Apparatus and method for growing silicon carbide by liquid phase method with removal of residual droplets

Abstract

The present application relates to a kind of liquid-phase method growth silicon carbide device and method of residual droplet can be removed, belong to silicon carbide crystal production technical field.The device includes crucible main body, crucible cover with opening, seed crystal rod and the liquid droplet removal component made of graphite soft felt between crucible main body and crucible cover;Graphite soft felt is provided with cross-cutting structure in central position;One end of seed crystal rod is connected with seed crystal holder, and seed crystal is connected on seed crystal holder, and the end of seed crystal rod connection seed crystal holder is sequentially through opening and cross-cutting structure and is inserted into the inside of crucible main body;After the end of liquid-phase method growth silicon carbide crystal, seed crystal rod can drive silicon carbide crystal pass through liquid droplet removal component, and contact rotation with the upper surface of liquid droplet removal component to remove residual droplet;The device also includes monitoring system for judging the position of silicon carbide crystal.The present application device compact structure, low cost, easy operation, can efficiently remove crystal surface residual droplet.

Description

Technical Field

[0001] This invention belongs to the field of silicon carbide crystal production technology, and particularly relates to an apparatus and method for growing silicon carbide by liquid phase method that can remove residual droplets. Background Technology

[0002] Silicon carbide (SiC) is one of the most important third-generation semiconductor materials. Its unique characteristics, such as large bandgap and high critical breakdown field strength, make it an ideal material for manufacturing high-frequency, high-power, radiation-resistant and light-resistant integrated devices. It is currently widely used in many fields such as new energy vehicles, 5G communications, and aerospace.

[0003] For liquid-phase silicon carbide single crystal growth technology, a stable cooling environment is a crucial factor in reducing thermal stress accumulation. However, in current liquid-phase silicon carbide single crystal growth methods, when the crystal is pulled out of the solution, it often carries some solution with it (residual droplets). This solution adheres to the crystal surface (growth plane) and is not easily detached naturally. Even increasing the crystal rotation speed, the residual droplets on the crystal are difficult to remove. During the subsequent cooling stage, the residual droplets on the crystal surface cause the local temperature to be higher than that of the main crystal, thereby inducing thermal stress accumulation and causing crystal cracking.

[0004] Chinese patent application CN119372760A discloses a liquid phase growth apparatus for improving the quality of semiconductor crystals. This apparatus uses an annular droplet removal device on the upper part of the crucible sidewall. After semiconductor crystal growth is complete, a crystal support shaft drives the semiconductor crystal to contact the droplet removal device to remove residual droplets from the crystal surface. However, the liquid phase growth apparatus in this patent application has the following main shortcomings in removing residual droplets from the crystal surface: 1. High device cost and increased crucible size: The annular droplet removal device in this patent application is located on the crucible sidewall. To cover the residual droplets beyond half the radius of the semiconductor crystal... 1. The annular droplet removal device itself needs a certain width in the droplet retention area, and to avoid collisions, a safe distance needs to be maintained between the annular droplet removal device and the crystal. This requires a significant increase in the crucible size, increasing the cost of the device. 2. The crystal support shaft structure is complex and requires high operational precision: In order for the crystal to contact the annular droplet removal device on the side wall, the crystal support shaft needs to be able to move towards the inner wall of the crucible. However, conventional crystal support shafts usually only have lifting and rotation functions. Adding this lateral movement function not only significantly increases the cost of modifying the support shaft, but also requires high operational precision, otherwise collisions are likely to occur. 3. The droplet removal efficiency is limited: Although the residual droplets are mainly distributed in the... While fewer droplets remain in the outer periphery and central region of the crystal, a small number may still be present. The annular droplet removal device in this patent application can only remove droplets from the outer periphery of the crystal, with limited effectiveness on droplets in the central region. Furthermore, droplets beyond half the crystal radius require two separate removal processes, reducing removal efficiency. 4. Limitations in the contact detection method: This patent application uses a detection circuit between the crystal support axis and the crucible axis to determine droplet contact, stopping crystal movement after current is applied to avoid collisions. However, depending on the formulation of the auxiliary solution used in the experiment, the size of the residual droplets varies, generally between 0.2 and 5 mm, with a wide distribution range. Using this method... The droplet removal accuracy is limited. When large and small droplets coexist, the crystal stops moving downwards when the large droplet contact detection circuit is activated. This makes it difficult to remove small droplets simultaneously, easily leading to incomplete removal. If the crystal continues to descend to contact small droplets, it is easy for the crystal to collide with the support layer or support of the droplet removal component. 5. Limitations of the droplet removal method: It is difficult to ensure uniform removal when there are large differences in droplet size. Furthermore, during the removal process, large droplets may become smaller, while small droplets may not be detected and may be ignored, reducing the removal effect. Therefore, the droplet removal effect is unstable, especially when there are droplets with large-scale size variations on the crystal surface.

[0005] Therefore, it is essential to provide a device and method for growing silicon carbide using a liquid phase method that is compact, low-cost, easy to operate, has stable removal effect, can efficiently remove residual droplets on the crystal surface, adapts to different crystal sizes and droplet distributions, and thus effectively reduces the risk of thermal stress accumulation and crystal cracking. Summary of the Invention

[0006] To address one or more technical problems existing in the prior art, this invention provides an apparatus and method for liquid-phase growth of silicon carbide capable of removing residual droplets. The apparatus of this invention is compact, low-cost, easy to operate, provides stable removal results, and can efficiently remove residual droplets from the crystal surface. It is adaptable to different crystal sizes and droplet distributions, thereby effectively reducing the risk of thermal stress accumulation and crystal cracking.

[0007] The present invention provides, in a first aspect, an apparatus for liquid-phase growth of silicon carbide capable of removing residual droplets. The apparatus includes a crucible body, a crucible lid with an opening, a seed crystal rod, and a droplet removal component disposed between the crucible body and the crucible lid. The droplet removal component is made of graphite felt, which has a radially arranged cross-cut structure at its center. One end of the seed crystal rod is connected to a seed crystal holder, on which a seed crystal is attached. The end of the seed crystal rod connected to the seed crystal holder passes sequentially through the opening of the crucible lid and the cross-cut structure of the droplet removal component, extending into the interior of the crucible body. After the liquid-phase growth of the silicon carbide crystal is completed, the seed crystal rod can drive the silicon carbide crystal through the droplet removal component and rotate in contact with the upper surface of the droplet removal component to remove residual droplets. The apparatus also includes a monitoring system for determining the position of the silicon carbide crystal.

[0008] Preferably, the device further includes a seed crystal rod rotation and lifting device for controlling the lifting and rotation of the seed crystal rod and a crucible rotation and lifting device for controlling the lifting and rotation of the crucible body; the other end of the seed crystal rod is connected to the single crystal furnace through the seed crystal rod rotation and lifting device, and the crucible body is connected to the single crystal furnace through the crucible rotation and lifting device.

[0009] Preferably, the monitoring system is a resistance monitoring system; the resistance monitoring system is configured on the single crystal furnace, and a monitoring circuit is formed between the seed crystal rod and the crucible body, and the position of the silicon carbide crystal is determined by the resistance change of the monitoring circuit.

[0010] Preferably, the graphite felt is provided with an opening at its center, and the graphite felt is provided with the cross-cut structure along the opening; the diameter of the opening is 3~10mm larger than the diameter of the seed crystal rod.

[0011] Preferably, the monitoring system is a gravity monitoring system; the gravity monitoring system is configured at the connection between the single crystal furnace and the seed crystal rod, and the position of the silicon carbide crystal is determined by the force change of the seed crystal rod.

[0012] Preferably, the length of the seed crystal rod is 400~500mm; the thickness of the seed crystal holder is 5~30mm; the thickness of the graphite soft felt is 5~10mm; and / or the cutting length of the cross-cutting structure is greater than the diameter of the seed crystal holder.

[0013] In a second aspect, the present invention provides a method for growing silicon carbide using a liquid-phase method capable of removing residual droplets. The method is performed using the apparatus for growing silicon carbide using a liquid-phase method capable of removing residual droplets described in the first aspect of the present invention, and includes the following steps:

[0014] (1) The growth material is placed in the crucible body and heated to obtain a high-temperature melt;

[0015] (2) The seed crystal is brought into contact with the high-temperature melt to grow silicon carbide crystals;

[0016] (3) After the silicon carbide crystal growth is completed, the silicon carbide crystal is driven through the droplet removal component by the seed crystal rod and rotates in contact with the upper surface of the droplet removal component to remove residual droplets; wherein, the position of the silicon carbide crystal is determined by the monitoring system.

[0017] (4) After the residual droplets are removed, the silicon carbide crystal is cooled down.

[0018] Preferably, the monitoring system is a resistance monitoring system, which is configured on the single crystal furnace and forms a monitoring circuit between the seed crystal rod and the crucible body. The position of the silicon carbide crystal is determined by the resistance change of the monitoring circuit. Step (3) includes the following sub-steps:

[0019] (a) Pulling the seed crystal rod causes the silicon carbide crystal to be pulled away from the high-temperature melt. The criterion for judging the pull-away is: the resistance reading displayed by the resistance monitoring system increases.

[0020] (b) Continue to pull the seed crystal rod upward until the resistance reading displayed by the resistance monitoring system first decreases and then increases, and then stop moving the seed crystal rod upward. At this time, the silicon carbide crystal has passed through the droplet removal component.

[0021] (c) Lower the seed crystal rod until the resistance reading displayed by the resistance monitoring system begins to decrease, then continue to lower it by 1~3mm so that the silicon carbide crystal contacts the upper surface of the droplet removal component;

[0022] (d) The rotating seed crystal rod drives the silicon carbide crystal to contact and rotate with the upper surface of the droplet removal component to remove residual droplets.

[0023] Preferably, the monitoring system is a gravity monitoring system, which is configured at the connection between the single crystal furnace and the seed crystal rod. The position of the silicon carbide crystal is determined by the force change of the seed crystal rod. Step (3) includes the following sub-steps:

[0024] S1. Pulling the seed crystal rod causes the silicon carbide crystal to be pulled away from the high-temperature melt. The criterion for judging the pull-away is: the force reading displayed by the gravity monitoring system decreases, and the force reading is set to zero.

[0025] S2. Continue to pull the seed crystal rod upwards until the force reading displayed by the gravity monitoring system changes from zero to a negative number and the absolute value corresponding to the negative number continues to increase. Then stop moving the seed crystal rod upwards when it returns to zero. At this time, the silicon carbide crystal has passed through the droplet removal component.

[0026] S3. Lower the seed crystal rod until the force reading displayed by the gravity monitoring system begins to turn positive, then continue to lower it by 1~3mm to make the silicon carbide crystal contact the upper surface of the droplet removal component.

[0027] S4. The rotating seed crystal rod drives the silicon carbide crystal to contact and rotate with the upper surface of the droplet removal component to remove residual droplets.

[0028] Preferably, the contact rotation time is 4 to 6 minutes.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] (1) This invention provides an apparatus for liquid-phase silicon carbide growth that can efficiently remove residual droplets. By setting the droplet removal component between the crucible body and the crucible cover, and cooperating with a monitoring system for determining the position of the silicon carbide crystal, the droplets remaining on the crystal surface can be eliminated during liquid-phase silicon carbide single crystal growth, reducing stress accumulation during crystal cooling and lowering the probability of cracking. The apparatus of this invention can efficiently and stably remove droplets of various sizes brought out by the crystal being pulled out of the solution during liquid-phase silicon carbide growth. It can be effectively applied to the field of liquid-phase silicon carbide single crystal growth, improving crystal quality and expanding economic benefits. This invention solves the problem of the solution not being able to be removed during liquid-phase silicon carbide single crystal growth, reducing the probability of cracking and increasing production capacity. The apparatus of this invention can achieve uniform crystal surface temperature and reduce local temperature gradients through efficient droplet removal, thereby effectively reducing thermal stress concentration and the risk of crystal cracking.

[0031] (2) The device described in this invention has a compact structure and low cost. The droplet removal component is directly set between the crucible body and the crucible cover. The droplet removal component is made of graphite soft felt. The graphite soft felt has a cross-cut structure in the radial direction at the center position. This droplet removal component does not depend on additional slots or support layers on the side wall of the crucible, and can also avoid the problem of the crucible being too large or the need to customize a large crucible. In addition, the device described in this invention reduces the complexity of the crystal support axis (seed crystal rod) and does not require lateral movement function, which significantly reduces manufacturing cost and maintenance difficulty.

[0032] (3) The device described in this invention is easy to operate, does not require high-precision lateral positioning, and can avoid operational errors or collision risks caused by differences in droplet size; the device described in this invention removes droplets comprehensively, has a stable removal effect, and a high removal effect repeatability. It can cover residual droplets in the outer and central areas of the crystal, ensuring that droplets on the entire surface of the silicon carbide single crystal can be removed. It can effectively handle both large and small droplets, has strong adaptability, and can adapt to uneven droplet size distribution, thereby improving droplet removal efficiency and single crystal yield.

[0033] (4) Based on the apparatus for growing silicon carbide by liquid phase method that can remove residual droplets, the present invention provides a method for growing silicon carbide by liquid phase method that can efficiently remove residual droplets on crystals, thereby effectively improving the quality of silicon carbide crystals grown by liquid phase method. The method of the present invention achieves real-time and accurate judgment of the contact and separation state between silicon carbide crystal and droplet removal component by setting droplet removal component and operating in conjunction with resistance monitoring system or gravity monitoring system. This ensures that the seed crystal rod can remove 100% of residual droplets by slightly over-moving downwards during the process of driving silicon carbide crystal to contact and rotate to remove droplets. This can achieve effective control of droplet removal process, improve droplet removal efficiency and crystal surface uniformity, thereby helping to improve the quality of silicon carbide single crystal. Attached Figure Description

[0034] The accompanying drawings are provided for illustrative purposes only, and the proportions, sizes, and quantities of the parts in the drawings may not necessarily match the actual product.

[0035] Figure 1 This is a schematic diagram of the structure of a liquid-phase silicon carbide growth apparatus capable of removing residual droplets provided in some specific embodiments of the present invention.

[0036] Figure 2 yes Figure 1 A top view of the droplet removal component included in the design;

[0037] Figure 3 This is a top view schematic diagram of the droplet removal component used in some other specific embodiments of the present invention;

[0038] Figure 4 The result is a graph showing the full width at half maximum (FWHM) of the diffraction peaks of the rocking curve of the silicon carbide crystal obtained in Example 1 of this invention, measured using the 5-point test method.

[0039] Figures 1 to 3 In the middle: 1: Seed crystal rod; 2: Crucible body; 3: Crucible lid; 4: Droplet removal component; 5: Growth raw material; 6: Opening; 7: Seed crystal holder; 8: Opening; 9: First cutting line; 10: Second cutting line. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments thereof. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0041] In a first aspect, the present invention provides an apparatus for liquid-phase growth of silicon carbide capable of removing residual droplets, for example, such as... Figure 1 As shown; the device includes a crucible body 2, a crucible lid 3 with an opening 6, a seed crystal rod 1, and a droplet removal component 4 disposed between the crucible body 2 and the crucible lid 3. The droplet removal component is used to remove residual droplets on the surface of the silicon carbide crystal. In this invention, the interior of the crucible body is a cylindrical cavity. Specifically, the droplet removal component is located at the upper edge of the crucible body and is pressed down by the crucible lid. The droplet removal component is made of graphite felt, which is a circular graphite felt. In this invention, for example, as shown... Figure 2 As shown, the graphite felt has a cross-cut structure radially arranged at its center; as Figure 2As shown, the cross-cutting structure is formed by cutting along the first cutting line 9 and the second cutting line 10. Both the first cutting line 9 and the second cutting line 10 pass through the center of the graphite felt and are perpendicular to each other. The first cutting line and the second cutting line are of the same length and extend symmetrically from the center of the graphite felt towards the edge of the graphite felt, with the extension length being the same. That is, the total length of the first cutting line and the second cutting line is the same, and the length extending from the center in four directions is the same. In this invention, the droplet removal component is made of graphite felt. This invention does not specifically limit the type of graphite felt; conventional graphite felt can be used. Graphite felt has flexibility and resilience, and its center... With a radially arranged cross-cutting structure, when the seed crystal rod, seed crystal holder, seed crystal, and / or silicon carbide crystal pass through, the cross-cutting structure can separate under external force, thus achieving free penetration. After the seed crystal rod, seed crystal holder, seed crystal, and / or silicon carbide crystal have penetrated, the cross-cutting structure can close under the elasticity of the material, maintaining the integrity of the droplet removal component and allowing it to remove residual droplets. This process is similar to creating a cutting structure in a sponge, allowing objects to pass freely through the sponge without compromising its overall function, and the cutting structure in the sponge can close after the object is removed. One end of the seed crystal rod 1 is connected to a seed crystal holder 7, and a seed crystal (not shown in the figure) is connected to the seed crystal holder 7. The seed crystal rod 1, with one end connected to the seed crystal holder 7, passes sequentially through the opening 6 of the crucible cover 3 and the cross-cutting structure of the droplet removal component 4, extending into the interior of the crucible body 2. After the liquid phase growth of silicon carbide crystal is completed, the seed crystal rod 1 can drive the silicon carbide crystal through the droplet removal component 4 and rotate in contact with the upper surface of the droplet removal component 4 to remove residual droplets. Specifically, in this invention, the seed crystal rod can drive the silicon carbide crystal through the cross-cutting structure of the droplet removal component. The device also includes a monitoring system (not shown in the figure) for determining the position of the silicon carbide crystal. In this invention, the crucible body and the crucible cover can be connected, for example, by a threaded connection. The connection can be made by first overlapping a graphite felt along the upper edge of the crucible body, and then tightening the crucible lid onto the part of the upper edge of the crucible body where the graphite felt is not overlapped, thereby pressing (compacting) the graphite felt and enhancing the tightness of the connection. Specifically, the part of the upper edge of the crucible body used for overlapping the graphite felt can be raised upwards, so that the part used for overlapping the graphite felt is higher than the part where the graphite felt is not overlapped. In this invention, the crucible body and the crucible lid are made of graphite. When growing silicon carbide in the liquid phase method, the growth raw material 5 is contained in the crucible body 2. The crucible body provides space for the growth of silicon carbide crystals and also serves as a carbon source to provide the carbon required for the reaction of silicon carbide crystal growth.

[0042] The apparatus described in this invention can remove residual droplets from the crystal surface during liquid-phase silicon carbide single crystal growth, thereby reducing crystal cracking caused by stress accumulation. Specifically, this invention provides an apparatus for efficiently removing residual droplets during liquid-phase silicon carbide growth. By setting the droplet removal component between the crucible body and the crucible lid, and cooperating with a monitoring system for determining the position of the silicon carbide crystal, the apparatus can eliminate the droplets remaining on the crystal surface during liquid-phase silicon carbide single crystal growth, reducing stress accumulation during crystal cooling and lowering the probability of cracking. The apparatus described in this invention can efficiently and stably remove droplets of various sizes brought out by the crystal being pulled from the solution during liquid-phase silicon carbide growth. It can be effectively applied to the field of liquid-phase silicon carbide single crystal growth, improving crystal quality and expanding economic benefits. This invention solves the problem of the inability to remove the solution during liquid-phase silicon carbide single crystal growth, reducing the probability of cracking and increasing production capacity. The apparatus described in this invention can achieve uniform crystal surface temperature and reduce local temperature gradients through efficient droplet removal, thereby effectively reducing thermal stress concentration and the risk of crystal cracking.

[0043] Although Chinese patent application CN119372760A provides a liquid phase growth apparatus capable of removing residual droplets from the surface of semiconductor crystals after growth, this apparatus still has several problems, such as: high cost, increased crucible size, complex crystal support axis structure, high operational precision requirements, limited droplet removal efficiency, limitations in contact judgment methods, difficulty in ensuring uniform removal when droplet sizes vary greatly, difficulty in removing small droplets, and unstable removal effect. Due to these problems, the removal effect of this liquid phase growth apparatus on crystal surface droplets may be greatly affected by droplet size and droplet distribution, and its repeatability of complete droplet removal is low, expected to be no more than 50%. The device described in this invention has a compact structure and low cost. The droplet removal component is directly disposed between the crucible body and the crucible lid. The droplet removal component is made of graphite soft felt, which has a cross-cut structure radially arranged at its center. This arrangement of the droplet removal component does not rely on additional slots or support layers on the crucible sidewalls, and also avoids the problem of excessively large crucible sizes or the need for custom-made large crucibles. In addition, the device described in this invention reduces the complexity of the crystal support axis (seed crystal rod), eliminates the need for lateral movement, and significantly reduces manufacturing costs and maintenance difficulty. The device described in this invention is simple to operate and requires no additional components. High-precision lateral positioning is required, and the device must avoid operational errors or collision risks caused by differences in droplet size. The device described in this invention provides comprehensive droplet removal with stable and high repeatability. It can cover residual droplets in the outer and central areas of the crystal, ensuring that droplets on the entire surface of the silicon carbide single crystal can be removed. It can effectively handle both large and small droplets, is highly adaptable, and can adapt to uneven droplet size distribution, thereby improving droplet removal efficiency. The droplet removal rate on the crystal long surface can reach 100%. When conducting repeated experiments in multiple batches under the same conditions, the repeatability of achieving 100% droplet removal rate is over 95%.

[0044] According to some preferred embodiments, the crucible body 2 and the crucible cover 3 constitute a growth crucible; the device also includes a heat insulation layer (not shown in the figure) disposed on the outside of the growth crucible, the material of the heat insulation layer being, for example, graphite felt; an induction heating device (not shown in the figure) for heating is disposed on the outside of the heat insulation layer, the induction heating device including an induction coil (also referred to as a heating coil), the induction coil being coaxially disposed with the seed crystal rod, and the induction heating device heating the growth crucible through electromagnetic induction.

[0045] According to some preferred embodiments, the device further includes a seed crystal rod rotation and lifting device (not shown in the figure) for controlling the lifting and rotation of the seed crystal rod 1 and a crucible rotation and lifting device (not shown in the figure) for controlling the lifting and rotation of the crucible body 2; the other end of the seed crystal rod 1 is connected to the single crystal furnace (not shown in the figure) through the seed crystal rod rotation and lifting device, and the crucible body 2 is connected to the single crystal furnace through the crucible rotation and lifting device; in this invention, the seed crystal rod is used to connect the seed crystal and the single crystal furnace, and the seed crystal rod can drive the lifting and rotation of the seed crystal, thereby realizing the lifting and rotation movement of the seed crystal during the crystal growth process.

[0046] According to some preferred embodiments, the monitoring system is a resistance monitoring system; the resistance monitoring system is configured on a single crystal furnace, and a monitoring circuit is formed between the seed crystal rod and the crucible body, and the position of the silicon carbide crystal is determined by the resistance change of the monitoring circuit.

[0047] According to some preferred embodiments, the graphite felt is further provided with an opening 8 at its center, for example, as shown below. Figure 3 As shown, the graphite felt is provided with the cross-cutting structure along the opening 8; the diameter of the opening 8 is 3~10mm larger than the diameter of the seed crystal rod 1 (e.g., 3, 4, 5, 6, 7, 8, 9 or 10mm); the cross-cutting structure is formed by cutting along the first cutting line 9 and the second cutting line 10, both of which pass through the center of the opening 8 of the graphite felt and are perpendicular to each other; in this invention, the droplet removal component is made of graphite felt. Due to the elastic deformation of the graphite felt, when there is no opening at the center of the graphite felt, it can be restored as a whole, thus ensuring that the entire crystal growth surface is free of dead corners to remove residual droplets, so that the droplet removal rate reaches 100%; however, when the monitoring system is a resistance monitoring system, an opening is provided at the center of the graphite felt. This opening can be used to prevent the seed crystal rod from contacting the graphite felt when passing through the cross-cutting structure of the droplet removal component, thereby helping to ensure the accuracy of the contact position judgment. However, this design has an opening in the center of the droplet removal component. This opening may not completely remove droplets during the droplet removal process. This is because there is a possibility that a very small number of residual droplets may remain in the central opening area during the pull-out process. Even if there are no residual droplets in the central opening area during the pull-out process, droplets may still be carried or dispersed to the central opening area during the contact rotation operation. This reduces the repeatability of achieving 100% droplet removal rate on the crystal growth surface. For example, in multiple repeatable droplet removal experiments, if there are no residual droplets dispersed in the central opening area, the droplet removal rate on the crystal growth surface can reach 100%. However, if there are residual droplets dispersed, the residual droplets in the central opening area cannot be effectively removed.

[0048] According to some preferred embodiments, the monitoring system is a gravity monitoring system; the gravity monitoring system is configured at the connection between the single crystal furnace and the seed crystal rod, and determines the position of the silicon carbide crystal by the force change of the seed crystal rod; in this invention, the gravity monitoring system is configured, for example, on the seed crystal rod rotation and lifting device.

[0049] This invention does not impose specific limitations on the resistance monitoring system and the gravity monitoring system. Those skilled in the art can conventionally select either a resistance monitoring system that can monitor and display the resistance changes of the monitoring circuit in real time or a gravity monitoring system that can monitor and display the force changes of the seed crystal rod in real time.

[0050] According to some preferred embodiments, the length of the seed crystal rod 1 is 400~500mm, which ensures that the seed crystal can enter the crucible body and has a margin to ensure that the seed crystal can contact or be pulled out from the high-temperature melt; and / or the thickness of the seed crystal support 7 is 5~30mm, and the specific selection can be determined according to actual needs.

[0051] According to some preferred embodiments, the thickness of the graphite felt is 5 to 10 mm (e.g., 5, 6, 7, 8, 9 or 10 mm).

[0052] According to some preferred embodiments, the cutting length of the cross-cutting structure is greater than the diameter of the seed crystal holder, for example, 5-15 mm greater than the diameter of the seed crystal holder. The cutting length of the cross-cutting structure is slightly greater than the diameter of the seed crystal holder, so that the seed crystal holder can pass through the droplet removal component. In this invention, the cutting length of the cross-cutting structure corresponds to the length of the first cutting line and the second cutting line.

[0053] According to some preferred embodiments, both the seed crystal rod 1 and the seed crystal holder 7 are made of graphite; both the crucible body 2 and the crucible lid 3 are made of graphite; in this invention, the crucible body and the crucible lid may, for example, be made of graphite with a density greater than 1.6 g / cm³. 3 It is made from high-purity graphite.

[0054] In a second aspect, the present invention provides a method for growing silicon carbide using a liquid-phase method capable of removing residual droplets. The method is performed using the apparatus for growing silicon carbide using a liquid-phase method capable of removing residual droplets described in the first aspect of the present invention, and includes the following steps:

[0055] (1) The growth material is placed in the crucible body and heated to obtain a high-temperature melt; the present invention does not specifically limit the growth material, and those skilled in the art can conventionally select it. For example, the growth material includes silicon (Si) and fluxing material X, and the fluxing material X is one or more of Al, B, Ti, Cr, Fe, Y, Yb, Pr, La, Cu, Ag, Nd, Ce, Sn, Ge, and Co;

[0056] (2) The seed crystal is brought into contact with the high-temperature melt to grow silicon carbide crystal; the present invention does not specifically limit the process of silicon carbide crystal growth, which is a conventional technique in the field;

[0057] (3) After the silicon carbide crystal growth is completed, the silicon carbide crystal is driven through the droplet removal component by the seed crystal rod and rotates in contact with the upper surface of the droplet removal component to remove residual droplets; wherein, the position of the silicon carbide crystal is determined by the monitoring system.

[0058] (4) After the residual droplets are removed, the silicon carbide crystal is cooled down.

[0059] This invention relates to a device for liquid-phase silicon carbide growth capable of removing residual droplets, and provides a method for efficiently removing residual droplets from the crystal, thereby effectively improving the quality of liquid-phase grown silicon carbide crystals. The method utilizes a droplet removal component coupled with a resistance monitoring system or a gravity monitoring system to achieve real-time and accurate judgment of the contact and separation states between the silicon carbide crystal and the droplet removal component. This ensures that during the process of the seed crystal rod driving the silicon carbide crystal to contact and rotate to remove droplets, residual droplets can be completely removed by slightly over-moving downwards. This allows for effective control of the droplet removal process, improving droplet removal efficiency and crystal surface uniformity, thus contributing to improved quality of silicon carbide single crystals.

[0060] According to some preferred embodiments, the monitoring system is a resistance monitoring system, which is configured on a single crystal furnace and forms a monitoring circuit between the seed crystal rod and the crucible body. The position of the silicon carbide crystal is determined by the resistance change of the monitoring circuit. Step (3) includes the following sub-steps:

[0061] (a) Pulling (moving up) the seed crystal rod causes the silicon carbide crystal to be pulled away from the high-temperature melt. The criterion for judging the pull-away is: the resistance reading displayed by the resistance monitoring system increases.

[0062] (b) Continue to pull the seed crystal rod upward until the resistance reading displayed by the resistance monitoring system first decreases and then increases, and then stop moving the seed crystal rod upward. At this time, the silicon carbide crystal has passed through the droplet removal component.

[0063] (c) Lower the seed crystal rod until the resistance reading displayed by the resistance monitoring system begins to decrease, then continue to lower it by 1~3mm so that the silicon carbide crystal contacts the upper surface of the droplet removal component;

[0064] (d) The rotating seed crystal rod drives the silicon carbide crystal to contact and rotate with the upper surface of the droplet removal component to remove residual droplets.

[0065] In this invention, the resistance monitoring system is configured on a single crystal furnace, forming a monitoring circuit between the seed crystal rod and the crucible body. This allows an electrical circuit to be formed in the device through the crucible body, single crystal furnace, seed crystal rod, seed crystal holder, seed crystal, and silicon carbide crystal with the high-temperature melt or droplet removal component. When the seed crystal rod pulls the silicon carbide crystal out of the high-temperature melt, the electrical contact between the silicon carbide crystal and the high-temperature melt is broken, resulting in an increase in the resistance reading, indicating that the silicon carbide crystal has been pulled out of the high-temperature melt. When the upper surface of the seed crystal holder contacts the lower surface of the droplet removal component, the resistance reading decreases. When the seed crystal holder, seed crystal, and silicon carbide crystal pass through the droplet removal component, they disconnect from the droplet removal component, and the resistance reading increases. When the seed crystal rod stops pulling upwards and is then lowered until the resistance reading decreases, the silicon carbide crystal contacts the upper surface of the droplet removal component. Through these resistance changes, the positional relationship between the silicon carbide crystal and the droplet removal component can be determined.

[0066] According to some preferred embodiments, the monitoring system is a gravity monitoring system, which is configured at the connection between the single crystal furnace and the seed crystal rod (the gravity monitoring system is configured, for example, on the seed crystal rod rotation and lifting device). The position of the silicon carbide crystal is determined by the force change of the seed crystal rod. Step (3) includes the following sub-steps:

[0067] S1. Pulling (moving) the seed crystal rod causes the silicon carbide crystal to be pulled away from the high-temperature melt. The criterion for judging the pull-away is: the force reading displayed by the gravity monitoring system decreases, and the force reading is set to zero.

[0068] S2. Continue to pull the seed crystal rod upwards until the force reading displayed by the gravity monitoring system changes from zero to a negative number and the absolute value corresponding to the negative number continues to increase. Then stop moving the seed crystal rod upwards when it returns to zero. At this time, the silicon carbide crystal has passed through the droplet removal component.

[0069] S3. Lower the seed crystal rod until the force reading displayed by the gravity monitoring system begins to turn positive, then continue to lower it by 1~3mm to make the silicon carbide crystal contact the upper surface of the droplet removal component.

[0070] S4. The rotating seed crystal rod causes the silicon carbide crystal to contact and rotate with the upper surface of the droplet removal component to remove residual droplets; In this invention, the gravity monitoring system is installed at the connection between the single crystal furnace and the seed crystal rod, and can monitor the force on the seed crystal rod.

[0071] According to some preferred embodiments, the contact rotation time is 4 to 6 minutes (e.g., 4, 5 or 6 minutes); and / or the contact rotation speed is, for example, 5 to 15 rpm.

[0072] According to some preferred embodiments, in steps (a) to (c) and in steps S1 to S3, the speed of lifting and / or lowering the seed crystal rod can be, for example, 1 to 3 mm / min. In this invention, by slowly lifting and / or lowering the seed crystal rod, it can be ensured that the graphite felt is not damaged.

[0073] In step (a) or S1, this invention can accurately determine the state of the silicon carbide crystal detached from the high-temperature melt by monitoring the changes in resistance or force when the silicon carbide crystal is pulled out of the high-temperature melt, ensuring the safety of the detachment action. In step (b) or S2, the invention can determine the penetration state of the silicon carbide crystal and the droplet removal component by monitoring the changes in resistance or force, preventing excessive upward movement that could lead to collision. In step (c) or S3, the invention can achieve precise downward movement by monitoring the state of the silicon carbide crystal in contact with the droplet removal component, ensuring close contact between the lower surface of the silicon carbide crystal and the upper surface of the droplet removal component. In step (d) or S4, rotating the seed crystal rod causes the silicon carbide crystal to rotate in contact with the droplet removal component to remove residual droplets, achieving efficient and uniform removal of residual droplets from the crystal surface. Through the coordination of these steps, this invention not only avoids damage or breakage of the crystal surface during residual droplet removal but also achieves high efficiency in the droplet removal process, improving the efficiency of residual droplet removal and the uniformity of the crystal surface, thereby contributing to improved quality of silicon carbide single crystals.

[0074] In this invention, even if the opening is provided at the center of the graphite felt, it is more preferable that step (3) monitors the position of the silicon carbide crystal by a gravity monitoring system. This is more conducive to improving the repeatability of the removal rate of residual droplets on the crystal growth surface to 100% in multiple batches of repeated experiments under the same conditions. The possible reason is that the resistance monitoring system has certain limitations in high-temperature environments. At high temperatures, there are gas molecules, so even if there is no contact, there is a resistance value. This may affect the judgment of the liquid contact and pull-off values ​​between the silicon carbide crystal and the high-temperature melt. For example, in actual use, the resistance reading is infinite when loading the furnace. As the furnace starts to burn, the resistance monitoring system begins to show a reading after the temperature rises. The higher the temperature, the lower the resistance reading becomes. The lower the resistance reading, the further it will decrease after contact with the liquid. At the end of silicon carbide crystal growth, the system temperature is still a high-temperature environment. When the seed crystal area is large enough and close enough to the surface of the high-temperature melt, the resistance monitoring system will show similar values ​​for contact with and without liquid, affecting the judgment. In addition, under high-temperature conditions, the resistance monitoring system may form a conductive path (electrical contact state) with the seed crystal rod and the crucible body due to the generation of volatiles. Even if the liquid surface is pulled away, the whole is still in an electrical contact state, which may make it impossible to accurately determine the pull-away position. Gravity monitoring system does not have these problems. That is, the gravity monitoring system is not affected by the conductivity of high-temperature gas molecules or volatiles, and only relies on the force change of the seed crystal rod for judgment, making the judgment more accurate and reliable.

[0075] According to some specific embodiments, the liquid-phase method for growing silicon carbide capable of removing residual droplets includes:

[0076] ① Provides the apparatus for liquid-phase growth of silicon carbide capable of removing residual droplets (the position of the silicon carbide crystal is determined by a resistance monitoring system). The apparatus involves placing growth material in the crucible body and heating the material to obtain a high-temperature melt; then, the seed crystal is brought into contact with the high-temperature melt to grow the silicon carbide crystal. Step ① includes, for example, fabricating a droplet removal component, preparing the growth material according to actual needs and placing it in the crucible body, and assembling the apparatus. Specifically, for example, the seed crystal rod along with the seed crystal holder is placed in the crucible body; the droplet removal component is placed (overlapped) along the upper edge of the crucible body through the seed crystal rod, and then pressed down by tightening the crucible lid; then… Then, the seed crystal rod is lowered and placed in a suitable position inside the crucible body by a seed crystal rod rotation and lifting device. During the heating and growth material stage, for example, the furnace is evacuated and then filled with inert gas, such as helium, nitrogen and / or argon. Then, the power is turned on to heat up the furnace, so that the growth material inside the crucible body melts to obtain a high-temperature melt. Then, the seed crystal is brought into contact with the high-temperature melt to grow silicon carbide crystals. During the silicon carbide crystal growth stage, the rotation of the seed crystal and the crucible body is controlled to make the composition of the high-temperature melt uniform. At the same time, the lifting or lowering of the seed crystal and the crucible body is controlled to ensure a suitable growth environment. This invention does not specifically limit these operations and are conventional techniques in the field.

[0077] ② After the silicon carbide crystal growth is completed, the seed crystal rod is pulled upward to pull the silicon carbide crystal off the high-temperature melt. The criterion for judging the detachment is: the resistance reading displayed by the resistance monitoring system configured in the single crystal furnace suddenly increases for the first time, indicating that the surface silicon carbide crystal has been detached from the high-temperature melt, and the seed crystal holder, seed crystal, and silicon carbide crystal are not in contact with the crucible body.

[0078] ③ Continue pulling the seed crystal rod upwards until the resistance reading displayed on the resistance monitoring system first decreases (the seed crystal holder contacts the droplet removal component) and then increases (the silicon carbide crystal separates from the droplet removal component). Then stop moving the seed crystal rod upwards. That is, continue pulling the seed crystal rod upwards. When the resistance reading changes from large to small, it indicates that the seed crystal holder is in contact with the droplet removal component. At this point, the upper surface of the seed crystal holder is in contact with the lower surface of the droplet removal component. Continue pulling the seed crystal rod upwards. When the resistance reading changes from small to large, it indicates that the seed crystal holder, the seed crystal, and the silicon carbide crystal have passed through the droplet removal component and have separated from it.

[0079] ④ Lower the seed crystal rod until the resistance reading displayed by the resistance monitoring system just decreases, then continue to move it down 2mm. At this point, the lower surface of the grown silicon carbide crystal is in complete contact with the upper surface of the droplet removal component.

[0080] ⑤ Turn on the seed crystal rod rotation function. Rotate the seed crystal rod for 5 minutes to make the silicon carbide crystal contact and rotate with the upper surface of the droplet removal component, so that the droplet removal component removes the residual droplets on the surface of the silicon carbide crystal.

[0081] ⑥ Move the seed crystal rod up 5mm. At this time, the resistance reading of the resistance monitoring system will increase from small to large. Cool down and wait for the silicon carbide crystal to come out of the furnace. During the unloading stage, open the furnace cover and remove the silicon carbide crystal from the seed crystal holder.

[0082] According to some specific embodiments, the liquid-phase method for growing silicon carbide capable of removing residual droplets includes:

[0083] ① Provide the apparatus for growing silicon carbide by liquid phase method that can remove residual droplets (the position of silicon carbide crystal is determined by gravity monitoring system), the growth material is placed in the crucible body and heated to obtain high temperature melt; the seed crystal is brought into contact with the high temperature melt to grow silicon carbide crystal;

[0084] ② After the silicon carbide crystal growth is completed, the seed crystal rod is pulled upward to pull the silicon carbide crystal out of the high-temperature melt. The criterion for judging the pull-out is: the force reading of the seed crystal rod displayed by the gravity monitoring system decreases, and the force reading is set to zero for easy subsequent judgment.

[0085] ③ Continue pulling the seed crystal rod upwards until the force reading displayed by the gravity monitoring system changes from zero to a negative number and the absolute value of the negative number continues to increase (the seed crystal holder contacts the droplet removal component and penetrates into the cross-cut structure), and then returns to zero (the silicon carbide crystal separates from the droplet removal component). Stop moving the seed crystal rod upwards at this point. When the force reading displayed by the gravity monitoring system changes from zero to a negative number, it indicates that the upper surface of the seed crystal holder contacts the lower surface of the droplet removal component. The subsequent return to zero indicates that the seed crystal holder, the seed crystal, and the silicon carbide crystal have passed through the droplet removal component and separated from it.

[0086] ④ Lower the seed crystal rod until the force reading displayed by the gravity monitoring system just turns positive, then continue to move it down 2mm. At this point, the lower surface of the grown silicon carbide crystal is in complete contact with the upper surface of the droplet removal component.

[0087] ⑤ Turn on the seed crystal rod rotation function. Rotate the seed crystal rod for 5 minutes to make the silicon carbide crystal contact and rotate with the upper surface of the droplet removal component, so that the droplet removal component removes the residual droplets on the surface of the silicon carbide crystal.

[0088] ⑥ Move the seed crystal rod up 5mm. At this point, the force reading displayed by the gravity monitoring system is zero. Cool down and wait for the silicon carbide crystal to come out of the furnace.

[0089] The device described in this invention can effectively remove liquid droplets remaining on the crystal surface due to the liquid phase method during growth of silicon carbide crystals, thereby reducing stress accumulation and decreasing the probability of crystal cracking by about 20%. The removal rate of residual liquid droplets on the crystal surface can reach 100%. When multiple batches of repeated experiments are conducted under the same conditions, the repeatability of the 100% droplet removal rate is over 95%.

[0090] The present invention will be further described below by way of examples, but the scope of protection of the present invention is not limited to these embodiments.

[0091] Example 1

[0092] This embodiment provides an apparatus and method for growing silicon carbide using a liquid-phase method that can remove residual droplets; for example, such as Figure 1As shown, the device includes a crucible body, a crucible lid with an opening, a seed crystal rod, and a droplet removal component disposed between the crucible body and the crucible lid. The droplet removal component is located at the upper edge of the crucible body and is pressed down by the crucible lid. The droplet removal component is made of graphite felt, with an opening in the center and a cross-cutting structure along the opening. One end of the seed crystal rod is connected to a seed crystal holder, and a seed crystal is attached to the seed crystal holder. The end of the seed crystal rod connected to the seed crystal holder passes sequentially through the opening of the crucible lid and the... The droplet removal component has a cross-cutting structure extending into the interior of the crucible body. After the liquid phase growth of silicon carbide crystals is completed, the seed crystal rod can drive the silicon carbide crystal through the droplet removal component and rotate in contact with the upper surface of the droplet removal component to remove residual droplets. The device also includes a monitoring system for determining the position of the silicon carbide crystal. The crucible body and the crucible cover constitute a growth crucible. The device also includes a heat insulation layer disposed on the outside of the growth crucible. An induction heating device for heating is disposed on the outside of the heat insulation layer. The induction heating device includes an induction coil, which is coaxially disposed with the seed crystal rod. The induction heating device heats the growth crucible through electromagnetic induction. The device also includes a seed crystal rod rotation and lifting device for controlling the lifting and rotation of the seed crystal rod and a crucible rotation and lifting device for controlling the lifting and rotation of the crucible body. The other end of the seed crystal rod is connected to the single crystal furnace through the seed crystal rod rotation and lifting device, and the crucible body is connected to the single crystal furnace through the crucible rotation and lifting device. The monitoring system is a resistance monitoring system. The monitoring system is configured on the single crystal furnace, forming a monitoring circuit between the seed crystal rod and the crucible body. The position of the silicon carbide crystal is determined by the change in resistance of the monitoring circuit. In this embodiment, the diameter of the seed crystal is φ150mm, the diameter of the seed crystal and the seed crystal holder are the same, the diameter of the seed crystal holder is φ150mm, and the diameter of the seed crystal rod is φ15mm. The thickness of the graphite soft felt used in the droplet removal component is 10mm, the diameter of the opening at the center of the graphite soft felt is φ20mm, and the cutting length of the cross-cutting structure is 160mm. For example, ... Figure 3 As shown, the cross-cutting structure is formed by cutting along the first cutting line and the second cutting line. The first cutting line and the second cutting line both pass through the center of the opening of the graphite soft felt and are perpendicular to each other. The first cutting line and the second cutting line have the same length and extend towards the edge of the graphite soft felt with the center of the opening as the symmetrical point, and the extension length is the same (the extension length from the center of the opening to the edge is 80mm).

[0093] In this embodiment, the method includes the following steps:

[0094] ① An apparatus for growing silicon carbide using a liquid phase method that can remove residual droplets is provided. The apparatus contains growth material in a crucible body and heats the material to obtain a high-temperature melt. A seed crystal is brought into contact with the high-temperature melt to grow silicon carbide crystals. During the heating stage, the furnace is evacuated, then filled with the protective gas argon, and the power is turned on to raise the temperature to 1800°C. This temperature is higher than the melting point of the growth material, causing the growth material in the growth crucible to melt and obtain a high-temperature melt. In this embodiment, the growth material is a mixture of Si, Cr, and Al. The mass percentages of these three components in the growth material are: Si: 50%, Cr: 48%, and Al: 2%.

[0095] ② After the silicon carbide crystal growth is completed, the seed crystal rod is pulled upward to pull the silicon carbide crystal out of the high-temperature melt. The criterion for judging the pull-out is: the resistance reading displayed by the resistance monitoring system configured in the single crystal furnace increases.

[0096] ③ Continue to pull the seed crystal rod upwards until the resistance reading displayed by the resistance monitoring system first decreases and then increases. Then stop moving the seed crystal rod upwards. At this time, the silicon carbide crystal has passed through the droplet removal component.

[0097] ④ Lower the seed crystal rod until the resistance reading displayed by the resistance monitoring system just decreases, then continue to move it down 2mm. At this point, the lower surface of the grown silicon carbide crystal is in complete contact with the upper surface of the droplet removal component.

[0098] ⑤ Turn on the seed crystal rod rotation function, rotate the seed crystal rod for 5 minutes to drive the silicon carbide crystal to contact and rotate with the upper surface of the droplet removal component, so that the droplet removal component removes the residual droplets on the surface of the silicon carbide crystal; the rotation speed of the contact rotation is 10 rpm;

[0099] ⑥ Move (pull) the seed crystal rod up by 5mm, cool it down to room temperature, and the silicon carbide crystal is taken out of the furnace to obtain the silicon carbide crystal; in steps ② to ⑥, the speed of pulling up the seed crystal rod and lowering the seed crystal rod is 2mm / min.

[0100] This embodiment employs a 5-point testing method to measure the full width at half maximum (FWHM) of the XRD rocking curve of the obtained silicon carbide crystal to evaluate the overall crystal orientation and crystallization quality of the sample. The present invention measures the FWHM of the XRD rocking curve of the silicon carbide crystal obtained in Example 1, as follows: Figure 4 As shown, the average of the results from the five measurement points yielded an average half-width at half-maximum (FWHM) of the diffraction peak of the rocking curve of 23.8 arcsec.

[0101] The liquid phase growth of silicon carbide crystals using the apparatus and method in this embodiment can effectively remove the liquid droplets remaining on the crystal surface due to the liquid phase pull-out, thereby reducing stress accumulation and decreasing the probability of crystal cracking by about 20%, and the removal rate of residual liquid droplets on the silicon carbide crystal surface reaches 100%.

[0102] Example 1 was repeated a total of 100 times under the same conditions, and the repeatability of the crystal surface residual droplet removal rate reaching 100% was 95%.

[0103] Example 2

[0104] This embodiment provides an apparatus and method for growing silicon carbide using a liquid-phase method that can remove residual droplets; for example, such as Figure 1 As shown, the device includes a crucible body, a crucible lid with an opening, a seed crystal rod, and a droplet removal component disposed between the crucible body and the crucible lid. The droplet removal component is located at the upper edge of the crucible body and is pressed down by the crucible lid. The droplet removal component is made of graphite felt, and the graphite felt has a cross-cut structure radially arranged at its center. One end of the seed crystal rod is connected to a seed crystal holder, and a seed crystal is connected to the seed crystal holder. The end of the seed crystal rod connected to the seed crystal holder extends into the interior of the crucible body through the opening of the crucible lid and the cross-cut structure of the droplet removal component. After the liquid phase growth of silicon carbide crystal is completed, the seed crystal rod can drive the silicon carbide crystal through the droplet removal component and contact and rotate with the upper surface of the droplet removal component to remove residual droplets. The device also includes a monitoring system for determining the position of the silicon carbide crystal. The crucible body and the crucible lid form a growth crucible. The device also includes a heat insulation layer disposed on the outside of the growth crucible, and an induction heating element is disposed on the outside of the heat insulation layer for heating. The heating device includes an induction heating coil coaxially arranged with the seed crystal rod. The induction heating device heats the growth crucible via electromagnetic induction. The device also includes a seed crystal rod rotation and pulling device for controlling the lifting and rotation of the seed crystal rod, and a crucible rotation and lifting device for controlling the lifting and rotation of the crucible body. The other end of the seed crystal rod is connected to the single crystal furnace via the seed crystal rod rotation and pulling device, and the crucible body is connected to the single crystal furnace via the crucible rotation and lifting device. The monitoring system is... A gravity monitoring system is configured at the connection between the single crystal furnace and the seed crystal rod (specifically, on the seed crystal rod rotation and lifting device). The system determines the position of the silicon carbide crystal by observing changes in the force applied to the seed crystal rod. In this embodiment, the seed crystal has a diameter of φ150mm, the seed crystal and the seed crystal holder have the same diameter (φ150mm), and the seed crystal rod has a diameter of φ15mm. The graphite felt used in the droplet removal component has a thickness of 10mm, and the cutting length of the cross-cutting structure is 160mm. For example, ... Figure 2As shown, the cross-cut structure is formed by cutting along the first cutting line and the second cutting line. The first cutting line and the second cutting line both pass through the center of the graphite felt and are perpendicular to each other. The first cutting line and the second cutting line have the same length and extend towards the edge of the graphite felt with the center of the graphite felt as the symmetrical point, and the extension length is the same (the extension length from the center of the graphite felt to the edge is 80mm).

[0105] In this embodiment, the method includes the following steps:

[0106] ① The apparatus for liquid-phase silicon carbide growth capable of removing residual droplets is provided. Growth raw materials are placed in the crucible body and heated to obtain a high-temperature melt. A seed crystal is brought into contact with the high-temperature melt to grow silicon carbide crystals. During the heating stage, the furnace is evacuated, then filled with the protective gas argon, and then the power is turned on to raise the temperature to 1800℃. This temperature is higher than the melting point of the growth raw materials, causing the growth raw materials in the growth crucible to melt and obtain a high-temperature melt. In this embodiment, the growth raw materials are a mixture of Si, Cr, and Al, with the following mass percentages: Si: 50%, Cr: 48%, Al: 2%.

[0107] ② After the silicon carbide crystal growth is completed, the seed crystal rod is pulled upward to pull the silicon carbide crystal out of the high-temperature melt. The criterion for judging the pull-out is: the force reading of the seed crystal rod displayed by the gravity monitoring system decreases, and the force reading is set to zero for easy subsequent judgment.

[0108] ③ Continue to pull the seed crystal rod upwards until the force reading displayed by the gravity monitoring system changes from zero to a negative number and the absolute value corresponding to the negative number continues to increase. Then stop moving the seed crystal rod upwards when it returns to zero. At this time, the silicon carbide crystal has passed through the droplet removal component.

[0109] ④ Lower the seed crystal rod until the force reading displayed by the gravity monitoring system just turns positive, then continue to move it down 2mm. At this point, the lower surface of the grown silicon carbide crystal is in complete contact with the upper surface of the droplet removal component.

[0110] ⑤ Activate the seed crystal rod rotation function, rotate the seed crystal rod for 5 minutes to drive the silicon carbide crystal to contact and rotate with the upper surface of the droplet removal component, so that the droplet removal component removes the droplets from the surface of the silicon carbide crystal; the rotation speed of the contact rotation is 10 rpm;

[0111] ⑥ Move the seed crystal rod upward by 5mm. At this time, the force reading displayed by the gravity monitoring system is zero. Cool down to room temperature, and the silicon carbide crystal is taken out of the furnace to obtain the silicon carbide crystal. In steps ② to ⑥, the speed of lifting and lowering the seed crystal rod is 2mm / min.

[0112] The liquid phase growth of silicon carbide crystals using the apparatus and method in this embodiment can effectively remove the liquid droplets remaining on the crystal surface due to the liquid phase pull-out, thereby reducing stress accumulation and decreasing the probability of crystal cracking by about 20%, and the removal rate of residual liquid droplets on the silicon carbide crystal surface reaches 100%.

[0113] Example 2 was repeated a total of 100 times under the same conditions, and the repeatability of the crystal surface residual droplet removal rate was 100%.

[0114] Comparative Example 1

[0115] In a traditional liquid-phase silicon carbide growth apparatus, silicon carbide crystals are grown using the liquid-phase method. The traditional apparatus includes: a crucible body, a crucible lid with an opening, and a seed crystal rod; one end of the seed crystal rod is connected to a seed crystal holder, and a seed crystal is attached to the seed crystal holder; the other end of the seed crystal rod connected to the seed crystal holder extends through the opening of the crucible lid into the interior of the crucible body; the crucible body and the crucible lid constitute a growth crucible; the apparatus further includes a heat insulation layer disposed on the outside of the growth crucible, and an induction heating device for heating is disposed on the outside of the heat insulation layer; the induction heating device includes an induction coil. The induction heating device heats the growth crucible via electromagnetic induction, and the device also includes a seed crystal rod rotation and lifting device for controlling the lifting and rotation of the seed crystal rod and a crucible rotation and lifting device for controlling the lifting and rotation of the crucible body. The other end of the seed crystal rod is connected to the single crystal furnace via the seed crystal rod rotation and lifting device, and the crucible body is connected to the single crystal furnace via the crucible rotation and lifting device. In this comparative example, the diameter of the seed crystal is φ150mm, the diameter of the seed crystal and the diameter of the seed crystal holder are the same, the diameter of the seed crystal holder is φ150mm, and the diameter of the seed crystal rod is φ15mm.

[0116] This comparative example uses the conventional liquid phase method for growing silicon carbide to grow silicon carbide crystals. The growth process of silicon carbide crystals is the same as that in Example 1, except that the operation of removing residual droplets on the surface of silicon carbide crystals after growth by contact rotation through a droplet removal component, as in Example 1, is not performed.

[0117] This comparative example cannot remove the droplets remaining after the silicon carbide crystal is pulled out of the high-temperature melt. The presence of droplets causes stress accumulation during the cooling stage, and when the threshold is reached, the crystal will crack, affecting the crystal quality.

[0118] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the appendix. Figure 1The orientations or positional relationships shown are for the purpose of facilitating and simplifying the description of the present invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0119] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can refer to a direct connection or an indirect connection through an intermediate medium, etc. Those skilled in the art can understand the specific meaning of this term in this invention depending on the specific circumstances.

[0120] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An apparatus for liquid-phase silicon carbide growth capable of removing residual droplets, characterized in that: The device includes a crucible body, a crucible lid with an opening, a seed crystal rod, and a droplet removal component disposed between the crucible body and the crucible lid; The droplet removal component is made of graphite soft felt, which has a cross-cut structure radially arranged at the center; the thickness of the graphite soft felt is 5~10mm. One end of the seed crystal rod is connected to a seed crystal holder, and a seed crystal is connected to the seed crystal holder. The end of the seed crystal rod connected to the seed crystal holder passes through the opening of the crucible lid and the cross-cutting structure of the droplet removal component in sequence and extends into the interior of the crucible body. The cutting length of the cross-cutting structure is greater than the diameter of the seed crystal holder. The device also includes a monitoring system for determining the position of the silicon carbide crystal. The monitoring system is a gravity monitoring system, which is configured at the connection between the single crystal furnace and the seed crystal rod. The position of the silicon carbide crystal is determined by the change in force on the seed crystal rod. After the silicon carbide crystal is grown by liquid phase method, the seed crystal rod can drive the silicon carbide crystal through the droplet removal component and rotate in contact with the upper surface of the droplet removal component to remove residual droplets, including the following sub-steps: S1. Pulling the seed crystal rod causes the silicon carbide crystal to be pulled away from the high-temperature melt. The criterion for judging the pull-away is: the force reading displayed by the gravity monitoring system decreases, and the force reading is set to zero. S2. Continue to pull the seed crystal rod upwards until the force reading displayed by the gravity monitoring system changes from zero to a negative number and the absolute value corresponding to the negative number continues to increase. Then stop moving the seed crystal rod upwards when it returns to zero. At this time, the silicon carbide crystal has passed through the droplet removal component. S3. Lower the seed crystal rod until the force reading displayed by the gravity monitoring system begins to turn positive, then continue to lower it by 1~3mm to make the silicon carbide crystal contact the upper surface of the droplet removal component. S4. The rotating seed crystal rod drives the silicon carbide crystal to contact and rotate with the upper surface of the droplet removal component to remove residual droplets; the rotation speed of the contact rotation is 5~15 rpm.

2. The apparatus according to claim 1, characterized in that: The device also includes a seed crystal rod rotation and lifting device for controlling the lifting and rotation of the seed crystal rod and a crucible rotation and lifting device for controlling the lifting and rotation of the crucible body. The other end of the seed crystal rod is connected to the single crystal furnace via a seed crystal rod rotation and lifting device, and the crucible body is connected to the single crystal furnace via a crucible rotation and lifting device.

3. The apparatus according to claim 1, characterized in that: The length of the seed crystal rod is 400~500mm; The thickness of the seed crystal holder is 5~30mm; The thickness of the graphite felt is 5~10mm.

4. A method for growing silicon carbide using a liquid phase method capable of removing residual droplets, characterized in that, The method is performed using the liquid-phase silicon carbide growth apparatus as described in any one of claims 1 to 3, capable of removing residual droplets, and the method includes the following steps: (1) The growth material is placed in the crucible body and heated to obtain a high-temperature melt; (2) The seed crystal is brought into contact with the high-temperature melt to grow silicon carbide crystals; (3) After the silicon carbide crystal growth is completed, the silicon carbide crystal is driven through the droplet removal component by the seed crystal rod and rotates in contact with the upper surface of the droplet removal component to remove residual droplets; wherein, the position of the silicon carbide crystal is determined by the monitoring system; the monitoring system is a gravity monitoring system, which is configured at the connection between the single crystal furnace and the seed crystal rod, and the position of the silicon carbide crystal is determined by the force change of the seed crystal rod. Step (3) includes the following sub-steps: S1. Pulling the seed crystal rod causes the silicon carbide crystal to be pulled away from the high-temperature melt. The criterion for judging the pull-away is: the force reading displayed by the gravity monitoring system decreases, and the force reading is set to zero. S2. Continue to pull the seed crystal rod upwards until the force reading displayed by the gravity monitoring system changes from zero to a negative number and the absolute value corresponding to the negative number continues to increase. Then stop moving the seed crystal rod upwards when it returns to zero. At this time, the silicon carbide crystal has passed through the droplet removal component. S3. Lower the seed crystal rod until the force reading displayed by the gravity monitoring system begins to turn positive, then continue to lower it by 1~3mm to make the silicon carbide crystal contact the upper surface of the droplet removal component. S4. The rotating seed crystal rod drives the silicon carbide crystal to contact and rotate with the upper surface of the droplet removal component to remove residual droplets; the rotation speed of the contact rotation is 5~15 rpm; (4) After the residual droplets are removed, the silicon carbide crystal is cooled down.

5. The method according to claim 4, characterized in that: The contact rotation time is 4-6 minutes.

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