A sintering device for purifying aluminum nitride and a purification process thereof

Abstract

The present application relates to a sintering device for purifying aluminum nitride and a purification method thereof, and provides a sintering device for purifying aluminum nitride, which includes a furnace body, wherein the furnace body is provided with multiple layers of thermal insulation layers, a growth chamber is provided in the center, a crucible for storing raw materials is provided in the center of the growth chamber, a cover is provided on the top of the crucible, the interior of the crucible is connected to the furnace body, a heater for heating is also provided in the growth chamber, an inflation channel is provided on the multiple layers of thermal insulation layers on the lower side of the growth chamber, an exhaust channel is provided on the multiple layers of thermal insulation layers on the upper side of the growth chamber, the inflation channel and the exhaust channel are respectively connected to an inflation pump and an exhaust pump at one end away from each other, and a solid sediment collection plate is provided between the multiple layers of thermal insulation layers on the upper side; the present application also includes a purification method using the device. The present application has the effect of improving the purification effect and ensuring the stability of sintering purification.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum nitride crystal purification production, and in particular to a sintering device for aluminum nitride purification and a purification process thereof. Background Art

[0002] Aluminum nitride (AlN) is a typical representative of ultra-wide bandgap semiconductor materials. Its excellent optical, electrical and thermal properties are very suitable for the preparation of radio frequency (microwave power) devices, high-power devices, bulk / surface acoustic wave devices and ultra-short wave optoelectronic devices. The characteristics of AlN crystals, such as weak thermal excitation, direct bandgap and absorption edge in the deep ultraviolet band (200nm), can be used for the preparation of deep ultraviolet diodes, lasers and detectors, and have important application prospects in the fields of ultraviolet disinfection, missile warning / warning, space exploration, etc. Its excellent properties such as large bandwidth, high thermal conductivity, high breakdown field strength and high saturated electron mobility are suitable for the preparation of power electronic devices, and have great application potential in the fields of 5G / 6G communications, ultra-high voltage transmission systems, radars, electric vehicles, etc. In addition, AlN and AlGaN belong to the same family of materials, with small lattice mismatch and thermal mismatch. The maximum lattice mismatch between the two is 2.4%, which is the best substrate material for epitaxial AlGaN; compared with heterogeneous substrates (Si, SiC, Sapphire), the dislocation density is reduced by 3 to 4 orders of magnitude. Therefore, the preparation of AlN crystal materials is of great significance.

[0003] The physical vapor transport (PVT) method is recognized as one of the most effective methods for growing AlN crystals. Its basic principle is that the AlN source sublimates at high temperature (>2000°C) and deposits at a lower temperature to obtain AlN crystals. The key factor for the successful preparation of high-purity, high-quality AlN crystals is the acquisition of high-purity and sublimation-stable AlN raw materials. The purity of commercially available AlN powder can reach up to 99.9%. The concentration of impurity elements such as Figure 1 As shown in the figure, the impurities exceeding 10 ppm wt include O, Fe, Si, Cl, V, C, Ga, Ni, Ti and Cr elements, among which the O impurity content is as high as 4500 ppm wt. In the growth of AlN crystals, O, C, Si impurity elements are easily introduced into AlN crystals to form impurity defects, affecting the optical and electrical properties of the crystals. Therefore, the material purification process is a key process in the growth process of AlN crystals.

[0004] In the related art, an aluminum nitride sintering and purification device includes a furnace body, a crucible is arranged in the furnace body, a heater is arranged around the crucible, a multi-layer tungsten insulation layer is arranged around the heater, and a cover body is provided on the top cover of the crucible, and a gap is formed between the cover body and the crucible. During the purification operation, the staff places the crucible and the cover body containing AlN raw materials in the furnace body, turns on the heater, and sinter and purify the AlN in the crucible. Under the continuous high temperature state, the AlN raw material continues to undergo a solid-gas-solid transformation, and the AlN raw material gradually transforms from an amorphous state to a polycrystalline state. However, in the process of gradually increasing the temperature in the crucible, different impurity elements form gas phase substances at different temperatures and diffuse into the furnace body, and are randomly transmitted to various parts of the furnace body with the flow of gas, and the condensed solid substances are attached to the cavity in the process of gradually decreasing the temperature. After long-term material purification, impurities will continue to accumulate in the furnace body, pollute the furnace body, affect the raw material purification effect, and cause secondary pollution of the raw materials in severe cases. At the same time, when sintering AlN raw materials at high temperatures, Al and N vapors will continue to sublimate. A part of them will be deposited at a lower temperature inside the crucible or cover to obtain AlN crystals, while the other part will diffuse to the tungsten insulation layer and deposit at a suitable low temperature to form AlN. Due to the different thermal expansion coefficients of AlN and tungsten, the tungsten insulation layer will produce stress, deformation or even rupture during the temperature increase and decrease process. With long-term accumulation, AlN will continue to increase, and even cause the tungsten insulation layers to connect with each other, increase thermal conductivity and reduce insulation performance. Changes in insulation structure and insulation performance will affect the thermal field changes in the furnace, and thus affect the stability of the sintering process. Summary of the invention

[0005] In order to improve the purification effect and ensure the stability of sintering purification, the present application provides a sintering device for purifying aluminum nitride and a purification process thereof.

[0006] The present application provides a sintering device for purifying aluminum nitride and a purification process thereof, which adopts the following technical solutions: A sintering device for purifying aluminum nitride comprises a furnace body, wherein a plurality of heat-insulating layers are arranged in the furnace body, a growth chamber is arranged in the center of the plurality of heat-insulating layers, a crucible for storing raw materials is arranged in the center of the growth chamber, a cover is arranged on the top of the crucible, a gap is formed between the crucible and the cover, so that the inside of the crucible and the furnace body are connected, a heater for heating is also arranged in the growth chamber, an air charging channel is arranged on the plurality of heat-insulating layers on the lower side of the growth chamber, an air extraction channel is arranged on the plurality of heat-insulating layers on the upper side of the growth chamber, one end of the air charging channel away from the growth chamber is connected to an air charging pump outside the furnace body, one end of the air extraction channel away from the growth chamber is connected to an air extraction pump outside the furnace body, a solid sediment collecting plate is arranged between the plurality of heat-insulating layers on the upper side, the solid sediment collecting plate is arranged horizontally, and when the temperature of the raw materials in the crucible reaches 2100-2250°C, the temperature on the solid sediment collecting plate is about 1700-1900°C.

[0007] By adopting the above technical solution, the staff placed the crucible containing the raw materials in the growth chamber, and filled the inflation channel with high-purity nitrogen through the inflation pump, and then filled the growth chamber with high-purity nitrogen. At the same time, the vacuum pump reduced the air pressure at the top of the growth chamber through the vacuum channel, thereby forming an airflow channel from bottom to top inside the chamber. This airflow layout effectively promotes the directional transmission of the escaped substances to the top, and by forming a stable gas transmission channel, it can avoid the random deposition of impurities in the cavity, reduce furnace pollution, and significantly improve the raw material purification efficiency and the stability of sintering purification. By setting a solid deposit collection plate in a specific temperature area and ensuring that the solid deposit collection plate is on the gas transmission channel, it is ensured that the ALN solid is deposited on the solid deposit collection plate.

[0008] Preferably, a plurality of the exhaust channels are arranged on the multi-layer insulation layer, the inner diameter of the exhaust channels is 5 to 30 mm, the axial directions of the plurality of the exhaust channels are perpendicular to the outer surface of the solid sediment collection plate, and the end of any exhaust channel close to the solid sediment collection plate is 3 to 30 mm away from the solid sediment collection plate.

[0009] By adopting the above technical solution, the evenly distributed exhaust channels can minimize the deposition of impurities inside the cavity, while improving the discharge efficiency of the escaped substances and further optimizing the uniformity of the thermal field in the furnace.

[0010] Preferably, a through hole is provided at the center of the insulation layer between the solid sediment collecting plate and the crucible, and the diameter of the through hole is about 5 to 50 mm.

[0011] By adopting the above technical solution, the through hole helps to adjust the airflow path and guide the escaped gas to flow directly from the crucible to the exhaust area. The central through hole can significantly reduce the residence time of the gas in the chamber, prevent impurities and gas phase substances from depositing in other areas, and further reduce the possibility of secondary contamination. Preferably, the gas filling channel is coaxially arranged with the crucible, the gas filling channel is located directly below the crucible, and the inner diameter of the gas filling channel is 5 to 30 mm.

[0012] By adopting the above technical solution, the gas charging channel located at the center of the lower side of the crucible provides sufficient high-purity nitrogen to the growth chamber, so that the crucible is in a constant pressure state. The stable gas transmission path also drives the escaped gas to flow to the exhaust channel with the air flow, and ensures the stability of the gas pressure in the raw material purification process.

[0013] Preferably, a plurality of solid sediment collecting plates are arranged at intervals from the inside to the outside, and during the sintering process, the temperature difference between two adjacent solid sediment collecting plates is about 100-150°C.

[0014] By adopting the above technical solution, the design of multi-layer collection plates can capture the fugitive substances under different temperature conditions in turn. For example, the temperature on the first layer of the second layer wall is 100-150℃ lower, which is mainly used to collect solid deposits such as Al2O3, AlON and some AlN. This layered design significantly improves the classification ability of impurity collection, further enhances the device's treatment effect on various impurities, and maintains the stability of the airflow.

[0015] Preferably, the solid sediment collecting plate is configured as a grid structure or a porous structure.

[0016] By adopting the above technical solutions, the grid plate or porous design allows the gas flow to pass smoothly while providing sufficient deposition surface area for capturing the escaped substances. While not hindering the smooth flow of gas flow, the gas transmission efficiency and collection efficiency are improved.

[0017] Preferably, a side of the exhaust channel facing away from the growth chamber is also connected to a gas filter assembly.

[0018] By adopting the above technical solutions, the filter assembly can effectively reduce harmful components in the escaped substances, ensure that the device emissions meet environmental protection requirements, and protect surrounding equipment and the environment.

[0019] A process for purifying aluminum nitride, comprising using the device for collecting aluminum nitride sintered fugitive substances according to any one of claims 1 to 7, comprising the following steps: S01: placing AlN raw material into the crucible, covering the cover, placing the crucible in the center of the growth chamber, filling nitrogen into the furnace body through the charging channel, a vacuum pump reducing the air pressure at a specific position on the top of the furnace body through the vacuum channel, constructing a gas transmission channel in the furnace body, so that the gas at the crucible position is directionally transmitted to the vacuum position; S02: heating the AlN raw material in the crucible to 1200°C through the heater, continuously filling high-purity nitrogen into the furnace body through the charging channel until the furnace body has an air pressure of 600-700 mbar, and maintaining the temperature and pressure for 5 hours, and removing impurities with low sublimation temperature in the raw material through the following reaction: Al2O3(s)+3C(s)+N2(g) 2AlN(s)+3CO(g); 2AlCl3(s) 2Al(g)+3Cl2(g); keep high-purity nitrogen flowing along the gas transmission channel through the exhaust channel to take out the impurity gas generated by the reaction from the furnace body; S03: further heat the AlN raw material in the crucible to 1600-1800°C through the heater, continuously fill the furnace body with high-purity nitrogen through the charging channel, maintain the gas pressure in the furnace body at 600-700mbar, and keep it warm for 10 hours, and take away the oxygen impurities in the raw material through the following reaction: Al2O3(s)+4Al(s) 3Al2O(g); keep high-purity nitrogen flowing along the gas transmission channel through the exhaust channel to take the impurity gas generated by the reaction out of the furnace body; S04: further heat the AlN raw material in the crucible to 2100-2250°C through the heater, continue to charge high-purity nitrogen into the furnace body through the charging channel, keep the gas pressure in the furnace body at 700-800mbar, maintain the pressure and sinter for 30 hours, and continue to remove oxygen impurities in the raw material through the following reaction: Al2O3(s)+4AlN(s) 3Al2O(g)+2N2(g); high-purity nitrogen is kept flowing along the gas transmission channel through the exhaust channel to bring the impurity gas generated by the reaction out of the furnace body; the AlN raw material undergoes a continuous solid-gas-solid transformation at high temperature, i.e., AlN(s) Al(g)+N(g), gradually transforming from amorphous state to polycrystalline state.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. Through the synergistic effect of the inflation channel and the exhaust channel, a stable gas transmission channel is formed from bottom to top in the cavity, and combined with the design of a multi-layer solid deposit collection plate, it effectively captures the scattered substances in different temperature zones (such as AlN vapor and oxide impurities), reducing the random deposition of impurities in the furnace body. This design provides an impurity collection method set in the furnace body, which protects the internal environment of the furnace body and improves the purification quality of AlN raw materials. The design of the multi-layer insulation layer and the layered solid deposit collection plate effectively collects the scattered substances while reducing the possibility of impurities adhering to the surface of the insulation layer, and reduces the risk of stress damage to the insulation layer due to differences in thermal expansion coefficients. By maintaining the structural integrity of the insulation layer, the device can maintain a uniform and stable thermal field for a long time, ensuring the stability and consistency of the sintering process; 2. The gas filter components are equipped to effectively remove harmful gases (such as Cl2 and CO) from the dissipated substances, ensuring that the emitted gases meet environmental protection requirements. At the same time, the solid sediment collection plate adopts a grid plate or a porous structure, which can condense more solid particles. The staff can quickly maintain the device and reuse it by replacing the solid sediment collection plate in the device, which significantly extends the service life of the device and reduces the operating cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the concentration distribution diagram of impurity elements in unpurified AlN raw materials; Figure 2 This is an axonometric diagram mainly showing the overall structure of the sintering device for purifying aluminum nitride in Example 1 of the present application; Figure 3 This is a diagram of the aluminum nitride purification process in Example 2 of the present application.

[0022] Figure numerals: 1. furnace body; 11. growth chamber; 12. charging channel; 13. through hole; 14. deposition chamber; 15. exhaust channel; 2. insulation layer; 3. heater; 4. crucible; 5. cover body; 6. solid sediment collection plate; 7. gas filter assembly. DETAILED DESCRIPTION

[0023] The following is combined with Figure 2-Figure 3 This application is described in further detail.

[0024] The embodiments of the present application disclose a sintering device for purifying aluminum nitride and a purification process thereof. Example

[0025] See also Figure 2The sintering device for purifying aluminum nitride includes a furnace body 1, in which a crucible 4 is arranged, and the crucible 4 is arranged at the center of the furnace body 1. A cover body 5 is arranged on the upper side of the crucible 4. After the cover body 5 is placed on the crucible 4, a gap is formed between the cover body 5 and the crucible 4. During the purification process, there will be a certain temperature difference between the cover body 5 and the crucible 4, and a part of AlN will condense on the cover body 5. An insulation layer 2 is also arranged around the crucible 4. The insulation layer 2 is a tungsten insulation layer, and the insulation layer 2 has multiple layers evenly spaced from the inside to the outside. A growth chamber 11 is formed on the side of the innermost insulation layer 2 that is close to each other. The crucible 4 is located in the center of the growth chamber 11. A heater 3 is also arranged in the growth chamber 11, and the heater 3 is evenly wound around the crucible 4.

[0026] A deposition chamber 14 is provided in the multilayer insulation layer 2 on the upper side of the growth chamber 11. A through hole 13 is provided between the deposition chamber 14 and the growth chamber 11. The diameter of the through hole 13 is about 5 to 50 mm. A solid sediment collecting plate 6 is provided in the deposition chamber 14. The solid sediment collecting plate 6 is arranged horizontally. The solid sediment collecting plate 6 is arranged as a sheet structure, a grid structure or a porous structure. A plurality of solid sediment collecting plates 6 are arranged at intervals along the vertical direction. A plurality of solid sediment collecting plates 6 are arranged at different temperature intervals at various positions during sintering. In this embodiment, two layers are provided. When the temperature of the raw materials in the crucible 4 is maintained at 2100 to 2250°C, the temperature on the bottommost solid sediment collecting plate 6 is about 1700 to 1900°C, and the temperature difference between two adjacent solid sediment collecting plates 6 is about 100 to 150°C.

[0027] An exhaust channel 15 is provided on the multi-layer insulation layer 2 on the upper side of the deposition chamber 14. The inner diameter of the exhaust channel 15 is 5 to 30 mm. There are multiple exhaust channels 15. The axial direction of the exhaust channel 15 is vertically arranged. The multiple exhaust channels 15 are evenly spaced. The distance between the end of any exhaust channel 15 close to the deposition chamber 14 and the nearest solid sediment collection plate 6 is 3 to 30 mm. The side of any exhaust channel 15 away from the deposition chamber 14 is connected to a gas filter assembly 7. The gas filter assembly 7 can be set as an activated carbon or a gas filter assembly 7 containing a HEPA filter structure. Any exhaust channel 15 is connected to the gas filter assembly 7. The side of the gas filter assembly 7 away from the exhaust channel 15 is connected to the exhaust pump.

[0028] An air charging channel 12 is provided in the multi-layer insulation layer 2 at the lower side of the growth chamber 11. The air charging channel 12 is coaxially arranged with the crucible 4, the air charging channel 12 is located at the center of the furnace body 1, the upper end of the air charging channel 12 is connected with the growth chamber 11, and the lower end of the air charging channel 12 away from the growth chamber 11 is connected with the air charging pump, and the inner diameter of the air charging channel 12 is 5 to 30 mm.

[0029] The implementation principle of a sintering device for purifying aluminum nitride in Example 1 is as follows: the staff places the AlN raw material in the crucible 4, covers the cover 5, places the crucible 4 in the center of the growth chamber 11, and the air pump fills high-purity nitrogen into the furnace body 1 through the air filling channel 12. The air pump reduces the air pressure at a specific position on the top of the deposition chamber 14 through the air extraction channel 15, so that a gas transmission channel is constructed in the furnace body 1, and the gas at the crucible 4 position is directionally transmitted to the air extraction position. The raw material in the crucible 4 is heated by the heater 3, so that the AlN raw material continues to undergo a solid-gas-solid transformation at high temperature. At the same time, as the temperature in the crucible 4 rises, impurities with a lower sublimation temperature will react with each other or with nitrogen, and become gas and flow along the gas transmission channel. At the same time, during the entire heating process, metal element impurities, such as Fe, Si, V, etc., form gaseous substances at different temperatures and are gradually pumped out of the furnace body 1 along the gas transmission channel by the air extraction pump. The waste gas containing pollutants is filtered by the gas filter component 7 and safely discharged from the entire device. Example

[0030] See also Figure 2-3 The aluminum nitride purification process uses the aluminum nitride purification sintering device in Example 1 to perform sintering purification, including the following steps: S01: Put AlN raw material into the crucible 4, cover it with the cover 5, place the crucible 4 in the center of the growth chamber 11, fill nitrogen into the furnace body 1 through the gas filling channel 12, and use the vacuum pump to reduce the air pressure at a specific position on the top of the furnace body 1 through the vacuum channel 15, and build a gas transmission channel in the furnace body 1 to transmit the gas at the crucible 4 position to the vacuum position in a directionally manner; S02: The AlN raw material in the crucible 4 is heated to 1200°C by the heater 3, and high-purity nitrogen is continuously charged into the furnace body 1 through the charging channel 12 until the pressure in the furnace body 1 reaches 600-700 mbar, and the temperature and pressure are maintained for 5 hours. Impurities with low sublimation temperature in the raw material are removed through the following reaction: Al2O3(s)+3C(s)+N2(g) 2AlN(s)+3CO(g); 2AlCl3(s) 2Al(g)+3Cl2(g); The high-purity nitrogen is kept flowing along the gas transmission channel through the exhaust channel 15 to bring the impurity gas generated by the reaction out of the furnace body 1; S03: The AlN raw material in the crucible 4 is further heated to 1600-1800° C. by the heater 3, and high-purity nitrogen is continuously charged into the furnace body 1 through the charging channel 12, and the pressure in the furnace body 1 is maintained at 600-700 mbar, and the temperature is kept for 10 hours, and oxygen impurities in the raw material are removed through the following reaction: Al2O3(s)+4Al(s) 3Al2O(g); The high-purity nitrogen is kept flowing along the gas transmission channel through the exhaust channel 15 to bring the impurity gas generated by the reaction out of the furnace body 1; S04: The AlN raw material in the crucible 4 is further heated to 2100-2250° C. by the heater 3, and high-purity nitrogen is continuously charged into the furnace body 1 through the charging channel 12 to keep the gas pressure in the furnace body 1 at 700-800 mbar. The pressure is maintained and sintered for 30 hours, and oxygen impurities in the raw material are continuously removed through the following reaction: Al2O3(s)+4AlN(s) 3Al2O(g)+2N2(g); The high-purity nitrogen is kept flowing along the gas transmission channel through the exhaust channel 15 to bring the impurity gas generated by the reaction out of the furnace body 1; At high temperatures, AlN raw materials undergo a continuous solid-gas-solid transition, i.e. AlN(s)⇌Al(g)+N(g), gradually transforming from amorphous state to polycrystalline state.

[0031] The AlN raw material is crystallized and purified through the above steps.

[0032] The implementation principle of the aluminum nitride purification process in Example 2 is: different gas phase substances have different reaction temperatures, therefore, two or more layers of solid sediment collection plates 6 are set in the heat preservation structure, wherein when the temperature of the raw material in the crucible 4 is 2100-2250°C, the temperature of the solid sediment collection plate 6 close to the growth chamber 11 is about 1700-1900°C, mainly used to collect AlN solids, and the temperature of the solid sediment collection plate 6 away from the growth chamber 11 is about 100-150°C lower than that of the other solid sediment collection plate 6, mainly used to collect deposited Al2O3, AlON and the remaining AlN and other solid sediments. The gas filter assembly 7 outside the furnace body 1 is used to filter pollutants such as CO and Cl2 in the gas.

[0033] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A sintering device for purifying aluminum nitride, comprising a furnace body (1), wherein a plurality of heat-insulating layers (2) are arranged in the furnace body (1), a growth chamber (11) is arranged in the center of the plurality of heat-insulating layers (2), a crucible (4) for storing raw materials is arranged in the center of the growth chamber (11), a cover (5) is arranged on the top of the crucible (4), a gap is formed between the crucible (4) and the cover (5), so that the inside of the crucible (4) and the furnace body (1) are connected, and a heater (3) for heating is also arranged in the growth chamber (11), characterized in that: An air charging channel (12) is arranged on the multi-layer heat-insulating layer (2) on the lower side of the growth cavity, and an air exhaust channel (15) is arranged on the multi-layer heat-insulating layer (2) on the upper side of the growth cavity. The end of the air charging channel (12) facing away from the growth cavity is connected to the air charging pump outside the furnace body (1), and the end of the air exhaust channel (15) facing away from the growth cavity is connected to the air exhaust pump outside the furnace body (1). A solid sediment collection plate (6) is arranged between the multi-layer heat-insulating layers (2) on the upper side. The solid sediment collection plate (6) is arranged horizontally. When the temperature of the raw material in the crucible (4) reaches 2100-2250°C, the temperature on the solid sediment collection plate (6) is approximately 1700-1900°C.

2. The sintering device for purifying aluminum nitride according to claim 1, characterized in that: A plurality of the exhaust channels (15) are provided on the multi-layer insulation layer (2); the inner diameter of the exhaust channels (15) is 5 to 30 mm; the axial direction of the plurality of exhaust channels (15) is perpendicular to the outer surface of the solid sediment collection plate (6); and an end of any exhaust channel (15) close to the solid sediment collection plate (6) is 3 to 30 mm away from the solid sediment collection plate (6).

3. A sintering device for purifying aluminum nitride according to claim 2, characterized in that: A through hole (13) is provided at the center of the thermal insulation layer (2) between the solid sediment collecting plate (6) and the crucible (4), and the diameter of the through hole (13) is approximately 5 to 50 mm.

4. The sintering device for purifying aluminum nitride according to claim 1, characterized in that: The gas filling channel (12) is coaxially arranged with the crucible (4); the gas filling channel (12) is located directly below the crucible (4); and the inner diameter of the gas filling channel (12) is 5 to 30 mm.

5. The sintering device for purifying aluminum nitride according to claim 1, characterized in that: A plurality of solid sediment collecting plates (6) are arranged at intervals from the inside to the outside, and during the sintering process, the temperature difference between two adjacent solid sediment collecting plates (6) is approximately 100 to 150°C.

6. The sintering device for purifying aluminum nitride according to claim 1, characterized in that: The solid sediment collecting plate (6) is configured as a grid structure or a porous structure.

7. The sintering device for purifying aluminum nitride according to claim 1, characterized in that: The side of the air extraction channel (15) facing away from the growth chamber (11) is also connected to a gas filtering component (7).

8. A process for purifying aluminum nitride, comprising using the sintering device for purifying aluminum nitride according to any one of claims 1 to 7, characterized in that: The following steps are involved: S01: placing AlN raw material into the crucible (4), covering it with the cover (5), placing the crucible (4) at the center of the growth chamber (11), filling nitrogen into the furnace body (1) through the gas filling channel (12), and using a vacuum pump to reduce the gas pressure at a specific position on the top of the furnace body (1) through the vacuum channel (15), constructing a gas transmission channel in the furnace body (1), so that the gas at the crucible (4) position is directionally transmitted to the vacuum position; S02: The AlN raw material in the crucible (4) is heated to 1200° C. by the heater (3), and high-purity nitrogen is continuously charged into the furnace body (1) through the charging channel (12) until the pressure in the furnace body (1) reaches 600-700 mbar. The temperature and pressure are maintained for 5 hours, and impurities with low sublimation temperature in the raw material are removed through the following reaction: Al2O3(s)+3C(s)+N2(g)⇌2AlN(s)+3CO(g); 2AlCl3(s)⇌2Al(g)+3Cl2(g); Maintaining high-purity nitrogen gas flowing along the gas transmission channel through the exhaust channel (15) to carry impurity gas generated by the reaction out of the furnace body (1); S03: The AlN raw material in the crucible (4) is further heated to 1600-1800° C. by the heater (3), and high-purity nitrogen is continuously introduced into the furnace body (1) through the gas charging channel (12), the gas pressure in the furnace body (1) is maintained at 600-700 mbar, and the temperature is kept for 10 hours, and oxygen impurities in the raw material are removed through the following reaction: Al2O3(s)+4Al(s)⇌3Al2O(g); Maintaining high-purity nitrogen gas flowing along the gas transmission channel through the exhaust channel (15) to carry impurity gas generated by the reaction out of the furnace body (1); S04: The AlN raw material in the crucible (4) is further heated to 2100-2250° C. by the heater (3), and high-purity nitrogen is continuously charged into the furnace body (1) through the charging channel (12) to maintain the gas pressure in the furnace body (1) at 700-800 mbar. The pressure is maintained and sintered for 30 hours, and oxygen impurities in the raw material are continuously removed through the following reaction: Al2O3(s)+4AlN(s)⇌3Al2O(g)+2N2(g); Maintaining high-purity nitrogen gas flowing along the gas transmission channel through the exhaust channel (15) to carry impurity gas generated by the reaction out of the furnace body (1); The AlN raw material undergoes a continuous solid-gas-solid transformation at high temperature, i.e., AlN(s)⇌Al(g)+N(g), gradually transforming from an amorphous state to a polycrystalline state.

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