Crucible device for growing silicon carbide single crystal with low-carbon wrappage and growing method

Abstract

The invention relates to the technical field of crystal growth, in particular to a crucible device for growth of silicon carbide single crystals with low-carbon wrappage and a growth method, and the crucible device comprises a crucible body, a crucible cover and silicon carbide seed crystals, a porous graphite cylinder used as a first filter is also arranged in the crucible body; the porous graphite cylinder is filled with tantalum particles used as a second filter; a shielding plate ring and a porous graphite plate used as a third filter are arranged above the porous graphite cylinder; a filling cavity used for containing silicon carbide powder is formed between the outer side wall of the porous graphite cylinder and the inner wall of the crucible body. According to the crucible device, gas components generated by sublimation of silicon carbide powder can be filtered through the porous graphite cylinder, the tantalum particles and the porous graphite plate, and carbon particles and other impurity particles in the gas components are filtered and removed; the crucible device solves the problems that silicon carbide single crystals grown by an existing crucible device in the prior art have the defects of carbon wrappage, microtubes, dislocation and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal growth, and in particular to a crucible device and a growth method for growing a silicon carbide single crystal with a low-carbon inclusion. Background Art

[0002] As a representative of new wide-bandgap semiconductor materials, silicon carbide (SiC) exhibits significant advantages in material properties. Compared with traditional single-crystal silicon materials, the bandgap width of silicon carbide has expanded to about 3 times, giving it a higher energy threshold and lower leakage current. The saturated electron drift rate has increased by 2 times, effectively enhancing the switching speed and high-frequency response capability of the device. The thermal conductivity has increased by 3 times, greatly improving its heat dissipation performance and ensuring the stable operation of the device in high-temperature environments. The breakdown field strength is as high as 10 times, significantly improving the voltage withstand limit and reliability of the device. At the same time, silicon carbide also has high mechanical strength and excellent physical and chemical stability. These characteristics together lay the foundation for its application in extreme working conditions, making it an ideal choice for manufacturing high-power devices in harsh environments such as high voltage and high temperature. At present, silicon carbide is usually prepared by physical vapor transport (PVT). During the crystal growth process, especially in the middle and late stages of crystal growth, the gas components escaping from the silicon carbide powder are mainly silicon-rich gases. These silicon-rich gases will react with the graphite crucible to form powdery carbon particles on the surface of the graphite crucible. The formed carbon particles will rise with the airflow, adhere to the silicon carbide seed crystals, and form carbon inclusions on the growth surface of the silicon carbide crystals. In addition, after a large amount of silicon-rich gas escapes from the silicon carbide powder, solid carbon particles in the silicon carbide powder will continue to accumulate. These carbon particles will also rise with the airflow, adhere to the silicon carbide seed crystals and form carbon inclusions. These carbon inclusions can further induce defects such as carbon inclusions, microtubes, and dislocations on the crystals, thereby significantly affecting the performance of crystal devices and reducing the yield of large-scale crystal production. Although existing patents have provided a variety of solutions to the problem of carbon inclusions that are prone to occur during crystal growth, these solutions still have many shortcomings. For example, Chinese patent No. 202311094900.2 discloses a crucible, growth control system, and control method for growing silicon carbide crystals. The method first filters the gas generated by heating silicon carbide powder through a porous graphite tube, and then further filters out some carbon particles through a layer of large-particle silicon carbide powder spread on the surface, thereby improving the quality of the silicon carbide crystals. However, both the porous graphite tube and the large-particle silicon carbide powder will become new sources of particles for the generation of carbon inclusions, thereby failing to effectively avoid the generation of carbon inclusions and failing to solve the problem of carbon inclusions.Chinese patent No. 202310823643.5 discloses a method for growing silicon carbide single crystals with low carbon inclusion density. By placing a tantalum carbide or niobium carbide mesh between the raw material and the seed crystal in the physical vapor transport method, it replaces the porous graphite material. While filtering the carbon particles generated by the carbonization of the raw material, it will not produce new carbon particles due to its own corrosion, which can effectively reduce the inclusion density in the silicon carbide single crystal. Chinese patent No. 202210870703.4 discloses a porous filter, a preparation method and its use in the growth of silicon carbide single crystals. By coating a tantalum carbide coating on the pore surface of the porous substrate, the porous substrate is prevented from becoming a new source of carbon inclusions under the corrosion of high temperature and silicon-rich gas, thereby reducing the carbon inclusions in the silicon carbide single crystal. Although the technical solutions provided by these two patents can prevent the porous filter from becoming a new source of carbon inclusions, these porous filters can only filter out some carbon particles. During the crystal growth process, a large amount of carbon inclusions will still be produced.

[0003] The present invention provides a crucible device and a growth method for growing a silicon carbide single crystal with low carbon inclusions, so as to solve the problems existing in the prior art such as the presence of carbon inclusions in the silicon carbide single crystal grown by the existing crucible device and defects such as micropipes and dislocations caused by the presence of the carbon inclusions. Summary of the Invention

[0004] The purpose of the present invention is to provide a crucible device and a growth method for growing silicon carbide single crystals with low carbon inclusions, so as to solve the problems existing in the prior art such as the presence of carbon inclusions in silicon carbide single crystals grown by existing crucible devices and defects such as micropipes and dislocations caused by the presence of carbon inclusions.

[0005] The technical solution of the present invention is: a crucible device for growing silicon carbide single crystals with low carbon inclusions, comprising a crucible body, a crucible cover, and a silicon carbide seed crystal; the silicon carbide seed crystal is fixedly arranged on the inner side of the crucible cover; the crucible cover is buckled onto the crucible body, so that the interior of the crucible body forms a sealed space for growing silicon carbide single crystals; wherein the interior of the crucible body is further provided with a porous graphite cylinder for serving as a first filter; the interior of the porous graphite cylinder is filled with tantalum particles for serving as a second filter; a shield is provided above the porous graphite cylinder ring and a porous graphite plate used as a third filter; the inner diameter of the baffle ring is not less than the inner diameter of the porous graphite tube, and not greater than the outer diameter of the porous graphite tube; the outer diameter of the baffle ring is the same as the inner diameter of the crucible body, so that the outer wall of the baffle ring is against the inner wall of the crucible body; the diameter of the porous graphite plate is the same as the inner diameter of the baffle ring, so that the side wall of the porous graphite plate is against the inner wall of the baffle ring; a filling cavity for accommodating silicon carbide powder is formed between the outer wall of the porous graphite tube and the inner wall of the crucible body.

[0006] Preferably, the particle size of the tantalum particles is 1 mm to 5 mm.

[0007] Preferably, the porous graphite cylinder is designed to be a trapezoidal cylinder that is wide at the top and narrow at the bottom; the inner diameter of the bottom end of the porous graphite cylinder is 60-140 mm, and the inner diameter of the upper end is 70-150 mm.

[0008] Preferably, the height of the porous graphite cylinder is 100 to 200 mm;

[0009] The thickness of the porous graphite cylinder, the porous graphite plate, and the shield ring are all 3 to 10 mm;

[0010] The porosity of the porous graphite cylinder and the porous graphite plate is set to 30% to 80%.

[0011] Preferably, the crucible body is further provided with a graphite block;

[0012] The graphite block is arranged at the bottom of the crucible body; the porous graphite cylinder is arranged on the graphite block;

[0013] The height of the graphite block is 10-40 mm; the diameter of the graphite block is 70-170 mm.

[0014] Preferably, the porous graphite cylinder, the porous graphite plate, the shield ring and the graphite block are all coated with a rare metal carbide or nitride coating; the rare metal is any one of tantalum, titanium, niobium, hafnium, tungsten, zirconium and vanadium.

[0015] The present invention also provides a method for growing a silicon carbide single crystal with a low-carbon inclusion. The method uses the crucible device for growing a silicon carbide single crystal with the low-carbon inclusion to grow the silicon carbide single crystal. The method comprises the following steps:

[0016] S1. Fill the porous graphite cylinder with tantalum pellets, fill the filling cavity with silicon carbide powder, and then place the shielding ring and porous graphite plate in the crucible body. Then, fasten the crucible cover with silicon carbide seed crystals on the crucible body to complete the assembly, and place the assembled crucible body on the platform in the heating furnace;

[0017] S2, first adjust the pressure inside the heating furnace to 1×10 -3 ~1×10 -5 pa, then, introducing a crystal growth atmosphere into the heating furnace, wherein the crystal growth atmosphere includes argon and nitrogen;

[0018] S3. Raise the temperature inside the heating furnace to 1800-2200°C, and control the pressure inside the heating furnace within the range of 0.25 atm-1 atm during the temperature rise process. Then, start crystal growth. During the crystal growth process, regulate the pressure and temperature inside the heating furnace to ensure that the pressure is maintained within the range of 100-250 Pa and the temperature is maintained within the range of 2000-2200°C. The crystal growth time is 80-120 hours.

[0019] S4. After the crystal growth is completed, the pressure inside the heating furnace is adjusted to atmospheric pressure. At the same time, the temperature inside the heating furnace is cooled to room temperature. Thereafter, the crucible body is taken out to obtain a silicon carbide ingot.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] (1) The present invention provides a crucible device and growth method for growing a silicon carbide single crystal with low carbon inclusions. The crucible device is provided with a porous graphite cylinder, tantalum particles and a porous graphite plate, which serve as a first filter, a second filter and a third filter respectively to filter the gas components generated by the sublimation of silicon carbide powder, and completely or almost completely filter out the carbon particles and other impurity particles contained in the gas components, thereby avoiding the formation of carbon inclusions in the silicon carbide single crystal and reducing microtubes, dislocations, etc. caused by the presence of carbon inclusions in the silicon carbide single crystal. The invention can improve the quality of silicon carbide single crystal by eliminating defects and improving the crystal quality of silicon carbide single crystal; and the porous graphite cylinder is designed to be a trapezoidal cylinder with a width at the top and a narrowness at the bottom, so that the porous graphite cylinder can serve as a guide plate and cooperate with the graphite block to jointly promote the gas components entering the porous graphite cylinder to flow upward, thereby improving the utilization rate of silicon carbide powder and the crystal growth efficiency, which is helpful to reduce the crystal production cost; and solves the problems existing in the prior art such as the presence of carbon inclusions in silicon carbide single crystals grown by the existing crucible device, and defects such as microtubes and dislocations caused by the presence of carbon inclusions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0023] Figure 1 Schematic diagram of the structure of the crucible device in Example 1 of the present invention;

[0024] Figure 2 This is a photograph of inclusion defects on the silicon carbide ingot described in Example 1 of the present invention;

[0025] Figure 3 Schematic diagram of the structure of the crucible device in Example 2 of the present invention;

[0026] Figure 4 This is a photograph of the silicon carbide ingot described in Example 2 of the present invention;

[0027] Figure 5Schematic diagram of the structure of the crucible device in Example 3 of the present invention;

[0028] Among them: 1. Crucible body; 2. Crucible cover; 3. Silicon carbide seed crystal; 4. Porous graphite cylinder; 5. Shield ring; 6. Porous graphite plate; 7. Tantalum particles; 8. Silicon carbide powder; 9. Graphite block. DETAILED DESCRIPTION

[0029] The present invention will be described in further detail below with reference to specific embodiments:

[0030] Example 1

[0031] A crucible device for growing silicon carbide single crystals with low carbon inclusions, such as Figure 1 As shown, the crucible device includes a crucible body 1, a crucible cover 2, and a silicon carbide seed crystal 3. The silicon carbide seed crystal 3 is fixedly arranged on the inner side of the crucible cover 2. The crucible cover 2 is snapped onto the crucible body 1 to form a sealed space inside the crucible body 1 for growing silicon carbide single crystals. A porous graphite tube 4, a shield ring 5, and a porous graphite plate 6 are also provided inside the crucible body 1. The bottom of the porous graphite tube 4 abuts against the bottom wall of the crucible body 1, so that a filling cavity is formed between the outer wall of the porous graphite tube 4 and the bottom and inner walls of the crucible body 1 to accommodate the silicon carbide powder 8 required for crystal growth. The shield ring 5 and the porous graphite plate 6 are arranged above the porous graphite tube 4. In addition, the outer wall of the shield ring 5 abuts against the inner wall of the crucible body 1, and the inner wall of the porous graphite plate 6 abuts against the inner wall of the shield ring 5. In this embodiment, the height of the porous graphite tube 4 is 135 mm, the inner diameter is 100 mm, and the outer diameter is 108 mm; the thickness of the porous graphite plate 6 is 5 mm, and the diameter is 84 mm; the porosity of the porous graphite tube 4 and the porous graphite plate 6 is set to 60%; the thickness of the shield ring 5 is 8 mm, the inner diameter is 84 mm, and the outer diameter is the same as the inner diameter of the crucible body 1; the surfaces and pores of the porous graphite tube 4, the porous graphite plate 6, and the shield ring 5 are coated with tantalum carbide coating.

[0032] In other embodiments, in other implementation methods, the porous graphite tube 4 can be designed to be a straight tube with the same upper and lower inner diameters, or it can be designed to be a trapezoidal tube with a wider upper part and a narrower lower part; the height of the porous graphite tube 4 needs to be controlled within the range of 100 to 200 mm, preferably within the range of 120 to 160 mm; when the porous graphite tube 4 is designed to be a straight tube with the same upper and lower inner diameters, its inner diameter needs to be controlled within the range of 60 to 150 mm, preferably within the range of 80 to 120 mm; the outer diameter is controlled within the range of 63 to 160 mm, preferably within the range of 85 to 128 mm; when the porous graphite tube 4 is designed to be a trapezoidal tube with a wider upper part and a narrower lower part, the inner diameter of the bottom end needs to be controlled within the range of 60 to 130 mm, and the inner diameter of the upper end needs to be controlled within the range of 70 to 150 mm. The thickness of the porous graphite plate 6 is controlled within the range of 3 to 10 mm, preferably within the range of 5 to 8 mm. The diameter of the porous graphite plate 6 needs to be larger than the inner diameter of the upper end of the porous graphite tube 4 and smaller than the outer diameter of the upper end of the porous graphite tube 4. The porosity of the porous graphite tube 4 and the porous graphite plate 6 needs to be controlled within the range of 30% to 80%, preferably within the range of 50% to 70%. The thickness of the shield ring 5 is controlled within the range of 3 to 10 mm, preferably within the range of 5 to 8 mm. The outer diameter of the shield ring 5 needs to be the same as the inner diameter of the crucible body 1, and its inner diameter needs to be the same as the diameter of the porous graphite plate 5, so that the outer side of the shield ring 5 abuts against the inner sidewall of the crucible body 1, and the inner side of the shield ring 5 is tightly fitted with the sidewall of the porous graphite plate 6. The surfaces and pores of the porous graphite cylinder 4, porous graphite plate 6, and shield ring 5 are coated with a rare metal carbide or nitride coating. The rare metal is one or more of tantalum, titanium, niobium, hafnium, tungsten, zirconium, and vanadium. The shield ring 5 functions to restrict the flow path of the gas components generated by the sublimation of the silicon carbide powder 8. Specifically, the gas components generated by the sublimation of the silicon carbide powder 8 can only be filtered through the porous graphite cylinder 4, enter the interior of the porous graphite cylinder 4, undergo subsequent filtration, and then flow to the silicon carbide seed crystal 3.

[0033] The silicon carbide single crystal is grown using the crucible device for growing the silicon carbide single crystal with the low-carbon wrapping, and the specific growth method includes the following steps:

[0034] S1. Place a porous graphite tube in the crucible body and perpendicular to the bottom wall of the crucible body, fill the silicon carbide powder into the filling cavity between the outer wall of the porous graphite tube and the inner wall of the crucible body, and make the filling height of the silicon carbide powder flush with the top of the porous graphite tube, then arrange a shielding ring and a porous graphite plate above the porous graphite tube, and then buckle the crucible cover with a silicon carbide seed crystal on the inside on the crucible body to complete the assembly, and place the assembled crucible body on the lifting and rotating platform in the heating furnace; at this time, the porous graphite tube serves as a first filter and the porous graphite plate serves as a second filter to filter the gas components generated by the sublimation of the silicon carbide powder and remove carbon particles and other particulate impurities in the gas components;

[0035] S2, first adjust the pressure inside the heating furnace to 1×10 -4 Then, a crystal growth atmosphere is introduced into the heating furnace, wherein the crystal growth atmosphere includes argon and nitrogen, and the flow rate ratio of argon to nitrogen is 10:1;

[0036] S3, raising the temperature inside the heating furnace to 2000° C., and controlling the pressure inside the heating furnace within the range of 0.25 atm to 0.3 atm during the heating process, then starting crystal growth at 2000° C., and during the crystal growth process, controlling the pressure inside the heating furnace so that the pressure inside the heating furnace is always maintained within the range of 150 to 250 Pa; the crystal growth time is 100 hours; during the crystal growth process, the gas generated by the sublimation of the silicon carbide powder is filtered through the porous graphite cylinder and then enters the porous graphite cylinder, and then is filtered through the porous graphite plate and flows to the silicon carbide seed crystal arranged on the inner side of the crucible cover, and is deposited on the silicon carbide seed crystal to form a silicon carbide ingot;

[0037] S4. After the crystal growth is completed, the pressure inside the heating furnace is slowly adjusted to the standard atmospheric pressure. At the same time, the temperature inside the heating furnace is cooled to room temperature. After that, the crucible body is taken out. Figure 2 As shown, a silicon carbide ingot with a thickness of 21.5 mm and containing radial inclusion defects was obtained.

[0038] Example 2

[0039] A crucible device for growing silicon carbide single crystals with low carbon inclusions, such as Figure 3As shown, the crucible device includes a crucible body 1, a crucible cover 2, and a silicon carbide seed crystal 3; wherein the silicon carbide seed crystal 3 is fixedly arranged on the inner side of the crucible cover 2; the crucible cover 2 is buckled on the crucible body 1, and is used to form a sealed space inside the crucible body 1 for the growth of silicon carbide single crystals. The interior of the crucible body 1 is also provided with a porous graphite tube 4, a shield ring 5, a porous graphite plate 6, and tantalum particles 7; wherein, the bottom of the porous graphite tube 4 is against the bottom wall of the crucible body 1, so that a filling cavity is formed between the outer wall of the porous graphite tube 4 and the bottom wall and inner wall of the crucible body 1, which is used to accommodate the silicon carbide powder 8 required for crystal growth; the tantalum particles 7 are placed inside the porous graphite tube 4, and the height of the tantalum particles is the same as the height of the porous graphite tube 4; the shield ring 5 and the porous graphite plate 6 are arranged above the porous graphite tube 4; and, the outer wall of the shield ring 5 is against the inner wall of the crucible body 1, and the inner wall of the porous graphite plate 6 is against the inner wall of the shield ring 5. In this embodiment, the porous graphite tube 4 has a height of 150 mm, an inner diameter of 85 mm, and an outer diameter of 105 mm. The porous graphite plate 6 has a thickness of 5 mm and a diameter of 83 mm. The porosity of both the porous graphite tube 4 and the porous graphite plate 6 is set to 50%. The shield ring 5 has a thickness of 5 mm and an inner diameter of 83 mm, and its outer diameter is the same as the inner diameter of the crucible body 1. The particle size of the tantalum pellets 7 is 3 mm. In other embodiments, the particle size of the tantalum pellets 7 needs to be controlled within the range of 1 to 5 mm, preferably within the range of 2 to 4 mm.

[0040] The silicon carbide single crystal is grown using the crucible device for growing the silicon carbide single crystal with the low-carbon wrapping, and the specific growth method includes the following steps:

[0041] S1. Place the porous graphite tube in the crucible body and perpendicular to the bottom wall of the crucible body, fill the silicon carbide powder into the filling cavity between the outer wall of the porous graphite tube and the inner wall of the crucible body, and make the filling height of the silicon carbide powder flush with the top of the porous graphite tube; then fill tantalum particles in the interior of the porous graphite tube, and make the height of the tantalum particles the same as the height of the porous graphite tube; then place the shielding ring and the porous graphite plate above the porous graphite tube, and then buckle the crucible cover with silicon carbide seed crystals arranged on the inside on the crucible body to complete the assembly, and place the assembled crucible body on the lifting and rotating platform in the heating furnace; at this time, the porous graphite tube serves as a first filter, the tantalum particles filled in the porous graphite tube serve as a second filter, and the porous graphite plate serves as a third filter for filtering the gas components generated by the sublimation of the silicon carbide powder to remove carbon particles and other particulate impurities in the gas components;

[0042] S2, first adjust the pressure inside the heating furnace to 1×10 -4 Then, a crystal growth atmosphere is introduced into the heating furnace, wherein the crystal growth atmosphere includes argon and nitrogen, and the flow rate ratio of argon to nitrogen is 10:1;

[0043] S3. Raise the temperature inside the heating furnace to 2000° C., and control the pressure inside the heating furnace within the range of 0.4 atm to 0.5 atm during the temperature raising process. Then, start crystal growth at 2000° C., and during the crystal growth process, control the pressure inside the heating furnace so that the pressure inside the heating furnace is always maintained within the range of 150 to 250 Pa. The crystal growth time is 100 hours. During the crystal growth process, the gas generated by the sublimation of the silicon carbide powder is first filtered through the porous graphite cylinder and then enters the porous graphite cylinder. The gas components entering the porous graphite cylinder are filtered through tantalum particles, so that the carbon particles and other impurity particles in the gas components are deposited on the tantalum particles. Afterwards, the gas components are filtered through the porous graphite plate and flow to the silicon carbide seed crystal arranged on the inner side of the crucible cover, and are deposited on the silicon carbide seed crystal to form a silicon carbide ingot.

[0044] S4. After the crystal growth is completed, the pressure inside the heating furnace is slowly adjusted to the standard atmospheric pressure. At the same time, the temperature inside the heating furnace is cooled to room temperature. After that, the crucible body is taken out. Figure 4 As shown, a silicon carbide ingot with a thickness of 20 mm and no inclusion defects was obtained.

[0045] Example 3

[0046] A crucible device for growing silicon carbide single crystals with low carbon inclusions, such as Figure 5 As shown, the difference between this crucible device and the crucible device for growing silicon carbide single crystals with low carbon inclusions provided in Example 2 is that a graphite block 9 is further provided in the crucible body 1 and the porous graphite tube 4 is designed as a trapezoidal tube with a wide top and a narrow bottom.

[0047] A graphite block 9 is disposed at the bottom of the crucible body 1, and a porous graphite tube 4 is disposed above the graphite block 9. The graphite block 9 has a height of 30 mm and a diameter of 90 mm. The graphite block 9 is also coated with a tantalum carbide coating. The inner diameter of the bottom end of the porous graphite tube 4 is 75 mm, and the outer diameter is 80 mm; the inner diameter of the top end is 105 mm, and the outer diameter is 110 mm. In other embodiments, the height of the graphite block 9 needs to be controlled within the range of 10 to 40 mm, preferably within the range of 20 to 30 mm. The diameter of the graphite block 9 needs to be larger than the outer diameter of the bottom end of the porous graphite tube 4 and needs to be controlled within the range of 70 to 170 mm, preferably within the range of 90 to 130 mm. The graphite block 9 may also be coated with other metal compound coatings.

[0048] A crucible device for growing silicon carbide single crystals using the above-mentioned low-carbon inclusions is used to grow silicon carbide single crystals. The specific steps and process parameters are the same as those in Example 2; a silicon carbide ingot with a thickness of 23.5 mm and free of inclusion defects is obtained. In the process of growing crystals, the gas generated by the sublimation of silicon carbide powder by heat is first filtered through a porous graphite tube and then enters the porous graphite tube, and then the carbon particles and other impurity particles are filtered out by tantalum particles. After that, it is filtered through a porous graphite plate and flows to the silicon carbide seed crystal arranged on the inner side of the crucible cover, and is deposited on the silicon carbide seed crystal to form a silicon carbide ingot. The purpose of arranging a graphite block at the bottom of the crucible body is to make the radial temperature in the crucible body more uniform, thereby increasing the temperature of the silicon carbide powder in the middle of the filling cavity and the silicon carbide powder near the porous graphite tube, making the temperature of the silicon carbide powder as a whole more uniform, and facilitating the sublimation of the silicon carbide powder. The porous graphite cylinder is designed as a trapezoidal cylinder that is wide at the top and narrow at the bottom. Not only can the porous graphite cylinder be used as the first filter to filter carbon particles and impurities in the gas components, but the porous graphite cylinder can also be used as a drainage plate to cooperate with the graphite block at the bottom to promote the gas components entering the porous graphite cylinder to flow to the upper part of the crucible body, thereby helping to improve the utilization rate of silicon carbide powder and the crystal growth efficiency, and reduce the crystal production cost.

[0049] Comparing Example 2 and Example 3 with Example 1, it can be seen that after the gas components generated by the sublimation of silicon carbide powder are filtered through three passes of the porous graphite cylinder, tantalum particles, and porous graphite plates, there are no obvious inclusion defects in the silicon carbide ingots deposited; while after the gas components generated by the sublimation of silicon carbide powder are filtered through three passes of the porous graphite cylinder and the porous graphite plate, there are obvious inclusion defects in the silicon carbide ingots deposited; and it can be explained that only using the porous graphite cylinder and the porous graphite plate to filter the gas components formed by the sublimation of silicon carbide powder cannot completely filter out the carbon particles and other impurity particles in the gas components, and the deposited There will still be inclusion defects such as carbon inclusions in the crystal ingot; the crucible device for growing silicon carbide single crystals with low carbon inclusions provided by the present invention can filter the gas components through three steps in sequence through a porous graphite cylinder, tantalum particles, and a porous graphite plate, and can completely or almost completely filter out the carbon particles in the gas components, thereby effectively avoiding the formation of carbon inclusions in the silicon carbide single crystal; at the same time, a layer of high-temperature resistant metal compound coating is coated on the porous graphite cylinder, the porous graphite plate, the shielding ring, and the graphite block, which can reduce the etching of the silicon-rich gas components on them, and can also effectively reduce the carbon inclusion defects formed in the silicon carbide single crystal.

[0050] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and they are not intended to limit the scope of protection of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A crucible device for growing a silicon carbide single crystal with a low carbon coating, comprising a crucible body (1), a crucible cover (2), and a silicon carbide seed crystal (3); the silicon carbide seed crystal (3) is fixedly arranged on the inner side of the crucible cover (2); the crucible cover (2) is buckled onto the crucible body (1), so that the interior of the crucible body (1) forms a sealed space for growing the silicon carbide single crystal; characterized in that The crucible body (1) is further provided with a porous graphite cylinder (4) for serving as a first filter; the porous graphite cylinder (4) is filled with tantalum particles (7) for serving as a second filter; a shielding ring (5) and a porous graphite plate (6) for serving as a third filter are provided above the porous graphite cylinder (4); The inner diameter of the baffle ring (5) is not less than the inner diameter of the porous graphite cylinder (4), and is not greater than the outer diameter of the porous graphite cylinder (4); the outer diameter of the baffle ring (5) is the same as the inner diameter of the crucible body (1), so that the outer wall of the baffle ring (5) abuts against the inner wall of the crucible body (1); The diameter of the porous graphite plate (6) is the same as the inner diameter of the shield ring (5), so that the side wall of the porous graphite plate (6) abuts against the inner side wall of the shield ring (5); A filling cavity for accommodating silicon carbide powder (8) is formed between the outer wall of the porous graphite cylinder (4) and the inner wall of the crucible body (1).

2. The crucible device for growing a silicon carbide single crystal with a low carbon coating according to claim 1, characterized in that: The particle size of the tantalum particles (7) is 1 mm to 5 mm.

3. The crucible device for growing a silicon carbide single crystal with a low carbon coating according to claim 2, characterized in that: The porous graphite cylinder (4) is designed to be a trapezoidal cylinder that is wide at the top and narrow at the bottom; the inner diameter of the bottom end of the porous graphite cylinder (4) is 60 to 140 mm, and the inner diameter of the top end is 70 to 150 mm.

4. The crucible device for growing a silicon carbide single crystal with a low carbon coating according to claim 2, wherein: The height of the porous graphite cylinder (4) is 100 to 200 mm; The thickness of the porous graphite cylinder (4), the porous graphite plate (6), and the shield ring (5) are all 3 to 10 mm; The porosity of the porous graphite cylinder (4) and the porous graphite plate (6) is set to 30% to 80%.

5. The crucible device for growing a silicon carbide single crystal with a low carbon coating according to claim 2, characterized in that: A graphite block (9) is also provided in the crucible body (1); The graphite block (9) is arranged at the bottom of the crucible body (1); the porous graphite cylinder (4) is arranged on the graphite block (9); The height of the graphite block (9) is 10 to 40 mm; the diameter of the graphite block (9) is 70 to 170 mm.

6. The crucible device for growing a silicon carbide single crystal with a low carbon coating according to claim 5, characterized in that: The porous graphite cylinder (4), the porous graphite plate (6), the shield ring (5) and the graphite block (9) are all coated with a rare metal carbide or nitride coating; the rare metal is any one of tantalum, titanium, niobium, hafnium, tungsten, zirconium and vanadium.

7. The method for growing a silicon carbide single crystal with a low-carbon coating according to claim 1, wherein: A crucible device for growing a silicon carbide single crystal using the low-carbon inclusion described in any one of items 1 to 6 above is used to grow a silicon carbide single crystal; the method comprises the following steps: S1. Fill the porous graphite cylinder with tantalum pellets, fill the filling cavity with silicon carbide powder, and then place the shielding ring and porous graphite plate in the crucible body. Then, fasten the crucible cover with silicon carbide seed crystals on the crucible body to complete the assembly, and place the assembled crucible body on the platform in the heating furnace; S2, first adjust the pressure inside the heating furnace to 1×10 -3 ~1×10 -5 pa, then, introducing a crystal growth atmosphere into the heating furnace, wherein the crystal growth atmosphere includes argon and nitrogen; S3. Raise the temperature inside the heating furnace to 1800-2200°C, and control the pressure inside the heating furnace within the range of 0.25 atm-1 atm during the temperature rise process. Then, start crystal growth. During the crystal growth process, regulate the pressure and temperature inside the heating furnace to ensure that the pressure is maintained within the range of 100-250 Pa and the temperature is maintained within the range of 2000-2200°C. The crystal growth time is 80-120 hours. S4. After the crystal growth is completed, the pressure inside the heating furnace is adjusted to atmospheric pressure. At the same time, the temperature inside the heating furnace is cooled to room temperature. Thereafter, the crucible body is taken out to obtain a silicon carbide ingot.

Images