Silicon carbide seed crystal bonding piece and bonding method thereof

Abstract

The invention relates to the technical field of silicon carbide single crystal materials, in particular to a silicon carbide seed crystal bonding piece and a bonding method thereof.The silicon carbide seed crystal bonding piece comprises a graphite base body, a glue layer and silicon carbide seed crystals; the glue layer is arranged between the graphite substrate and the silicon carbide seed crystal; a plurality of through holes are longitudinally formed in the graphite base body; the through holes are designed to be in a gradient hole pattern. The through holes are formed in the graphite substrate, so that gas generated in the curing and sintering stages of the adhesive layer is effectively promoted to be smoothly discharged through the through holes, and the probability that bubbles appear between the silicon carbide seed crystals and the graphite substrate in the bonding process can be reduced; through fine optimization and design of the through holes, the contradiction between exhaust and glue permeation amount control can be effectively balanced, and excessive permeation of glue into the through holes is avoided; and the glue which is pressed to permeate into the through hole can be filled into the through hole in the curing stage to form a mechanical anchoring point, so that the bonding quality of the silicon carbide seed crystal and the graphite substrate is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide single crystal materials, and particularly to a silicon carbide seed crystal bonding part and a bonding method thereof. Background Art

[0002] Silicon carbide single crystal materials are usually prepared by physical vapor transport method (PVT); that is, silicon carbide powder is placed in a closed graphite crucible and at the bottom of the graphite crucible, and a silicon carbide seed crystal is fixed at the top of the crucible; the graphite crucible is heated by a side heater on the outer periphery. Under high temperature conditions, the silicon carbide powder decomposes and sublimes into gas; under the action of an axial temperature gradient, the gas is transported to the silicon carbide seed crystal in the low temperature zone and deposits on its surface to form a silicon carbide single crystal; among them, the method of setting the silicon carbide seed crystal at the top of the crucible includes mechanical fixation, silicon carbide seed crystal bonding, etc.; because the processing accuracy of setting the silicon carbide seed crystal at the top of the crucible by mechanical fixation is low, it may interfere with the temperature field distribution inside the crucible and lead to a decrease in crystal growth quality. Usually, the method of bonding the silicon carbide seed crystal is used to fix the silicon carbide seed crystal at the top of the crucible, that is, an adhesive (high temperature glue) is evenly coated on the back surface of the silicon carbide seed crystal and the surface of the graphite matrix at the top of the crucible to make the two closely bonded. However, during the growth of silicon carbide single crystals, bubbles will be generated in the glue layer due to the escape of volatiles or thermal expansion during high temperature sintering, and then the following problems will occur: 1) Bubbles remaining in the glue layer cause local bonding failure at the contact surface between the silicon carbide seed crystal and the graphite matrix, and the silicon carbide seed crystal falls off at high temperature; 2) Bubbles lead to uneven heat conduction, induce stress concentration at the crystal growth interface, and form dislocation defects.

[0003] Currently, usually, methods such as reducing the amount of glue applied or optimizing the glue formula are used to alleviate problems such as bonding failure and uneven heat conduction caused by the presence of bubbles in the glue layer, but the problem of how to discharge the bubbles and gas generated in the glue layer cannot be solved; moreover, methods such as reducing the amount of glue applied and optimizing the glue formula may also sacrifice bonding strength. Although the patent number 202410826428.5 discloses a high-strength bubble-free bonding method for silicon carbide seed crystals, specifically discloses that a number of criss-cross etching grooves are first etched on the bonding surface of the silicon carbide seed crystal, and then the silicon carbide seed crystal is bonded on the bonding surface of the silicon carbide seed crystal; through continuous etching grooves, while ensuring firm bonding, the bubbles are exported to reduce the probability of bubbles appearing during the bonding process; however, the operation of this bonding method is complex and requires prior etching and processing of the silicon carbide seed crystal; because the silicon carbide seed crystal itself is expensive, and in the process of etching and processing, etching failure will inevitably occur, resulting in damage to the silicon carbide seed crystal, which will increase the total consumption of the silicon carbide seed crystal, significantly increase the bonding cost of the silicon carbide seed crystal, and ultimately have an adverse impact on the crystal growth cost.

[0004] The present invention provides a silicon carbide seed crystal bonding part and a bonding method thereof to solve the problems in the prior art that the existing silicon carbide seed crystal bonding method cannot discharge the air bubbles generated in the adhesive layer, and the cost of silicon carbide seed crystal bonding is high, etc. Summary of the Invention

[0005] The object of the present invention is: a silicon carbide seed crystal bonding part and a bonding method thereof to solve the problems in the prior art that the existing silicon carbide seed crystal bonding method cannot discharge the air bubbles generated in the adhesive layer, and the cost of silicon carbide seed crystal bonding is high, etc.

[0006] The technical solution of the present invention is: a silicon carbide seed crystal bonding part, including a graphite matrix, an adhesive layer, and a silicon carbide seed crystal; the adhesive layer is arranged between the graphite matrix and the silicon carbide seed crystal; a plurality of through holes are longitudinally arranged on the graphite matrix; the through holes are all designed in a gradient hole shape, and from the surface close to the silicon carbide seed crystal bonding surface to the surface far from the silicon carbide seed crystal bonding surface, the aperture of the through hole gradually increases.

[0007] Preferably, the aperture of one end of a plurality of the through holes close to the silicon carbide seed crystal is 50 - 100 μm, and the aperture of the end far from the silicon carbide seed crystal is 200 - 300 μm; The graphite matrix is a graphite substrate or a combined carrier including at least two pieces of graphite paper.

[0008] Preferably, the graphite matrix is a graphite substrate; A plurality of first micropores are arranged on the end surface of the graphite substrate close to the silicon carbide seed crystal, and on the end surface far from the silicon carbide seed crystal, second micropores are arranged at positions corresponding to the plurality of first micropores; The second micropores and the first micropores are coaxially arranged and communicate with each other to form the through holes.

[0009] Preferably, the graphite matrix is a combined carrier including at least two pieces of graphite paper; In the combined carrier, a plurality of through holes are correspondingly arranged on each piece of graphite paper, and from the graphite paper close to the silicon carbide seed crystal bonding surface to the graphite paper far from the silicon carbide seed crystal bonding surface, the aperture of the through hole gradually increases.

[0010] Preferably, a plurality of the through holes on the graphite matrix are arranged in a honeycomb shape or in a staggered arrangement.

[0011] Preferably, the graphite paper is high-density isostatic pressing graphite paper; the thickness of the graphite paper is 0.15 - 0.5 mm.

[0012] This application also provides a bonding method for the above-mentioned silicon carbide seed crystal part, including the following steps: S1. Perform drilling processing on the graphite matrix to form a plurality of through holes on the graphite matrix; S2. Coat glue on the bonding surface of the silicon carbide seed crystal and the bonding surface of the graphite matrix respectively. Then, fit the bonding surface of the silicon carbide seed crystal with the bonding surface of the graphite matrix and perform pre-pressing treatment to form a bonded part. S3. Place the formed bonded part in a heating device and perform stepwise temperature-rising curing treatment to obtain a silicon carbide seed crystal bonded part. The stepwise temperature-rising curing treatment includes a first-stage curing treatment and a second-stage curing treatment. The treatment temperature of the first-stage curing treatment is 80 - 150 °C, and the treatment pressure is 0.01 Mpa - 0.03 Mpa. The treatment temperature of the second-stage curing treatment is 200 - 300 °C, and the treatment pressure is 0.05 - 0.1 Mpa.

[0013] Preferably, in step S1, the treatment method of the punching process is laser punching or punching.

[0014] Preferably, the glue is epoxy resin or polyimide glue. In step S2, the coating method of applying the glue on the bonding surface of the silicon carbide seed crystal and the bonding surface of the graphite matrix is spin coating or blade coating.

[0015] Compared with the prior art, the advantages of the present invention are: (1) A silicon carbide seed crystal bonded part and its bonding method provided by the present invention. The silicon carbide seed crystal bonded part uses the through holes provided on the graphite matrix as exhaust channels, effectively promoting the smooth discharge of the gas generated during the curing and sintering stages of the glue layer, and effectively reducing the probability of bubbles appearing between the silicon carbide seed crystal and the graphite matrix during the bonding process. At the same time, through the refined optimization and design of the through hole structure, not only effectively balances the contradiction between the exhaust effect and the control of the glue infiltration amount, avoiding excessive glue infiltration into the through holes, but also ensures that the glue pressed into the first micropores or the first through holes fills the through holes during the curing stage to form mechanical anchor points, thereby significantly improving the bonding quality and process economy of the silicon carbide seed crystal and the graphite matrix. In addition, compared with the silicon carbide seed crystal, the prices of the graphite substrate and graphite paper are very low. Even if the graphite substrate or graphite paper is damaged due to punching failure during the punching process, it will not significantly increase the bonding cost of the silicon carbide seed crystal and the crystal growth cost. It solves the problems existing in the prior art that the existing silicon carbide seed crystal bonding method cannot discharge the bubbles generated in the glue layer and the bonding cost of the silicon carbide seed crystal is high.

[0016] (2)The silicon carbide seed crystal bonding part and its bonding method provided by the present invention. In this bonding method, a stepped temperature rise curing treatment is carried out on the bonding part to achieve a dynamic exhaust-filling two-stage mechanism. During the curing treatment in the first stage, at the initial stage of temperature rise, the glue is in a high-viscosity state and partially penetrates into the first micropores or the first through holes. By controlling the heating rate and the magnitude of the applied pressure, the penetration depth of the glue is regulated, so that the glue completely fills the first micropores or the first through holes, and does not fill the second through holes, promoting the gas in the glue to escape at the second through holes after flowing through the first through holes. During the curing treatment in the second stage, the glue boils, the gas is released rapidly, and the glue gradually cures. By increasing the pressure and controlling the heating rate in the second stage, the gas in the glue is completely released. Finally, the glue fills the first micropores or the first through holes, eliminating the pores in the first micropores or the first through holes, which helps to strengthen the interfacial bonding. That is, through the gradient design of the pore diameter, the design of the curing temperature curve, and the coordination and cooperation of the magnitude of the applied pressure, the through-hole structure is adapted to the thermosetting property of the glue, thereby accurately regulating the penetration depth of the glue and the closing time of the first micropores or the first through holes, and exhausting the bubbles in the glue as thoroughly as possible while improving the bonding strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the drawings and embodiments: Figure 1 It is a schematic structural diagram of the silicon carbide seed crystal bonding part described in Embodiment 1 of the present invention; Figure 2 It is a schematic structural diagram of the silicon carbide seed crystal bonding part described in Embodiment 2 of the present invention; Figure 3 It is a schematic structural diagram of the silicon carbide seed crystal bonding part described in Embodiment 3 of the present invention; Figure 4 It is a schematic structural diagram of the first graphite paper described in Embodiment 4 of the present invention; Figure 5 It is a schematic structural diagram of the second graphite paper described in Embodiment 4 of the present invention; Figure 6 It is a schematic structural diagram of the silicon carbide seed crystal bonding part described in Embodiment 4 of the present invention; Figure 7 It is a schematic structural diagram of the silicon carbide seed crystal bonding part of the present invention; Wherein: 1. graphite substrate; 2. combined carrier; 21. first graphite paper; 22. second graphite paper; 23. third graphite paper; 3. silicon carbide seed crystal; 4. glue layer; 5. through hole; 51. first micropore; 52. second micropore; 53. first through hole; 54. second through hole; 55. third through hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The content of the present invention will be further described in detail below in conjunction with the specific embodiments: The present application provides a silicon carbide seed crystal bonding part, which includes a graphite matrix, an adhesive layer, and a silicon carbide seed crystal; wherein, the adhesive layer is arranged between the graphite matrix and the silicon carbide seed crystal; a plurality of through holes with a pore diameter of 50-300 μm and a hole pitch of 1-5 mm are longitudinally arranged on the graphite matrix; the graphite matrix is a graphite substrate or a combined carrier including at least two pieces of graphite paper. The purpose of arranging a plurality of longitudinal through holes on the graphite matrix is: using the through holes as exhaust channels to discharge the bubbles formed in the adhesive layer during the bonding process of the silicon carbide seed crystal and the graphite matrix, specifically the bubbles formed in the adhesive layer during stages such as pre-pressing, curing, and sintering. The plurality of through holes on the graphite matrix can be arranged in a honeycomb pattern or in a staggered pattern.

[0019] The present application also provides a bonding method for the above-mentioned silicon carbide seed crystal bonding part, which specifically includes the following steps: S1. Perform punching processing on the graphite matrix by means of laser punching or punching, etc., to form a plurality of through holes on the graphite matrix; S2. Use methods such as spin coating or doctor blade coating to coat glue on the bonding surface of the silicon carbide seed crystal and the bonding surface of the graphite matrix respectively. Then, fit the bonding surface of the silicon carbide seed crystal and the bonding surface of the graphite matrix together, and use a pressing block with the same size as the silicon carbide seed crystal and a weight of 3-8 kg to perform pre-pressing treatment on the graphite paper and the silicon carbide seed crystal. After pre-pressing for several minutes, a bonding part is formed; wherein, the glue is a high-temperature resistant epoxy resin or polyimide glue; the epoxy resin can be selected from commercially available epoxy resin AB glue with a model of HY-914B or JL-510, or other models or brands of epoxy resin, such as DER 6508, DER 669-20, EPON 1001F, etc.; the polyimide glue can be selected from commercially available YJ-16 polyimide glue, UV curing glue, and the UV curing glue is preferably of brands such as Tadhe (TADHE), or other models or brands of polyimide glue; S3. Place the formed bonding part in a heating device and perform stepwise temperature-rising curing treatment, that is, first raise the temperature from room temperature to 80-150°C at a heating rate of 5-10°C / min, and perform the first-stage curing treatment at a temperature of 80-150°C and a pressure of 0.01-0.03 Mpa. After maintaining for 5-20 min, then raise the temperature to 200-300°C at a heating rate of 0.5-2°C / min and raise the pressure to 0.05-0.1 Mpa to perform the second-stage curing treatment, and maintain for 20-50 min. After the stepwise temperature-rising curing treatment is completed, a silicon carbide seed crystal bonding part is obtained. Through the first-stage curing treatment, a temporary exhaust channel can be formed at the through holes by the glue, so that the gas formed in the glue can be discharged through the through holes; through the second-stage curing treatment, the glue infiltrated into the through holes can be cured and filled in the through holes to form mechanical anchor points, thereby increasing the bonding strength between the silicon carbide seed crystal and the graphite matrix. Embodiment 1

[0020] A silicon carbide seed crystal bonding part, as Figure 1 shown, includes a graphite substrate 1, a silicon carbide seed crystal 3, and an adhesive layer 4 provided between the graphite matrix and the silicon carbide seed crystal; wherein, the thickness of the graphite substrate 1 is 0.6 mm, and a plurality of through holes 5 with a pore diameter of 100 μm and a hole pitch of 3 mm are longitudinally arranged on the graphite substrate 1.

[0021] The bonding method of this silicon carbide seed crystal bonding part is specifically as follows: S1. Perform drilling processing on the graphite substrate by using a femtosecond laser drilling method to form a plurality of through holes with a pore diameter of 100 μm and a hole pitch of 3 mm on the graphite substrate; S2. Use a spin coater and adopt the spin coating method to respectively coat a layer of epoxy resin of model HY-914B on the bonding surface of the silicon carbide seed crystal and the bonding surface of the graphite substrate. Then, fit the bonding surface of the silicon carbide seed crystal with the bonding surface of the graphite substrate, and use a pressing block of the same size as the silicon carbide seed crystal to pre-press the graphite substrate and the silicon carbide seed crystal under a pressure of 0.005 Mpa for 5 min to form a bonding part; S3. Place the formed bonding part in the chamber of a vacuum heating device, and adjust the pressure inside the chamber to 500 Pa. Then, perform stepwise temperature-rising curing treatment, that is, first raise the temperature from room temperature to 100 °C at a heating rate of 8 °C / min, and maintain it for 10 min at a temperature of 100 °C and a pressure of 0.03 Mpa to complete the first-stage curing treatment; then raise the temperature to 300 °C and the pressure to 0.08 Mpa at a heating rate of 1 °C / min for the second-stage curing treatment. After maintaining for 30 min, the stepwise temperature-rising curing treatment is completed to obtain a silicon carbide seed crystal bonding part. In this embodiment and other implementation methods, the pressure inside the heating device needs to be adjusted to the range of 200 - 800 Pa before performing the stepwise temperature-rising curing treatment.

[0022] Through experimental research and repeated verification, it is found that during the bonding process of the silicon carbide seed crystal and the graphite substrate, if the through holes on the graphite substrate are designed as straight holes with the same aperture at both ends, as shown in Embodiment 1, a series of technical problems will be caused; specifically, when the aperture of the through hole is relatively large, although it is more conducive to discharging the bubbles and gases formed in the glue; however, more glue will seep into the through hole, and excessive glue infiltration will overflow from the substrate, destroying the flatness of the contact surface between the silicon carbide seed crystal and the substrate, thereby reducing the bonding strength and affecting the bonding stability between the silicon carbide seed crystal and the graphite substrate; moreover, it will also greatly increase the consumption of glue and increase the bonding cost; while when the aperture of the through hole is relatively small, the bubbles in the glue are difficult to be effectively discharged. Therefore, in this application, it is further proposed to design the through holes on the graphite substrate as a gradient hole type. Embodiment 2

[0023] A silicon carbide seed crystal bonding part, as Figure 2 shown, includes a graphite substrate 1, a silicon carbide seed crystal 3, and a glue layer 4 disposed between the graphite substrate and the silicon carbide seed crystal; wherein, the thickness of the graphite substrate 1 is 0.6 mm, and a plurality of through holes 5 are longitudinally provided on the graphite substrate 1; and, the aperture of one end of the through hole close to the bonding surface of the silicon carbide seed crystal is 80 μm, and the aperture of the other end far from the bonding surface of the silicon carbide seed crystal is 150 μm; on the end surface of the graphite substrate close to the bonding surface of the silicon carbide seed crystal, the hole pitch of the through holes is 3 mm.

[0024] The bonding method of this silicon carbide seed crystal bonding part is specifically as follows: S1. Use a femtosecond laser drilling method to perform drilling processing on the graphite substrate to form a plurality of trapezoidal through holes on the graphite substrate; S2. Use a spin coater to spin coat a layer of epoxy resin of model HY-914B on the bonding surface of the silicon carbide seed crystal and the bonding surface of the graphite substrate respectively. Then, bring the bonding surface of the silicon carbide seed crystal into contact with the bonding surface of the graphite substrate, and use a pressing block of the same size as the silicon carbide seed crystal to pre-press the graphite substrate and the silicon carbide seed crystal under a pressure of 0.005 Mpa for 5 minutes to form a bonded part. S3. Place the formed bonded part in the chamber of a vacuum heating device, and adjust the pressure inside the chamber to 500 Pa. Then, perform a stepwise temperature rise curing process, that is, first raise the temperature from room temperature to 100 °C at a heating rate of 10 °C / min, and maintain it for 10 minutes at a temperature of 100 °C and a pressure of 0.03 Mpa to complete the first-stage curing process. Then, raise the temperature to 300 °C at a heating rate of 1.5 °C / min and adjust the pressure to 0.08 Mpa for the second-stage curing process. After maintaining it for 30 minutes, the stepwise temperature rise curing process is completed to obtain a silicon carbide seed crystal bonded part.

[0025] In the embodiments and through repeated verification by a large number of experiments, it is found that during the bonding process of the silicon carbide seed crystal and the graphite matrix, by arranging a number of trapezoidal through holes in the graphite matrix, that is, in a gradient hole pattern design, it can effectively discharge the bubbles or gases formed in the glue during the processes such as curing and sintering; and it can also reduce the infiltration amount of the glue in the through holes to a certain extent, improving the bonding stability between the silicon carbide seed crystal and the graphite substrate. To further improve the bonding stability between the silicon carbide seed crystal and the graphite substrate, effectively discharge the bubbles in the glue, and reduce the infiltration amount of the glue in the through holes, the through holes on the graphite matrix are further optimized in this application. Embodiment 3

[0026] A silicon carbide seed crystal bonded part, as Figure 3 shown, includes a graphite substrate 1, a silicon carbide seed crystal 3, and a glue layer 4 provided between the graphite substrate and the silicon carbide seed crystal; wherein, the thickness of the graphite substrate 1 is 0.6 mm. A number of first micro holes 51 are provided on the end face of the graphite substrate close to the bonding surface of the silicon carbide seed crystal, and the depth of the first micro holes 51 is 0.3 mm; on the end face of the graphite substrate far from the bonding surface of the silicon carbide seed crystal, and at positions corresponding to the number of first micro holes 51, second micro holes 52 are provided; the second micro holes 52 are coaxially arranged with and communicate with the first micro holes 51 to form a through hole 5 with a gradient hole pattern; wherein, the aperture of the first micro holes 51 is 100 μm, and the hole pitch is 3 mm; the aperture of the second micro holes 52 is 200 μm, and the hole pitch is 2 mm. In other embodiments, the thickness of the graphite substrate 1 is preferably 0.2 - 1.5 mm; the depth of the first micro holes 51 on the graphite substrate 1 does not exceed half of the thickness of the graphite substrate 1.

[0027] The bonding method of the silicon carbide seed crystal bonding part is as follows: S1. Use the drilling method of femtosecond laser to drill the graphite substrate, and form a number of first micro-holes on the end face of the graphite substrate close to the bonding surface of the silicon carbide seed crystal. On the end face far from the bonding surface of the silicon carbide seed crystal, and at positions corresponding to the number of first micro-holes, second micro-holes are provided, and the second micro-holes are communicated with the first micro-holes to form a through-hole with a gradient hole type; S2. Use a spin coater and apply a layer of epoxy resin of model HY-914B on the bonding surface of the silicon carbide seed crystal and the bonding surface of the graphite substrate respectively by spin coating. Then, fit the bonding surface of the silicon carbide seed crystal with the bonding surface of the graphite substrate, and use a pressing block of the same size as the silicon carbide seed crystal to pre-press the graphite substrate and the silicon carbide seed crystal under a pressure of 0.05 Mpa for 5 minutes to form a bonding part; S3. Place the formed bonding part in the chamber of a vacuum heating device, and adjust the pressure inside the chamber to 500 Pa. Then, perform stepwise temperature rising and curing treatment, that is, first raise the temperature from room temperature to 100 °C at a heating rate of 6 °C / min, and maintain it for 10 minutes at a temperature of 100 °C and a pressure of 0.03 Mpa to complete the first-stage curing treatment; then raise the temperature to 300 °C and the pressure to 0.08 Mpa at a heating rate of 1 °C / min for the second-stage curing treatment. After maintaining it for 30 minutes, the stepwise temperature rising and curing treatment is completed to obtain a silicon carbide seed crystal bonding part. Embodiment 4

[0028] A silicon carbide seed crystal bonding part includes a combined carrier composed of two graphite papers, a silicon carbide seed crystal, and an adhesive layer provided between the combined carrier and the silicon carbide seed crystal; as Figure 4 shown, a number of first through-holes 53 are provided on the first graphite paper 21 in the combined carrier, and the aperture of the first through-holes 53 is 100 μm, and the hole pitch is 3 mm; as Figure 5 shown, second through-holes 54 are provided at positions corresponding to the number of first through-holes 53 on the second graphite paper 22 in the combined carrier, and the aperture of the second through-holes 54 is 200 μm, and the hole pitch is 2 mm; both the first graphite paper 21 and the second graphite paper 22 are high-density isostatic pressing graphite papers, and the thicknesses are both 0.25 mm, and the densities are both 1.9 g / cm³.

[0029] The bonding method of the silicon carbide seed crystal bonding part is as follows: S1. Use the drilling method of femtosecond laser to drill the first graphite paper and the second graphite paper respectively, and set a number of first through-holes on the first graphite paper, and set second through-holes at positions corresponding to the number of first through-holes on the second graphite paper; S2. Use a spin coater to spin coat a layer of YJ-16 polyimide adhesive on the bonding surface of the silicon carbide seed crystal, the bonding surface of the first graphite paper, and the bonding surface of the second graphite paper respectively. Then, first fit the bonding surface of the silicon carbide seed crystal with the bonding surface of the first graphite paper, and use a pressing block of the same size as the silicon carbide seed crystal to pre-press the graphite substrate and the silicon carbide seed crystal under a pressure of 5 kg for 5 minutes. After 5 minutes of pre-pressing, then fit the second graphite paper with the first graphite paper in alignment so that the central axes of the first through hole and the second through hole coincide to form a bonded part. In other embodiments, the first graphite paper and the second graphite paper can also be first adhered and pre-pressed together to form a combined carrier; then the combined carrier and the silicon carbide seed crystal are adhered and pre-pressed together; S3. Place the formed bonded part in the chamber of a vacuum heating device, and adjust the pressure inside the chamber to 500 Pa. Then, perform stepwise temperature-rising curing treatment, that is, first raise the temperature from room temperature to 100 °C at a heating rate of 8 °C / min, and maintain it for 10 minutes at a temperature of 100 °C and a pressure of 0.03 Mpa to complete the first-stage curing treatment; then raise the temperature to 300 °C and the pressure to 0.08 Mpa at a heating rate of 2 °C / min for the second-stage curing treatment. After maintaining for 30 minutes, the stepwise temperature-rising curing treatment is completed, as Figure 6 shown, to obtain a silicon carbide seed crystal bonded part.

[0030] In this embodiment, the graphite matrix is a combined carrier including the first graphite paper and the second graphite paper; while in other embodiments, the graphite matrix can also be a combined carrier including at least two graphite papers; and in this combined carrier, a number of through holes are correspondingly provided on each graphite paper, and from the graphite paper close to the bonding surface of the silicon carbide seed crystal to the graphite paper far from the bonding surface of the silicon carbide seed crystal, the aperture of the through holes gradually increases. For example, as Figure 7 shown, the graphite matrix is a combined carrier including three graphite papers. From the end face close to the bonding surface of the silicon carbide seed crystal to the end face far from the bonding surface of the silicon carbide seed crystal, they are the first graphite paper 21, the second graphite paper 22, and the third graphite paper 23 in sequence; a number of first through holes 53 are provided on the first graphite paper 21, and second through holes 54 are provided at positions corresponding to the number of first through holes 53 on the second graphite paper 22, and third through holes 55 are provided at positions corresponding to the number of second through holes 54 on the third graphite paper 23; and the apertures of the first through hole, the second through hole, and the third through hole gradually increase. In addition, the graphite paper is preferably high-density isostatic graphite paper, and the thickness of the graphite paper is preferably 0.15 - 0.5 mm.

[0031] In Embodiment 3 and Embodiment 4, the through holes on the graphite matrix of the silicon carbide seed crystal bonding part are also designed with a gradient hole pattern, that is, the aperture of the end of the through hole close to the silicon carbide seed crystal bonding surface is smaller, and the aperture of the end of the through hole far from the silicon carbide seed crystal bonding surface is larger. The capillary action principle of the first through hole or the first micropore can be used to limit the excessive infiltration of glue into the through hole; the large aperture at the end of the through hole far from the silicon carbide seed crystal bonding surface is used to expand the gas escape volume, effectively discharging the bubbles in the glue; moreover, the glue infiltrating into the first through hole or the first micropore at the end close to the silicon carbide seed crystal bonding surface can form mechanical anchor points after stepwise temperature rise curing treatment, thereby increasing the bonding strength and bonding stability between the silicon carbide seed crystal and the graphite matrix, and also enhancing the tensile strength of the graphite paper; making the silicon carbide seed crystal bonding part and its bonding method better applicable to the industrial production scenario of large-size silicon carbide single crystals of 6 inches and above.

[0032] The above embodiments are only for illustrating the technical concept and characteristics of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

Claims

1. A silicon carbide seed crystal bonding component, characterized in that: It includes a graphite substrate, a glue layer, and a silicon carbide seed crystal; the glue layer is arranged between the graphite substrate and the silicon carbide seed crystal; a plurality of through holes are longitudinally arranged on the graphite substrate; the through holes are designed to be gradient holes, and the aperture of the through holes gradually increases from close to the silicon carbide seed crystal bonding surface to far away from the silicon carbide seed crystal bonding surface.

2. The silicon carbide seed crystal bonding member according to claim 1, characterized in that: The aperture of the through holes at one end close to the silicon carbide seed crystal is 50-100 μm, and the aperture of the through holes at one end away from the silicon carbide seed crystal is 200-300 μm; The graphite matrix is ​​a graphite substrate or a combined carrier including at least two graphite papers.

3. The silicon carbide seed crystal bonding member according to claim 2, characterized in that: The graphite matrix is ​​a graphite substrate; A plurality of first micropores are arranged on the end surface of the graphite substrate close to the silicon carbide seed crystal, and second micropores are arranged on the end surface away from the silicon carbide seed crystal and at positions corresponding to the plurality of first micropores; The second micropore is coaxially arranged with the first micropore and is interconnected to form the through hole.

4. The silicon carbide seed crystal bonding member according to claim 2, characterized in that: The graphite substrate is a composite carrier comprising at least two graphite papers; In the combined carrier, each of the graphite papers is correspondingly provided with a plurality of through holes, and the apertures of the through holes gradually increase from the graphite paper close to the silicon carbide seed crystal bonding surface to the graphite paper far from the silicon carbide seed crystal bonding surface.

5. The silicon carbide seed crystal bonding member according to claim 2, characterized in that: The plurality of through holes on the graphite substrate are arranged in a honeycomb shape or in a staggered arrangement.

6. The silicon carbide seed crystal bonding component according to claim 2, characterized in that: The graphite paper is high-density isostatically pressed graphite paper; the thickness of the graphite paper is 0.15-0.5 mm.

7. A method for bonding a silicon carbide seed crystal according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, performing a punching process on the graphite substrate to form a plurality of through holes on the graphite substrate; S2, respectively coating glue on the bonding surface of the silicon carbide seed crystal and the bonding surface of the graphite substrate, and then laminating the bonding surface of the silicon carbide seed crystal and the bonding surface of the graphite substrate, and performing a pre-pressing process to form a bonding part; S3, placing the formed bonding piece in a heating device, and performing a step-by-step temperature-raising curing treatment to obtain a silicon carbide seed crystal bonding piece; The step-by-step temperature curing process includes a first-stage curing process and a second-stage curing process; The treatment temperature of the first stage curing treatment is 80-150°C and the treatment pressure is 0.01-0.03Mpa; The treatment temperature of the second stage curing treatment is 200-300° C. and the treatment pressure is 0.05-0.1 MPa.

8. The method for bonding silicon carbide seed crystals according to claim 7, characterized in that: In step S1, the drilling process is performed by laser drilling or punching.

9. The method for bonding silicon carbide seed crystals according to claim 7, characterized in that: The glue is epoxy resin or polyimide glue; In step S2, the glue is coated on the bonding surface of the silicon carbide seed crystal and the bonding surface of the graphite substrate by spin coating or blade coating.

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