Silicon carbide seed crystal plate and preparation method thereof, and silicon carbide crystal and growth method thereof

Abstract

The invention relates to the technical field of silicon carbide, in particular to a silicon carbide seed crystal plate and a preparation method thereof, and a silicon carbide crystal and a growth method thereof. The method comprises the following steps: carrying out chemical corrosion treatment on the silicon surface of a silicon carbide seed wafer by using an alkaline reagent to obtain a first intermediate; the silicon surface of the first intermediate is coated with an adhesive, the adhesive is attached to graphite paper, a second intermediate is obtained, and the adhesive comprises an epoxy resin matrix and an anhydride curing agent; and sintering the second intermediate to obtain the silicon carbide seed crystal plate. According to the preparation method of the silicon carbide seed crystal plate, high-strength and low-residual-stress bonding of the seed crystal plate and the graphite paper is realized through a chemical cross-linked network and a mechanical synergistic effect, and the high-temperature stability of the seed crystal plate is improved through a carbon film formed through sintering treatment.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide technology, and more particularly to silicon carbide seed crystal plates and their preparation methods, silicon carbide crystals and their growth methods. Background Technology

[0002] Silicon carbide (SiC), a typical representative of third-generation semiconductor materials, possesses excellent electrothermal properties such as wide bandgap, high breakdown voltage, high thermal conductivity, and high saturated electron drift velocity. In the fabrication of silicon carbide single-crystal substrates, high-quality bonding between the seed crystal and the crucible cap is a crucial step in crystal growth. Current mainstream processes use organic adhesives for bonding; however, due to the inherent warpage difference between the seed crystal and the crucible cap, bubble defects easily form at the bonding interface. These defects lead to uneven temperature gradient distribution during growth, causing quality problems such as crystal cracking, detachment, and back corrosion due to reverse sublimation. To improve this issue, related technologies introduce graphite paper as a flexible buffer layer. While this alleviates material warpage and thermal expansion mismatch, it increases the complexity of the bonding process, leading to a higher risk of bonding defects. Therefore, optimizing the reliability of the bonding process while ensuring interface flatness has become a core technological challenge for improving the quality of silicon carbide crystals. Summary of the Invention

[0003] This invention provides a silicon carbide seed crystal plate and its preparation method, as well as silicon carbide crystals and their growth method. The silicon carbide seed crystal plate preparation method achieves high-strength, low-residual-stress bonding between the seed crystal and graphite paper through the synergistic effect of a chemical cross-linking network and mechanical processes. Furthermore, the carbon film formed through sintering treatment improves the high-temperature stability of the seed crystal plate.

[0004] The first aspect of the present invention provides a method for preparing a silicon carbide seed crystal plate, comprising: chemically etching the silicon surface of a silicon carbide seed crystal plate with an alkaline reagent to obtain a first intermediate; coating the silicon surface of the first intermediate with an adhesive and bonding it with graphite paper to obtain a second intermediate, wherein the adhesive comprises an epoxy resin matrix and an acid anhydride curing agent; and sintering the second intermediate to obtain a silicon carbide seed crystal plate.

[0005] Chemical etching increases the roughness of the silicon surface of the seed wafer, creating a micro-mechanical interlocking effect with the adhesive (mechanical interlocking structures are molecular aggregates that use intermolecular mechanical interactions to combine multiple molecules to synergistically achieve complex mechanical functions), thereby improving the adhesion between the silicon surface and the adhesive. Based on the high-temperature esterification reaction characteristics of anhydride curing agents, the epoxy resin matrix in the adhesive and the anhydride curing agent form a three-dimensional cross-linked network at high temperatures, thus strengthening interfacial adhesion through chemical bonding. This chemical-mechanical dual synergistic mechanism effectively solves the stress concentration problem caused by interfacial porosity in traditional organic adhesives, achieving high-strength, low-residual-stress bonding between the seed wafer and graphite paper, and improving the growth quality of silicon carbide crystals.

[0006] According to embodiments of the present invention, the alkaline reagent includes at least one of potassium hydroxide and sodium hydroxide. Therefore, the alkaline reagent has a good chemical etching effect on the silicon surface.

[0007] According to an embodiment of the present invention, the chemical etching treatment is carried out at a temperature of 60°C-100°C for a time of 10 min-30 min. Therefore, the chemical etching can proceed fully and the degree of etching can be controlled.

[0008] According to embodiments of the present invention, the anhydride curing agent includes at least one of phthalic anhydride and tetrahydrophthalic anhydride. Therefore, the adhesive has a high crosslinking density, which helps to improve the adhesion between the adhesive and the seed wafer.

[0009] According to an embodiment of the present invention, the sintering process includes: a first sintering process at 50℃-80℃ for 0.5h-1h; a second sintering process at 120℃-140℃ for 1h-2h; a third sintering process at 140℃-160℃ for 3h-5h; and a fourth sintering process at 160℃-180℃ for 0.5h-1h. The first to fourth sintering processes are degassing stages, which can effectively remove small molecule gases from the adhesive, thereby reducing interface defects.

[0010] According to an embodiment of the present invention, the sintering treatment further includes: a fifth sintering treatment at 350℃-450℃ for 1-2 hours; and a sixth sintering treatment at 700℃-900℃ for 1-2 hours. As a result, the resin component in the adhesive undergoes pyrolysis and carbonization, generating a gradient-dense carbon film on the seed crystal surface. This carbon film not only buffers the interfacial stress caused by thermal expansion mismatch, but its densified structure also suppresses back corrosion defects caused by reverse sublimation during high-temperature growth.

[0011] According to an embodiment of the present invention, during the first sintering process, the second sintering process, the third sintering process, and the fourth sintering process, a surface pressure of 0.9 × 10⁻⁶ is applied to the second intermediate. 5 N / m 2 –1.6×10 5 N / m 2 Therefore, it can inhibit excessive volume expansion of the second intermediate and help to complete degassing.

[0012] According to an embodiment of the present invention, the sintering process is carried out in a vacuum environment. Thus, the vacuum environment facilitates complete degassing in the first to fourth sintering processes (i.e., the degassing stage) and effectively inhibits the oxidation of the generated carbon film in the fifth to sixth sintering processes.

[0013] A second aspect of the present invention provides a silicon carbide seed plate prepared according to the method described in the first aspect. Silicon carbide crystals grown using this seed plate have smooth back surfaces, minimal reverse sublimation, and good crystal quality.

[0014] A third aspect of the present invention provides a method for growing silicon carbide crystals, comprising: placing a silicon carbide seed crystal plate in a crystal growth furnace for growth to obtain silicon carbide crystals; wherein the silicon carbide seed crystal plate comprises a silicon carbide seed crystal plate prepared according to the method of the first aspect or the silicon carbide seed crystal plate described in the second aspect.

[0015] The fourth aspect of the present invention provides a silicon carbide crystal obtained according to the growth method described in the third aspect.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0018] Figure 1 A schematic diagram of the vacuum sintering furnace used in this invention is shown;

[0019] Figure 2 The image shows the morphology of the silicon carbide seed crystal plate obtained in Example 1 of the present invention;

[0020] Figure 3 The surface morphology of the silicon carbide crystal obtained in Example 1 of the present invention is shown.

[0021] Figure 4 The back-side morphology of the silicon carbide crystal obtained in Example 1 of the present invention is shown. Detailed Implementation

[0022] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0023] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] To facilitate understanding of the invention, certain technical and scientific terms are specifically defined below. Unless otherwise expressly defined elsewhere in this document, all other technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] In this document, the terms “comprising” or “including” are open-ended expressions, meaning that they include the contents specified in this invention, but do not exclude other aspects.

[0027] In this document, the terms “optionally,” “optionally,” or “optionally” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0028] The first aspect of this invention provides a method for preparing a silicon carbide seed crystal plate, comprising:

[0029] (1) The silicon surface of the silicon carbide seed wafer is chemically etched using an alkaline reagent to obtain the first intermediate.

[0030] Specifically, "silicon facet" refers to the (0001) crystal facet of a silicon carbide wafer, that is, the surface of the crystal cut along the positive direction of the c-axis, where the terminating atom is a silicon atom. Chemical etching can increase the roughness of the silicon facet of the seed wafer, creating a micro-mechanical interlocking effect with the adhesive, thereby improving the bonding strength between the silicon facet and the adhesive.

[0031] According to specific embodiments of the present invention, the type of alkaline reagent is not particularly limited, but as some specific examples, it includes at least one of potassium hydroxide and sodium hydroxide. Therefore, the alkaline reagent has a good chemical etching effect on the silicon surface.

[0032] According to specific embodiments of the present invention, the temperature of the chemical etching treatment is 60℃-100℃, and the time is 10min-30min. As some specific examples, the temperature of the chemical etching treatment can be 60℃, 70℃, 80℃, 90℃, 100℃, etc., and the time can be 10min, 20min, 30min, etc. Therefore, the chemical etching can be carried out fully and the degree of etching can be controlled.

[0033] According to a specific embodiment of the present invention, the method further includes: cleaning the seed wafer after chemical etching treatment. The cleaning method is not particularly limited, but may specifically include: rinsing the surface of the seed wafer with a large amount of deionized water for 1 min–2 min, then immersing the seed wafer in a 3% dilute hydrochloric acid neutralizing solution for 5 min–10 min, rinsing again with deionized water for 3 min–8 min, followed by ultrasonic cleaning at 40 kHz–60 kHz for 5 min–10 min, and finally vacuum drying at 80°C for 5 min–10 min.

[0034] (2) An adhesive is coated on the silicon surface of the first intermediate and bonded to graphite paper to obtain a second intermediate, wherein the adhesive includes an epoxy resin matrix and an acid anhydride curing agent.

[0035] Based on the high-temperature esterification reaction characteristics of anhydride curing agents, the epoxy resin matrix and anhydride curing agents in the adhesive form a three-dimensional cross-linked network at high temperatures, thereby strengthening interfacial adhesion through chemical bonding. This chemical action and the mechanical action in step (1) constitute a dual synergistic mechanism, effectively solving the stress concentration problem caused by interfacial porosity in traditional organic adhesives during bonding, achieving high-strength, low-residual-stress bonding between the seed wafer and graphite paper, and improving the growth quality of silicon carbide crystals.

[0036] Specifically, in addition to the main components (i.e., epoxy resin matrix and acid anhydride curing agent), the adhesive may also contain solvents, plasticizers and other components. This patent does not impose any special restrictions on this, and those skilled in the art can make selections according to actual needs.

[0037] According to specific embodiments of the present invention, the type of anhydride curing agent is not particularly limited, but some specific examples include at least one of phthalic anhydride and tetrahydrophthalic anhydride. Therefore, the adhesive has a high crosslinking density, which helps to improve the adhesion between the adhesive and the seed wafer.

[0038] According to specific embodiments of the present invention, the amount of adhesive used is not particularly limited and can be selected and adjusted according to actual conditions. For example, the amount of adhesive used on a 6-inch diameter silicon carbide seed wafer can be 12mL-18mL, and the amount of adhesive used on an 8-inch diameter silicon carbide seed wafer can be 15mL-20mL.

[0039] According to specific embodiments of the present invention, the method of applying the adhesive is not particularly limited; for example, a spin coater can be used. Specifically, during spin coater application, a low-speed spin coater (1000 rpm / min-3000 rpm / min) can be used first, followed by a high-speed spin coater (3000 rpm / min-5000 rpm / min). The low-speed spin coater first can spread the adhesive evenly on the surface of the seed wafer, while the high-speed spin coater can make the adhesive evenly distributed.

[0040] (3) The second intermediate is sintered to obtain a silicon carbide seed crystal plate.

[0041] According to a specific embodiment of the present invention, the sintering process includes:

[0042] ① The first sintering treatment is carried out at 50℃-80℃ for 0.5h-1h. Therefore, step ① removes the solvent and promotes the melting of the anhydride curing agent in the adhesive.

[0043] ② A second sintering treatment is performed at 120℃-140℃ for 1-2 hours. This completes the initial cross-linking of the adhesive in step ②. The heating rate in step ② is not particularly limited; for example, it can be increased to 120℃-140℃ at a rate of 1℃ / min-5℃ / min.

[0044] ③ A third sintering treatment is carried out at 140℃-160℃ for 3-5 hours. Therefore, step ③ maximizes the degree of degassing. The heating rate in step ③ is not particularly limited; for example, it can be increased to 140℃-160℃ at a rate of 1℃ / min-3℃ / min.

[0045] ④ Perform the fourth sintering treatment at 160℃-180℃ for 0.5h-1h. This eliminates residual stress in step ④. The heating rate in step ④ is not particularly limited; for example, it can be increased to 160℃-180℃ at a rate of 3℃ / min-7℃ / min.

[0046] Specifically, steps ① to ④ are the degassing stages, which can effectively remove small molecule gases from the adhesive, thereby reducing interface defects.

[0047] According to a specific embodiment of the present invention, the sintering process further includes:

[0048] ⑤ The fifth sintering treatment is carried out at 350℃-450℃ for 1-2 hours. Therefore, the adhesive in step ⑤ mainly undergoes pyrolysis. The heating rate in step ⑤ is not particularly limited; for example, it can be increased to 350℃-450℃ at a rate of 1℃ / min-5℃ / min.

[0049] ⑥ A sixth sintering treatment is performed at 700℃-900℃ for 1-2 hours. This completely carbonizes the resin component of the adhesive in step ⑥, forming a dense carbon film. The heating rate in step ⑥ is not particularly limited; for example, it can be increased to 700℃-900℃ at a rate of 1℃ / min-5℃ / min.

[0050] Specifically, in steps ⑤-⑥, the resin component in the adhesive undergoes pyrolysis and carbonization, generating a gradient-dense carbon film on the seed crystal surface. This carbon film not only buffers the interfacial stress caused by thermal expansion mismatch, but its densified structure also suppresses back corrosion defects caused by reverse sublimation during high-temperature growth.

[0051] According to a specific embodiment of the present invention, during the first sintering process, the second sintering process, the third sintering process, and the fourth sintering process, a surface pressure of 0.9 × 10⁻⁶ is applied to the second intermediate. 5 N / m 2 –1.6×10 5 N / m 2 As some specific examples, the surface pressure may be 0.9 × 10⁻⁶. 5 N / m 2 1.0×10 5 N / m 2 1.3×10 5 N / m 2 1.6×10 5 N / m 2 Therefore, excessive volume expansion of the second intermediate can be suppressed, which helps to complete degassing. Specifically, the method of applying surface pressure is not particularly limited. For example, a pressure block can be placed on the surface of the second intermediate. A 200kg-300kg pressure block is used for a 6-inch diameter seed wafer, and a 300kg-400kg pressure block is used for an 8-inch diameter seed wafer.

[0052] According to a specific embodiment of the present invention, the sintering process is carried out in a vacuum environment. Thus, the vacuum environment facilitates complete degassing in the first to fourth sintering processes (i.e., steps ①-④), and effectively inhibits the oxidation of the generated carbon film in the fifth to sixth sintering processes (i.e., steps ⑤-⑥).

[0053] According to a specific embodiment of the present invention, the apparatus used for the sintering process is not particularly limited; for example, a vacuum sintering furnace (see schematic diagram) can be used. Figure 1 (As shown).

[0054] According to a specific embodiment of the present invention, the method further includes: after sintering, naturally cooling to room temperature to obtain a silicon carbide seed crystal plate. This avoids warping caused by rapid cooling.

[0055] A second aspect of the present invention provides a silicon carbide seed plate prepared according to the method described in the first aspect. Silicon carbide crystals grown using this seed plate have smooth back surfaces, minimal reverse sublimation, and good crystal quality.

[0056] A third aspect of the present invention provides a method for growing silicon carbide crystals, comprising: placing a silicon carbide seed crystal plate in a crystal growth furnace for growth to obtain silicon carbide crystals; wherein the silicon carbide seed crystal plate comprises a silicon carbide seed crystal plate prepared according to the method of the first aspect or the silicon carbide seed crystal plate described in the second aspect.

[0057] The fourth aspect of the present invention provides a silicon carbide crystal obtained according to the growth method described in the third aspect.

[0058] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0059] Example 1

[0060] This embodiment provides a silicon carbide seed crystal plate and its preparation method, including the following steps:

[0061] S1: Chemical corrosion treatment

[0062] S1.1: First, immerse a 6-inch diameter silicon carbide seed wafer in an 80°C potassium hydroxide solution for 20 minutes;

[0063] S1.2: Cleaning the seed wafer

[0064] S1.2.1: Preliminary rinsing: Rinse the surface of the seed wafer with deionized water for 2 minutes to remove most of the soluble potassium. + and OH - ;

[0065] S1.2.2: Acid neutralization: Immerse the seed wafer in 3% dilute hydrochloric acid neutralization solution for 8 minutes, with ultrasonic assistance;

[0066] S1.2.3: Second rinse: Rinse again with deionized water for 5 minutes to ensure pH neutral;

[0067] S1.2.4: Ultrasonic rinsing: Clean with deionized water at 50kHz for 8 minutes;

[0068] S1.2.5: Drying: Vacuum dry at 80℃ for 10 minutes to avoid water residue.

[0069] S2: Apply adhesive

[0070] Place the seed wafer on a spin coater, first spin coat at a low speed of 2000 rpm / min, then spin coat at a high speed of 4000 rpm / min (the amount of adhesive used is 15 mL, the main components of the adhesive are epoxy resin matrix and phthalic anhydride curing agent), and then center-bond it with graphite paper.

[0071] S3: Sintering treatment

[0072] The sintering process is carried out under vacuum conditions. In the first to fourth stages, a 300kg weight is placed on the surface of the seed wafer.

[0073] Phase 1: Maintain temperature at 60℃ for 1 hour;

[0074] Second stage: Increase the temperature to 130℃ at 3℃ / min and maintain for 2 hours;

[0075] Third stage: Increase the temperature to 150℃ at a rate of 2℃ / min and maintain for 4 hours;

[0076] Fourth stage: Increase the temperature to 180℃ at a rate of 5℃ / min and hold for 0.5h;

[0077] In the fifth and sixth stages, the briquettes are lifted up for subsequent carbonization.

[0078] Fifth stage: Increase the temperature to 400℃ at a rate of 3℃ / min and maintain for 2 hours;

[0079] Stage 6: Increase the temperature to 800℃ at a rate of 3℃ / min and maintain for 2 hours.

[0080] After sintering, the silicon carbide seed crystal plate is naturally cooled to room temperature (e.g., Figure 2 As shown), a silicon carbide seed crystal plate is placed in a crystal growth furnace for 12 days to grow silicon carbide crystals (the surface of the crystal is as shown). Figure 3 As shown, the back side of the crystal is as follows Figure 4 As shown), by Figure 3 and Figure 4 It can be seen that the surface of the silicon carbide crystal is free of defects, and the back side is smooth with no back corrosion.

[0081] Example 2

[0082] The difference between this embodiment and Embodiment 1 is that the process parameters for the sintering treatment in step S3 are as follows:

[0083] Phase 1: Maintain temperature at 60℃ for 1 hour;

[0084] Second stage: Increase the temperature to 120℃ at a rate of 1℃ / min and maintain for 2 hours;

[0085] Third stage: Increase the temperature to 140℃ at a rate of 1℃ / min and maintain it for 5 hours;

[0086] Fourth stage: Increase the temperature to 160℃ at a rate of 3℃ / min and hold for 1 hour;

[0087] Fifth stage: Increase the temperature to 350℃ at a rate of 1℃ / min and maintain for 2 hours;

[0088] Stage 6: Increase the temperature to 700℃ at a rate of 1℃ / min and maintain for 2 hours.

[0089] Example 3

[0090] The difference between this embodiment and Embodiment 1 is that the process parameters for the sintering treatment in step S3 are as follows:

[0091] Phase 1: Maintain temperature at 60℃ for 1 hour;

[0092] Second stage: Increase the temperature to 140℃ at 5℃ / min and maintain for 1 hour;

[0093] Third stage: Increase the temperature to 160℃ at 3℃ / min and maintain for 3 hours;

[0094] Fourth stage: Increase the temperature to 180℃ at a rate of 7℃ / min and hold for 0.5 hours;

[0095] Fifth stage: Increase the temperature to 450℃ at a rate of 5℃ / min and hold for 1 hour;

[0096] Stage 6: Increase the temperature to 900℃ at a rate of 5℃ / min and maintain for 1 hour.

[0097] Comparative Example 1

[0098] The difference between this comparative example and Example 1 is that step S1 was not performed, that is, the silicon carbide seed wafer was not chemically etched.

[0099] Comparative Example 2

[0100] The difference between this comparative example and Example 1 is that the curing agent in the adhesive is replaced with ethylenediamine instead of phthalic anhydride.

[0101] Comparative Example 3

[0102] The difference between this comparative example and Example 1 is that step S3 was not performed, i.e., sintering was not performed.

[0103] Test Case

[0104] The silicon carbide seed crystal plates prepared in the examples and comparative examples were subjected to performance testing. The specific steps are as follows:

[0105] (1) Bond strength test between seed crystal plate and graphite paper:

[0106] The bonding strength is determined by evaluating the ease of cleaning the prepared silicon carbide seed crystal plate. The stronger the bonding strength between the seed crystal plate and the graphite paper, the more difficult it is to clean the seed crystal plate; the weaker the bonding strength between the seed crystal plate and the graphite paper, the easier it is to clean the seed crystal plate.

[0107] (2) Thermal stability test:

[0108] The prepared silicon carbide seed crystal plate was placed in a crystal growth furnace for 12 days to grow silicon carbide crystals. The back side of the silicon carbide crystal product was observed. If the back side was smooth and there was no back corrosion, it indicated that the silicon carbide seed crystal plate had high thermal stability; if the back side was rough and there was back corrosion, it indicated that the silicon carbide seed crystal plate had low thermal stability. When the back corrosion area accounted for 0-5% of the total back area and was not 0, it was considered mild back corrosion; when the back corrosion area accounted for 5%-10% of the total back area, it was considered moderate back corrosion.

[0109] The performance test results of the silicon carbide seed crystal plates prepared in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1.

[0110] Table 1

[0111] Difficulty of cleaning seed crystal plates Back side view of silicon carbide crystal Example 1 Cleaned in 40 minutes, difficult to clean The crystal has a smooth back surface and is free from back corrosion. Example 2 Cleaned in 40 minutes, difficult to clean The crystal has a smooth back surface and is free from back corrosion. Example 3 Cleaned in 40 minutes, difficult to clean The crystal has a smooth back surface and is free from back corrosion. Comparative Example 1 Cleans in 5 minutes, easy to clean The back of the crystal is rough and has moderate back corrosion. Comparative Example 2 Cleans in 10 minutes, easy to clean The back of the crystal is rough, with slight back corrosion. Comparative Example 3 Cleans in 5 minutes, easy to clean Crystal shedding due to poor thermal stability

[0112] Results analysis:

[0113] As shown in Table 1, compared with the comparative example, the silicon carbide seed crystal plate and graphite paper prepared in Examples 1-3 all have excellent bonding strength and excellent thermal stability.

[0114] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0115] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a silicon carbide seed crystal plate, characterized in that, include: The silicon surface of a silicon carbide seed wafer is chemically etched using an alkaline reagent to obtain the first intermediate. An adhesive is coated onto the silicon surface of the first intermediate and then bonded to graphite paper to obtain a second intermediate, wherein the adhesive comprises an epoxy resin matrix and an acid anhydride curing agent. The second intermediate is sintered to obtain a silicon carbide seed crystal plate.

2. The method according to claim 1, characterized in that, The alkaline reagent includes at least one of potassium hydroxide and sodium hydroxide.

3. The method according to claim 1, characterized in that, The chemical etching treatment is performed at a temperature of 60℃-100℃ for a time of 10min-30min.

4. The method according to claim 1, characterized in that, The anhydride curing agent includes at least one of phthalic anhydride and tetrahydrophthalic anhydride.

5. The method according to any one of claims 1-4, characterized in that, The sintering process includes: The first sintering treatment was carried out at 50℃-80℃ for 0.5h-1h. The second sintering treatment was carried out at 120℃-140℃ for 1-2 hours. The third sintering treatment was carried out at 140℃-160℃ for 3-5 hours. The fourth sintering treatment was carried out at 160℃-180℃ for 0.5h-1h.

6. The method according to claim 5, characterized in that, The sintering process further includes: The fifth sintering treatment was carried out at 350℃-450℃ for 1-2 hours. The sixth sintering treatment was carried out at 700℃-900℃ for 1-2 hours.

7. The method according to claim 5, characterized in that, During the first sintering process, the second sintering process, the third sintering process, and the fourth sintering process, a surface pressure of 0.9 × 10⁻⁶ is applied to the second intermediate. 5 N / m 2 –1.6×10 5 N / m 2 ; Optionally, the sintering process is performed in a vacuum environment.

8. A silicon carbide seed plate prepared by the method according to any one of claims 1-7.

9. A method for growing silicon carbide crystals, characterized in that, include: Silicon carbide seed plates are placed in a crystal growth furnace for growth to obtain silicon carbide crystals; The silicon carbide seed plate includes the silicon carbide seed plate prepared by the method according to any one of claims 1-7 or the silicon carbide seed plate according to claim 8.

10. A silicon carbide crystal obtained by the growth method according to claim 9.

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