Silicon carbide crystal growth apparatus and growth method

Abstract

The application discloses a silicon carbide crystal growth device and a growth method, and particularly relates to the field of silicon carbide crystal growth. The silicon carbide crystal growth device comprises a crucible, a seed crystal tray, at least one layer of inert metal mesh and a bottom plate; the crucible is electrically connected with a positive electrode or a negative electrode of a first power supply, and the crucible comprises a first area for placing silicon carbide raw materials; the seed crystal tray is arranged above the crucible; the at least one layer of inert metal mesh is arranged between the first area and the seed crystal tray through an electrode rod, and the electrode rod is electrically connected with a positive electrode or a negative electrode of a second power supply; the bottom plate is arranged below the crucible, and the bottom plate is electrically connected with a positive electrode or a negative electrode of a third power supply; wherein at least one of the crucible, the electrode rod and the bottom plate is electrically connected with the first power supply, the second power supply and the third power supply. The silicon carbide crystal growth device can prevent carbon particles from entering the silicon carbide crystal and affecting the quality of the silicon carbide crystal.

Description

A silicon carbide crystal growth apparatus and growth method Technical Field

[0001] This invention relates to the field of silicon carbide crystal growth, and more specifically to a silicon carbide crystal growth apparatus and growth method. Background Technology

[0002] Significant progress has been made in the research of SiC-based semiconductor devices both domestically and internationally, with 6-inch silicon carbide inevitably becoming thicker. The physical vapor transport method (PVT) has gradually become the standard method for SiC single crystal growth due to its high growth rate, relatively stable growth process, and cost advantages. The PVT growth process can be summarized as follows: polycrystalline silicon carbide sublimates under high temperature and low pressure conditions, and the resulting gaseous components (mainly Si, Si2C, and SiC2) reach the seed crystal at a lower temperature under the drive of the temperature gradient, generating supersaturation and crystallizing on the seed crystal to continuously grow a single crystal.

[0003] As silicon carbide raw materials decompose and are consumed, silicon is depleted, and the raw materials pulverize. Carbon particles rise towards the crystallization interface due to natural convection and thermophoresis, and there is a certain probability that they will be swallowed by the interface, causing inclusion defects. To address these defects, domestic manufacturers have adopted various technical methods, such as CN112746316B, which relies on arranging the carbonized area of ​​the raw material away from the crystallization interface to prevent inclusions from drifting into the crystal; CN102965733A, which uses hydrogen to react chemically with graphite particles to eliminate inclusions in the crystal; CN113445121A, which uses porous graphite filtration to reduce carbon inclusions in the crystal; CN114990696A, which places a graphite barrier plate in the crucible to alleviate natural convection and also has a filtration effect to reduce inclusions; and CN11748843B, which uses excess silicon powder to neutralize carbon and reduce inclusions.

[0004] While the above solutions can reduce the generation of inclusions to some extent, hydrogen, while consuming carbon particles, also significantly reduces the lifespan of the insulation material, causing accelerated heat field consumption and temperature field deformation. Porous graphite or graphite disks are inevitably corroded and pulverized during crystal growth, producing some carbon particles. Furthermore, the temperature of the PVT method is much higher than the melting point of silicon, making it difficult to balance its evaporation rate with the crystal growth pressure. Increasing the outer diameter of the crucible, without using the raw material in the center, would increase costs excessively and is not suitable for mass production. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a silicon carbide crystal growth apparatus and growth method to improve the problems of easy entry of carbon particles into silicon carbide crystals, low raw material utilization and high cost during the silicon carbide crystal growth process.

[0006] To achieve the above and other related objectives, the present invention provides a silicon carbide crystal growth apparatus, comprising a crucible, a seed crystal tray, at least one layer of inert metal mesh, and a base plate; the crucible is electrically connected to the positive or negative terminal of a first power source, and the crucible includes a first region for placing silicon carbide raw materials; the seed crystal tray is disposed above the crucible; the at least one layer of inert metal mesh is disposed between the first region and the seed crystal tray via electrode rods, and the electrode rods are electrically connected to the positive or negative terminal of a second power source; the base plate is disposed below the crucible, and the base plate is electrically connected to the positive or negative terminal of a third power source; wherein at least one of the following is electrically connected: the crucible to the first power source, the electrode rods to the second power source, and the base plate to the third power source.

[0007] In one example of the present invention, the silicon carbide crystal growth apparatus further includes a graphite barrel, which is disposed between the crucible and the seed crystal tray, and the outer diameter of the graphite barrel is the same as that of the crucible.

[0008] In one example of the present invention, a metal barrel is fitted inside the graphite barrel, and the outer wall of the metal barrel is in contact with the inner wall of the graphite barrel.

[0009] In one example of the present invention, the distance between the metal bucket and the lower surface of the seed crystal is -5 to 5 mm.

[0010] In one example of the present invention, the distance between the metal mesh and the lower surface of the seed crystal is 5-85 mm, and the distance between the metal mesh and the upper surface of the silicon carbide raw material is 0.5-75 mm.

[0011] In one example of the present invention, the length-to-diameter ratio of the metal fiber is 1000:1 to 1:1, and the thickness of the metal fiber layer is 1 to 50 mm.

[0012] In one example of the present invention, the distance between the crucible and the tray is 0 to 50 mm.

[0013] In one example of the present invention, the first power supply, the second power supply and the third power supply are all DC power supplies, and the voltage of the first power supply, the second power supply and the third power supply is 1V to 12kV.

[0014] The present invention also provides a method for growing silicon carbide crystals, comprising the following steps:

[0015] A silicon carbide crystal growth apparatus as described above is provided;

[0016] The growth device containing silicon carbide raw materials and seed crystals is placed in the silicon carbide single crystal growth equipment;

[0017] Adjust the temperature and pressure inside the growth equipment, turn on at least one of the first power supply, the second power supply and the third power supply, and stabilize the growth of silicon carbide crystals;

[0018] After growth is complete, adjust the pressure inside the growth equipment to 50-500 mbar, turn off the power, slowly cool down, and remove the crystal.

[0019] In one example of the present invention, the stable growth of silicon carbide crystals includes: adjusting the temperature of the silicon carbide raw material to 1600-2400°C, adjusting the pressure inside the growth device to 200-800 mbar, adjusting the temperature of the silicon carbide raw material to 1700-2500°C, turning on at least one of the first power supply, the second power supply, and the third power supply, and stabilizing the growth of silicon carbide crystals; after 1-50 hours, reducing the pressure inside the growth device to 0.1-100 mbar, and stabilizing the growth for 50-150 hours.

[0020] The silicon carbide crystal growth apparatus of the present invention comprises at least one layer of inert metal mesh between the silicon carbide raw material and the seed crystal, and a base plate at the bottom of the crucible. At least one of the following connections is made: the crucible is connected to a first power source, the electrode rod to a second power source, and the base plate to a third power source. When the crucible is connected to the first power source, the electrode rod to the second power source, or the base plate to the third power source, due to electric field polarization, the electrical charge of the silicon carbide raw material near the electric field is opposite to that of the electric field. Carbon particles generated from the decomposition of the silicon carbide raw material are adsorbed onto the lower surface of the inert metal mesh or the bottom of the crucible under the action of the electric field, preventing carbon particles from entering the silicon carbide crystal and affecting its quality. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 is a schematic diagram of the silicon carbide growth apparatus of the present invention in one embodiment;

[0023] Figure 2 is a schematic diagram of the silicon carbide growth apparatus of the present invention in another embodiment;

[0024] Figure 3 is a schematic diagram of the chassis of the present invention in one embodiment;

[0025] Figure 4 is a flowchart of the silicon carbide crystal growth process of the present invention.

[0026] Component designation explanation

[0027] 100, Crucible; 110, Silicon carbide raw material; 120, First region; 200, Seed crystal tray; 210, Seed crystal; 300, Inert metal mesh; 310, Electrode rod; 400, Base plate; 410, Electrode; 500, Graphite bucket; 600, Metal bucket. Detailed Implementation

[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of the present invention is for describing specific implementation schemes and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0029] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" used in this specification are only for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as part of the scope of the invention.

[0030] The silicon carbide raw material is polycrystalline silicon carbide. During the growth of silicon carbide crystals, some of the silicon carbide raw material decomposes into solid carbon and silicon. The decomposition formula of the silicon carbide raw material is shown in formula (1):

[0031]

[0032] During the growth of silicon carbide crystals, solid carbon particles are subjected to thermophoretic force within the particle growth device. When the radius of the carbon particles is extremely small and gravity cannot overcome the thermophoretic force, the carbon particles will float up. The thermophoretic force formula for carbon particles is shown in formula (2):

[0033]

[0034] Among them, F τ Where R is the thermophoretic force, R is the radius of the graphite powder, and Cs is the thermal slip coefficient. Let ρ be the temperature gradient, ρ be the graphite density, T be the temperature, Cm be the momentum exchange coefficient, and μ be the free path of gas molecules.

[0035] Considering that only particles with extremely small diameters can overcome gravity and that the tips are prone to gaining electrons, an electrostatic field E can be introduced into the raw material. When the fine particles are uncharged, they cannot continue to rise due to electrostatic adsorption. When the particles are charged, they are pushed downwards by the electric field force, thus preventing carbon particles from entering the silicon carbide crystal and eliminating carbon inclusions within the silicon carbide crystal.

[0036] Please refer to Figure 1. The present invention provides a silicon carbide crystal growth apparatus, including a crucible 100, a seed crystal tray 200, at least one layer of inert metal mesh 300, and a base plate 400; the crucible 100 is electrically connected to the positive or negative terminal of a first power source, and the crucible 100 is used to place silicon carbide raw material 110; the crucible 100 can be connected to the positive terminal of the first power source, or it can be connected to the negative terminal of the first power source, or the crucible 100 can be not connected to the first power source. A seed crystal tray 200 is positioned above the crucible 100 and is used to hold the seed crystal 210. An inert metal mesh 300 is positioned between the silicon carbide raw material 110 and the seed crystal 210 via an electrode rod 310, and the inert metal mesh 300 is not in contact with the crucible 100. The electrode rod 310 is electrically connected to either the positive or negative terminal of the second power supply. The electrode rod 310 is made of graphite and can be connected to either the positive or negative terminal of the second power supply, or it can be de-connected. The crucible 100 has a first region 120 for placing the silicon carbide raw material 110 within the first region 120. The base 400 is positioned below the crucible 100 and is electrically connected to either the positive or negative terminal of the third power supply. The base 400 can be connected to the positive terminal, the negative terminal, or not connected to the third power supply. At least one of the following connections must be made: crucible 100 connected to the first power supply, electrode rod 310 connected to the second power supply, and base 400 connected to the third power supply.

[0037] Referring to Figure 1, in one embodiment, the silicon carbide crystal growth apparatus further includes a graphite barrel 500, which is disposed between the crucible 100 and the seed crystal tray 200. The outer diameter of the graphite barrel 500 is the same as the outer diameter of the crucible 100. A metal barrel 600 is fitted inside the graphite barrel 500, and the outer wall of the metal barrel 600 is in contact with the inner wall of the graphite barrel 500. The metal barrel 600 can prevent the graphite on the graphite barrel 500 from volatilizing into the silicon carbide crystal during the silicon carbide crystal growth process and affecting the quality of the silicon carbide crystal. The diameter of the metal container 600 is 145–251 mm, the wall thickness is 0.1–5 mm, and the height is 5–75 mm. The ratio of the inner diameter of the upper end to the inner diameter of the lower end of the metal container 600 is 1:1 to 1:2. For example, the diameter of the metal container 600 can be any value within the range of 145 mm, 200 mm, or 251 mm; the wall thickness can be any value within the range of 0.1 mm, 2 mm, or 5 mm; and the height can be any value within the range of 5 mm, 20 mm, 50 mm, or 75 mm. The dimensions of the metal container 600 are adjusted according to the dimensions of the crucible 100 and the graphite container 500, as well as actual usage requirements.

[0038] Referring to Figure 1, in one embodiment, an inert metal mesh 300 is disposed between the graphite barrel 500 and the crucible 100 via electrode rods 310. The electrode rods 310 are connected to the positive terminal of the second power supply, and the base 400 is connected to the positive terminal of the third power supply. The number of electrode rods 310 is 2 to 6, for example, any number within the range of 2, 4, or 6. In other embodiments, the electrode rods 310 may be connected to the negative terminal of the second power supply or may not be connected to the second power supply; the base 400 may be connected to the negative terminal of the third power supply or may not be connected to the third power supply; or the electrode rods 310 may be connected to either the second power supply or the base 400 may be connected to either the third power supply; or neither the electrode rods 310 nor the base 400 may be connected to the second power supply or the third power supply, while the crucible 100 is connected to either the positive or negative terminal of the first power supply. In this embodiment, the inert metal mesh 300 is one layer. In other embodiments, the number of layers of the inert metal mesh 300 may be two or more. The number of inert metal meshes 300 is not limited here.

[0039] Preferably, a metal fiber layer is laid on the inert metal mesh 300, wherein the length-to-diameter ratio of the metal fibers is 1000:1 to 1:1, and the thickness of the metal fiber layer is 1 to 50 mm. For example, the length-to-diameter ratio of the metal fibers can be any value within the range of 1000:1 to 1:1, such as 1000:1, 800:1, 500:1, 300:1, or 1:1, and the thickness of the metal fiber layer can be any value within the range of 1 to 50 mm, such as 1 mm, 30 mm, or 50 mm. The metal fiber layer on the inert metal mesh 300 can improve the filtration efficiency for carbon particles. The inert metal mesh 300, the metal fiber layer, and the metal container 600 are made of niobium, tantalum, tungsten, rhenium, or carbides with a carbon atom ratio of niobium, tantalum, tungsten, rhenium to carbon of 0.1 to 5. When carbon particles come into contact with the inert metal mesh 300, the metal fiber layer, and the metal barrel 600, niobium, tantalum, tungsten, or rhenium are converted into high-temperature resistant materials such as niobium carbide, tantalum carbide, tungsten carbide, or rhenium carbide.

[0040] Referring to Figures 1 to 3, in one embodiment, the base 400 is disposed below the crucible 100, and the distance between the crucible 100 and the base 400 is 0–50 mm. For example, the distance between the crucible 100 and the base 400 can be any value within the range of 0–50 mm, such as 0 mm, 20 mm, 30 mm, or 50 mm. The base 400 includes a plurality of electrodes 410 arranged in a ring array. In this embodiment, there are six electrodes 410 arranged in a ring array, and the electrodes 410 are alternately connected to the positive and negative terminals of the third power supply. In other embodiments, the number of electrodes 410 can be four, five, or other numbers, and the distribution of the electrodes 410 can be symmetrical or other distribution patterns. The number and distribution pattern of the electrodes 410 are not limited here.

[0041] The present invention also provides a method for growing silicon carbide crystals, comprising the following steps:

[0042] S1. A silicon carbide crystal growth apparatus is provided;

[0043] S2. Place the seed crystal on the seed crystal tray 200, place the silicon carbide raw material 110 in the first region 120 of the crucible 100, and place the silicon carbide crystal growth device in the silicon carbide crystal growth equipment.

[0044] S3. Adjust the temperature and pressure inside the growth equipment, turn on at least one of the first power supply, the second power supply and the third power supply, and grow silicon carbide crystals.

[0045] S4. After growth is complete, adjust the pressure inside the growth equipment, turn off the power, cool down, and remove the crystal.

[0046] Please refer to Figure 1. Specifically, the silicon carbide crystal growth apparatus in step S1 is the silicon carbide crystal growth apparatus of the present invention. Its structure can be found in the specific description above, and will not be repeated here.

[0047] Referring to Figure 1, in step S2, the seed crystal 210 is placed on the seed crystal tray 200, the silicon carbide raw material 110 is placed in the first region 120 of the crucible 100, and the silicon carbide crystal growth apparatus is placed in the silicon carbide crystal growth equipment. The crystal growth equipment is a conventional growth furnace used for silicon carbide crystal growth.

[0048] In step S3, the temperature and pressure inside the growth equipment are adjusted to raise the temperature of the silicon carbide raw material 110 to 1600–2400°C, such as any value within the range of 1600°C, 1900°C, 2100°C, or 2400°C; the growth equipment is evacuated and an inert gas, such as Ar, is introduced to raise the pressure inside the growth equipment to 200–800 mbar, such as any value within the range of 200 mbar, 500 mbar, or 800 mbar; the temperature inside the growth equipment is then adjusted to raise the temperature of the silicon carbide raw material 110 to 1700–2500°C. 00℃, for example, it can be any value in the range of 1700℃ to 2500℃, such as 1700℃, 2000℃, 2300℃ or 2500℃; turn on at least one of the first power supply, the second power supply and the third power supply, all of which are DC power supplies, and the voltage of the first power supply, the second power supply and the third power supply is 1V to 12kV; reduce the pressure in the growth equipment to 0.1 to 100mbar in 1 to 50 hours, for example, any value in the range of 0.1 to 100mbar, such as 0.1mbar, 20mbar, 50mbar or 100mbar, and grow stably for 50 to 150 hours.

[0049] In step S4, after growth is complete, adjust the pressure inside the growth equipment to 50-500 mbar, such as any value within the range of 50-500 mbar, 200 mbar, or 500 mbar, turn off the power, slowly cool down, and remove the crystal.

[0050] The crystal growth method of the present invention will be specifically described below through specific embodiments.

[0051] Example 1

[0052] In this embodiment, in the silicon carbide crystal growth apparatus, a layer of thallium carbide metal mesh is placed between the seed crystal and the silicon carbide raw material. The thallium carbide metal mesh is fixed between the crucible and the graphite barrel by two graphite electrode rods. The graphite electrode rods are connected to the positive terminal of the second power supply, and the voltage of the second power supply is 3V.

[0053] The thallium carbide metal mesh has a diameter of 155 mm, a distance of 55 mm between the thallium carbide metal mesh and the upper surface of the raw material, and a distance of 30 mm between the thallium carbide metal mesh and the lower surface of the seed crystal. A tungsten carbide fiber layer is laid on the thallium carbide metal mesh. The thickness of the tungsten carbide fiber layer is 10 mm, the length-to-diameter ratio of the tungsten carbide fiber is 500:1, and the diameter of the tungsten carbide fiber is 0.2 mm.

[0054] The graphite container contains an inner metal container made of tungsten carbide. The metal container is bonded to the graphite container. The inner diameter of the metal container is 150mm at the end closer to the seed crystal and 155mm at the end farther from the seed crystal. The distance between the metal container and the seed crystal is 0.2mm. The thickness of the metal container is 0.5mm, and its height is 35mm. The distance between the crucible and the tray is 10mm. The tray is connected to the positive terminal of a third power supply with a voltage of 3kV.

[0055] The growth of silicon carbide crystals includes the following steps:

[0056] First, place the silicon carbide growth apparatus described above inside the growth equipment; raise the raw material temperature to 2300℃, adjust the pressure inside the growth equipment to 600 mbar, and turn on the second and third power supplies; reduce the pressure inside the growth equipment to 20 mbar over 3 hours, and allow it to grow stably for 100 hours. After growth is complete, raise the pressure inside the growth equipment to 100 mbar, turn off the power, slowly cool it down, and remove the silicon carbide crystal.

[0057] Optical inspection of the tail of the silicon carbide crystal grown in Example 1 showed no inclusions.

[0058] Example 2

[0059] In this embodiment, the silicon carbide crystal growth apparatus differs from that in Embodiment 1 in that: in the silicon carbide crystal growth apparatus, two layers of thallium carbide metal mesh are arranged between the seed crystal and the silicon carbide raw material. Each layer of thallium carbide metal mesh is fixed by two graphite electrode rods, and the distance between the two layers of thallium carbide metal mesh is 30mm. The thallium carbide metal mesh closer to the seed crystal is connected to the positive terminal of the second power supply, and the thallium carbide metal mesh farther from the seed crystal is connected to the negative terminal of the second power supply. The voltage of the second power supply is 5V, and the voltage of the third power supply is 3kV.

[0060] The growth of silicon carbide crystals includes the following steps:

[0061] Place the aforementioned silicon carbide growth apparatus inside the growth equipment; raise the raw material temperature to 2400℃, adjust the pressure inside the growth equipment to 300 mbar, and turn on the first and second power supplies; reduce the pressure inside the growth equipment to 35 mbar over 5 hours, and allow it to grow stably for 150 hours. After growth is complete, raise the pressure inside the growth equipment to 100 mbar, turn off the first and second power supplies, slowly cool down, and remove the silicon carbide crystal.

[0062] Optical inspection of the tail of the silicon carbide crystal grown in Example 2 showed no inclusions.

[0063] Example 3

[0064]

[0065]

[0066] Formula (3) above represents the Coulomb force experienced by carbon particles in an electrostatic field, formula (4) is Paschen's law, and V is the breakdown voltage. s The relationship between u and gas pressure p and gap d is shown. Here, u is the voltage, ε is the dielectric constant, d is the distance between electrodes, R is the carbon particle radius, and A, B, and γ are the characteristics of the Ar and N mixed gas. It can be seen that to obtain a larger force, only the voltage needs to be increased and the distance between electrodes reduced. Considering that the growth process will use low pressure (0.1–100 mbar), according to Equation 4, it can be deduced that at 0.2 mbar, the breakdown voltage Vs of Ar is approximately 40 V / cm. When the carbon particle size is 0.1–10 μm, the Coulomb force F and gravity are insufficient to overcome the upward thermophoretic force of the carbon particles.

[0067] Given that the relationship between F and d is inversely proportional to the square, increasing d to obtain a higher Vs is not worthwhile. Only by adjusting the process pressure to 0.1-0.2 mbar or 0.2-100 mbar can a sufficient breakdown voltage be obtained.

[0068] In this embodiment, the chassis includes six electrodes arranged in a ring array, with the six electrodes alternately connected to the positive and negative terminals of the second power supply. The distance between the crucible and the tray is adjusted so that the resistivity between them is between 10. 10 ~10 12 At Ωcm, the Johnsen-Rahbek adsorption effect begins to strengthen, with the main adsorption force occurring in the charging region, while the gap does not produce an adsorption effect. Therefore, to avoid electrostatic discharge (EDS), the smaller the electrode gap, the better. From Equation 5, the voltage u distribution is as follows:

[0069]

[0070] Where βn is the Bessel function, s is the electrode gap, l is the characteristic length of the electrode, r is the polar radius (maximum to tray diameter), and θ is the polar angle. Combining formula (3), it can be seen that the Johnsen-Rahbek adsorption force is greater than that of coulombic adsorption, and both voltage and gap can be reduced simultaneously.

[0071] In this embodiment, the silicon carbide growth apparatus includes two layers of thallium carbide metal mesh placed between the seed crystal and the silicon carbide raw material. Each thallium carbide metal mesh is fixed by two graphite electrode rods, with a spacing of 30 mm between the two layers. The thallium carbide metal mesh closer to the seed crystal is covered with fibers of 2 cm diameter and a length-to-diameter ratio of 200:1. The thallium carbide metal mesh farther from the seed crystal is covered with fiber particles of 0.2 mm diameter and a length-to-diameter ratio of 1:1. The thallium carbide metal mesh farther from the seed crystal is connected to the positive terminal of the second power supply, while the thallium carbide metal mesh closer to the seed crystal is connected to the negative terminal of the second power supply. Six electrodes on the tray are alternately connected to the positive and negative terminals of a third power supply, with a minimum spacing of 0.5 cm between the electrodes. The distance between the base and the crucible is 0.5 cm, and the voltage of the second power supply is 400 V.

[0072] In this embodiment, the growth of silicon carbide crystals includes the following steps:

[0073] First, the aforementioned silicon carbide growth apparatus is placed inside the growth equipment. The raw material temperature is raised to 2450℃, and the pressure inside the growth equipment is adjusted to 600 mbar. The second and third power supplies are turned on. After 5 hours, the pressure inside the growth equipment is reduced to 1.5 mbar, and the growth is stabilized for 200 hours. After growth is complete, the pressure inside the growth equipment is increased to 300 mbar, the power is turned off, the temperature is slowly lowered, and the crystal is removed.

[0074] In Example 3, the chassis uses an array of electrodes, achieving the same adsorption effect on carbon particles with a smaller voltage. Optical microscopy revealed no inclusions at the tail of the prepared silicon carbide crystal.

[0075] The silicon carbide crystal growth apparatus of the present invention comprises at least one layer of inert metal mesh between the silicon carbide raw material and the seed crystal, and a base plate at the bottom of the crucible. At least one of the following connections is made: the crucible is connected to a first power source, the electrode rod to a second power source, and the base plate to a third power source. When the crucible is connected to the first power source, the electrode rod to the second power source, or the base plate to the third power source, due to electric field polarization, the electrical charge of the silicon carbide raw material near the electric field is opposite to that of the electric field. Carbon particles generated from the decomposition of the silicon carbide raw material are adsorbed onto the lower surface of the inert metal mesh or the bottom of the crucible under the action of the electric field, preventing carbon particles from entering the silicon carbide crystal and affecting its quality. Therefore, the present invention effectively overcomes some practical problems in the prior art, thus possessing high utilization value and practical significance.

[0076] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A silicon carbide crystal growth apparatus, characterized in that, include: A crucible electrically connected to the positive or negative terminal of a first power source, the crucible including a first region for placing silicon carbide raw material; a seed crystal tray disposed above the crucible; at least one layer of inert metal mesh disposed between the first region and the seed crystal tray via electrode rods, the electrode rods being electrically connected to the positive or negative terminal of a second power source; and a base disposed below the crucible, the base being electrically connected to the positive or negative terminal of a third power source; wherein at least one of the following is electrically connected: the crucible to the first power source, the electrode rods to the second power source, and the base to the third power source.

2. The silicon carbide crystal growth apparatus according to claim 1, characterized in that, The silicon carbide crystal growth apparatus also includes a graphite barrel, which is disposed between the crucible and the seed crystal tray, and the outer diameter of the graphite barrel is the same as that of the crucible.

3. The silicon carbide crystal growth apparatus according to claim 2, characterized in that, The graphite barrel is fitted with a metal barrel inside, and the outer wall of the metal barrel is in contact with the inner wall of the graphite barrel.

4. The silicon carbide crystal growth apparatus according to claim 3, characterized in that, The distance between the metal bucket and the lower surface of the seed crystal is -5 to 5 mm.

5. The silicon carbide crystal growth apparatus according to claim 1, characterized in that, The distance between the inert metal mesh and the lower surface of the seed crystal is 5-85 mm, and the distance between the inert metal mesh and the upper surface of the silicon carbide raw material is 0.5-75 mm.

6. The silicon carbide crystal growth apparatus according to claim 1, characterized in that, A metal fiber layer is laid on the inert metal mesh, wherein the length-to-diameter ratio of the metal fibers is 1000:1 to 1:1, and the thickness of the metal fiber layer is 1 to 50 mm.

7. The silicon carbide crystal growth apparatus according to claim 1, characterized in that, The distance between the crucible and the base plate is 0-50 mm.

8. The silicon carbide crystal growth apparatus according to claim 1, characterized in that, The first power supply, the second power supply, and the third power supply are all DC power supplies, and the voltage of the first power supply, the second power supply, and the third power supply is 1V to 12kV.

9. A method for growing silicon carbide crystals, characterized in that, Includes the following steps: A silicon carbide crystal growth apparatus according to any one of claims 1 to 8 is provided; a seed crystal is installed on a seed crystal tray, silicon carbide raw material is placed in a crucible, and the silicon carbide crystal growth apparatus is placed in a silicon carbide crystal growth device; the temperature and pressure inside the growth device are adjusted, at least one of a first power supply, a second power supply, and a third power supply is turned on to stabilize the growth of the silicon carbide crystal; after the growth is completed, the pressure inside the growth device is adjusted to 50 to 500 mbar, the power supply is turned off, the temperature is slowly reduced, and the crystal is removed.

10. The silicon carbide crystal growth method according to claim 9, characterized in that, The stable growth of silicon carbide crystals includes: adjusting the temperature of the silicon carbide raw material to 1600-2400°C, adjusting the pressure inside the growth device to 200-800 mbar, adjusting the temperature of the silicon carbide raw material to 1700-2500°C, turning on at least one of the first power supply, the second power supply, and the third power supply, reducing the pressure inside the growth device to 0.1-100 mbar after 1-50 hours, and stabilizing the growth for 50-150 hours.

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