A device and method for rapidly growing large-size, high-quality silicon carbide single crystals

Abstract

The present invention provides a device and method for rapidly growing large-sized, high-quality silicon carbide single crystals, belonging to the technical field of crystal growth. The device includes a crucible assembly, a seed crystal assembly, a heating assembly arranged outside the crucible assembly, and a heat preservation assembly located between the heating assembly and the crucible assembly; the crucible assembly includes a crucible and a pushing and rotating component arranged below the crucible for pushing and rotating the crucible; the seed crystal assembly includes a seed crystal rod, a seed crystal holder, and a turbine radiator; the seed crystal holder includes a seed crystal holder base plate and a connecting rod fixedly connected to the seed crystal holder base plate; the connecting rod is connected to the seed crystal rod through a mortise and tenon structure; the mortise and tenon structure is locked by a locking component; the turbine radiator includes a turbine shaft barrel and turbine blades distributed on the turbine shaft barrel; the turbine shaft barrel is sleeved on the connecting rod; the turbine radiator accelerates heat dissipation when rotating in a first direction, and inhibits heat dissipation when rotating in a second direction. The device provided by the present invention can achieve rapid growth of large-sized, high-quality silicon carbide single crystals.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal growth, and in particular to a device and method for rapidly growing large-size, high-quality silicon carbide single crystals. Background Art

[0002] As one of the typical representatives of wide bandgap semiconductors, silicon carbide has excellent properties such as large bandgap width, high breakdown field strength, high saturated electron mobility, high thermal conductivity, good thermal stability and chemical stability. It is an ideal substrate material for making high-frequency, high-voltage, high-efficiency, radiation-resistant, high-temperature resistant high-power devices and blue light-emitting diodes, which makes it have huge application prospects in new energy vehicles, high-speed rail transit, aerospace, high-voltage smart grids and clean energy. Therefore, it has received widespread attention from academia and governments of various countries.

[0003] The current mainstream method for growing silicon carbide single crystal substrates is physical vapor transport (PVT). Although this method has become relatively mature after decades of continuous research and development and improvement, and can currently supply a large number of silicon carbide single crystal substrates to the market, it still has some unavoidable limitations, mainly manifested in its unstable growth environment, difficulty in eliminating defects, low yield, high cost, difficulty in diameter expansion, and difficulty in achieving continuous and effective P-type doping.

[0004] Compared with the gas phase method, the liquid phase method requires a low growth temperature and a relatively stable growth environment, which can achieve the growth of crystals in a near-equilibrium state. Not only is the growth cost relatively low, but also theoretically higher crystal quality can be achieved. In the liquid phase method of growing silicon carbide single crystals, the uniformity of the radial temperature field of the crystal and the uniformity of the back heat dissipation of the seed crystal have a very important influence on the growth quality and rate of silicon carbide crystals, especially large-sized (4-8 inches) silicon carbide crystals. At present, the heat dissipation rate and radial temperature gradient during crystal growth are generally changed by adjusting the size of the opening of the insulation felt above the crystal. This method is difficult to take into account both the heat dissipation rate and the radial temperature gradient at the same time, and it is also impossible to achieve in-situ real-time regulation of crystal heat dissipation during the growth process, and thus it is impossible to take into account the growth quality and rate of the crystal well, and it is also difficult to achieve long-term stable growth. Summary of the invention

[0005] In response to one or more technical problems existing in the prior art, the present invention provides a device and method for rapidly growing large-sized, high-quality silicon carbide single crystals. The device provided by the present invention can effectively improve the heat dissipation rate and uniformity of the crystal, and regulate the radial temperature gradient and axial heat dissipation rate at the crystal growth interface in real time, thereby meeting the heat dissipation requirements of each stage of crystal growth and realizing the rapid growth of large-sized, high-quality silicon carbide single crystals.

[0006] The present invention provides a device for rapidly growing large-size, high-quality silicon carbide single crystals, the device comprising a crucible assembly, a seed crystal assembly, a heating assembly arranged outside the crucible assembly, and a heat preservation assembly located between the heating assembly and the crucible assembly; the crucible assembly comprises a crucible and a pushing and rotating component arranged below the crucible for pushing and rotating the crucible; the seed crystal assembly comprises a seed crystal rod, a seed crystal holder and a turbine radiator; the seed crystal holder comprises a seed crystal holder base plate and a connecting rod fixedly connected to the seed crystal holder base plate; the connecting rod is connected to the seed crystal rod by a mortise and tenon structure; the mortise and tenon structure is locked by a locking component; the turbine radiator comprises a turbine shaft cylinder and turbine blades distributed on the turbine shaft cylinder; the turbine shaft cylinder is sleeved on the connecting rod; the turbine radiator accelerates heat dissipation when rotating in a first direction, and inhibits heat dissipation when rotating in a second direction.

[0007] Preferably, the crucible is a graphite crucible.

[0008] Preferably, the mortise and tenon structure comprises a mortise and tenon structure arranged at the lower end of the seed rod and a tenon structure arranged at the upper end of the connecting rod; the locking component is fixed to the mortise and tenon structure by means of threads.

[0009] The present invention also provides a method for rapidly growing large-size, high-quality silicon carbide single crystals, which is implemented by the device described in the first aspect, and the method comprises the following steps:

[0010] S1. placing the flux and silicon in a crucible and heating the mixture until it is completely liquefied to obtain a melt;

[0011] S2. After rotating the seed crystal rod in a second direction at a first preset speed for a first preset time, the seed crystal is brought into contact with the melt to grow a crystal to obtain a silicon carbide single crystal; during the crystal growth process, the rotation direction and speed of the seed crystal rod are regulated according to the heat dissipation requirements at different stages; the rotation direction of the crucible is always opposite to the rotation direction of the seed crystal.

[0012] Preferably, during the crystal growth process, after the seed crystal contacts the melt, the seed crystal rod rotates at a second preset speed along the second direction for a second preset time, and then at a third preset time, the speed is decelerated to 0 and accelerated to a third preset speed along the first direction, and then rotated at the third preset speed for a fourth preset time, and finally, according to the thermal insulation performance attenuation curve of the thermal insulation material used in the thermal insulation component, the speed is reduced to a fourth preset speed at a fifth preset time to ensure that the heat dissipation rate remains stable.

[0013] Preferably, the second preset speed is greater than the first preset speed;

[0014] The third preset rotation speed is greater than the second preset rotation speed.

[0015] Preferably, the first preset speed is 5-30 rpm;

[0016] The second preset speed is 10-60 rpm; and / or

[0017] The third preset rotation speed is 60~240 rpm.

[0018] Preferably, during the crystal growth process, the rotation speed of the crucible is 2-10 rpm;

[0019] The crucible moves upward at a speed of 0 to 1000 μm / h; and / or

[0020] The pulling speed of the seed crystal rod is 0-1500 μm / h.

[0021] Preferably, the second preset time is 0.5~2h;

[0022] The third preset time is 0.5~2h;

[0023] The fourth preset time is 10 to 20 hours; and / or

[0024] The fifth preset time is 20 to 60 hours.

[0025] Preferably, after the crystal growth is completed, at a sixth preset time, the rotation speed is reduced to 0 and accelerated along the second direction to a fifth preset rotation speed, and then maintained for a seventh preset time.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] A turbine radiator is installed above the seed crystal holder substrate. The rotation of the seed crystal rod drives the turbine radiator and the seed crystal holder to rotate synchronously, so that the airflow in the crucible will perform orderly directional movement under the drive of the turbine radiator during the crystal growth process. It can not only limit the gas turbulence in the crucible but also quickly bring the heat at the crucible wall to the center area of ​​the crucible, thereby effectively improving the temperature uniformity at the crystal growth interface, which is beneficial to improving the growth quality of the crystal and also provides a basis for the growth of large-sized crystals. During the crystal growth process, the rotation of the turbine radiator can accelerate the directional flow rate of heat, effectively improve the heat dissipation rate and uniformity of the crystal, and make the generated crystallization latent heat timely and uniformly extracted from the growth interface, which is beneficial to improve the crystal growth rate. During the crystal growth process, the rotation speed and rotation direction of the turbine radiator can be adjusted in real time by controlling the seed crystal rod, and then the radial temperature gradient and axial heat dissipation rate at the crystal growth interface during the crystal growth process can be controlled in real time, which is beneficial to the long-term stable growth of the crystal.

[0028] The seed crystal holder and the seed crystal rod in the seed crystal assembly of the present invention are connected by a mortise and tenon structure and then locked by a locking component tube, so as to achieve a firm connection between the seed crystal rod and the seed crystal holder, and also can limit the turbine radiator to avoid sliding of the turbine radiator during the rotation of the seed crystal holder. The structure has good reliability, can withstand greater rotational torque, can meet greater torque transmission requirements, and better achieve high-speed rotation of large-sized crystals in a melt with higher viscosity during crystal growth, and can meet the process requirements of long-term high-speed rotation and pulling growth of large-sized silicon carbide crystals, and overcomes the limitations of the existing seed crystal rod and seed crystal holder due to the loose connection, such as the inability to achieve higher requirements of crystal rotation process, difficulty in supporting high-speed rotation of larger-sized crystals, easy wear or damage of the connecting thread, and poor reusability.

[0029] The device provided by the present invention can effectively improve the heat dissipation rate and uniformity of the crystal, and regulate the radial temperature gradient and axial heat dissipation rate at the crystal growth interface in real time, meet the heat dissipation requirements of each stage of crystal growth, and realize the long-term rapid and stable growth of large-size, high-quality silicon carbide single crystals.

[0030] The present invention is based on the provided device and is combined with the heat dissipation requirements at different stages of the entire silicon carbide crystal growth process. By adjusting the seed crystal rod to control the rotation direction and speed of the turbine radiator to regulate the heat dissipation rate on the back of the seed crystal, the heat dissipation rate and heat dissipation uniformity of the crystal can be effectively improved, and the radial temperature gradient and axial heat dissipation rate at the crystal growth interface can be regulated in real time to meet the heat dissipation requirements at each stage of crystal growth and achieve rapid growth of large-size, high-quality silicon carbide single crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a schematic structural diagram of a device for rapidly growing large-size, high-quality silicon carbide single crystals provided by the present invention;

[0033] Figure 2 It is a schematic diagram of the assembly process of a seed crystal assembly in a device for rapidly growing large-size, high-quality silicon carbide single crystals provided by the present invention;

[0034] Figure 3 It is a graph showing the change of the rotation direction and rotation speed of the seed crystal rod with time during the growth process of a large-size high-quality silicon carbide single crystal provided by the present invention;

[0035] Figure 4This is an optical photograph of a 4-inch high-quality silicon carbide single crystal provided in Example 2 of the present invention;

[0036] Figure 5 is an optical photograph of a 6-inch high-quality silicon carbide single crystal provided in Example 3 of the present invention;

[0037] Figure 6 This is a graph showing the rocking curve test results of a 6-inch high-quality silicon carbide single crystal provided in Example 3 of the present invention;

[0038] Figure 7 This is an optical photograph of a 4-inch silicon carbide single crystal provided in Comparative Example 1 of the present invention;

[0039] Figure 8 This is an optical photograph of a 6-inch silicon carbide single crystal provided in Comparative Example 2 of the present invention;

[0040] Fig. 9 This is an optical photograph of a 4-inch silicon carbide single crystal provided in Comparative Example 3 of the present invention.

[0041] Reference numerals:

[0042] 1- Crucible assembly;

[0043] 11-crucible; 12-promoting rotating parts;

[0044] 2-seed crystal assembly;

[0045] 21-seed crystal rod;

[0046] 211- tongue and groove structure;

[0047] 22-seed crystal holder;

[0048] 221-seed crystal supporting base plate; 222-connecting rod; 223-tenon structure;

[0049] 23-Turbine radiator;

[0050] 231-turbine shaft; 232-turbine blade;

[0051] 24-locking member;

[0052] 3- Insulation components;

[0053] 4- Heating component;

[0054] 5-Furnace cavity. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0056] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple groups" refers to two or more groups; the terms "connected", "fixed" and the like should be understood in a broad sense, for example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. The terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including a ..." do not exclude the existence of other identical factors in the process, method, article or device including the elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0057] In the description of this specification, it should be understood that the directional words such as "upper" and "lower" described in the embodiments of the present invention are described at the angles shown in the drawings and should not be understood as limiting the embodiments of the present invention. In addition, in the context, it should also be understood that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0058] like Figure 1-2As shown, the present invention provides a device for rapidly growing large-size high-quality silicon carbide single crystals, the device comprising a crucible assembly 1, a seed crystal assembly 2, a heating assembly 4 arranged outside the crucible assembly 1, and a heat preservation assembly 3 located between the heating assembly 4 and the crucible assembly 1; The crucible assembly 1 includes a crucible 11 and a pushing and rotating component 12 arranged under the crucible 11 for pushing and rotating the crucible 11; the seed crystal assembly 2 includes a seed crystal rod 21, a seed crystal holder 22 and a turbine radiator 23; the seed crystal holder 22 includes a seed crystal holder base plate 221 and a connecting rod 222 fixedly connected to the seed crystal holder base plate 221; the connecting rod 222 is connected to the seed crystal rod 21 through a mortise and tenon structure; the mortise and tenon structure is locked by a locking component 24; the turbine radiator 23 includes a turbine shaft cylinder 231 and turbine blades 232 distributed on the turbine shaft cylinder 231; the turbine shaft cylinder 231 is sleeved on the connecting rod 222; the turbine radiator 23 accelerates heat dissipation when rotating in a first direction, and inhibits heat dissipation when rotating in a second direction.

[0059] A turbine radiator is installed above the seed crystal holder substrate. The rotation of the seed crystal rod drives the turbine radiator and the seed crystal holder to rotate synchronously, so that the airflow in the crucible will perform orderly directional movement under the drive of the turbine radiator during the crystal growth process. It can not only limit the gas turbulence in the crucible but also quickly bring the heat at the crucible wall to the center area of ​​the crucible, thereby effectively improving the temperature uniformity at the crystal growth interface, which is beneficial to improving the growth quality of the crystal and also provides a basis for the growth of large-size high-quality crystals. During the crystal growth process, the rotation of the turbine radiator can accelerate the directional flow rate of heat, effectively improve the heat dissipation rate and uniformity of the crystal, and make the generated crystallization latent heat timely and uniformly extracted from the growth interface, which is beneficial to improve the crystal growth rate. During the crystal growth process, the rotation speed and rotation direction of the turbine radiator can be adjusted in real time by controlling the seed crystal rod, and then the radial temperature gradient and axial heat dissipation rate at the crystal growth interface during the crystal growth process can be controlled in real time, which is beneficial to the long-term stable growth of the crystal.

[0060] The seed crystal holder and the seed crystal rod in the seed crystal assembly of the present invention are connected by a mortise and tenon structure and then locked by a locking component tube, so as to achieve a firm connection between the seed crystal rod and the seed crystal holder, and also can limit the turbine radiator to avoid sliding of the turbine radiator during the rotation of the seed crystal holder. The structure has good reliability, can withstand greater rotational torque, can meet greater torque transmission requirements, and better achieve high-speed rotation of large-sized crystals in a melt with higher viscosity during crystal growth, and can meet the process requirements of long-term high-speed rotation and pulling growth of large-sized silicon carbide crystals, and overcomes the limitations of the existing seed crystal rod and seed crystal holder due to the loose connection, such as the inability to achieve higher requirements of crystal rotation process, difficulty in supporting high-speed rotation of larger-sized crystals, easy wear or damage of the connecting thread, and poor reusability.

[0061] like Figure 2 The assembly process of the seed crystal assembly and the turbine radiator in the device provided by the present invention includes: fitting the turbine radiator onto a connecting rod fixedly connected to a seed crystal support base plate, then connecting the connecting rod and the seed crystal rod through a mortise and tenon structure, and then locking the mortise and tenon structure through a locking component, while limiting the turbine radiator and preventing the turbine radiator from moving axially during rotation.

[0062] According to some preferred embodiments, the crucible 11 is a graphite crucible.

[0063] According to some preferred embodiments, the mortise and tenon structure includes a mortise and tenon structure 211 disposed at the lower end of the seed rod 21 and a tenon structure 223 disposed at the upper end of the connecting rod 222; the locking component 24 is fixed to the mortise and tenon structure by threads.

[0064] In some preferred embodiments of the present invention, the cross-section of the turbine shaft cylinder and the connecting rod is polygonal, preferably one of a triangle, square, rectangle, trapezoid, pentagon, and hexagon; in this way, a greater torque can be provided during rotation while preventing the turbine radiator from sliding relative to the connecting rod.

[0065] According to some preferred embodiments, the device further comprises a furnace chamber 5 .

[0066] The present invention also provides a method for rapidly growing large-size, high-quality silicon carbide single crystals, which is implemented by the device described in the first aspect, and the method comprises the following steps:

[0067] S1. placing the flux and silicon in a crucible and heating the mixture until it is completely liquefied to obtain a melt;

[0068] S2. After rotating the seed crystal rod in a second direction at a first preset speed for a first preset time, the seed crystal is brought into contact with the melt to grow a crystal to obtain a silicon carbide single crystal; during the crystal growth process, the rotation direction and speed of the seed crystal rod are regulated according to the heat dissipation requirements at different stages; the rotation direction of the crucible is always opposite to the rotation direction of the seed crystal.

[0069] The present invention is based on the provided device and is combined with the heat dissipation requirements at different stages of the entire silicon carbide crystal growth process. By adjusting the seed crystal rod to control the rotation direction and speed of the turbine radiator to regulate the heat dissipation rate on the back of the seed crystal, the heat dissipation rate and heat dissipation uniformity of the crystal can be effectively improved, and the radial temperature gradient and axial heat dissipation rate at the crystal growth interface can be regulated in real time to meet the heat dissipation requirements at each stage of crystal growth, thereby achieving long-term, rapid and stable growth of large-size, high-quality silicon carbide single crystals.

[0070] According to some preferred embodiments, during the crystal growth process, after the seed crystal contacts the melt, the seed crystal rod rotates at a second preset speed along the second direction for a second preset time, and then at a third preset time, the speed is decelerated to 0 and accelerated to a third preset speed along the first direction, and then rotated at the third preset speed for a fourth preset time, and finally, according to the thermal insulation performance attenuation curve of the thermal insulation material used in the thermal insulation component, the speed is reduced to a fourth preset speed at a fifth preset time to ensure that the heat dissipation rate remains stable.

[0071] According to some preferred embodiments, the second preset speed is greater than the first preset speed;

[0072] The third preset rotation speed is greater than the second preset rotation speed.

[0073] According to some preferred embodiments, the first preset rotation speed is 5-30 rpm (for example, it may be 5 rpm, 10 rpm, 15 rpm, 20 rpm, 25 rpm or 30 rpm).

[0074] According to some preferred embodiments, the second preset rotation speed is 10-60 rpm (for example, it may be 10 rpm, 20 rpm, 30 rpm, 40 rpm, 50 rpm or 60 rpm).

[0075] According to some preferred embodiments, the third preset rotation speed is 60-240 rpm (for example, it may be 60 rpm, 80 rpm, 100 rpm, 120 rpm, 150 rpm, 180 rpm, 200 rpm, 220 rpm or 240 rpm).

[0076] According to some preferred embodiments, during the crystal growth process, the rotation speed of the crucible is 2-10 rpm (for example, it may be 2 rpm, 3 rpm, 4 rpm, 5 rpm, 6 rpm, 7 rpm, 8 rpm, 9 rpm or 10 rpm).

[0077] According to some preferred embodiments, during the crystal growth process, the crucible moves upward at a speed of 0 to 1000 μm / h (for example, 0 μm / h, 100 μm / h, 200 μm / h, 300 μm / h, 400 μm / h, 500 μm / h, 600 μm / h, 700 μm / h, 800 μm / h, 900 μm / h or 1000 μm / h).

[0078] According to some preferred embodiments, during the crystal growth process, the pulling speed of the seed rod is 0~1500μm / h (for example, it can be 0μm / h, 100μm / h, 200μm / h, 300μm / h, 400μm / h, 500μm / h, 600μm / h, 700μm / h, 800μm / h, 900μm / h, 1000μm / h, 1100μm / h, 1200μm / h, 1300μm / h, 1400μm / h or 1500μm / h).

[0079] According to some preferred embodiments, the second preset time is 0.5-2 hours (for example, it can be 0.5 hours, 0.6 hours, 0.8 hours, 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours or 2 hours).

[0080] According to some preferred embodiments, the third preset time is 0.5-2 h (for example, it may be 0.5 h, 0.6 h, 0.8 h, 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h or 2 h).

[0081] According to some preferred embodiments, the fourth preset time is 10-20 hours (for example, it may be 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours or 20 hours).

[0082] According to some preferred embodiments, the fifth preset time is 20 to 60 hours (for example, it can be 20 hours, 24 hours, 30 hours, 36 hours, 40 hours, 48 ​​hours, 50 hours, 56 hours, 58 hours or 60 hours).

[0083] According to some preferred embodiments, after the crystal growth is completed, at a sixth preset time, the rotation speed is reduced to 0 and accelerated along the second direction to a fifth preset rotation speed, and then maintained for a seventh preset time.

[0084] According to some preferred embodiments, the sixth preset time is 10 to 60 minutes (for example, it may be 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes or 60 minutes).

[0085] According to some preferred embodiments, the seventh preset time is 10 to 30 hours (for example, it can be 10 hours, 12 hours, 14 hours, 15 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours or 30 hours).

[0086] In some specific embodiments of the present invention, the seed rod rotation process in the silicon carbide crystal growth process includes the following multiple stages, such as Figure 3 shown.

[0087] Phase 1: 0 -t 1 (first preset time), at this time, the seed crystal has not yet contacted the melt, and the seed crystal moves along the second direction at a first preset speed v 1 Rotate at a constant speed to ensure that the seed crystal is evenly heated before growth;

[0088] Phase 2: 1 -t 2 (Second preset time), t 1 At this moment, the seed crystal contacts the melt and crystal growth begins. At this time, the seed crystal speed changes to the second preset speed. v 2 , and then at a constant speed v 2 Rotate at a constant speed, v 2 > v 1 At this time, the larger second direction rotation of the turbine radiator reduces the heat dissipation rate of the seed crystal in the reverse direction, inhibits the crystal growth, and causes the seed crystal surface to reversely dissolve to obtain an ideal initial growth surface, which is beneficial to improving the crystal growth quality;

[0089] Phase 3: 2 -t 3 (third preset time), first uniformly rotate the seed crystal rod from v 2 Reduce to 0, and then accelerate evenly along the first direction to the third preset speed v 3 (in, v 3 > v 2 ), thereby achieving a slow increase in the heat dissipation rate on the back of the seed crystal and gradually increasing the crystal growth rate;

[0090] Stage 4: t 3 -t4 (Fourth preset time), the seed crystal rotates at a constant speed v 3 Rotate at a constant speed to maintain a stable heat dissipation rate;

[0091] Stage 5: t 4 -t 5 (fifth preset time), considering that during the long-term growth process, the heat preservation performance of the heat preservation material continues to decline, which will cause the heat dissipation to become faster. Therefore, according to the attenuation curve of the heat preservation performance of the heat preservation material, the speed of the radiator is set from the third preset speed to v 3 Reduce to the fourth preset speed v 4 , dynamically compensate the heat dissipation rate to maintain a stable heat dissipation rate;

[0092] Stage 6: t 5 -t 6 (sixth preset time), t 5 Always slowly pull the crystal out of the melt; first, uniformly increase the rotation speed of the seed crystal rod from the fourth preset rotation speed to v 4 Reduce to 0, and then accelerate evenly along the first direction to the first preset speed v 1 , in order to reduce the heat dissipation rate of the seed crystal in the back direction, and prevent the crystal from dissipating heat too quickly and causing thermal stress cracking of the crystal;

[0093] Stage 7: t 6 -t 7 (Seventh preset time), the seed crystal rotates at a constant speed v 1 The uniform rotation ensures uniform radial temperature distribution of the crystal while allowing the crystal to be annealed in situ at a lower heat dissipation rate after growth. 6 The rotation speed of the seed crystal rod at the moment is not necessarily v 1 , which is only an example and not a limitation.

[0094] In order to more clearly illustrate the technical solutions and advantages of the present invention, the present invention is further described below in conjunction with the examples. The present invention does not specifically limit the sources of the reagents used in the examples and comparative examples, and the reagents can be directly purchased or synthesized by themselves.

[0095] The testing method for the performance data of the silicon carbide crystals grown in the embodiments of the present invention and the comparative examples is as follows:

[0096] Crystal size and quality measurement: Place the processed crystal on standard coordinate paper or standard caliper to confirm the size; Use laser confocal Raman scattering to measure the crystal form; Use XRD diffractometer to measure the rocking curve of the crystal to determine its crystalline quality.

[0097] Example 1

[0098] like Figure 1-2 As shown, a device for rapidly growing large-size, high-quality silicon carbide single crystals comprises:

[0099] A crucible assembly 1, a seed crystal assembly 2, a heating assembly 4 arranged outside the crucible assembly 1, and a heat preservation assembly 3 located between the heating assembly 4 and the crucible assembly 1; wherein the heat preservation assembly 3 is a heat preservation material, and the heating assembly 4 is an induction heating coil;

[0100] The crucible assembly 1 comprises a crucible 11 and a driving and rotating component 12 for driving the crucible 11 to rotate; the crucible 11 is a graphite crucible;

[0101] The seed crystal assembly includes a seed crystal rod 21, a seed crystal holder 22 and a turbine radiator 23; the seed crystal holder 22 includes a seed crystal holder base plate 221 and a connecting rod 222 fixedly connected to the seed crystal holder base plate 221; the connecting rod 222 is connected to the seed crystal rod 21 through a mortise and tenon structure; the mortise and tenon structure includes a mortise and tenon structure 211 arranged at the lower end of the seed crystal rod 21 and a tenon structure 223 arranged at the upper end of the connecting rod 222; the mortise and tenon structure is locked by a locking component 24; the locking component 24 is fixed to the mortise and tenon structure 211 by threads; the turbine radiator 23 includes a turbine shaft cylinder 231 and turbine blades 232 distributed on the turbine shaft cylinder 231; the turbine shaft cylinder 231 is sleeved on the connecting rod 222; the turbine radiator 23 accelerates heat dissipation when rotating in a first direction, and inhibits heat dissipation when rotating in a second direction.

[0102] Example 2

[0103] A method for rapidly growing large-size, high-quality silicon carbide single crystals is implemented by the apparatus of embodiment 1, comprising:

[0104] S1. After assembling the device, close the furnace chamber and evacuate the chamber. When the chamber pressure is less than or equal to 1×10 -4 After Pa, high-purity argon is filled into the furnace chamber as a protective gas, and flux and silicon are placed in a crucible, and the crucible is heated to 1800°C to completely liquefy the raw materials in the crucible to obtain a melt, wherein the flux is Cr; the mass ratio of Cr to Si is 40:60, and the total mass of Cr and Si is 12 kg;

[0105] S2. After the temperature of the mixed melt is stabilized, the seed crystal rod is rotated along the second direction at the first preset speed (10 rpm) for the first preset time (30 min), and the seed crystal is brought into contact with the melt to grow a crystal to obtain a silicon carbide single crystal; during the crystal growth process, the seed crystal is a silicon carbide wafer with a diameter of 100 mm, the diameter of the seed crystal support substrate is 100 mm, and the maximum diameter of the bottom of the turbine radiator is 120 mm. After the silicon carbide seed crystal is in contact with the melt, the seed crystal rod is rotated along the second direction at the second preset speed (30 rpm) for the second preset time (1 h), and then at the third preset time (1.5 h), the speed is decelerated to 0 and accelerated to the third preset speed (200 rpm) along the first direction, and rotated at the third preset speed (200 rpm) for the fourth preset time (15 h). Finally, according to the insulation performance attenuation curve of the insulation material used in the insulation component, the speed is reduced to the fourth preset speed (150 rpm) at the fifth preset time (50 h) to ensure that the heat dissipation rate remains stable. During the crystal growth process, the upward pulling speed of the seed crystal rod is 560μm / h, the upward moving speed of the crucible is 360μm / h, the rotation direction of the crucible is always opposite to the seed crystal rod, and the rotation speed of the crucible is 5 rpm. After the crystal growth is completed, at the sixth preset time (30 min), the speed is decelerated to 0 and accelerated to the fifth preset speed (20 rpm) in the second direction, and maintained for the seventh preset time (24 h).

[0106] The optical photograph of the 4-inch silicon carbide single crystal grown in this example is as follows: Figure 4 As shown, the crystal surface is the original growth surface without processing. It can be seen that the crystal growth surface is very smooth, indicating that the crystal has excellent crystallization quality. The average growth rate of the crystal is 200 μm / h.

[0107] Example 3

[0108] A method for rapidly growing large-size, high-quality silicon carbide single crystals is implemented by the apparatus of embodiment 1, comprising:

[0109] S1. After assembling the device, close the furnace chamber and evacuate the chamber. When the chamber pressure is less than or equal to 1×10 -4 After Pa, high-purity argon is filled into the furnace chamber as a protective gas, and flux and silicon are placed in a crucible, and the crucible is heated to 1800°C to completely liquefy the raw materials in the crucible to obtain a melt, wherein the flux is Cr; the mass ratio of Cr to Si is 40:60, and the total mass of Cr and Si is 12 kg;

[0110] S2. After the temperature of the mixed melt is stabilized, the seed crystal rod is rotated along the second direction at the first preset speed (20 rpm) for the first preset time (30 min), and the seed crystal is brought into contact with the melt to grow a crystal to obtain a silicon carbide single crystal; during the crystal growth process, the seed crystal is a silicon carbide wafer with a diameter of 150 mm, the diameter of the seed crystal support substrate is 150 mm, and the maximum diameter of the bottom of the turbine radiator is 170 mm. After the silicon carbide seed crystal is brought into contact with the melt, the seed crystal rod is rotated along the second direction at the second preset speed (50 rpm) for the second preset time (1 h), and then the speed is decelerated to 0 at the third preset time (2 h) and accelerated to the third preset speed (200 rpm) along the first direction, and rotated at the third preset speed (200 rpm) for the fourth preset time (510 h). Finally, according to the insulation performance attenuation curve of the insulation material used in the insulation component, the speed is reduced to the fourth preset speed (120 rpm) at the fifth preset time (50 h) to ensure that the heat dissipation rate remains stable. During the crystal growth process, the upward pulling speed of the seed crystal rod is 500 μm / h, the upward moving speed of the crucible is 300 μm / h, the rotation direction of the crucible is always opposite to that of the seed crystal rod, and the rotation speed of the crucible is 5 rpm. After the crystal growth is completed, the seed crystal rotation speed is decelerated to 0 at the sixth preset time (1 h) and accelerated to the fifth preset speed (40 rpm) in the second direction, and maintained for the seventh preset time (30 h).

[0111] The optical photograph of the 6-inch silicon carbide single crystal grown in this embodiment is as follows: Figure 5 As shown, the crystal surface is the original growth surface without processing. It can be seen that the crystal growth surface is very smooth, indicating that the crystal has excellent crystallization quality. The average growth rate of the crystal is 160 μm / h.

[0112] The X-ray rocking curve test results of the 6-inch silicon carbide single crystal grown in this embodiment are as follows: Figure 6 As shown, the half-widths of the X-ray rocking curves of five evenly distributed points are 32.4, 32.4, 28.8, 32.4, and 28.8 arcsec, respectively, and the average half-width is 30.96 arcsec, proving that high-quality 6-inch silicon carbide crystals can be grown using the apparatus and method provided by the present invention.

[0113] Comparative Example 1

[0114] The embodiment is basically the same as the second embodiment, except that the device for growing silicon carbide single crystal is not provided with a turbine radiator 23 .

[0115] Optical photographs of 4-inch silicon carbide single crystals grown using the apparatus and method of this comparative example, as shown in FIG. Figure 7As shown, it can be clearly seen that although the crystal center area has high crystal quality and a smooth surface, there are a large number of defects in the edge area, and the average growth rate of the crystal is 60μm / h. It can be seen that without the device provided by the present invention, the radial temperature difference of the solid-liquid interface is large, and the heat dissipation efficiency is low, resulting in poor crystal quality in the edge area.

[0116] Comparative Example 2

[0117] The embodiment is basically the same as the third embodiment, except that the apparatus for growing silicon carbide crystals is not provided with a turbine radiator 23 .

[0118] After the silicon carbide seed crystal contacts the melt, the seed crystal rod rotates in a single phase at a speed of 200 rpm until the growth is completed.

[0119] The optical photograph of the 6-inch silicon carbide single crystal grown by the apparatus and method described in this comparative example is as follows: Figure 8 As shown, it can be clearly seen that there are a large number of defects on the crystal surface, the crystal quality is very poor, and the average growth rate of the crystal is 50 μm / h. It can be seen that when growing large-sized silicon carbide crystals without using the device and method provided by the present invention, the problem of slow heat dissipation and uneven heat dissipation is more prominent.

[0120] Comparative Example 3

[0121] It is basically the same as Example 2, except that after the silicon carbide seed crystal contacts the melt, the seed crystal rod rotates unidirectionally at a speed of 200 rpm until the crystal growth is completed.

[0122] Optical photographs of 4-inch silicon carbide single crystals grown using the apparatus and method described in this comparative example, as shown in FIG. Fig. 9 As shown in the figure, there is no dynamic control process of heat dissipation rate during the crystal growth process. Due to the gradual degradation of the insulation performance of the insulation material in the later stage of crystal growth, the heat dissipation rate of the crystal gradually increases, resulting in a large number of crystal defects caused by the too fast growth rate in the later stage of crystal growth. The average growth rate of the crystal is 230 μm / h.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for rapidly growing large-size, high-quality silicon carbide single crystals, characterized in that: The method comprises the following steps: S1. placing the flux and silicon in a crucible and heating the mixture until it is completely liquefied to obtain a melt; S2. After rotating the seed crystal rod along the second direction at a first preset speed for a first preset time, the seed crystal is brought into contact with the melt to grow a crystal to obtain a silicon carbide single crystal; during the crystal growth process, the rotation direction and speed of the seed crystal rod are regulated according to the heat dissipation requirements at different stages, and the rotation direction of the crucible is always opposite to the rotation direction of the seed crystal; during the crystal growth process, after the seed crystal is in contact with the melt, the seed crystal rod is rotated along the second direction at a second preset speed for a second preset time, and then at a third preset time, the speed is decelerated to 0 and accelerated along the first direction to a third preset speed, and then rotated at the third preset speed for a fourth preset time, and finally, according to the insulation performance attenuation curve of the insulation material used in the insulation component, the speed is reduced to a fourth preset speed at a fifth preset time to ensure that the heat dissipation rate remains stable; the second preset speed is greater than the first preset speed; the third preset speed is greater than the second preset speed; the first preset speed is 5~30 rpm; the second preset speed is 10~60 rpm; the third preset speed is 60~240 rpm; The method is implemented by a device for rapidly growing large-size and high-quality silicon carbide single crystals, the device comprising a crucible assembly, a seed crystal assembly, a heating assembly arranged outside the crucible assembly, and a heat preservation assembly located between the heating assembly and the crucible assembly; The crucible assembly includes a crucible and a pushing and rotating component disposed below the crucible for pushing and rotating the crucible; The seed crystal assembly comprises a seed crystal rod, a seed crystal holder and a turbine radiator; the seed crystal holder comprises a seed crystal holder base plate and a connecting rod fixedly connected to the seed crystal holder base plate; the connecting rod is connected to the seed crystal rod through a mortise and tenon structure; the mortise and tenon structure is locked by a locking component; The turbine radiator comprises a turbine shaft cylinder and turbine blades distributed on the turbine shaft cylinder; the turbine shaft cylinder is sleeved on the connecting rod; the turbine radiator accelerates heat dissipation when rotating in a first direction, and suppresses heat dissipation when rotating in a second direction.

2. The method according to claim 1, characterized in that: The crucible is a graphite crucible.

3. The method according to claim 1, characterized in that The mortise and tenon structure comprises a mortise and tenon structure arranged at the lower end of the seed crystal rod and a tenon structure arranged at the upper end of the connecting rod; the locking component is fixed to the mortise and tenon structure by threads.

4. The method according to claim 1, characterized in that: During the crystal growth process, the crucible rotates at a speed of 2 to 10 rpm; The crucible moves upward at a speed of 0 to 1000 μm / h; and / or The pulling speed of the seed crystal rod is 0-1500 μm / h.

5. The method according to claim 1, characterized in that The second preset time is 0.5~2h; The third preset time is 0.5~2h; The fourth preset time is 10 to 20 hours; and / or The fifth preset time is 20 to 60 hours.

6. The method according to claim 1, characterized in that After the crystal growth is completed, at a sixth preset time, the rotation speed is reduced to 0 and accelerated along the second direction to a fifth preset rotation speed, and then maintained for a seventh preset time.

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