Silicon carbide seed crystal bonding device and method

Abstract

The embodiment of the invention discloses a silicon carbide seed crystal bonding device and method. The device comprises a graphite substrate, a rotary degumming sleeve and an upper pressing block. The rotary glue removing sleeve is rotatably arranged above the graphite substrate, and a buffer glue containing groove and a glue discharging opening which are communicated with each other are formed in the rotary glue removing sleeve; the buffering glue containing groove is filled with granular sugar, and the granular sugar is matched with the protrusions distributed on the periphery to achieve point hard face soft supporting, silicon carbide seed crystal deviation is prevented, and edge damage is reduced. Meanwhile, gas and excessive glue on the bonding surface can be discharged through gaps of the granular sugar, the flowing resistance of the glue can be increased, and insufficient local glue amount is avoided. During heating and curing, the granular sugar melts, the rotary glue removing sleeve rotates, the protruding block scrapes excessive glue, meanwhile, the granular sugar provides lubrication, and damage to the side wall of the seed crystal is reduced. In addition, the granular sugar is easy to dissolve in water and small in residue, glue residue can be reduced, the seed crystal is prevented from being scratched and damaged, the crystal growth quality is improved, and the problems of deviation, damage and glue residue existing in a traditional method are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial crystal growth, and particularly relates to a silicon carbide seed crystal bonding device and method. Background Art

[0002] Currently, in the technical field of silicon carbide single crystal growth, the physical vapor transport method (PVT) has become the dominant mainstream process technology. The specific implementation process of this method is as follows: First, place the silicon carbide polycrystalline raw material at the bottom of the graphite crucible; second, precisely bond the silicon carbide seed crystal to the graphite seed crystal holder; finally, install the graphite seed crystal holder with the silicon carbide seed crystal fixed thereon to the upper part of the graphite crucible. During the entire process of silicon carbide single crystal growth, by heating the silicon carbide polycrystalline raw material at the bottom of the graphite crucible, the raw material is sublimated, thereby promoting the gradual growth of silicon carbide single crystals on the silicon carbide seed crystal.

[0003] However, in the existing technical system, the bonding operation of silicon carbide seed crystals generally follows a traditional method: First, evenly coat the bonding surface of the silicon carbide seed crystal with bonding glue, and then apply a specific pressure using a pressure plate to directly bond and fix the silicon carbide seed crystal to the graphite disk substrate.

[0004] However, many problems have emerged in the actual operation process. On the one hand, in the bonding process of applying pressure, the silicon carbide seed crystal often shows phenomena such as position deviation or dislocation. This disrupts the normal growth process of the silicon carbide single crystal, causes the crystal growth to deviate from the expected trajectory, greatly affects the crystal quality of the final silicon carbide single crystal, and may even lead to the failure of the entire single crystal growth process. On the other hand, if the bonding glue cannot overflow smoothly during the pressure application process, an uneven distribution will be formed on the bonding surface. The uneven distribution of the bonding glue will affect the flatness of the seed crystal bonding, resulting in an unstable and uneven bonding state between the seed crystal and the graphite disk substrate. This further affects key factors such as heat transfer and stress distribution during the growth of silicon carbide, and ultimately has a negative impact on the growth quality of the silicon carbide crystal.

[0005] To improve the problems of uneven distribution of the bonding glue and offset and dislocation of the seed crystal wafer, some existing technologies have tried to adopt technical solutions such as opening grooves or pits on the seed crystal holder, attempting to design them as channels for accommodating the adhesive and gas overflow. Although this method alleviates the problems of gas permeability and stability of adhesive overflow to a certain extent, due to the opening of these specific structures on the seed crystal holder, it inevitably causes uneven distribution of the adhesive amount and differences in thermal conductivity within the area. It still has a greater interference on the bonding of the seed crystal, for example, affecting the flatness of the seed crystal bonding, and further affecting the growth quality of silicon carbide.

[0006] In view of the above problems existing in the prior art, there is an urgent need to develop a silicon carbide seed crystal bonding device that can effectively overcome the above problems to meet the production requirements of high-quality silicon carbide single crystal growth. Summary of the Invention

[0007] In order to solve the problems existing in the bonding process of silicon carbide seeds in the prior art, such as the offset and misalignment of silicon carbide seed bonding, poor control of adhesive overflow, and difficulty in gas overflow, the present application proposes a silicon carbide seed bonding device and method. The technical solutions provided by the present application are as follows: On the one hand, the present application provides a silicon carbide seed bonding device, including: A graphite substrate for carrying silicon carbide seeds; A rotating degumming sleeve rotatably arranged above the graphite substrate, with a buffer glue-containing groove and a glue discharge port communicating with each other inside; wherein, the buffer glue-containing groove is used to accommodate granular sugar, and the glue discharge port is used to discharge the melted granular sugar and excess overflow glue; convex blocks are evenly distributed around the buffer glue-containing groove for forming point contact support with the edge of the silicon carbide seed; An upper pressing block located above the rotating degumming sleeve for pressing down the silicon carbide seed.

[0008] In some specific embodiments, heat-conducting blocks are arranged around the upper pressing block.

[0009] In some specific embodiments, the device further includes a pressing cover covering above the buffer glue-containing groove for closing the buffer glue-containing groove.

[0010] In some specific embodiments, the device further includes a telescopic center pressing disk and a liftable annular pressing ring; The telescopic center pressing disk is installed above the center position of the upper pressing block and coincides with the central axis of the upper pressing block for pressing down the silicon carbide seed telescopically from the center; The liftable annular pressing ring is installed above the edge position of the upper pressing block and is arranged around the telescopic center pressing disk for pressing down the silicon carbide seed from the periphery by lifting.

[0011] In some specific embodiments, a rotating member is arranged on the rotating degumming sleeve, and the rotating member drives the rotating degumming sleeve to rotate through a driving device.

[0012] In some specific embodiments, the center of the telescopic center pressing disk coincides with the center of the silicon carbide seed, and the area of the telescopic center pressing disk covers 0.8 - 0.9 of the area of the silicon carbide seed.

[0013] In some specific embodiments, the relationship between the volume V1 of the buffer glue-containing groove above the interface reference plane between the upper pressing block and the silicon carbide seed and the volume V2 below is V1≥1.1V2.

[0014] In some specific embodiments, the rotary degumming sleeve is coaxially arranged with the graphite substrate.

[0015] On the other hand, the present application also provides a method for bonding a silicon carbide seed crystal. The silicon carbide seed crystal is bonded according to the silicon carbide seed crystal bonding device described above, including the following steps: Coat the bonding surface of the silicon carbide seed crystal with a bonding adhesive. Coat a graphite-containing bonding adhesive on the edge of the graphite substrate. Place the silicon carbide seed crystal coated with the bonding adhesive at the center position of the graphite substrate and install a rotary degumming sleeve; wherein, the buffer glue-containing groove of the rotary degumming sleeve contains granular sugar. After applying pressure to the silicon carbide seed crystal through the upper pressing block to press it tightly, place the entire assembly into a hot pressing device for pressure curing.

[0016] In some specific embodiments, heating and bonding are performed in the hot pressing device, including: The first stage: Under a vacuum environment pressure ≤ 9 Pa, heat up to 90 - 100 °C at a heating rate of 71 - 80 °C / h and maintain for 5 - 15 min; meanwhile, apply pressure to the center of the silicon carbide seed crystal through a telescopic center pressing disk. The second stage: Increase the applied pressure of the telescopic center pressing disk, heat up to 150 - 190 °C at a heating rate of 30 - 40 °C / h and maintain for 1 - 1.3 h; meanwhile, start the rotary degumming sleeve to make it rotate for 3 - 5 min. The third stage: Raise the temperature to 400 - 450 °C at a heating rate of 25 - 35 °C / h and maintain for 3 - 4 h; meanwhile, apply pressure to the edge of the silicon carbide seed crystal through a liftable annular pressing ring. The fourth stage: Heat to 460 - 499 °C at a heating rate of 17 - 27 °C / h until the bonding is completely cured.

[0017] In some specific embodiments, the graphite-containing bonding adhesive is coated on the outer edge position of 1 / 10 - 1 / 5 of the diameter of the graphite substrate.

[0018] In some specific embodiments, the bonding adhesive is a phenolic resin adhesive, and its composition includes phenolic resin and propylene glycol monomethyl ether acetate solvent. Among them, the content of the phenolic resin is 13% - 17%.

[0019] In some specific embodiments, the graphite-containing bonding adhesive includes graphite and phenolic resin. The content of the graphite is 10% - 40%, and the content of the phenolic resin is 7% - 8%.

[0020] In some specific embodiments, the particle size of the granular sugar is 0.12 - 0.24 mm.

[0021] With the above technical solution, a silicon carbide seed crystal bonding device and method provided by the present application have the following beneficial effects: The embodiments of the present application disclose a silicon carbide seed crystal bonding device and method. The device includes a graphite substrate, a rotating degumming sleeve, and an upper pressing block. The rotating degumming sleeve is rotatably arranged above the graphite substrate, and a buffer glue storage groove and a glue discharge port that communicate with each other are formed inside it; the buffer glue storage groove is filled with granular sugar, which cooperates with the protrusions distributed around to achieve a hard surface and soft support, preventing the silicon carbide seed crystal from shifting and reducing edge breakage. At the same time, the gas and overflow glue on the bonding surface can be discharged through the gaps between the granular sugars, and the flow resistance of the glue can be increased to avoid insufficient glue amount in local areas. During heating and curing, the granular sugar melts, the rotating degumming sleeve rotates, and the convex blocks scrape off the overflow glue. At the same time, the granular sugar provides lubrication, reducing damage to the side wall of the seed crystal and improving the crystal growth quality, effectively solving the problems of offset, breakage, and glue residue existing in the traditional method. During the use process, through testing, the concentricity between the silicon carbide seed crystal and the graphite substrate 1 is relatively small. The concentricity between the silicon carbide seed crystal and the graphite substrate 1: the unilateral offset distance < 0.01 mm, and the unilateral offset distance is the shortest distance between one side of the silicon carbide seed crystal and the same-side edge of the graphite cover plate. Currently, during the use process, there is less glue residue on the seed crystal, which is easy to remove, and there are no phenomena such as weak bonding of the seed crystal, broken pieces of the seed crystal, and cracks. Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is the front view of the silicon carbide seed crystal bonding device provided by the embodiment of the present application; Figure 2 It is the top view of the silicon carbide seed crystal bonding device provided by the embodiment of the present application; Figure 3 It is the flowchart of the silicon carbide seed crystal method provided by the embodiment of the present application.

[0024] The following is a supplementary description of the drawings: 1 - Graphite substrate; 2 - Rotating degumming sleeve; 21 - Buffer glue storage groove; 22 - Convex block; 23 - Glue discharge port; 3 - Upper pressing block; 4 - Pressing cover; 5 - Telescopic center pressing disc; 6 - Liftable annular pressing ring; 7 - Heat conduction block; 8 - Rotating part. Detailed Embodiments

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0026] As used herein, the term "one embodiment" or "embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present application. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0027] When a numerical range is disclosed herein, the above range is considered continuous and includes the minimum and maximum values of the range, as well as each value therebetween. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein. For example, the specified range from "1 to 10" should be considered to include any and all sub-ranges between the minimum value 1 and the maximum value 10. Exemplary sub-ranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0028] Please refer to Figure 1 and Figure 2 , a silicon carbide seed crystal bonding device provided by an embodiment of the present application includes: A graphite substrate 1 for carrying a silicon carbide seed crystal; The rotary glue removing sleeve 2 is rotatably arranged above the graphite substrate 1, and a buffer glue containing groove 21 and a glue discharging port 23 which are communicated with each other are formed inside the rotary glue removing sleeve 2. Among them, the buffer glue containing groove 21 is used for containing granular sugar, and the glue discharging port 23 is used for discharging the melted granular sugar and the redundant overflow glue. Convex blocks 22 are evenly distributed around the buffer glue containing groove 21 and are used for forming point contact supports with the edges of the silicon carbide seeds. Understandably, the buffer glue containing groove 21 is formed on the base body of the rotary glue removing sleeve 2, and two adjacent buffer glue containing grooves 21 are spaced apart in the vertical direction by the convex blocks 22.

[0029] The upper pressing block 3 is located above the rotary glue removing sleeve 2 and is used for pressing down the silicon carbide seeds.

[0030] Specifically, the graphite substrate 1 serves as the basic bearing component of the entire silicon carbide seed bonding device and provides stable and reliable support for the silicon carbide seeds. During the growth process of silicon carbide single crystals, the graphite substrate 1 needs to have good thermal stability, chemical stability, and relatively high mechanical strength to ensure that it can still maintain its shape and performance stability under the action of high temperature, complex chemical environment, and certain mechanical stress, so as to provide a solid foundation for the bonding of silicon carbide seeds and the subsequent growth process. The graphite substrate 1 is usually made of high-purity graphite material to reduce the influence of impurities on the growth of silicon carbide crystals. In addition, the surface of the graphite substrate 1 is finely processed and has relatively high flatness and smoothness to ensure good contact between the silicon carbide seeds and the graphite substrate 1 and avoid problems such as additional stress introduced due to uneven surface or uneven bonding caused by uneven surface.

[0031] The rotary glue removing sleeve 2 is rotatably arranged above the graphite substrate 1, and a buffer glue containing groove 21 is formed inside the rotary glue removing sleeve 2, and the buffer glue containing groove 21 is used for containing granular sugar. The granular sugar can be white granulated sugar, rock sugar, etc. There are gaps between the granular sugars. When the bonding surfaces are joined, the gaps can allow gas to escape and at the same time allow the overflow glue to flow in. In addition, the granular sugar will increase the resistance of the glue flow on the bonding surface to a certain extent, thereby avoiding problems such as too little glue amount and insufficient bonding force at the local part when the bonding surface is pressed down due to too fast fluidity of the glue on the bonding surface. In addition, when the granular sugar melts into a liquid, it can provide a lubricating effect for the rotation of the rotary glue removing sleeve 2 and reduce the damage to the side wall of the silicon carbide seed. In addition, the granular sugar is easy to remove by means of water solubility, etc., that is, it has the characteristic of being easier to remove, with a small residual amount, which can greatly reduce the defects such as glue residue when bonding the silicon carbide seed base, scratching and breakage of the silicon carbide seed, etc. that affect the growth quality of the silicon carbide seed in the later stage, and is beneficial to improving the crystal growth quality.

[0032] The degumming port 23 is in communication with the buffer glue storage tank 21, and is used to discharge molten granular sugar, excess overflow glue, etc. Before initial use, molten sugar solution is injected into the degumming port 23, and after solidification, the degumming port 23 is sealed thereby. Then, the silicon carbide seed crystal coated with adhesive glue is placed at the center of the graphite substrate 1, and then the rotary degumming sleeve 2 is installed. Subsequently, granular sugar is added into the buffer glue storage tank 21 of the rotary degumming sleeve 2, and finally the pressing cover 4 is covered. After the above preparatory work is completed, the upper pressing block 3 is used to slowly apply pressure to the silicon carbide seed crystal, so that during the process of better fitting between the silicon carbide seed crystal and the graphite substrate 1 through the adhesive glue, the degumming port 23 is sealed to avoid premature loss of granular sugar. During use, as the sugar in the buffer glue storage tank 21 gradually melts, the degumming port 23 is opened, and the molten granular sugar and excess overflow glue can be discharged through the degumming port 23. During the bonding process, as the temperature rises, the granular sugar continuously melts and flows through the buffer glue storage tank 21. At this time, part of the excess molten sugar and the overflowing glue will be discharged outside the device through the degumming port 23.

[0033] The convex blocks 22 are evenly distributed around the buffer glue storage tank 21. When the convex blocks 22 contact the silicon carbide seed crystal, a point-contact hard support structure will be formed. Combining with the relatively soft supporting effect of the granular sugar, a point-hard support and a surface-soft support are jointly realized. While providing effective support for the silicon carbide seed crystal, it can effectively reduce the contact area between the silicon carbide seed crystal and the support structure, thereby reducing the possibility of damage to the edge of the silicon carbide seed crystal due to stress. On the other hand, the point-contact support and the buffering effect of the granular sugar cooperate with each other, which can better prevent the silicon carbide seed crystal from shifting and misaligning during the bonding process, and ensure the position accuracy of the silicon carbide seed crystal during the bonding process. When the bonding surface is heated and cured, the granular sugar melts into a liquid state. At this time, the rotary degumming sleeve 2 rotates, and the protrusion 23 can play a role in scraping the glue to remove the overflow glue adhered to the side wall of the silicon carbide seed crystal.

[0034] The upper pressing block 3 is located above the rotary degumming sleeve 2 and is used to press down the silicon carbide seed crystal to achieve uniform bonding with the base.

[0035] In some specific embodiments, heat-conducting blocks 7 are arranged around the upper pressing block 3.

[0036] Specifically, annular grooves are formed on the four peripheral edges of the upper pressing block 3, and the heat conducting block 7 is arranged in the annular grooves and can be fixed by means of bonding, clamping, etc. The heat conducting block 7 is made of silicon carbide, while the upper pressing block is made of stainless steel. Through the high heat conductivity of the silicon carbide heat conducting block 7, the heating speed at the edge is faster than that at the center, which helps to accelerate the heating of the graphite adhesive at the edge, promote the rapid generation and discharge of bubbles, reduce the bubble discharge resistance, and at the same time is conducive to the discharge of bubbles generated at the center to the edge. In addition, the rapid heating at the edge can also accelerate the melting of granular sugar, further optimizing the bonding process. The stainless steel material ensures the uniformity of the heating process, avoids local overheating, and thus improves the bonding quality. It effectively solves the problems of difficult bubble discharge, uneven heating, and inconsistent melting rate of granular sugar in the traditional bonding process.

[0037] In some specific embodiments, the device further includes a pressing cover 4, which covers the upper part of the buffer glue storage tank 21 for closing the buffer glue storage tank 21.

[0038] Specifically, the pressing cover 4 covers the upper part of the buffer glue storage tank 21 and is used to close the buffer glue storage tank 21 when containing granular sugar. In some embodiments, positioning card slots can be provided on the inner wall of the buffer glue storage tank 21, and corresponding positioning bosses are provided at the corresponding positions on the edge of the pressing cover 4. When the pressing cover 4 is installed, the positioning bosses can be accurately inserted into the positioning card slots to ensure the accurate alignment of the pressing cover 4 and the buffer glue storage tank 21 in the horizontal direction. At the same time, a ring of high-temperature resistant rubber gaskets is provided at the edge where the pressing cover 4 contacts the buffer glue storage tank 21, which can not only further enhance the sealing effect and prevent the leakage of granular sugar, but also buffer the impact force of the pressing cover 4 on the buffer glue storage tank 21. In terms of the fixing method, a plurality of threaded holes are evenly distributed around the pressing cover 4, and corresponding screw holes are provided at the corresponding positions of the buffer glue storage tank 21. By rotating and tightening the bolts, the pressing cover 4 can be quickly and firmly fixed on the buffer glue storage tank 21 to ensure that the pressing cover 4 always fits tightly against the buffer glue storage tank 21 during the process of containing granular sugar, realizing reliable sealing.

[0039] In some specific embodiments, the device further includes a telescopic center pressing disc 5 and a liftable annular pressing ring 6; The telescopic center pressing disc 5 is installed above the center position of the upper pressing block 3 and coincides with the central axis of the upper pressing block 3, and is used to press down the silicon carbide seed crystal telescopically from the center; The liftable annular pressing ring 6 is installed above the edge position of the upper pressing block 3 and is arranged around the telescopic center pressing disc 5, and is used to press down the silicon carbide seed crystal from the periphery by lifting.

[0040] Specifically, a telescopic center pressing disc 5 is arranged above the center position of the upper pressing block 3. The telescopic center pressing disc 5 can contact the upper pressing block 3 through a guide post, ensuring that it can stably move up and down in the vertical direction. At the same time, the center of the telescopic center pressing disc 5 coincides with the central axis of the upper pressing block 3, and precisely presses down the silicon carbide seed crystal from the center in a telescopic manner.

[0041] In addition, a liftable annular pressing ring 6 is arranged above the edge position of the upper pressing block 3, and its lifting is driven by a lifting mechanism such as a hydraulic cylinder or an electric push rod. A limiting device is arranged around the liftable annular pressing ring 6, such as a limiting groove or a limiting block fixed on the fixed frame, and the edge of the liftable annular pressing ring 6 matches with it to ensure that its position does not deviate during the lifting process. In the high-temperature curing stage, after the bubbles are discharged, the liftable annular pressing ring 6 descends to perform secondary auxiliary pressing on the edge, which helps to improve the overall bonding density and bonding strength.

[0042] In some specific embodiments, a rotating member 8 is arranged on the rotating degumming sleeve 2, and the rotating member 8 drives the rotating degumming sleeve 2 to rotate through a driving device.

[0043] Specifically, a rotating member 8 is arranged on the rotating degumming sleeve 2. Power transmission between the rotating member 8 and the rotating degumming sleeve 2 can be achieved through key connection or spline connection to drive the rotating degumming sleeve 2 to rotate. The rotating member 8 itself can be powered by a motor or other power sources. In some embodiments, the rotating member 8 rotates through a gear transmission method. For example, the rotating member 8 can be set as a driving gear connected to the power source, and the power is transmitted to the rotating degumming sleeve 2 through a driven gear meshing with it. To ensure the stability of the rotating degumming sleeve 2 during rotation, the rotating degumming sleeve 2 can be installed on the fixed bracket through bearings. The bearings can effectively reduce the frictional resistance during rotation and ensure the coaxiality of rotation. At the same time, positioning rings or slot structures can be arranged at both ends of the rotating degumming sleeve 2, and there are matching positioning protrusions or blocks on the corresponding fixed components. Through this clamping or positioning method, it is further ensured that the rotating degumming sleeve 2 will not have axial movement during rotation, thereby ensuring the accuracy and stability of the entire rotating degumming process.

[0044] In some specific embodiments, the center of the telescopic center pressing disc 5 coincides with the center of the silicon carbide seed crystal, and the area of the telescopic center pressing disc 5 covers 0.8 - 0.9 of the area of the silicon carbide seed crystal.

[0045] Specifically, by arranging the center of the retractable center pressure plate 5 to coincide with the center of the silicon carbide seed crystal, the area of ​​the retractable center pressure plate 5 covers 0.8-0.9 of the area of ​​the silicon carbide seed crystal. The incompletely covered setting is conducive to leaving a channel for gas discharge at the edge, so as to avoid the bubbles being unable to be discharged or being discharged incompletely and affecting the bonding quality. If the retractable center pressure plate 5 completely covers the silicon carbide seed crystal, during the heating and other operations, the gas generated inside may accumulate between the silicon carbide seed crystal and the adhesive due to nowhere to be discharged, forming bubbles. If the bubbles cannot be discharged or are not discharged completely, it will seriously affect the bonding quality, for example, causing defects such as holes and gaps in the bonding layer, thereby reducing the bonding strength and stability between the silicon carbide seed crystal and other components. By setting the retractable center pressure plate 5 to cover 0.8-0.9 of the area of ​​the silicon carbide seed crystal, a certain space is left at the edge of the silicon carbide seed crystal, thereby forming a channel for gas discharge. The gas generated during the heating process can be discharged smoothly along the channel, avoiding the problem of bubble accumulation.

[0046] In some specific implementations, the relationship between the volume V1 of the buffering glue containing groove 21 above the interface reference plane between the upper pressing block 3 and the silicon carbide seed crystal and the volume V2 of the lower part is V1≥1.1V2.

[0047] Specifically, the interface between the pressing block 3 and the silicon carbide seed crystal is a reference plane, and the volume V1 of the buffering glue holding groove 21 above the reference plane is more than 1.1 times the volume V2 of the buffering glue holding groove 21 below. When heating is carried out, the granular sugar will gradually melt, and its volume will shrink accordingly, and liquid sugar may flow out under certain conditions. By ensuring that V1 is greater than or equal to 1.1 times V2, a sufficient amount of accommodation space and sufficient residence time can be provided for the liquid sugar, so that it can fully exert its lubrication effect. The liquid sugar is able to form a good lubrication effect between the silicon carbide seed crystal and the rotating de-glue sleeve 2, reducing the friction between them, and helping the silicon carbide seed crystal to maintain a stable position and posture during the bonding process, avoiding problems such as positional displacement or surface damage caused by excessive friction.

[0048] In some specific embodiments, the rotating debonding sleeve 2 is coaxially arranged with the graphite substrate 1 .

[0049] Specifically, in the bonding process of the silicon carbide seed crystal and the graphite substrate, the rotating glue removal sleeve 2 and the graphite substrate 1 are coaxially arranged, which can effectively prevent the silicon carbide seed crystal from deviating. Since the rotating glue removal sleeve 2 and the graphite substrate 1 maintain a precise coaxial relationship, a stable guide frame is provided for the silicon carbide seed crystal, which limits its irregular movement in all directions, thereby ensuring that the silicon carbide seed crystal and the graphite substrate 1 can be precisely coaxially installed. In addition, the uniformity of heat transfer and the balance of stress distribution can be improved, and the bonding quality can be improved.

[0050] Please refer to Figure 3 , the embodiment of the present application also provides a method for bonding a silicon carbide seed crystal. Bond the silicon carbide seed crystal according to the above-mentioned silicon carbide seed crystal bonding device, including the following steps: Coat the bonding surface of the silicon carbide seed crystal with a bonding adhesive; Coat a graphite-containing bonding adhesive on the edge of the graphite substrate 1; Place the silicon carbide seed crystal coated with the bonding adhesive at the center position of the graphite substrate 1, and install the rotating degumming sleeve 2; wherein, the buffer glue-containing groove 21 of the rotating degumming sleeve 2 contains granular sugar; After applying pressure to the silicon carbide seed crystal through the upper pressing block 3 to press it tightly, place the entire assembly into a hot pressing device for pressure curing.

[0051] Specifically, the method for bonding a silicon carbide seed crystal is as follows: In step S101, evenly coat a layer of bonding adhesive (this bonding adhesive can be phenolic resin adhesive) on the bonding surface of the silicon carbide seed crystal to ensure that the glue layer on the bonding surface is evenly covered.

[0052] In step S102, coat a graphite-containing bonding adhesive on the edge of the graphite substrate 1. When heating during the gluing process, due to the gaps between graphite particles, a relatively stable flow channel is constructed for the internal gas, enabling the bubbles to be discharged smoothly along these channels. There is no need to specifically set up a gas discharge channel, and the bubbles in the graphite-containing bonding adhesive can be quickly removed. At the same time, the graphite-containing bonding adhesive coated on the edge of the graphite substrate 1 can also provide an excellent bonding effect for the edge of the silicon carbide seed crystal, enhancing the stability of the bonding.

[0053] In step S103, place the silicon carbide seed crystal coated with the bonding adhesive at the center position of the graphite substrate 1, then install the rotating degumming sleeve 2, then add granular sugar into the buffer glue-containing groove 21 of the rotating degumming sleeve 2, and finally cover the pressing cover 4.

[0054] In step S104, after completing the above preparations, slowly apply pressure to the silicon carbide seed crystal using the upper pressing block 3 so that the silicon carbide seed crystal and the graphite substrate 1 fit better through the bonding adhesive. Then place the entire assembly into a hot pressing device for pressure curing. Through this step, under the pressure and specific temperature environment provided by the hot pressing device, the bonding adhesive undergoes a curing reaction, thereby achieving a firm bond between the silicon carbide seed crystal and the graphite substrate 1, ensuring that there will be no loosening or separation during subsequent use or processing.

[0055] In some specific embodiments, heating and bonding are performed in a hot pressing device, including: The first stage: Under a vacuum environment pressure ≤ 9 Pa, heat at a heating rate of 71 - 80 °C / h to 90 - 100 °C and hold for 5 - 15 min; meanwhile, apply pressure to the center of the silicon carbide seed crystal through the telescopic center chuck 5. The second stage: Increase the applied pressure of the telescopic center chuck 5, heat at a heating rate of 30 - 40 °C / h to 150 - 190 °C and hold for 1 - 1.3 h; meanwhile, start the rotating degumming sleeve 2 and make it rotate for 3 - 5 min. The third stage: Raise the temperature to 400 - 450 °C at a heating rate of 25 - 35 °C / h and hold for 3 - 4 h; meanwhile, apply pressure to the edge of the silicon carbide seed crystal through the liftable annular pressing ring 6. The fourth stage: Heat at a heating rate of 17 - 27 °C / h to 460 - 499 °C until the bonding is completely cured.

[0056] Specifically, the heating process mainly includes the following four stages: In the first stage, the entire heating operation needs to be carried out under a vacuum environment, and the vacuum degree needs to be maintained below 9 Pa to ensure the stability and controllability of the heating process. Subsequently, heat the material at a heating rate of 71 - 80 °C / h until it reaches the temperature range of 90 - 100 °C, and keep it at a constant temperature for 5 - 15 min, with a preferred constant temperature duration of 10 min. Meanwhile, during this process, the telescopic center chuck 5 starts to press down to extrude the material. Under this specific temperature condition, materials such as granular sugar have not started to melt, and part of the glue will overflow due to thermal expansion and flow into the gaps between the granular sugar. At this time, bubbles begin to form initially inside the glue, and the bubbles can be pre-discharged through the gaps between the granular sugar, thus avoiding potential quality problems caused by bubble accumulation during subsequent heating. Moreover, performing a short-time constant temperature treatment at this temperature can make the glue distribute more evenly at a higher temperature for the subsequent heating process, thereby providing a good foundation for the entire heating process and subsequent process operations, ensuring that the material can obtain a uniform and stable heating effect.

[0057] In the second stage, increase the pressure of the retractable central pressure plate 5, and then heat the material at a heating rate of 30 - 40 °C / h until the temperature rises to the range of 150 - 190 °C, and maintain it at this temperature for 1 - 1.3 h. During the heating process of this stage, simultaneously start the rotation of the rotating degumming sleeve 2, and control the rotation duration within 3 - 5 min. Within this temperature range, a large number of bubbles will quickly generate and escape inside the material. As the reaction progresses, the speed of bubble escape will gradually slow down. Increasing the pressure of the retractable central pressure plate 5 can further enhance the bonding strength between the materials. At the same time, as the temperature rises, the glue will gradually overflow. At this time, through the rotational movement of the rotating degumming sleeve 2, the overflowing glue can be effectively scraped off. In addition, under the temperature condition of 150 - 190 °C, the granular sugar will melt and be removed, thus leaving sufficient bubble discharge channels inside the material to ensure that the bubbles can be discharged smoothly and avoid potential quality risks caused by bubble accumulation.

[0058] In the third stage, raise the temperature to 400 - 450 °C at a heating rate of 25 - 35 °C / h and keep it constant for 3 - 4 h, which helps the remaining tiny bubbles to slowly escape. At the same time, the liftable annular pressure ring 6 applies pressure to the edge to increase the bonding strength without affecting the slow escape of the remaining tiny bubbles.

[0059] In the fourth stage, raise the temperature to 460 - 499 °C at a heating rate of 17 - 27 °C / h until the adhesive is completely cured. In this stage, if the heating process is not properly controlled, it may lead to incomplete bubble discharge, resulting in defects such as holes, air vortices, and pores, which will in turn affect the growth quality of the silicon carbide seed crystal. Therefore, it is necessary to precisely control the heating rate and temperature range to enable the adhesive to cure evenly and the bubbles to be effectively discharged, thereby improving the bonding strength and growth quality of the silicon carbide seed crystal.

[0060] In some specific embodiments, the graphite-containing adhesive is coated on the outer edge position of the graphite substrate 1 with a diameter of 1 / 10 - 1 / 5.

[0061] Specifically, the edge of the graphite substrate 1 is coated with the graphite-containing adhesive, preferably coated at the outermost edge position with a diameter of 1 / 10 - 1 / 5 of the graphite substrate 1. Selecting this position for coating can, on the one hand, effectively disperse the external force received by the substrate during use, enhance the structural stability of the edge, and prevent the edge from being damaged due to stress concentration; on the other hand, this coating range is convenient for precisely controlling the amount of glue, avoiding glue waste, and at the same time ensuring the best bonding effect between the edge and other components to meet the actual application requirements.

[0062] In some specific embodiments, the adhesive is a phenolic resin adhesive, and its composition includes phenolic resin and propylene glycol methyl ether acetate solvent. Among them, the content of phenolic resin is 13% - 17%.

[0063] Specifically, in the preparation process of the silicon carbide seed crystal, a uniform adhesive is coated on its bonding surface. The adhesive is preferably a phenolic resin adhesive, which is mainly composed of phenolic resin and propylene glycol methyl ether acetate solvent, and the preferred content of phenolic resin is 13% - 17%. Using a phenolic resin adhesive with high fluidity can fully exert the fluidity advantage, maintain good fluidity, quickly and uniformly fill the tiny gaps on the bonding surface, and make the glue more evenly distributed within the bonding surface. It can not only increase the contact area between the silicon carbide seed crystal and the bonding surface, but also effectively avoid problems such as insufficient or excessive local adhesive force caused by uneven glue distribution, thus significantly improving the bonding stability and reliability of the silicon carbide seed crystal.

[0064] In some specific embodiments, the graphite-containing adhesive includes graphite and phenolic resin, with the content of graphite being 10% - 40% and the content of phenolic resin being 7% - 8%.

[0065] Specifically, the edge of the graphite substrate 1 is coated with a graphite-containing adhesive, which is composed of graphite, phenolic resin, and a solvent. Among them, the content of graphite is 10% - 40%, preferably 26% - 34%; the content of phenolic resin is 7% - 8%; and the rest is the solvent. During the gluing process, bubbles can be quickly removed by heating. The gaps between graphite particles provide a stable flow channel for the internal gas, so there is no need to specifically set up a gas discharge channel. It not only improves the stability and reliability of the bonding effect, but also provides a better bonding effect for the edge of the silicon carbide seed crystal.

[0066] In some specific embodiments, the particle size of the granular sugar is 0.12 - 0.24 mm.

[0067] Specifically, the granular sugar preferably has a particle size of 0.12 - 0.24 mm. The granular sugar within this particle size range has good air permeability, can effectively discharge gas when the bonding surfaces are joined, and at the same time provides a suitable channel for the inflow of overflow glue, thus ensuring the stability and reliability of the bonding effect. In addition, its density is moderate, neither too loose to cause gas accumulation nor too tight to hinder the flow of overflow glue, but provides a moderate resistance to block the overflow glue.

[0068] The embodiment of the present application discloses a silicon carbide seed crystal bonding device and method. The device includes a graphite substrate, a rotating glue removal sleeve and an upper pressure block. The rotating glue removal sleeve can be rotatably arranged above the graphite substrate, and is provided with a buffer glue holding groove and a glue discharge port that are interconnected; the buffer glue holding groove is filled with granular sugar, which cooperates with the protrusions distributed around to achieve point hard surface soft support, prevent the silicon carbide seed crystal from shifting, and reduce edge damage. At the same time, the gap between the granular sugars can discharge the gas and overflow glue on the bonding surface, and can increase the flow resistance of the glue to avoid insufficient local glue. During heating and curing, the granular sugar melts, the rotating glue removal sleeve rotates, and the protrusions scrape off the overflow glue. At the same time, the granular sugar provides lubrication, reduces damage to the side wall of the seed crystal, improves the quality of crystal growth, and effectively solves the problems of shift, breakage and glue residue in traditional methods. During use, after testing, the concentricity of the silicon carbide seed crystal and the graphite substrate 1 is small. The concentricity of the silicon carbide seed crystal and the graphite substrate 1 is: the single-side offset distance is less than 0.01mm, and the single-side offset distance is the shortest distance between one side of the silicon carbide seed crystal and the same side edge of the graphite cover plate. At present, during use, the seed crystal glue residue is small and easy to remove, and there is no phenomenon such as loose seed crystal adhesion, seed crystal fragmentation, and cracks.

[0069] The above are only optional embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A silicon carbide seed crystal bonding device, characterized in that, Comprising: A graphite substrate (1) for carrying a silicon carbide seed crystal; A rotary degumming sleeve (2) rotatably disposed above the graphite substrate (1), having a buffer glue-containing groove (21) and a glue discharge port (23) communicating with each other therein; wherein, the buffer glue-containing groove (21) is used for accommodating granular sugar, and the glue discharge port (23) is used for discharging the melted granular sugar and excess overflow glue; convex blocks (22) are uniformly distributed around the buffer glue-containing groove (21) for forming point contact support with the edge of the silicon carbide seed crystal; An upper pressing block (3) located above the rotary degumming sleeve (2) for pressing down the silicon carbide seed crystal.

2. The silicon carbide seed crystal bonding device according to claim 1, wherein Heat conducting blocks (7) are disposed around the upper pressing block (3).

3. The silicon carbide seed crystal bonding device according to claim 1, wherein The device further includes a gland (4) covering above the buffer glue-containing groove (21) for closing the buffer glue-containing groove (21).

4. The silicon carbide seed crystal bonding device according to claim 1, wherein, The device further includes a telescopic center pressing disc (5) and a liftable annular pressing ring (6); The telescopic center pressing disc (5) is installed above the center position of the upper pressing block (3) and coincides with the central axis of the upper pressing block (3) for pressing down the silicon carbide seed crystal by telescoping from the center; The liftable annular pressing ring (6) is installed above the edge position of the upper pressing block (3) and disposed around the telescopic center pressing disc (5) for pressing down the silicon carbide seed crystal from the periphery by lifting.

5. The silicon carbide seed crystal bonding device according to claim 1, characterized in that, A rotating member (8) is provided on the rotary degumming sleeve (2), and the rotating member (8) drives the rotary degumming sleeve (2) to rotate through a driving device.

6. The silicon carbide seed crystal bonding device according to claim 4, characterized in that, The center of the telescopic center pressing disc (5) coincides with the center of the silicon carbide seed crystal, and the area of the telescopic center pressing disc (5) covers 0.8 - 0.9 of the area of the silicon carbide seed crystal.

7. The silicon carbide seed crystal bonding device according to claim 1, the relationship between the volume V1 of the buffer glue-containing groove (21) above the interface reference plane between the upper pressing block (3) and the silicon carbide seed crystal and the volume V2 of the following part is V1≥1.1V2.

8. The silicon carbide seed crystal bonding device according to claim 1, characterized in that, The rotary degumming sleeve (2) and the graphite substrate (1) are coaxially arranged.

9. A method for bonding a silicon carbide seed crystal, which uses the silicon carbide seed crystal bonding device described in any one of claims 1-8 to bond the silicon carbide seed crystal, characterized in that, Including the following steps: Coating an adhesive on the bonding surface of the silicon carbide seed crystal; Coating a graphite-containing adhesive on the edge of the graphite substrate (1); Placing the silicon carbide seed crystal coated with the adhesive at the center position of the graphite substrate (1) and installing the rotary degumming sleeve (2); wherein, the buffer glue-containing groove (21) of the rotary degumming sleeve (2) contains granular sugar; After applying pressure to the silicon carbide seed crystal by the upper pressing block (3) to press it tightly, placing the entire assembly into a hot pressing device for pressure curing.

10. The silicon carbide seed crystal bonding method according to claim 9, wherein Performing heating and bonding in the hot pressing device, including: The first stage: Under a vacuum environment pressure ≤ 9 Pa, heating at a heating rate of 71 - 80 °C / h to 90 - 100 °C and maintaining for 5 - 15 min; meanwhile, applying pressure to the center of the silicon carbide seed crystal through the telescopic center pressing disc (5); The second stage: Increase the applied pressure of the telescopic center pressing plate (5), heat up to 150 - 190 °C at a heating rate of 30 - 40 °C / h, and maintain for 1 - 1.3 h; at the same time, start the rotating degumming sleeve (2) and make it rotate for 3 - 5 min; The third stage: Increase the temperature to 400 - 450 °C at a heating rate of 25 - 35 °C / h and maintain for 3 - 4 h; at the same time, apply pressure to the edge of the silicon carbide seed crystal through the liftable annular pressing ring (6); The fourth stage: Heat to 460 - 499 °C at a heating rate of 17 - 27 °C / h until the bonding is completely cured.

11. The silicon carbide seed crystal bonding method according to claim 9, wherein The graphite-containing adhesive is coated at the outer edge position of the graphite substrate (1) with a diameter of 1 / 10 - 1 / 5.

12. The silicon carbide seed crystal bonding method according to claim 9, wherein, The adhesive is a phenolic resin adhesive, and its composition includes phenolic resin and propylene glycol methyl ether acetate solvent. Among them, the content of the phenolic resin is 13% - 17%.

13. The silicon carbide seed crystal bonding method according to claim 9, wherein, The graphite-containing adhesive includes graphite and phenolic resin. The content of the graphite is 10% - 40%, and the content of the phenolic resin is 7% - 8%.

14. According to the method for bonding a silicon carbide seed crystal described in claim 9, the particle size of the granulated sugar is 0.12 - 0.24 mm.

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