too large, thus affecting the powder synthesis efficiency and improving the yield of silicon carbide powder synthesis.

[0014] Furthermore, the furnace body is also provided with heat insulation material, which is disposed around the heating coil.

[0015] Beneficial effects: The insulation material can effectively block the heat generated by the heating coil from dissipating to the outside of the furnace, greatly improving the heat utilization rate and reducing energy consumption, while avoiding safety hazards caused by high temperature outside the furnace; the insulation material can form a stable thermal barrier around the heating coil, preventing uneven raw material synthesis reaction caused by temperature fluctuations, reducing the risk of nitrogen doping, and improving the preparation qualification rate of silicon carbide powder. Attached Figure Description

[0016] Figure 1 This is the main structural view of the present invention. Detailed Implementation

[0017] The following detailed description illustrates the specific implementation method: The markings in the attached drawings of the instruction manual include: furnace body 1, air inlet pipe 2, bell mouth 201, heater 3, insulation material 4, graphite crucible 5, porous graphite splice 6, air outlet pipe 7, raw material area 8.

[0018] Example 1 like Figure 1 As shown, a semi-insulating powder synthesis device includes a furnace body 1, an insulation material 4 disposed within the furnace body 1, a heater 3 located within the insulation material 4, a graphite crucible 5 disposed within the inner ring of the heater 3, and a gas pipe fixed to the furnace body 1.

[0019] The gas pipe includes an inlet pipe 2 and an outlet pipe 7. The inlet pipe 2 and the outlet pipe 7 are horizontally positioned in the space above the raw material area 8 near the graphite crucible 5. Both the inlet pipe 2 and the outlet pipe 7 extend horizontally from the outside of the furnace body 1 into the furnace body 1. Heater 3 is an induction heater with a heating coil, and the graphite crucible 5 is located at the center of the heating coil. The heating coil is spiral-shaped, which does not obstruct the air intake and exhaust of the inlet pipe 2 and outlet pipe 7, improving the rationality of the device design. At the same time, induction heating allows heat to be transferred directly from the crucible to the raw material, resulting in faster heating and higher thermal efficiency, and can quickly reach the high-temperature environment required for powder synthesis. Heater 3 controls the formation of a positive temperature difference between the raw material zone 8 inside the graphite crucible 5 and the space above the raw material zone 8; and the positive temperature difference ranges from 200℃ to 350℃. Utilizing the temperature difference effect, nitrogen gas in the raw material zone 8 can move towards and converge in the space above the raw material zone 8. Precisely limiting the positive temperature difference between the raw material zone 8 controlled by heater 3 and the space above the raw material zone 8 to the range of 200℃-350℃ provides the optimal temperature environment for efficient denitrification and high-quality semi-insulating powder synthesis. This temperature difference range avoids the problem that when the temperature difference is too small, the nitrogen molecules adsorbed in the raw material do not have enough thermal kinetic energy, making it difficult for them to quickly detach from the raw material and converge to the lower-temperature space above, resulting in low nitrogen discharge efficiency and easy residual doping. At the same time, it prevents the raw material zone 8 from being heated when the temperature difference is too large, thus affecting the powder synthesis efficiency and improving the yield of silicon carbide powder synthesis.

[0020] A porous graphite splice 6 is symmetrically arranged on the crucible wall of the graphite crucible 5. The porous graphite splice 6 is positioned opposite the inlet pipe 2 and the outlet pipe 7. The lower edge of the porous graphite splice 6 is located above the material surface in the raw material zone 8. When inert gas is introduced from the inlet pipe 2, it can quickly enter the crucible without being blocked by the raw material, thereby accelerating the nitrogen discharge rate and promoting the improvement of the yield of silicon carbide powder synthesis. The ends of the inlet pipe 2 and the outlet pipe 7 near the porous graphite splice 6 are both flared vents 201 in shape. Designing the ends of the inlet pipe 2 and outlet pipe 7 near the porous graphite splice 6 as a funnel shape 201 can significantly optimize the flow and diffusion of airflow in the furnace, improve denitrification efficiency and powder synthesis quality. For the inlet pipe 2, the funnel shape 201 can expand the output cross-sectional area of ​​inert gas, reduce airflow output resistance, and allow the inert gas to diffuse quickly and evenly into the porous graphite splice 6 after being ejected from the pipe, ensuring that the inert gas forms a stable and comprehensive gas curtain in the space above the raw material zone 8. For the outlet pipe 7, the flared design of the funnel shape 201 can increase the nitrogen intake range and improve the nitrogen discharge rate, while reducing nitrogen eddies and stagnation at the pipe inlet, avoiding local nitrogen accumulation, and promoting the stability and pass rate of powder synthesis.

[0021] The installation method for this device is as follows: Charging and sealing the furnace: The proportioned silicon carbide raw materials are loaded into the graphite crucible 5 raw material area 8, the porous graphite splice 6 is fixed, and the furnace body 1 is sealed after ensuring that the inlet pipe and outlet pipe 7 bell mouth 201 are not blocked.

[0022] Temperature control to create temperature difference: Start the induction heater 3, first raise the graphite crucible 5 to the basic synthesis temperature, and then precisely control the temperature of the lower part of the raw material zone 8 to 2400℃-2450℃, and the temperature of the space above the raw material zone 8 to 2100℃-2200℃, so as to cause the nitrogen in the raw material to gather in the space above.

[0023] Nitrogen removal by ventilation: Inert gas is introduced through the inlet pipe 2. In this embodiment, argon gas is introduced. A uniform gas curtain is formed through the flared end 201 and the porous graphite splice 6, which pushes the gathered nitrogen gas to be quickly discharged from the furnace through the flared end 201 of the outlet pipe 7, thus completing the nitrogen removal.

[0024] Synthesis cooling: Maintain stable temperature and temperature difference inside the furnace to allow the raw materials to complete the silicon carbide synthesis reaction, and then slowly cool down to avoid damage to the powder lattice.

[0025] Furnace cleaning and material preparation: After the furnace body 1 has cooled to room temperature, remove the powder, clean the equipment of any remaining impurities and maintain the gas circuit components in preparation for the next use.

[0026] The above are merely embodiments of this utility model, and the utility model is not limited to the field covered by this embodiment. Commonly known structures and characteristics in the solutions are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of this utility model, and these should also be considered within the scope of protection of this utility model. These modifications will not affect the effectiveness of the implementation of this utility model or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A device for synthesizing semi-insulating powder, characterized in that: A device for synthesizing semi-insulating powder includes a furnace body, a heater located inside the furnace body, and a graphite crucible disposed in the inner ring of the heater. It also includes a gas pipe fixed on the furnace body; the gas pipe includes an inlet pipe and an outlet pipe, which are horizontally arranged in the space above the raw material area inside the graphite crucible, and both the inlet pipe and the outlet pipe extend horizontally into the furnace body from the outside of the furnace body. The heater is used to control the formation of a positive temperature difference between the raw material zone inside the graphite crucible and the space above the raw material zone; The outer wall of the graphite crucible is symmetrically provided with porous graphite splicing parts, which are arranged opposite to the inlet pipe and the outlet pipe.

2. The equipment for synthesizing semi-insulating powder according to claim 1, characterized in that: Both the intake pipe and the exhaust pipe have a flared shape at the end near the porous graphite splice.

3. The equipment for synthesizing semi-insulating powder according to claim 2, characterized in that: The heater is an induction heater with a heating coil, and the graphite crucible is located at the center of the heating coil.

4. The equipment for synthesizing semi-insulating powder according to claim 3, characterized in that: The heater controls the positive temperature difference between the raw material zone inside the graphite crucible and the space above the raw material zone to be within the range of 200℃-350℃.

5. The equipment for synthesizing semi-insulating powder according to claim 4, characterized in that: The furnace body is also equipped with heat insulation material, which is disposed around the heating coil.

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