Method and apparatus for growing silicon carbide single crystal by liquid phase method

Abstract

The present application relates to the technical field of silicon carbide single crystal preparation, and particularly relates to a method and device for growing silicon carbide single crystal by liquid phase method. The present application provides a method for growing silicon carbide single crystal by liquid phase method, which comprises: placing a material containing solvent elements in a crucible resistant to high-temperature melt corrosion to heat and melt, and obtaining a high-temperature solution in the crucible; placing a raw material block for preparing silicon carbide in the high-temperature solution to provide carbon elements and silicon elements in the high-temperature solution; and using a first rotating pulling rod to drive a silicon carbide seed crystal into the crucible, so that the silicon carbide seed crystal is in contact with a liquid surface of the high-temperature solution to grow silicon carbide single crystal. The present application provides a method and device for growing silicon carbide single crystal by liquid phase method, and can realize long-time stable growth of silicon carbide crystal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon carbide single crystal preparation, in particular to a method and device for growing silicon carbide single crystal by liquid phase method. BACKGROUND

[0002] As one of the typical representatives of wide band gap semiconductors, silicon carbide has excellent characteristics such as large band gap, high breakdown field strength, high saturated electron mobility, high thermal conductivity, good thermal stability and chemical stability, and is an ideal substrate material for making high-frequency, high-voltage, high-efficiency and radiation-resistant, high-temperature-resistant large power devices and blue light emitting diodes, which has a huge application prospect in new energy vehicles, high-speed rail transportation, aerospace, high-voltage smart grid and clean energy, etc., and therefore has been widely concerned by the academic circles and governments of various countries.

[0003] At present, the crystalline quality and manufacturing cost of silicon carbide single crystal substrate are still one of the main factors restricting the further expansion of its application. Exploring and researching the method of obtaining high-quality, large-size and low-cost silicon carbide single crystal substrate plays a very important role in fully exerting the great application potential of silicon carbide.

[0004] At present, the mainstream method for growing silicon carbide single crystal substrate is physical vapor transport method (PVT), although this method has been relatively mature after decades of continuous research and improvement, and can currently supply a large amount of silicon carbide single crystal substrate to the market, but it still has some unavoidable limitations, mainly in the aspects of unstable growth environment, difficult to eliminate defects, low yield, high cost, difficult to expand the diameter, and difficult to realize continuous and effective P-type doping.

[0005] Compared with the gas phase method, the liquid phase method has low growth temperature, relatively stable growth environment, can realize the growth of crystal in the near equilibrium state, not only has relatively low growth cost, but also can theoretically realize higher crystal quality. In addition, the liquid phase method also has good application prospect in the obtaining of P-type substrate and crystal diameter expansion. Therefore, in recent years, the liquid phase method has been paid more and more attention, and related technologies have also made breakthrough progress. In the growth of silicon carbide single crystal by liquid phase method, the carbon source for crystal growth is provided by etching the crucible, which will cause the stability of the growth time to be very poor due to the continuous corrosion of the crucible during crystal growth. In addition, only Si and C elements will continuously precipitate from the solution during the growth process, and C element can be continuously supplemented by etching the crucible, but Si element is consumed without being supplemented during the growth process, which will cause the Si content in the high-temperature solution to continuously decrease during the growth process, and further seriously affect the long-term stability of crystal growth. Therefore, it is very important to develop a method that can realize long-term stable growth of crystal for the further development of the liquid phase method. SUMMARY

[0006] The embodiment of the present application provides a method and device for growing silicon carbide single crystal by liquid phase method, and long-time stable growth of silicon carbide crystal can be realized.

[0007] In a first aspect, the embodiment of the present application provides a method for growing silicon carbide single crystal by liquid phase method, comprising:

[0008] placing a material containing solvent elements into a crucible resistant to corrosion of high-temperature melt to heat and melt, and obtaining a high-temperature solution in the crucible;

[0009] placing a raw material block for preparing silicon carbide into the high-temperature solution to provide carbon elements and silicon elements in the high-temperature solution;

[0010] using a first rotating pulling rod to drive a silicon carbide seed crystal into the crucible, so that the silicon carbide seed crystal is in contact with a liquid surface of the high-temperature solution to grow silicon carbide single crystal.

[0011] In a possible design, before the step of placing the raw material block for preparing silicon carbide into the high-temperature solution to provide carbon elements and silicon elements in the high-temperature solution, the method further comprises:

[0012] rotating the crucible to uniformly mix the high-temperature solution; wherein the rotating speed of the crucible is 10-60 rpm;

[0013] rotating the silicon carbide seed crystal and the raw material block to uniformly heat the silicon carbide seed crystal and the raw material block; wherein the rotating speed of the silicon carbide seed crystal and the raw material block is 10-60 rpm.

[0014] In a possible design, the step of placing the raw material block for preparing silicon carbide into the high-temperature solution comprises:

[0015] using a second rotating pulling rod to immerse the raw material block for preparing silicon carbide into the high-temperature solution;

[0016] After the step of using the first rotating pulling rod to drive the silicon carbide seed crystal into the crucible, so that the silicon carbide seed crystal is in contact with the liquid surface of the high-temperature solution to grow silicon carbide single crystal, the method further comprises:

[0017] monitoring the liquid surface height of the high-temperature solution in the crucible, and using the second rotating pulling rod to adjust the volume of the raw material block immersed in the high-temperature solution to keep the liquid surface height of the high-temperature solution unchanged.

[0018] In a possible design, the step of placing the raw material block for preparing silicon carbide into the high-temperature solution further comprises:

[0019] after the high-temperature solution is uniformly mixed, immersing the raw material block into the high-temperature solution by using the second rotating pulling rod;

[0020] rotating the crucible in a first direction while rotating the raw material block in a second direction at a first rotation speed; wherein the first direction and the second direction are opposite.

[0021] In a possible design, after the step of driving the silicon carbide seed crystal into the crucible by the first rotating pulling rod, and making the silicon carbide seed crystal contact with the liquid surface of the high-temperature solution to grow the silicon carbide single crystal, the method further comprises:

[0022] maintaining the rotation of the crucible in the first direction, reducing the rotation speed of the raw material block from the first rotation speed to a second rotation speed, and rotating the silicon carbide seed crystal in a second direction.

[0023] In a possible design, the rotation speed of the crucible is 5-30 rpm, the first rotation speed is 50-300 rpm, the second rotation speed is 10-100 rpm, and the rotation speed of the silicon carbide seed crystal is 30-200 rpm.

[0024] In a possible design, the crucible comprises a tantalum carbide crucible.

[0025] or,

[0026] The inner wall of the crucible is plated with a tantalum carbide corrosion-resistant coating.

[0027] In a possible design, the method further comprises:

[0028] The crucible is wrapped with an insulation layer outside, the insulation layer comprises a first channel and a second channel, the first rotating pulling rod passes through the first channel, the second rotating pulling rod passes through the second channel, and the caliber of the first channel is larger than the caliber of the second channel.

[0029] In a possible design, the caliber of the first channel is 80-200 mm, and the caliber of the second channel is 20-50 mm.

[0030] In a second aspect, the embodiments of the present application further provide a device for growing silicon carbide single crystal by liquid phase method, which is used to realize the method described above, and the device comprises a crucible, an insulation layer, an induction coil, a first rotating pulling rod, a second rotating pulling rod, and a crucible rotating device.

[0031] The crucible in the growth furnace is used to contain the high-temperature solution, the insulation layer is arranged outside the crucible to keep the crucible warm, the induction coil is used to heat the crucible, the first rotating pulling rod is used to rotate and pull the silicon carbide seed crystal, the second rotating pulling rod is used to rotate and pull the raw material block, and the crucible rotating device is used to rotate the crucible.

[0032] Compared with the prior art, the present application has at least the following beneficial effects:

[0033] The silicon carbide raw material block provides Si and C elements for crystal growth, which can ensure that the concentration of Si and C elements in the solution remains unchanged during long-time growth, and is conducive to stable growth for a long time. Specifically, the carbon source and silicon source required for the growth of the silicon carbide single crystal come from the raw material block, the raw material block is immersed in a high-temperature solution, the high-temperature solution will dissolve the raw material block, and the carbon element and the silicon element are obtained in the high-temperature solution. With the growth of the silicon carbide, the carbon element and the silicon element in the solution are consumed, on the other hand, the raw material block is also continuously dissolved, compensating the carbon element and the silicon element to the high-temperature solution, and finally realizing the long-time stable growth of the silicon carbide. In addition, since the carbon element in the growth raw material of the silicon carbide single crystal comes from the raw material block, the crucible itself does not need to provide a carbon source. In order to ensure the stable growth of the silicon carbide single crystal, a crucible resistant to corrosion of the high-temperature melt is selected, so that after long-time growth, the crucible does not need to be replaced, and only the raw material block needs to be simply supplemented. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0035] Figure 1 is a structure schematic diagram of a method and device for growing a silicon carbide single crystal by a liquid phase method provided by an embodiment of the present application;

[0036] Figure 2 is an optical photo of a high-quality silicon carbide single crystal provided by embodiment 1 of the present application;

[0037] Figure 3 is a cross-sectional optical photo of a crucible after growth provided by comparative example 1 of the present application, and the crucible sidewall has been partially dissolved by the flux;

[0038] Figure 4 is the growth result of the silicon carbide crystal provided by comparative example 3 of the present application, and a significant necking phenomenon occurs in the later stage of crystal growth.

[0039] In the drawings:

[0040] 1-controller; 2-signal transmission line; 3-first driving device; 4-second driving device; 5-laser range finder; 6-second rotary lifting rod; 7-first rotary lifting rod; 8-heat preservation layer; 9-growth furnace; 10-crucible; 11-induction coil; 12-raw material block; 13-seed crystal holder; 14-silicon carbide seed crystal; 15-high-temperature solution; 16-crucible support tray; 17-crucible rotating device. DETAILED DESCRIPTION

[0041] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0042] In the description of the embodiments of the present application, unless explicitly defined and limited, the terms "first", "second" are only for the purpose of description and cannot be understood as indicating or implying relative importance; unless otherwise specified or stated, the term "plurality" means two or more; the terms "connection", "fixation" and the like should be understood in a broad sense, for example, "connection" can be fixed connection, can be detachable connection, or integral connection, or electrical connection; can be directly connected, or indirectly connected through an intermediate medium. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0043] In the description of the present application, it should be understood that the "upper", "lower" and the like described in the embodiments of the present application are described from the angle shown in the drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it should also be understood that when referring to one element connected to another element "on" or "under", it can be directly connected to another element "on" or "under", or indirectly connected to another element "on" or "under" through an intermediate element.

[0044] As shown in Figure 1 The embodiments of the present application provide a method for growing silicon carbide single crystal by liquid phase method, comprising:

[0045] The material containing solvent elements is placed in a crucible 10 resistant to high-temperature melt corrosion for heating and melting, and a high-temperature solution 15 is obtained in the crucible 10;

[0046] The raw material block 12 for preparing silicon carbide is placed in the high-temperature solution 15 to provide carbon elements and silicon elements for the high-temperature solution 15;

[0047] The first rotating pulling rod 7 is used to drive the silicon carbide seed crystal 14 into the crucible 10, so that the silicon carbide seed crystal 14 is in contact with the liquid surface of the high-temperature solution 15 to grow silicon carbide single crystal.

[0048] The silicon carbide raw material block 12 provides Si and C elements for crystal growth, which can ensure that the concentration of Si and C elements in the solution remains unchanged during long-time growth, and is conducive to stable growth for a long time. Specifically, the carbon source and silicon source required for the growth of the silicon carbide single crystal come from the raw material block 12, the raw material block 12 is immersed in the high-temperature solution 15, the high-temperature solution 15 will dissolve the raw material block 12, and the carbon element and the silicon element are obtained in the high-temperature solution 15, with the growth of the silicon carbide, the carbon element and the silicon element in the solution are consumed, on the other hand, the raw material block 12 is also continuously dissolved, and the carbon element and the silicon element are compensated to the high-temperature solution 15, and finally the long-time stable growth of the silicon carbide is realized. In addition, since the carbon element in the growth raw material of the silicon carbide single crystal comes from the raw material block 12, the crucible 10 itself does not need to provide a carbon source, in order to ensure the stable growth of the silicon carbide single crystal, the crucible 10 resistant to corrosion of the high-temperature melt is selected, and thus after long-time growth, the crucible 10 does not need to be replaced, and only the raw material block 12 needs to be simply supplemented.

[0049] In the embodiment, the element composition of the raw material block satisfies the molar ratio Si:C = 1:1, and the shape is a cylinder or a prism, which can be a single crystal silicon carbide block with poor crystal quality, a polycrystalline silicon carbide block, or a block sintered after uniform mixing of silicon and carbon.

[0050] In some embodiments of the present application, the element composition of the solvent raw material is Si + transition metal elements (including Cr, Fe, Ni, Ti, Al, Mn, Co, Sc, etc.) + rare earth elements (including Y, Ce, Pr, etc.).

[0051] In some embodiments of the present application, before placing the raw material block 12 prepared from silicon carbide in the high-temperature solution 15 to provide carbon elements and silicon elements for the high-temperature solution 15, the following steps are further included:

[0052] The crucible 10 is rotated to mix the high-temperature solution uniformly; wherein the rotation speed of the crucible 10 is 10-60 rpm;

[0053] The silicon carbide seed crystal 14 and the raw material block 12 are rotated to heat the silicon carbide seed crystal 14 and the raw material block 12 uniformly; wherein the rotation speed of the silicon carbide seed crystal 14 and the raw material block 12 is 10-60 rpm.

[0054] In the embodiment, the crucible is rotated to rotate the molten high-temperature solution, and then to mix the internal components uniformly. When the silicon carbide seed crystal 14 and the raw material block 12 are not immersed in the high-temperature solution, the silicon carbide seed crystal 14 and the raw material block 12 are first rotated, which can preheat the silicon carbide seed crystal 14 and the raw material block 12 uniformly.

[0055] In some embodiments of the present application, the raw material block 12 prepared from silicon carbide is placed in the high-temperature solution 15, including:

[0056] The raw material block 12 prepared by silicon carbide is immersed into the high-temperature solution 15 by the second rotating pulling rod 6;

[0057] After the silicon carbide seed crystal 14 is brought into the crucible 10 by the first rotating pulling rod 7 and the silicon carbide seed crystal 14 is contacted with the liquid surface of the high-temperature solution 15 to grow the silicon carbide single crystal, the method further comprises:

[0058] The liquid level of the high-temperature solution 15 in the crucible 10 is monitored, and the volume of the raw material block 12 immersed into the high-temperature solution 15 is adjusted by the second rotating pulling rod 6 to keep the liquid level of the high-temperature solution 15 unchanged.

[0059] In the embodiment, the depth of the raw material block 12 immersed into the high-temperature solution 15 can be controlled to control the liquid level during the crystal growth process, and the liquid level can be kept stable during the long-time growth process by combining the liquid level monitoring and feedback device, which is very beneficial to the growth of high-quality crystals. Specifically, the laser range finder 5 can be used to detect the liquid level of the high-temperature solution, the laser range finder 5 is connected with the controller 1 through the signal transmission line 2, the laser range finder 5 feeds back the collected liquid level information to the controller 1, and the controller 1 controls the second rotating pulling rod 6 to keep the height of the high-temperature solution 15 unchanged. It should be noted that the laser range finder 5 can be arranged outside the heat preservation layer 8, and in order to facilitate the laser range finder 5 to measure the liquid level position of the high-temperature solution 15, a light-transmitting hole can be arranged on the heat preservation layer 8 so that the laser can pass through the heat preservation layer 8 to reach the liquid surface of the high-temperature solution 15.

[0060] In the embodiment, the controller 1 can control the first rotating pulling rod 7 and the second rotating pulling rod 6 to ascend and descend and rotate through the first driving device 3 and the second driving device 4 respectively.

[0061] In some embodiments of the present application, the raw material block 12 prepared by silicon carbide is placed in the high-temperature solution 15, and the method further comprises:

[0062] After the high-temperature solution is uniformly mixed, the raw material block is immersed into the high-temperature solution by the second rotating pulling rod;

[0063] The crucible 10 is rotated in a first direction, and the raw material block 12 is rotated in a second direction at a first rotating speed; wherein the first direction and the second direction are opposite.

[0064] In the embodiment, the raw material block 12 is first immersed into the high-temperature solution, and the crucible 10 and the raw material block are reversely rotated, so that the Si and C elements in the raw material block are quickly dissolved into the high-temperature solution to reach saturation.

[0065] In some embodiments of the present application, after the silicon carbide seed crystal 14 is brought into the crucible 10 by the first rotating pulling rod 7 and the silicon carbide seed crystal 14 is contacted with the liquid surface of the high-temperature solution 15 to grow the silicon carbide single crystal, the method further comprises:

[0066] The crucible is kept rotating along the first direction, and the rotation speed of the raw material block is reduced from the first rotation speed to a second rotation speed, while the silicon carbide seed crystal 14 is rotated along the second direction.

[0067] In the present embodiment, the high-temperature solution 15 in the crucible 10 is a solvent for crystal growth, which can dissolve and transport Si and C elements and precipitate SiC at the low-temperature end; during the growth process, the raw material block 12 is rotated in the high-temperature solution 15, which can promote the high-temperature solution 15 to dissolve Si and C elements from the raw material block 12, and the Si and C elements dissolved into the high-temperature solution 15 will be transported to the end of the silicon carbide seed crystal 14 with relatively low temperature under the joint action of the rotation of the crucible 10 and the convection of the high-temperature solution 15 and solute diffusion, and the Si and C elements will continuously precipitate and deposit on the silicon carbide seed crystal 14 in the form of SiC to realize the continuous growth of the crystal. The convection of the high-temperature solution 15 is realized by counter-rotating the crucible 10 and the raw material block 12.

[0068] It can be understood that, during the silicon carbide single crystal growth stage, the Si and C elements in the high-temperature solution reach a dynamic balance, and the rotation speed of the raw material block is reduced, so the rotation speed of the raw material block is reduced.

[0069] In some embodiments of the present application, the rotation speed of the crucible 10 is 5-30 rpm, the first rotation speed is 50-300 rpm, the second rotation speed is 10-100 rpm, and the rotation speed of the silicon carbide seed crystal 14 is 30-200 rpm.

[0070] In the present embodiment, the rotation speed of the silicon carbide seed crystal 14, the rotation speed of the raw material block 12 and the rotation speed of the crucible 10 can be controlled during the growth process to regulate the dissolution rate of the raw material block 12 and the growth rate of the silicon carbide single crystal, so that the dissolution of the raw material block and the growth of the silicon carbide reach a dynamic balance. Through experimental verification, when the rotation speeds of the crucible 10, the silicon carbide seed crystal 14 and the raw material block 12 are within the above ranges, the growth quality is the highest.

[0071] In some embodiments of the present application, the crucible 10 comprises a tantalum carbide crucible 10.

[0072] Or,

[0073] The inner wall of the crucible 10 is plated with a tantalum carbide corrosion-resistant coating.

[0074] In some embodiments of the present application, further comprising:

[0075] The crucible 10 is wrapped with a heat preservation layer 8 outside, the heat preservation layer 8 comprises a first channel and a second channel, the first rotating pulling rod 7 passes through the first channel, and the second rotating pulling rod 6 passes through the second channel, and the caliber of the first channel is larger than that of the second channel.

[0076] In the embodiment, the first channel of the heat preservation layer 8 on the top of the silicon carbide seed crystal 14 has a large diameter, and the second channel of the heat preservation layer 8 on the top of the raw material block 12 has a small diameter, so that the temperature at the silicon carbide seed crystal 14 is lower than the temperature at the raw material block 12, and the raw material is dissolved to provide Si and C elements, which migrate to the silicon carbide seed crystal 14 to grow.

[0077] In some embodiments of the present application, the diameter of the first channel is 80-200 mm, and the diameter of the second channel is 20-50 mm.

[0078] In the embodiment, when the diameters of the first channel and the second channel are within the above range, the growth effect of the silicon carbide single crystal is optimal.

[0079] The embodiment of the present application also provides a device for growing a silicon carbide single crystal by a liquid phase method, which is used to realize any method in the above method, and the device comprises a crucible 10, a heat preservation layer 8, an induction coil, a first rotating lifting rod 7, a second rotating lifting rod 6, and a crucible rotating device 17.

[0080] The crucible 10 in the growth furnace 9 is used to contain a high-temperature solution 15, the heat preservation layer 8 is sleeved outside the crucible 10 and is used to preserve the temperature of the crucible 10, the induction coil is used to heat the crucible 10, the first rotating lifting rod 7 is used to rotate and lift the silicon carbide seed crystal 14, the second rotating lifting rod 6 is used to rotate and lift the raw material block 12, and the crucible rotating device 17 is used to rotate the crucible 10.

[0081] In the embodiment, the first rotating lifting rod 7 is connected to the silicon carbide seed crystal 14 through a seed crystal holder 13. The growth crucible 10 is placed on a crucible support tray 16.

[0082] The embodiment of the present application also provides a method for preparing a silicon carbide single crystal by a liquid phase method, which comprises the following steps.

[0083] 1) The solvent raw material is loaded into a high-temperature melt corrosion-resistant crucible 10;

[0084] 2) The crucible 10 is placed into a growth furnace 9, a silicon carbide seed crystal 14 and a silicon carbide raw material block 12 are respectively fixed on first and second rotating lifting rods at the top of the device, and it is ensured that the raw material block 12 and the silicon carbide seed crystal 14 do not contact the material surface at this time;

[0085] 3) After the heat preservation layer 8 is configured, the furnace chamber is closed, high-vacuum treatment is performed on the furnace chamber, and then a growth protection atmosphere is configured;

[0086] 4) The crucible 10 is heated to 1800 ℃ to completely liquefy the solvent raw material in the crucible 10, and the crucible 10 is rotated at a speed of 10 rpm to completely homogenize the high-temperature solvent;

[0087] 5) control the second rotating lifting rod 6 to slowly descend and immerse the raw material block 12 in the high-temperature solution 15 until the liquid level reaches a preset height, while controlling the raw material to rotate at a speed of 60 rpm in a direction opposite to the crucible 10 to accelerate the solution of the silicon carbide raw material block 12;

[0088] 6) after the high-temperature solution 15 dissolves the raw material block 12 to saturation, adjust the height of the raw material block 12 to restore the liquid level to the preset height;

[0089] 7) control the first rotating lifting rod to slowly descend the silicon carbide seed crystal 14 and make it contact with the liquid level, and the crystal growth starts;

[0090] 8) control the silicon carbide seed crystal 14 to periodically rotate and be pulled at a certain pulling speed during the crystal growth;

[0091] 9) during the growth, the laser ranging at the top of the device monitors the height data of the liquid level in real time and feeds back to the controller 1, the controller 1 calculates according to the feedback data of the laser ranging instrument 5 and sends an adjustment signal to the second driving device 4, and the depth of the raw material block immersed in the high-temperature solution 15 is adjusted in situ in real time to ensure that the height of the liquid level remains unchanged during the growth;

[0092] 10) after the growth is completed, the crystal and the raw material block 12 are pulled away from the liquid level and slowly cooled;

[0093] 11) after the temperature reaches room temperature, the crystal is taken off.

[0094] In order to more clearly illustrate the technical solutions and advantages of the present application, several embodiments will be described in detail below. Embodiment 1

[0095] This embodiment uses the device and method for growing silicon carbide crystals in a liquid phase provided by the present application to grow silicon carbide single crystals, including the following steps:

[0096] The solvent raw material is loaded into a high-temperature melt corrosion-resistant crucible, the composition and ratio of the solvent raw material are Cr: Fe: Ti = 60:20:20, and the total mass is 15 kg; the high-temperature corrosion-resistant crucible is a graphite crucible with a carbon tantalum coating on the inner wall.

[0097] The crucible is placed in the growth furnace, the silicon carbide seed crystal and the silicon carbide raw material block are fixed on the first and second rotating lifting rods at the top of the device respectively, and it is ensured that the raw material block and the silicon carbide seed crystal do not contact the liquid level at this time;

[0098] After the heat insulation layer is configured, the furnace chamber is closed, the furnace chamber is subjected to high vacuum treatment, and then the growth protection atmosphere is configured;

[0099] Heat the crucible to 1800°C to completely liquefy the solvent raw materials in the crucible, and rotate the crucible at a speed of 10 rpm to completely homogenize the high-temperature solvent;

[0100] Control the second rotating lifting rod to slowly descend and immerse the raw material block in the high-temperature solution until the liquid level reaches a preset height. At the same time, control the raw material to rotate at a speed of 60 rpm in the opposite direction of the crucible to accelerate the dissolution of the silicon carbide raw material block;

[0101] After the high-temperature solution dissolves the raw material block to saturation, adjust the height of the raw material block so that the liquid level returns to the preset height;

[0102] Second, the first rotating lifting rod is controlled to slowly lower the silicon carbide seed crystal and contact the liquid surface, and crystal growth begins;

[0103] During the crystal growth process, the silicon carbide seed crystal is controlled to rotate periodically and pulled at a certain pulling speed;

[0104] During the growth process, a laser rangefinder located at the top of the device monitors the liquid level in real time and feeds it back to the controller. The controller calculates the data based on the laser rangefinder and sends an adjustment signal to the second drive device. By adjusting the depth of the raw material immersed in the high-temperature solution in real time, the liquid level remains constant during the growth process.

[0105] After the growth is completed, the crystals and raw material blocks are pulled away from the liquid surface and slowly cooled;

[0106] After the temperature reaches room temperature, remove the crystal.

[0107] Figure 2 This is a photo of the silicon carbide crystal grown in this example. The crystal surface is bright and the crystal quality is very high. The growth rate was 300 μm / h and the grown thickness was 20 mm. This demonstrates that the apparatus and method provided by the present invention can effectively improve the stability of long-term rapid crystal growth and produce high-quality silicon carbide crystals.

[0108] Comparative Example 1

[0109] The process parameters of this comparative example are basically the same as those of Example 1, except that the device according to the present invention is not used.

[0110] In this comparative example, the growth crucible is severely corroded. Figure 3 As shown, the crucible sidewalls have been dissolved through. Furthermore, numerous groove-like defects appear in the later stages of crystal growth, indicating poor long-term growth stability. This comparison demonstrates that, without the device provided by the present invention, the growth process is unstable when the crucible is corroded to provide raw materials for crystal growth, making it highly unfavorable for long-term crystal growth.

[0111] Comparative Example 2

[0112] The process parameters in the present comparative example are basically consistent with those in Example 1, except that the crucible is not rotated during the growth process.

[0113] In the present comparative example, the crystal growth rate is 60 μm / h, and the crystal surface has a small amount of grooves, and the crystal has a poor crystalline quality. The comparison shows that, in the case where the crucible is not rotated, the solute transport rate is low, which leads to insufficient solute supply during the growth process, and further leads to low crystal growth rate and poor crystal crystalline quality.

[0114] Comparative Example 3

[0115] The process parameters in the present comparative example are basically consistent with those in Example 1, except that the liquid level control technology is not used.

[0116] Figure 4 The optical photograph of the silicon carbide crystal grown in the present comparative example can clearly show that a serious necking phenomenon occurs in the later stage of the crystal growth, and there are some obvious defects on the crystal surface, indicating that the crystalline quality is poor. The comparison shows that, in the case where the liquid level control technology provided by the present application is not used, the liquid level will continuously decrease as the crystal growth proceeds, which will continuously increase the meniscus height during the crystal growth process, and will not only lead to crystal necking, but also affect the stability of the crystal growth interface, and further make the crystal crystalline quality worse.

[0117] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of growing a silicon carbide single crystal by a liquid phase method, characterized by, The method comprises the following steps: putting a material containing solvent elements into a crucible (10) resistant to high-temperature melt corrosion to heat and melt, and obtaining a high-temperature solution (15) in the crucible (10); putting a raw block (12) of silicon carbide into the high-temperature solution (15) to provide carbon elements and silicon elements in the high-temperature solution (15); using a first rotating pulling rod (7) to drive a silicon carbide seed crystal (14) into the crucible (10) to make the silicon carbide seed crystal (14) contact with the liquid surface of the high-temperature solution (15) to grow a silicon carbide single crystal; before the step of putting the raw block (12) of silicon carbide into the high-temperature solution (15) to provide carbon elements and silicon elements in the high-temperature solution (15), the method further comprises the following steps: rotating the crucible (10) to make the high-temperature solution mix uniformly; wherein the rotating speed of the crucible (10) is 10-60 rpm; rotating the silicon carbide seed crystal (14) and the raw block (12) to make the silicon carbide seed crystal (14) and the raw block (12) heat uniformly; wherein the rotating speed of the silicon carbide seed crystal (14) and the raw block (12) is 10-60 rpm; the step of putting the raw block (12) of silicon carbide into the high-temperature solution (15) comprises the following steps: using a second rotating pulling rod (6) to drive the raw block (12) of silicon carbide to immerse into the high-temperature solution (15); after the step of using the first rotating pulling rod (7) to drive the silicon carbide seed crystal (14) into the crucible (10) to make the silicon carbide seed crystal (14) contact with the liquid surface of the high-temperature solution (15) to grow a silicon carbide single crystal, the method further comprises the following steps: monitoring the liquid level of the high-temperature solution (15) in the crucible (10), and using the second rotating pulling rod (6) to adjust the volume of the raw block (12) immersed in the high-temperature solution (15) to keep the liquid level of the high-temperature solution (15) unchanged; after the step of using the first rotating pulling rod (7) to drive the silicon carbide seed crystal (14) into the crucible (10) to make the silicon carbide seed crystal (14) contact with the liquid surface of the high-temperature solution (15) to grow a silicon carbide single crystal, the method further comprises the following steps: keeping the crucible rotate in a first direction, and reducing the rotating speed of the raw block from a first rotating speed to a second rotating speed, while rotating the silicon carbide seed crystal (14) in a second direction; the rotating speed of the crucible (10) is 5-30 rpm, the first rotating speed is 50-300 rpm, the second rotating speed is 10-100 rpm, and the rotating speed of the silicon carbide seed crystal (14) is 30-200 rpm.

2. The method of claim 1, wherein, the method further comprises the following steps: after the high-temperature solution mixes uniformly, using the second rotating pulling rod to immerse the raw block into the high-temperature solution; rotating the crucible (10) in a first direction, and rotating the raw block (12) in a second direction at a first rotating speed; wherein the first direction and the second direction are opposite.

3. The method of claim 1, wherein, the crucible (10) comprises a tantalum carbide crucible (10); or, the inner wall of the crucible (10) is plated with a corrosion-resistant tantalum carbide coating.

4. The method of claim 1, wherein, the method further comprises the following steps: A heat-insulating layer (8) is wrapped outside the crucible (10), the heat-insulating layer (8) comprises a first channel and a second channel, the first rotating pulling rod (7) passes through the first channel, the second rotating pulling rod (6) passes through the second channel, and the caliber of the first channel is larger than the caliber of the second channel.

5. The method of claim 4, wherein, The caliber of the first channel is 80-200 mm, and the caliber of the second channel is 20-50 mm.

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