Silicon carbide seed crystal adhesive and bonding method

Abstract

The invention discloses a silicon carbide seed crystal adhesive and a bonding method, the adhesive is prepared from epoxy resin, m-xylylenediamine and carbon powder, during bonding, three parts of epoxy resin, m-xylylenediamine and carbon powder with different proportions are firstly weighed for preparing adhesives A, B and C; then carrying out plasma bombardment etching treatment on the graphite crucible cover and the back surface of the seed crystal; uniformly coating the adhesive A and the adhesive C on the bonding surfaces of the seed crystal and the crucible cover respectively, and pre-curing after coating; after the pre-curing is finished, uniformly coating a binding agent B on the binding surface of the seed crystal and the crucible cover; and finally, bonding the seed crystal coated with the binder B with a crucible cover, and sequentially carrying out step-by-step curing and step-by-step carbonization treatment to complete the bonding of the seed crystal. The problems that in the colloid carbonization process in the prior art, due to the fact that a large number of light elements are rapidly volatilized, air holes of different sizes are formed in a bonding layer, and the bonding uniformity is poor are solved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, specifically relating to silicon carbide seed crystal adhesive and bonding method. Background Technology

[0002] With the rapid development of 5G communication, new energy vehicles, photovoltaic inverters, and high-speed trains, people have put forward new requirements for the stable operation of related devices under extreme conditions such as high power, high frequency, and high temperature. Silicon carbide, a third-generation semiconductor material, has become an ideal substrate material for power electronic devices due to its advantages such as large bandgap, high saturated electron mobility, high thermal conductivity, stable chemical properties, and strong breakdown field.

[0003] Currently, the main method for industrial production of silicon carbide single crystals is physical vapor deposition (PVT). The preparation method involves first attaching a silicon carbide seed crystal to a crucible lid, placing silicon carbide powder at the bottom of the crucible, and then sublimating the silicon carbide powder through induction heating or resistance heating. The gaseous components are deposited at the end of the silicon carbide seed crystal through heat and mass transport, thus growing the crystal.

[0004] In the physical vapor deposition (PVD) growth of silicon carbide single crystals, seed crystals are introduced primarily through two methods: one is to use organic adhesive as a bonding medium to directly fix the seed crystal onto a seed crystal holder or a graphite crucible lid; the other is to first bond the seed crystal to graphite paper, and then further bond the two together to the crucible lid. However, currently available adhesives have low residual carbon content, and existing bonding processes are overly simplified. This leads to the rapid and large-scale volatilization of elements such as hydrogen and oxygen during the carbonization process, causing the adhesive layer to form pores of varying sizes, resulting in poor bonding uniformity. Simultaneously, the significant difference in thermal conductivity between the adhesive layer, the seed crystal, and the crucible lid not only compromises its high-temperature resistance but also easily leads to bonding interface failure and seed crystal detachment. These issues can cause severe sublimation on the back of the silicon carbide seed crystal during crystal growth, even resulting in seed crystal burn-through. The final grown silicon carbide single crystal may also exhibit defects such as polycrystalline structure, inconsistent crystal form, microtubes penetrating the crystal, and dislocation clusters, severely impacting the overall quality of the silicon carbide crystal. Summary of the Invention

[0005] The purpose of this invention is to provide a silicon carbide seed crystal adhesive, which solves the problem in the prior art where, during the colloidal carbonization process, a large amount of light elements rapidly volatilize, causing the adhesive layer to form pores of varying sizes, resulting in poor bonding uniformity.

[0006] Another object of the present invention is to provide a method for bonding silicon carbide seed crystals.

[0007] The first technical solution adopted in this invention is a silicon carbide seed crystal adhesive, wherein the adhesive is composed of epoxy resin, m-phenylenediamine and carbon powder, wherein the mass ratio of epoxy resin to m-phenylenediamine is 2.5:1 to 3:1; and the mass of carbon powder accounts for 5% to 30% of the total mass of the adhesive. The epoxy resin, m-phenylenediamine, and toner all have a purity greater than 99%.

[0008] The first technical solution of the present invention is further characterized in that, The toner is nano-onion toner with a particle size range of 10nm to 100nm.

[0009] The second technical solution adopted in this invention is a silicon carbide seed crystal bonding method, which includes the following steps: S1, Weigh out three parts of epoxy resin, m-phenylenediamine and toner in different proportions to prepare adhesives A, B and C; S2, Plasma bombardment etching is performed on the graphite crucible lid and the back of the seed crystal; S3, apply adhesives A and C evenly to the bonding surfaces of the seed crystal and the crucible lid respectively, and pre-cure them after application; S4. After pre-curing, apply adhesive B evenly to the bonding surface of the seed crystal and the crucible lid. S5, the seed crystal coated with binder B is bonded to the crucible lid, and then the step-by-step curing and carbonization processes are carried out to complete the seed crystal bonding.

[0010] The first technical solution of the present invention is further characterized in that, In step S1, adhesive A is coated on the bonding surface of the seed crystal to form a high thermal conductivity layer. The mass ratio of epoxy resin to m-phenylenediamine is 2.5:1 to 3:1, and the mass of carbon powder accounts for 25% to 30% of the total mass of the adhesive. Adhesive C is coated onto the bonding surface of the graphite crucible lid as a low thermal conductivity layer. The mass ratio of epoxy resin to m-phenylenediamine is 2.5:1 to 3:1, and the mass of carbon powder accounts for 5% to 10% of the total mass of the adhesive. Adhesive B serves as the intermediate layer, with an epoxy resin-to-m-phenylenediamine mass ratio of 2.5:1 to 3:1, and the toner mass accounts for 15% to 20% of the total adhesive mass. The thickness of the high thermal conductivity layer ranges from 10μm to 20μm, the thickness of the intermediate layer ranges from 20μm to 40μm, and the thickness of the low thermal conductivity layer ranges from 10μm to 20μm, with the thickness ratio of the three layers being 1:2:1.

[0011] In step S1, when preparing the adhesive, epoxy resin, m-phenylenediamine and toner are dried in a vacuum drying environment for 2 hours to remove moisture. Then, epoxy resin and m-phenylenediamine are mixed evenly in a container, stirred evenly with a magnetic stirrer, and left to stand for 30 minutes to allow the bubbles to rise and disappear, thus obtaining the basic adhesive. Carbon powder of different mass ratios was added to the base adhesive. After stirring with a magnetic stirrer, the mixture was allowed to stand until the air bubbles were eliminated to obtain adhesives A, B, and C.

[0012] In step S2, the flatness of the graphite crucible lid and the back of the seed crystal after plasma bombardment etching does not exceed 100 μm.

[0013] In steps S3 and S4, the adhesive is applied by mechanical spin coating or manual application. When using mechanical spin coating, the adhesive is first evenly distributed at a low speed, and then the thickness is fixed at a high speed. When evenly distributing the adhesive at a low speed, the rotation speed is 300 r / min to 500 r / min and the time is 8 s to 12 s. When fixing the thickness at a high speed, the rotation speed is 1500 r / min to 2000 r / min and the time is 8 s to 20 s.

[0014] In step S3, the pre-curing is carried out at a temperature of 60℃~100℃ for 0.5h~1h, the pre-curing pressure is 10kPa~1000kPa, and the pre-curing is carried out in a nitrogen or argon atmosphere.

[0015] In step S5, the stepwise curing process specifically involves curing at 100℃~150℃ for 1h~2h to complete the initial curing, and then raising the temperature to 150℃~200℃ and maintaining it for 1h~2h to complete the curing. The stepwise curing pressure is 10kPa~1000kPa, and the stepwise curing is carried out in a nitrogen or argon atmosphere. The stepwise carbonization process involves maintaining a temperature of 200℃~240℃ for 1h~3h to break amine bonds in the adhesive, then raising the temperature to 300℃~350℃ and maintaining it for 1h~3h to break ether bonds, isopropyl bonds, and C / C bonds in the adhesive, and finally raising the temperature to 500℃~800℃ for 2h~4h to break benzene ring bonds in the adhesive. The stepwise carbonization pressure is 1kPa~100kPa, and the stepwise carbonization is carried out in a nitrogen or argon atmosphere.

[0016] The beneficial effects of this invention are: This invention utilizes a gradient composite structure of "high thermal conductivity layer - intermediate layer - balance layer" and combines it with different proportions of nano-onion carbon powder to construct a differentiated thermal conductivity network. This allows the thermal conductivity of the adhesive layer to gradually change from the seed crystal end to the graphite end, effectively alleviating the problem of thermal stress concentration caused by the large difference in thermal conductivity between the traditional single adhesive layer and the seed crystal and graphite matrix. It also reduces the risk of excessive sublimation and burn-through on the back of the seed crystal caused by thermal stress during crystal growth, providing a stable thermal environment for uniform crystal growth.

[0017] Furthermore, the step-by-step process of pre-curing, step-curing, and step-carbonization allows lightweight elements in the adhesive to slowly escape, and all types of chemical bonds break stably within their corresponding stable temperature ranges. This avoids problems such as uneven pore size and disordered distribution caused by rapid element volatilization in traditional simplified processes. Simultaneously, the step-by-step process creates a dense and uniform microstructure in the adhesive layer, significantly improving the bond's strength and stability, and effectively preventing the risk of interface failure and seed crystal detachment during crystal growth. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of the silicon carbide seed crystal bonding method of the present invention; Figure 2 This is a side plan view of the bonding effect in Embodiment 5 of the present invention; Figure 3 Infrared example image of the bonding effect in Embodiment 5 of the present invention; Figure 4 Side plan view of the bonding effect in Embodiment 6 of the present invention; Figure 5 Infrared illustrative image of the bonding effect in Embodiment 6 of the present invention; Detailed Implementation The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] Example 1 The present invention relates to a silicon carbide seed crystal adhesive, which is composed of epoxy resin, m-phenylenediamine and carbon powder, wherein the purity of epoxy resin and m-phenylenediamine is greater than 99%.

[0020] The mass ratio of epoxy resin to m-phenylenediamine is 2.5:1 to 3:1; the mass of toner accounts for 5% to 30% of the total mass of the adhesive. Furthermore, the toner is nano-onion toner with a particle size ranging from 10nm to 100nm and a purity greater than 99%. The blending of toner can build a carbon thermally conductive network in the adhesive layer. By reasonably increasing the proportion of toner doping, the thermal conductivity of the adhesive layer can be effectively improved while ensuring the bonding quality.

[0021] Example 2 The present invention provides a method for bonding silicon carbide seed crystals, such as... Figure 1 As shown, it includes the following steps: S1, Weigh out three parts of epoxy resin, m-phenylenediamine and toner in different proportions to prepare adhesives A, B and C; S2, Plasma bombardment etching is performed on the graphite crucible lid and the back of the seed crystal; S3, apply adhesives A and C evenly to the bonding surfaces of the seed crystal and the crucible lid respectively, and pre-cure them after application; S4. After pre-curing, apply adhesive B evenly to the bonding surface of the seed crystal and the crucible lid. S5, the seed crystal coated with binder B is bonded to the crucible lid, and then subjected to step-by-step curing and carbonization treatments to complete the seed crystal bonding. After bonding, it can withstand tensile forces ranging from 0.2kN to 0.4kN at 1000℃ to 2500℃.

[0022] Furthermore, in step S1, adhesive A is coated on the bonding surface of the seed crystal to form a high thermal conductivity layer, wherein the mass ratio of epoxy resin to m-phenylenediamine is 2.5:1 to 3:1, and the mass of carbon powder accounts for 25% to 30% of the total mass of the adhesive; Adhesive C is coated onto the bonding surface of the graphite crucible lid as a low thermal conductivity layer. The mass ratio of epoxy resin to m-phenylenediamine is 2.5:1 to 3:1, and the mass of carbon powder accounts for 5% to 10% of the total mass of the adhesive. Adhesive B serves as the intermediate layer, with an epoxy resin-to-m-phenylenediamine mass ratio of 2.5:1 to 3:1, and the toner mass accounts for 15% to 20% of the total adhesive mass. The thickness of the high thermal conductivity layer ranges from 10μm to 20μm, the thickness of the intermediate layer ranges from 20μm to 40μm, and the thickness of the low thermal conductivity layer ranges from 10μm to 20μm, with a thickness ratio of 1:2:1. The adhesive layer formed by these three layers exhibits a gradient composite layered structure.

[0023] Furthermore, the total thickness of the adhesive layer is 60μm~100μm, and the total thickness after carbonization is 15μm~30μm.

[0024] Example 3 Based on Example 2 above, in step S1 of the silicon carbide seed crystal bonding method of the present invention, when preparing the adhesive, epoxy resin, m-phenylenediamine and carbon powder are dried in a vacuum drying environment for 2 hours to remove moisture. Then, epoxy resin and m-phenylenediamine are uniformly mixed and placed in a container. After being stirred evenly with a magnetic stirrer, the mixture is left to stand for 30 minutes to allow the bubbles to rise and be eliminated, thus obtaining the basic adhesive. Carbon powder of different mass ratios was added to the base adhesive. After stirring with a magnetic stirrer, the mixture was allowed to stand until the air bubbles were eliminated to obtain adhesives A, B, and C.

[0025] Specifically, this embodiment includes the following steps in preparing the adhesive: S101, take 30g of epoxy resin, 12g of m-phenylenediamine, and three portions of nano-onion carbon powder, namely 1.56g, 3.52g, and 6g respectively; S102, Place the above three items in a vacuum drying oven for 2 hours to remove moisture; S103, epoxy resin and m-phenylenediamine are mixed evenly, the mixture is placed in a beaker, a 20mm rotor is selected, and a magnetic stirrer is used at 500rpm for 20min, and then it is left to stand for 30min to allow the bubbles to rise and disappear, thus obtaining the basic adhesive. S104. Divide the obtained base adhesive into three equal portions, each weighing 14g, and label them A, B, and C respectively. Take 6g of nano-onion carbon powder and place it in portion A. Use a 20mm rotor and a magnetic stirrer at 1000rpm for 20min. Take 3.52g of nano-onion carbon powder and place it in portion B. Use a 20mm rotor and a magnetic stirrer at 800rpm for 20min. Take 1.56g of nano-onion carbon powder and place it in portion C. Use a 20mm rotor and a magnetic stirrer at 600rpm for 20min. Let the colloids A, B, and C stand for 30min to eliminate air bubbles.

[0026] S105, after eliminating air bubbles, yields adhesive A with high thermal conductivity, adhesive B for the intermediate layer, and adhesive C with low thermal conductivity.

[0027] Furthermore, adhesives A, B, and C have a viscosity range of 3000 mPa at room temperature. s~5000mPa s.

[0028] Example 4 Based on Example 2 above, in step S2 of the silicon carbide seed crystal bonding method of the present invention, the flatness of the graphite crucible cover and the back of the seed crystal after plasma bombardment etching treatment does not exceed 100 μm.

[0029] Since plasma bombardment etching technology is an existing technology, it will not be described in detail in this solution.

[0030] Furthermore, in steps S3 and S4, the adhesive is applied by mechanical spin coating or manual application. When mechanical spin coating is used, it is divided into two steps: first, uniform adhesive application at low speed, and then thickness setting at high speed. When uniform adhesive application at low speed, the rotation speed is 300 r / min to 500 r / min and the time is 8 s to 12 s; when setting the thickness at high speed, the rotation speed is 1500 r / min to 2000 r / min and the time is 8 s to 20 s.

[0031] Furthermore, in step S3, the pre-curing of the coated adhesives A and C is specifically carried out at a temperature of 60℃~100℃ for 0.5h~1h.

[0032] Furthermore, the step-by-step curing process in step S5 specifically involves curing at 100℃~150℃ for 1h~2h to complete the initial curing, and then raising the temperature to 150℃~200℃ and maintaining it for 1h~2h to complete the curing. The stepwise carbonization process involves maintaining a temperature of 200℃~240℃ for 1h~3h to facilitate the smooth breaking of amine bonds in the adhesive, then raising the temperature to 300℃~350℃ and maintaining it for 1h~3h to facilitate the slow breaking of ether bonds, isopropyl bonds, and C / C bonds in the adhesive, and finally raising the temperature to 500℃~800℃ for 2h~4h to facilitate the slow breaking of benzene rings in the adhesive.

[0033] The curing and carbonization processes of colloids need to be carried out under certain pressure and atmosphere. The pressure range during pre-curing and distribution curing is 10 kPa to 1000 kPa, and the pressure range during carbonization is 1 kPa to 100 kPa. Nitrogen or argon atmosphere can be selected.

[0034] Example 5 This embodiment, based on Example 3, uses adhesives A, B, and C prepared in Example 3; specifically, it includes the following steps: S1, take one 6-inch silicon carbide seed crystal and one 6-inch silicon carbide seed crystal holder; S2. An inductively coupled plasma etching (ICP-C) machine was used to etch silicon carbide seed crystals. Sulfur hexafluoride was used as the main etching gas, and oxygen as the auxiliary etching gas, with a gas flow ratio of 5:1, a power of 800W, and etching time of 20 minutes at room temperature. Graphite seed crystal holders were etched using oxygen as the main etching gas and argon as the auxiliary etching gas, with a gas flow ratio of 2:1, a power of 800W, and etching time of 20 minutes at room temperature, achieving a flatness of 50μm. S3, take 6g of adhesive A, drop it onto the seed crystal, and use an automatic spin coater at 500r / min for 12s at a low speed to achieve uniform coating. Then spin coat at 2000r / min for 10s to stabilize the thickness at 20μm. S4. Take 6g of adhesive C and drop it onto the seed crystal holder or graphite crucible lid. Use an automatic spin coater at 500r / min for 10s to achieve uniform coating. Then spin coat at 1500r / min for 8s to stabilize the thickness at 20μm. S5, the seed crystals and seed crystal holders obtained in S3 and S4 after coating are left to stand at room temperature for 30 minutes to defoam, and then placed on a flat plate heating oven at 60°C for 30 minutes to cure at a low temperature. S6. Take 12g of adhesive B and divide it into two equal parts. Drop them onto the coated side of the seed crystal and the seed crystal holder respectively. Use an automatic spin coater to spin coat at 500r / min for 10s at a low speed, and then spin coat at 2000r / min for 10s to stabilize the thickness of both at 20μm. S7. After bonding the seed crystal holder to the seed crystal, place it in a sintering furnace and heat it to 120°C at 3°C / min for 1 hour to allow the epoxy resin and m-phenylenediamine to undergo a curing reaction and form a stable chain structure. Then heat it to 200°C at 1°C / min for 2 hours to remove solvent moisture, surface adsorbed moisture, and moisture released during the curing reaction. During this process, the pressure is kept stable at 100 kPa and the process is carried out under an argon atmosphere. S8, Next, the adhesive is heated to 240°C at 1°C / min and carbonized for 1 hour to allow the amine bonds in the adhesive to break smoothly; then the temperature is increased to 330°C at 1°C / min and carbonized for 1 hour to allow the ether bonds, isopropyl bonds, and C / C bonds in the adhesive to break slowly; finally, the temperature is increased to 600°C at 1°C / min and carbonized for 2 hours to allow the benzene rings in the adhesive to break slowly. This process is carried out under an argon atmosphere while maintaining a stable pressure of 100 kPa. S9, the carbonized adhesive is slowly cooled to room temperature at 3℃ / min to obtain a uniform adhesive layer with excellent performance.

[0035] Ultimately, the adhesive layer obtained by the bonding method has a tensile strength of 0.38 kN. For example... Figure 2 and Figure 3 As shown, observation of the adhesive layer prepared in this embodiment reveals that its pore uniformity is good.

[0036] Example 6 This embodiment, based on Example 3, uses adhesives A, B, and C prepared in Example 3; specifically, it includes the following steps: S1, take one 6-inch silicon carbide seed crystal and one 6-inch graphite crucible lid; S2, using an inductively coupled plasma etching machine, etch the silicon carbide seed crystal and the graphite crucible cover to achieve a flatness of 80μm; S3, take 6g of adhesive A and drop it onto the seed crystal. Take 6g of adhesive C and drop it onto the graphite crucible lid. Use manual scraping to spread the adhesive evenly so that its thickness is stable at 20μm. After standing at room temperature for 30 minutes to defoam, place it on a flat plate heating furnace at 50℃ and cure at low temperature for 1 hour. S4, take 12g of adhesive B and divide it into two equal parts. Drop them onto the coated side of the seed crystal and the graphite crucible lid respectively. Use manual scraping to spread the adhesive evenly so that the thickness of the two is stable at 20μm. S5. After bonding the graphite crucible lid to the seed crystal, place it in a silicon carbide crystal growth furnace, heat to 100℃ at 3℃ / min for 1 hour, heat to 180℃ at 1℃ / min for 2 hours, then heat to 220℃ at 1℃ / min for 1 hour, heat to 400℃ at 1℃ / min for 2 hours, and heat to 800℃ at 1℃ / min for 2 hours. The curing and carbonization processes are completed in one go, and the pressure is kept stable at 100 kPa under a nitrogen atmosphere. S6. The carbonized adhesive is slowly cooled to room temperature at 3℃ / min to obtain a uniform adhesive layer with excellent performance.

[0037] Ultimately, the adhesive layer obtained by the bonding method has a tensile strength of 0.35 kN. For example... Figure 4 and Figure 5 As shown, observation of the adhesive layer prepared in this embodiment reveals that its pore uniformity is good.

[0038] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0039] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A silicon carbide seed crystal glue, characterized by, The adhesive is composed of epoxy resin, m-xylylenediamine and carbon powder, the mass ratio of epoxy resin to m-xylylenediamine is 2.5:1-3:1, and the mass of the carbon powder accounts for 5%-30% of the total mass of the adhesive. The purity of the epoxy resin, m-xylylenediamine and carbon powder is greater than 99%.

2. The silicon carbide seed gel binder of claim 1, wherein, The carbon powder is nano onion carbon powder, and the particle size range is 10 nm-100 nm.

3. A method for bonding silicon carbide seeds, characterized by, The method comprises the following steps: S1, three different proportions of epoxy resin, m-xylylenediamine and carbon powder are weighed for preparing adhesives A, B and C; S2, the graphite crucible cover and the seed crystal back are subjected to plasma bombardment etching treatment; S3, the seed crystal and the crucible cover are respectively uniformly coated with adhesives A and C on the bonding surfaces, and then pre-curing is performed after coating; S4, after pre-curing, adhesive B is uniformly coated on the bonding surfaces of the seed crystal and the crucible cover; S5, the seed crystal coated with adhesive B is bonded with the crucible cover, and step-by-step curing and step-by-step carbonization treatment are sequentially performed to complete the bonding of the seed crystal.

4. The silicon carbide seed gel binder of claim 3, wherein, In the step S1, the adhesive A is coated on the bonding surface of the seed crystal to form a high thermal conductivity layer, the mass ratio of epoxy resin to m-xylylenediamine is 2.5:1-3:1, and the mass of the carbon powder accounts for 25%-30% of the total mass of the adhesive; The adhesive C is coated on the bonding surface of the graphite crucible cover to form a low thermal conductivity layer, the mass ratio of epoxy resin to m-xylylenediamine is 2.5:1-3:1, and the mass of the carbon powder accounts for 5%-10% of the total mass of the adhesive; The adhesive B is used as an intermediate layer, the mass ratio of epoxy resin to m-xylylenediamine is 2.5:1-3:1, and the mass of the carbon powder accounts for 15%-20% of the total mass of the adhesive; The thickness of the high thermal conductivity layer is 10 μm-20 μm, the thickness of the intermediate layer is 20 μm-40 μm, and the thickness of the low thermal conductivity layer is 10 μm-20 μm, and the thickness ratio of the three is 1:2:

1.

5. The silicon carbide seed gel binder of claim 3, wherein, In the step S1, when preparing the adhesive, the epoxy resin, m-xylylenediamine and carbon powder are dried in a vacuum drying environment for 2 h to remove water, then the epoxy resin and m-xylylenediamine are uniformly mixed in a container, stirred uniformly by a magnetic stirrer, and then left still for 30 min to allow the bubbles to rise and eliminate, thereby obtaining a base adhesive; Different mass ratios of carbon powder are added to the base adhesive, and after stirring by a magnetic stirrer, the adhesive A, B and C are obtained after the bubbles are eliminated.

6. The silicon carbide seed gel binder of claim 3, wherein, In the step S2, the flatness of the graphite crucible cover and the seed crystal back after the plasma bombardment etching treatment is not more than 100 μm.

7. The silicon carbide seed gel binder of claim 3, wherein, In the steps S3 and S4, the coating of the adhesive is performed by mechanical spin coating or manual coating, when the mechanical spin coating is used, the adhesive is uniformly coated at a low speed first, and then the thickness is determined at a high speed, the speed is 300 r / min-500 r / min and the time is 8 s-12 s when the adhesive is uniformly coated at a low speed, the speed is 1500 r / min-2000 r / min and the time is 8 s-20 s when the thickness is determined at a high speed.

8. The silicon carbide seed gel binder of claim 3, wherein, In the step S3, the pre-curing is performed at a temperature of 60 ℃-100 ℃ for 0.5 h-1 h, the pre-curing pressure is 10 kPa-1000 kPa, and the pre-curing is performed in a nitrogen or argon environment.

9. The silicon carbide seed gel binder of claim 3, wherein, The step S5 is specifically curing at 100-150℃ for 1-2h to complete preliminary curing, then heating to 150-200℃ for 1-2h to complete curing; The step S5 is specifically curing at 100-150℃ for 1-2h to complete preliminary curing, then heating to 150-200℃ for 1-2h to complete curing; The step S5 is specifically curing at 100-150℃ for 1-2h to complete preliminary curing, then heating to 150-200℃ for 1-2h to complete curing; The step S5 is specifically curing at 100-150℃ for 1-2h to complete preliminary curing, then heating to 150-200℃ for 1-2h to complete curing;

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