Porous material for silicon carbide crystal growth and preparation method thereof

Abstract

The invention discloses a porous material for silicon carbide crystal growth and a preparation method thereof, and belongs to the field of silicon carbide crystal growth. Melamine and cyanuric chloride are used as polymer monomers to prepare a nitrogen-containing polymer, tantalum chloride is used as a doping agent, so that tantalum can be uniformly distributed in a polymer network, and after sintering, the nitrogen-containing polymer is prepared. Tantalum and TaN / TaC are doped to form a TaC / TaN doped porous material, uniform distribution of silicon carbide grains can be promoted through doping of tantalum and generation of TaN / TaC, formation of large grains is prevented, then silicon carbide crystals with fine and uniform granularity are obtained, and due to the stability of tantalum compounds, the tantalum compounds can effectively promote form control of the silicon carbide crystals at high temperature (such as control of the length-width ratio of the crystals).

Description

Technical Field

[0001] The invention belongs to the technical field of silicon carbide crystal growth, and specifically refers to a porous material for silicon carbide crystal growth and a preparation method thereof. Background Art

[0002] Silicon carbide (SiC) is an important wide bandgap semiconductor material with excellent electrical, thermal and mechanical properties. Due to its high breakdown electric field strength, high temperature stability, radiation resistance and chemical stability, silicon carbide has a wide range of applications in high power, high frequency, high temperature resistance and other fields (such as power electronics, optoelectronics, sensors, LEDs, etc.). Common methods for growing silicon carbide crystals include physical vapor deposition (PVT), chemical vapor deposition (CVD), liquid phase epitaxy (LPE), etc. Among them, PVT is the most commonly used growth method. It reacts carbon source and silicon source to generate silicon carbide through gas phase reaction at high temperature, and then deposits it on a suitable substrate to form crystals. The basic principle is to carry out gas phase reaction in a high temperature furnace to generate SiC crystals through the reaction of carbon source (such as graphite or methane) and silicon source (such as silane). During the growth process, factors such as gas flow, temperature distribution, and concentration of reactive gases have an important influence on the quality and growth rate of the crystal. Although the PVT method can obtain high-quality silicon carbide crystals at a higher growth temperature, the growth rate of the crystal is slow and defects such as dislocations are prone to occur, making it difficult to further improve the quality of the crystal; Chemical vapor deposition is also commonly used for the growth of silicon carbide thin films and single crystals. This method generates SiC films or crystals by decomposing silicon source gases (such as silane, trichlorosilane, etc.) and carbon source gases (such as methane) in a reaction chamber. Compared with the PVT method, the CVD method can usually obtain good uniformity and higher deposition rates at lower temperatures. CVD technology has higher requirements for process parameters (such as gas flow, temperature, pressure, etc.), so this method requires precise control; During the growth of silicon carbide crystals, the quality of the crystal is affected by many factors, among which crystal defects (such as dislocations, vacancies, impurities, etc.) are the main factors affecting the performance of silicon carbide devices. Especially at high temperatures, dislocations will increase the brittleness of the crystal and affect the stability of the device. Therefore, reducing the defects generated during the growth process and improving the quality of the crystal have always been the focus of silicon carbide crystal growth research.

[0003] During the growth of silicon carbide crystals, the choice of substrate plays an important role in the quality of the crystals. Traditionally, silicon carbide substrates are often used in the PVT method, but due to the large thermal expansion coefficient of silicon carbide itself, thermal stress may occur in the crystal during growth, affecting the quality of the crystal. Therefore, researchers have explored the application of other substrate materials, such as quartz, molybdenum, and ceramics. In recent years, porous materials have been proposed as a method to optimize the growth quality of silicon carbide crystals. These porous materials can improve gas flow, provide uniform temperature distribution, and reduce thermal stress, thereby optimizing crystal growth conditions. As a porous material, graphite has good chemical stability and moderate thermal conductivity, so it is widely used in the growth process of silicon carbide crystals. However, graphite has a short service life and is susceptible to corrosion and wear in high temperature environments, so it needs to be replaced frequently, which increases the cost of silicon carbide crystal growth. With the increasing requirements for cost and material performance, the application of graphite faces certain challenges. Summary of the invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a porous material for growing silicon carbide crystals and a preparation method thereof. A nitrogen-containing polymer is prepared by using melamine and cyanuric chloride as polymer monomers, and tantalum chloride is used as a dopant to enable the tantalum element to be evenly distributed in the polymer network. After sintering, a TaC / TaN-doped porous material is formed. The doping of tantalum and the generation of TaN / TaC can promote the uniform distribution of silicon carbide grains and prevent the formation of large grains, thereby obtaining silicon carbide crystals with finer and uniform particle size. Since tantalum compounds have high stability, they can effectively promote the growth morphology of silicon carbide crystals at high temperatures (such as controlling the aspect ratio of the crystal).

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows: The present invention proposes a method for preparing a porous material for growing silicon carbide crystals, which specifically comprises the following steps:

[0006] S1, dissolving melamine in DMF / anhydrous ethanol solution, heating and stirring until dissolved, adding cyanuric chloride solution under flowing nitrogen atmosphere, stirring continuously to make the reaction system evenly mixed, raising the reaction temperature to 50-80°C, stirring and reacting for 6-12h, adding sodium carbonate as an acid binding agent, washing, filtering and drying after the reaction is completed to obtain a nitrogen-containing polymer;

[0007] Preferably, in step S1, the mass ratio of melamine to cyanuric chloride is 1.5-2.5:2;

[0008] Preferably, in step S1, in the DMF / anhydrous ethanol solution, the volume ratio between DMF and anhydrous ethanol is 1.5-2:1;

[0009] Preferably, in step S1, the mass concentration of melamine in the DMF / anhydrous ethanol solution is 60-80 mg / mL;

[0010] Preferably, in step S1, the cyanuric chloride solution is a solution of cyanuric chloride dissolved in DMF, wherein the mass concentration of cyanuric chloride in DMF is 0.1-0.2 g / mL;

[0011] S2, dissolving the nitrogen-containing polymer prepared in step S1 in a DMF / anhydrous ethanol solution, introducing flowing nitrogen, slowly adding a tantalum chloride / anhydrous ethanol solution, stirring evenly, raising the reaction temperature to 40-60° C., stirring the reaction for 3-5 hours, distilling under reduced pressure, washing, and drying to obtain a tantalum-doped polymer;

[0012] Preferably, in step S2, the mass concentration of the nitrogen-containing polymer in DMF / anhydrous ethanol is 40-60 mg / mL;

[0013] Preferably, in step S2, the added mass of tantalum chloride is 1%-5% of the mass of the nitrogen-containing polymer;

[0014] Preferably, in step S2, in the tantalum chloride / anhydrous ethanol solution, the mass concentration of tantalum chloride in anhydrous ethanol is 0.05-0.06 g / mL;

[0015] S3, transferring the tantalum-doped polymer prepared in step S2 to a high-temperature reactor, raising the reaction temperature to 300-400°C for pre-sintering in a nitrogen atmosphere, maintaining the temperature for 1-2 hours, and then continuing to raise the temperature to 1000-1400°C, maintaining the temperature for sintering for 8-12 hours, and naturally cooling to room temperature to obtain a porous material;

[0016] The invention also provides a porous material prepared according to the method and used for growing silicon carbide crystals.

[0017] The beneficial effects achieved by the present invention are as follows:

[0018] The present invention provides a porous material for growing silicon carbide crystals and a preparation method thereof. A nitrogen-containing polymer is prepared by using melamine and cyanuric chloride as polymer monomers, and tantalum chloride is used as a dopant so that tantalum elements can be evenly distributed in a polymer network. After sintering, a TaC / TaN-doped porous material is formed. The doping of tantalum and the generation of TaN / TaC can promote the uniform distribution of silicon carbide grains and prevent the formation of large grains, thereby obtaining silicon carbide crystals with finer grains and uniformity. Since tantalum compounds have higher stability, they can effectively promote the morphology control of silicon carbide crystals (such as controlling the aspect ratio of the crystals) at high temperatures. In the present invention, the polymer formed by the reaction of melamine and cyanuric chloride has a highly cross-linked triazine network structure. Since this cross-linked structure has strong stability, it can effectively embed tantalum (such as TaCl5) into the polymer in a coordinated or ion exchange manner. In this way, tantalum can be evenly dispersed in the polymer structure, avoiding the aggregation or uneven distribution of tantalum, thereby providing a stable doping source for the subsequent sintering process. Melamine contains multiple amino groups, which can react with tantalum to enhance the stability of tantalum and form stable nitrides or carbides. The amino groups of melamine can also improve the reactivity of polymers at high temperatures and provide support for the conversion of tantalum during sintering. Since the polymer formed by melamine and cyanuric chloride has good structural regulation ability, it can control the morphology, size and distribution of tantalum during the sintering process, thereby affecting the particle size, lattice structure and conductivity of the final tantalum nitride (TaN) and tantalum carbide (TaC). During the sintering process, as organic matter (such as melamine and cyanuric chloride) is removed, the structure of the polymer changes to form a porous material. The formation of porosity helps to reduce the density of the material and can improve the electrical conductivity, thermal conductivity and other properties of TaC / TaN. The porous material prepared by the present invention has a porous structure, can provide nucleation points, and is conducive to the uniform distribution of crystals. Tantalum compounds (TaN and TaC) can catalyze the growth of silicon carbide, increase the reaction rate and reduce the growth temperature, accurately control the concentration of nitrogen and carbon sources, optimize the crystal quality of silicon carbide, and improve the grain size and crystal morphology. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the XRD image of the porous material prepared in Example 1 of the present invention;

[0020] Figure 2 This is a SEM image of the porous material prepared in Example 1 of the present invention;

[0021] Figure 3 The porosity results of the porous materials prepared in Examples 1-3 and Comparative Examples 1-2 of the present invention are shown in FIG.

[0022] Figure 4 This is a graph showing the thermal conductivity results of the porous materials prepared in Examples 1-3 of the present invention and Comparative Examples 1-2.

[0023] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein may be applied to the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only and are not intended to limit the content of this application.

[0026] The experimental methods in the following examples are conventional methods unless otherwise specified; the experimental materials and test strains used in the following examples are purchased from commercial channels unless otherwise specified.

[0027] Example 1

[0028] This embodiment provides a method for preparing a porous material for growing silicon carbide crystals, which specifically includes the following steps:

[0029] S1. DMF and anhydrous ethanol were prepared into a DMF / anhydrous ethanol solution at a volume ratio of 1.5:1. 1.5 g of melamine was accurately weighed and dissolved in 25 mL of DMF / anhydrous ethanol solution. The temperature was raised to 50°C. The mixture was stirred at 200 rpm until the melamine was completely dissolved. Then, flowing nitrogen was introduced. 2.0 g of cyanuric chloride was dissolved in 10 mL of DMF to obtain a cyanuric chloride solution. After adding the solution to the reaction system, the reaction temperature was maintained at 50°C. 10 mL of 0.1 g / mL sodium carbonate / anhydrous ethanol solution was added. After stirring at 200 rpm for 8 h, the reaction was terminated. After cooling, the solution was repeatedly washed three times with deionized water, 0.05 M HCl aqueous solution and anhydrous ethanol. The solid was collected by suction filtration and dried under vacuum at 50°C for 12 h to obtain a nitrogen-containing polymer:

[0030] S2, DMF and anhydrous ethanol are prepared into a DMF / anhydrous ethanol solution at a ratio of 5:1, 5.0 g of the nitrogen-containing polymer prepared in step S1 is accurately weighed and dissolved in 100 mL of DMF / anhydrous ethanol solution, flowing nitrogen is introduced, 0.5 g of tantalum chloride is accurately weighed and dissolved in 10 mL of anhydrous ethanol to obtain a tantalum chloride / anhydrous ethanol solution, 1 mL of the tantalum chloride / anhydrous ethanol solution is added to the reaction system, and stirred at a speed of 300 rpm. After the reaction temperature is increased to 50° C., the stirring reaction is continued for 4 hours, and the excess solution is distilled off under reduced pressure, and the excess tantalum chloride is removed by reaction washing with anhydrous ethanol, and the mixture is placed at 50° C. and vacuum dried for 12 hours to obtain a tantalum-doped polymer;

[0031] S3. The tantalum-doped polymer prepared in step S2 is transferred to a high-temperature reactor. In a nitrogen atmosphere, the reaction temperature is increased to 300°C at a rate of 10°C / min for pre-sintering. After maintaining for 2 hours, the temperature is further increased to 1000°C. After maintaining the temperature for 12 hours, the porous material is naturally cooled to room temperature to obtain the porous material.

[0032] This embodiment also provides a porous material prepared by the above method for growing silicon carbide crystals.

[0033] The sample phase was analyzed using ADVANCE D8 X-ray diffraction (XRD). Figure 1 The XRD image of the porous material prepared in Example 1 of the present invention is shown in the figure. The porous material prepared in Example 1 has diffraction peaks of TaC, TaN, CN and C. The material contains TaC, TaN and CN phases at the same time. In addition to the main peak of TaC, the diffraction peaks of TaN should be observed at 2θ≈36°, 42°, 61°, 72°~79° and other positions; if it contains g-C3N4 with high crystallinity, characteristic peaks may appear near 13° and 27°. If CN is amorphous or low crystallinity, a broad and weak diffuse peak appears in the 20°~30° region.

[0034] The microstructure of the samples was observed using a JEOL FE6460 scanning electron microscope (SEM). Figure 2 This is a SEM image of the porous material prepared in Example 1 of the present invention. As shown in the figure, the porous material prepared in Example 1 has a good pore structure and presents a highly interconnected pore network with different pore sizes. Some pores have regular shapes, while others are relatively irregular. This shows that the porous material prepared in Example 1 forms uniformly distributed pores during the synthesis process, which helps to improve the diffusion and heat transfer performance of the reactants.

[0035] Example 2

[0036] This embodiment provides a method for preparing a porous material for growing silicon carbide crystals, which specifically includes the following steps:

[0037] S1. DMF and anhydrous ethanol were prepared into a DMF / anhydrous ethanol solution at a volume ratio of 2:1. 2.0 g of melamine was accurately weighed and dissolved in 25 mL of DMF / anhydrous ethanol solution. The temperature was raised to 50°C. The mixture was stirred at 200 rpm until the melamine was completely dissolved. Then, flowing nitrogen was introduced. 2.0 g of cyanuric chloride was dissolved in 15 mL of DMF to obtain a cyanuric chloride solution. After adding the solution to the reaction system, the reaction temperature was maintained at 80°C. 10 mL of 0.1 g / mL sodium carbonate / anhydrous ethanol solution was added. The mixture was stirred at 200 rpm for 6 hours. The reaction was terminated. After cooling, the mixture was repeatedly washed three times with deionized water, 0.05 M HCl aqueous solution and anhydrous ethanol. The solid was collected by suction filtration and dried under vacuum at 50°C for 12 hours to obtain a nitrogen-containing polymer:

[0038] S2, DMF and anhydrous ethanol are prepared into a DMF / anhydrous ethanol solution at a ratio of 5:1, 5.0 g of the nitrogen-containing polymer prepared in step S1 is accurately weighed and dissolved in 100 mL of DMF / anhydrous ethanol solution, flowing nitrogen is introduced, 0.5 g of tantalum chloride is accurately weighed and dissolved in 10 mL of anhydrous ethanol to obtain a tantalum chloride / anhydrous ethanol solution, 1 mL of the tantalum chloride / anhydrous ethanol solution is added to the reaction system, and stirred at a speed of 300 rpm. After the reaction temperature is increased to 50° C., the stirring reaction is continued for 4 hours, and the excess solution is distilled off under reduced pressure, and the excess tantalum chloride is removed by reaction washing with anhydrous ethanol, and the mixture is placed at 50° C. and vacuum dried for 12 hours to obtain a tantalum-doped polymer;

[0039] S3. The tantalum-doped polymer prepared in step S2 is transferred to a high-temperature reactor. In a nitrogen atmosphere, the reaction temperature is increased to 350°C at a rate of 10°C / min for pre-sintering. After maintaining for 2 hours, the temperature is further increased to 1200°C. After maintaining the temperature for 8 hours, the porous material is naturally cooled to room temperature to obtain the porous material.

[0040] This embodiment also provides a porous material prepared by the above method for growing silicon carbide crystals.

[0041] Example 3

[0042] This embodiment provides a method for preparing a porous material for growing silicon carbide crystals, which specifically includes the following steps:

[0043] S1. DMF and anhydrous ethanol were prepared into a DMF / anhydrous ethanol solution at a volume ratio of 1.5:1. 2.5 g of melamine was accurately weighed and dissolved in 35 mL of DMF / anhydrous ethanol solution. The temperature was raised to 50°C. The mixture was stirred at 200 rpm until the melamine was completely dissolved. Then, flowing nitrogen was introduced. 2.0 g of cyanuric chloride was dissolved in 20 mL of DMF to obtain a cyanuric chloride solution. After adding the solution to the reaction system, the reaction temperature was maintained at 70°C. 10 mL of 0.1 g / mL sodium carbonate / anhydrous ethanol solution was added. The mixture was stirred at 200 rpm for 12 h. The reaction was terminated. After cooling, the mixture was repeatedly washed three times with deionized water, 0.05 M HCl aqueous solution and anhydrous ethanol. The solid was collected by suction filtration and dried in vacuo at 50°C for 12 h to obtain a nitrogen-containing polymer:

[0044] S2, DMF and anhydrous ethanol are prepared into a DMF / anhydrous ethanol solution at a ratio of 5:1, 5.0 g of the nitrogen-containing polymer prepared in step S1 is accurately weighed and dissolved in 100 mL of DMF / anhydrous ethanol solution, flowing nitrogen is introduced, 0.5 g of tantalum chloride is accurately weighed and dissolved in 10 mL of anhydrous ethanol to obtain a tantalum chloride / anhydrous ethanol solution, 1 mL of the tantalum chloride / anhydrous ethanol solution is added to the reaction system, and stirred at a speed of 300 rpm. After the reaction temperature is increased to 50° C., the stirring reaction is continued for 4 hours, and the excess solution is distilled off under reduced pressure, and the excess tantalum chloride is removed by reaction washing with anhydrous ethanol, and the mixture is placed at 50° C. and vacuum dried for 12 hours to obtain a tantalum-doped polymer;

[0045] S3. The tantalum-doped polymer prepared in step S2 is transferred to a high-temperature reactor. In a nitrogen atmosphere, the reaction temperature is increased to 400°C at a rate of 10°C / min for pre-sintering. After maintaining for 1 hour, the temperature is further increased to 1400°C. After maintaining the temperature for 10 hours, the porous material is naturally cooled to room temperature to obtain the porous material.

[0046] This embodiment also provides a porous material prepared by the above method for growing silicon carbide crystals.

[0047] Comparative Example 1

[0048] This comparative example provides a porous material and a preparation method thereof, which is different from Example 1 only in that the preparation method of the porous material does not include step S2, and the remaining components, component contents and preparation method are the same as those of Example 1.

[0049] Comparative Example 2

[0050] The present comparative example provides a porous material and a preparation method thereof, which differs from Example 1 only in that steps S1 and S2 of the preparation method of the porous material are modified as follows: DMF and anhydrous ethanol are prepared into a DMF / anhydrous ethanol solution at a volume ratio of 1.5:1, 1.5 g of melamine is accurately weighed and dissolved in 25 mL of the DMF / anhydrous ethanol solution, the temperature is raised to 50° C., and the melamine is completely dissolved after stirring at a speed of 200 rpm, and flowing nitrogen is introduced, 0.5 g of tantalum chloride is dissolved in 10 mL of anhydrous ethanol to obtain a tantalum chloride / anhydrous ethanol solution, 1 mL of the tantalum chloride / anhydrous ethanol solution is added to the reaction system, the reaction temperature is maintained at 50° C., 10 mL of a 0.1 g / mL sodium carbonate / anhydrous ethanol solution is added, and the reaction is completed after stirring at a speed of 200 rpm for 8 hours. After cooling, deionized water, 0.05 M After repeated washing three times with HCl aqueous solution and anhydrous ethanol, the solid was collected by suction filtration and vacuum dried at 50° C. for 12 h to obtain a tantalum-doped polymer; step S3 was the same as in Example 1 to prepare a porous material.

[0051] Experimental Example 1

[0052] Porosity refers to the percentage of the pore volume in a bulk material to the total volume of the material in its natural state. The porosity or density of a material directly reflects the density of the material. A high porosity of a material indicates a low density. The porosity of the porous material samples prepared in Examples 1-3 and Comparative Examples 1-2 was measured using an Ultrapyc 5000 true density meter from Anton Paar, with the temperature set at 25°C and a nitrogen atmosphere. Five data were measured for each sample and the average value was taken.

[0053] Figure 3 This is a graph showing the porosity results of the porous materials prepared in Examples 1-3 of the present invention and Comparative Examples 1-2. As shown in the figure, the porosity of the porous materials prepared in Examples 1-3 is between 50-55%, while the porosity of the porous material prepared in Comparative Example 1 is 34.2%, and the porosity of the porous material prepared in Comparative Example 2 is 87.3%. The porous materials prepared in Examples 1-3 have uniform pores and moderate porosity.

[0054] Experimental Example 2

[0055] This experimental example analyzes the thermal conductivity of the porous materials prepared in Examples 1-3 and Comparative Examples 1-3. When there is no relative displacement between the parts of an object, the heat energy transfer generated by the thermal motion of microscopic particles such as molecules, atoms, and free electrons is called thermal conduction. The laser flash method is a common method for measuring the thermal conductivity of materials. The basic principle of the measurement is: at a certain set temperature, a laser source emits a beam of light pulses at an instant, which is evenly irradiated on the lower surface of the sample, so that the surface layer absorbs light energy and the temperature rises instantly. As the hot end, the energy is transmitted to the upper surface in a one-dimensional heat conduction manner, and an infrared detector is used to continuously measure the corresponding temperature rise process in the center of the upper surface. The LFA467 flash method thermal conductivity instrument produced by NETZSCH in Germany is used to analyze and test the thermal conductivity and thermal diffusion coefficient of the sample. The sample is cut into 10mm×10mm squares, the temperature is set to 25°C, the measurement is repeated 3 times, and the measurement is carried out under a nitrogen atmosphere.

[0056] Figure 4 The thermal conductivity results of the porous materials prepared in Examples 1-3 of the present invention and Comparative Examples 1-2 are shown in the figure. As shown in the figure, the thermal conductivity of the porous materials prepared in Examples 1-3 of the present invention is significantly higher than that of Comparative Examples 1-2. Due to the uneven pore distribution in Comparative Example 1, the thermal conductivity is poor, while in Comparative Example 2, due to the excessively high porosity, heat conduction in the porous material is hindered, resulting in a significant decrease in thermal conductivity.

[0057] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the invention.

[0058] The present invention and its implementation methods are described above, which is not restrictive. The drawings are only one of the implementation methods of the present invention, and the actual application is not limited thereto. In short, if ordinary technicians in the field are inspired by it and design methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a porous material for growing silicon carbide crystals, characterized in that: The specific steps include: S1, dissolving melamine in DMF / anhydrous ethanol solution, heating and stirring until dissolved, adding cyanuric chloride solution under flowing nitrogen atmosphere, stirring continuously to make the reaction system evenly mixed, raising the reaction temperature to 50-80°C, stirring and reacting for 6-12h, adding sodium carbonate as an acid binding agent, washing, filtering and drying after the reaction is completed to obtain a nitrogen-containing polymer; S2, dissolving the nitrogen-containing polymer prepared in step S1 in a DMF / anhydrous ethanol solution, introducing flowing nitrogen, slowly adding a tantalum chloride / anhydrous ethanol solution, stirring evenly, raising the reaction temperature to 40-60° C., stirring the reaction for 3-5 hours, distilling under reduced pressure, washing, and drying to obtain a tantalum-doped polymer; S3. The tantalum-doped polymer prepared in step S2 is transferred to a high-temperature reactor. In a nitrogen atmosphere, the reaction temperature is increased to 300-400°C for pre-sintering. After maintaining for 1-2 hours, the temperature is further increased to 1000-1400°C. After maintaining the temperature for 8-12 hours, the porous material is naturally cooled to room temperature to obtain the porous material.

2. The method for preparing a porous material for growing silicon carbide crystals according to claim 1, characterized in that: In step S1, the mass ratio of melamine to cyanuric chloride is 1.5-2.5:

2.

3. The method for preparing a porous material for growing silicon carbide crystals according to claim 2, characterized in that: In step S1, in the DMF / anhydrous ethanol solution, the volume ratio between DMF and anhydrous ethanol is 1.5-2:

1.

4. The method for preparing a porous material for growing silicon carbide crystals according to claim 3, characterized in that: In step S1, the mass concentration of melamine in the DMF / anhydrous ethanol solution is 60-80 mg / mL.

5. The method for preparing a porous material for growing silicon carbide crystals according to claim 4, characterized in that: In step S1, the cyanuric chloride solution is a solution of cyanuric chloride dissolved in DMF, wherein the mass concentration of cyanuric chloride in DMF is 0.1-0.2 g / mL.

6. The method for preparing a porous material for growing silicon carbide crystals according to claim 5, characterized in that: In step S2, the mass concentration of the nitrogen-containing polymer in DMF / anhydrous ethanol is 40-60 mg / mL.

7. The method for preparing a porous material for growing silicon carbide crystals according to claim 6, characterized in that: In step S2, the added mass of tantalum chloride is 1%-5% of the mass of the nitrogen-containing polymer.

8. The method for preparing a porous material for growing silicon carbide crystals according to claim 7, characterized in that: In step S2, in the tantalum chloride / anhydrous ethanol solution, the mass concentration of tantalum chloride in anhydrous ethanol is 0.05-0.06 g / mL.

9. A porous material for growing silicon carbide crystals, characterized in that: The porous material is made according to the preparation method according to any one of claims 1-8.

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