Laser light path, device and method for growing silicon carbide substrate by LCVD (Liquid Chemical Vapor Deposition) method

Abstract

The invention relates to a laser light path, device and method for growing a silicon carbide substrate through an LCVD method, in particular to the field of crystal preparation, and the laser light path comprises a laser generator set, an attenuator, a beam expander, a homogenizing mirror, a collimating mirror, a spectroscope, an X / Y galvanometer set and an F-theta lens which are connected in sequence; the laser generator group comprises N layers of annularly distributed lasers, wherein N is equal to 3-6; in the N layers of annularly distributed lasers, the distance between the (I + 1) th ring and the I th ring in the radial direction with the center as the starting point is 60-80% of the distance between the (I-1) th ring and the I th ring, and I is larger than or equal to 2 and smaller than N. According to the laser light path provided by the invention, through the design of the laser light path used in LCVD and the cooperation effect of the laser generator group, the homogenizing mirror and the X / Y galvanometer group, the homogenization of the obtained laser energy distribution is realized, and the homogenization preparation of the large-area silicon carbide single crystal substrate is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal preparation, and specifically to a laser optical path, device, and method for growing a silicon carbide substrate using an LCVD method, and more particularly to a laser optical path, growth device, and growth method for growing a silicon carbide substrate using an LCVD method. Background Art

[0002] At present, silicon carbide, as a third-generation semiconductor material, has excellent properties such as high breakdown field strength, high saturated electron drift rate, high thermal conductivity, and strong chemical stability. It has significant application value in electric vehicles, rail transportation, high-voltage transmission and transformation, photovoltaics, 5G communications and other fields. The usual preparation methods of silicon carbide substrates include: CVD (chemical vapor deposition), PVT (physical vapor transport), etc.

[0003] For example, CN114318515A discloses a PVT growth device for large-size silicon carbide single crystals, comprising a growth furnace, an X-ray in-situ imaging module and a control system. The growth furnace comprises a furnace wall, a thermal insulation felt, a plate-type resistance heater and a crucible from the outside to the inside. The X-ray in-situ imaging module comprises an X-ray source and an X-ray imaging receiver respectively arranged on opposite sides of the radial direction of the single crystal growth in the growth furnace; the furnace wall has non-metallic windows on both sides in the radial direction for X-ray transmission, and the thermal insulation felt, the plate-type resistance heater and the crucible are all made of non-metallic materials; the control system receives imaging signals from the X-ray imaging receiver and controls the operation of the X-ray source and the plate-type resistance heater.

[0004] CN109797374A discloses a method for preparing a silicon carbide substrate and its batch preparation method. The method involves etching a silicon carbide wafer, growing a layer of graphene on its surface, and then using this as a seed crystal to continue growing graphene on its surface using chemical vapor deposition to prepare a silicon carbide substrate. This method has a short preparation cycle, and the prepared silicon carbide substrate has good performance consistency, with a pass rate of over 90%. The resistivity of the prepared P-type silicon carbide substrate is below 0.5Ω·cm, the resistivity of the N-type silicon carbide substrate is between 0.01-0.02Ω·cm, and the microtube density is above 0.1cm. -2 the following.

[0005] CVD (chemical vapor deposition) is a method of growing single crystals on pre-set seed crystals by chemical reactions between atoms and molecules using precursor gases under high temperature and high pressure. Compared with the PVT method, it can effectively control the introduction of impurities and grow high-quality single crystal substrates with specific structures through precise control of gas flow, pressure and temperature. However, the CVD method has low growth efficiency and high growth cost.

[0006] Currently, LCVD (Laser Chemical Vapor Deposition) is a method that uses a laser beam to locally heat the substrate, causing the gaseous precursor to undergo a chemical reaction in the laser irradiation area and deposit silicon carbide. By introducing laser energy to locally heat the reaction area, the temperature required for the overall process can be significantly reduced, reducing the risk of thermal stress and thermal damage. Since the laser can provide additional energy, it can theoretically accelerate the chemical reaction and thus increase the deposition rate, thereby compensating for the low growth efficiency of the traditional CVD method. However, during the current LCVD process, the uneven heating caused by the laser scanning causes uneven heating, resulting in silicon carbide growth defects and an uneven surface, which is not conducive to the preparation of high-quality silicon carbide substrates. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a laser optical path, device and method for growing silicon carbide substrates by the LCVD method, so as to solve the problem that when LCVD is used to prepare silicon carbide substrates, uneven heating is caused by uneven laser scanning, resulting in silicon carbide growth defects and uneven surface, which is not conducive to the preparation of high-quality silicon carbide substrates.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a laser optical path for growing a silicon carbide substrate using an LCVD method, the laser optical path comprising:

[0010] The laser generator group, attenuator, beam expander, homogenizer, collimator, beam splitter, X / Y galvanometer group and F-θ lens are connected in sequence;

[0011] The laser generator group includes: N layers of lasers distributed in an annular pattern, N=3-6;

[0012] In the N-layer annularly distributed laser, the distance between the I+1th ring and the Ith ring along the radial direction starting from the center is 60-80% of the distance between the I-1th ring and the Ith ring, and 2≤I<N.

[0013] The laser optical path provided by the present invention achieves uniformity in the distribution of the obtained laser energy by designing the laser optical path used in LCVD with the help of the synergistic effect of the laser generator group, the homogenizing mirror and the X / Y galvanometer group, which is conducive to the uniform preparation of large-area silicon carbide single crystal substrates.

[0014] As a preferred technical solution of the present invention, the magnification of the beam expander is 2-5 times.

[0015] Preferably, the size of the microlens unit of the homogenizer is 0.1-0.5 mm.

[0016] Preferably, the focal length f of the homogenizer is 50-200 mm, f>2D, and D is the diameter of the light beam obtained after expansion by the beam expander.

[0017] As a preferred technical solution of the present invention, the reflector in the X / Y galvanometer group makes the incident angle of each layer of laser beam tilted by 5-10°.

[0018] Preferably, the scanning field diameter of the F-θ lens is ≥200 mm.

[0019] In a second aspect, the present invention provides a growth device for growing a silicon carbide substrate using an LCVD method, the growth device comprising: using the laser light path described in the first aspect as a laser light source.

[0020] As a preferred technical solution of the present invention, the crystal growth chamber in the growth device is a gradually narrowing structure along the laser direction.

[0021] Preferably, two axially symmetrical air inlets are provided on the side of the crystal growth chamber at positions that are (1 / 2 to 2 / 3) the height of the crystal growth chamber away from the growth platform.

[0022] Preferably, the growth platform is an axially rotating growth platform.

[0023] In a third aspect, the present invention provides a method for growing a silicon carbide substrate using an LCVD method, the method comprising:

[0024] The silicon carbide seed crystal is subjected to LCVD silicon carbide crystal growth using the laser generated by the laser optical path as described in the first aspect to obtain a silicon carbide single crystal substrate.

[0025] As a preferred technical solution of the present invention, the purity of the silicon carbide seed crystal is ≥5N5 level.

[0026] Preferably, the silicon carbide seed crystal is cleaned before LCVD silicon carbide crystal growth.

[0027] Preferably, the cleaning method includes: organic solvent cleaning, water cleaning, acid cleaning or alkaline cleaning, or a combination of at least two of them.

[0028] As a preferred technical solution of the present invention, the volume ratio of silicon source gas to carbon source gas in the gas precursor used in the LCVD silicon carbide crystal growth is (1-3):1.

[0029] Preferably, the flow rate of the gas precursor during the LCVD silicon carbide crystal growth is 50-200 sccm.

[0030] Preferably, the pressure of the gas precursor during the LCVD silicon carbide crystal growth is 50-200 Pa.

[0031] As a preferred technical solution of the present invention, the single-layer power density of the laser used in the LCVD silicon carbide crystal growth is 10-50kW / cm 2 .

[0032] Preferably, the spot diameter of the laser used in the LCVD silicon carbide crystal growth is 0.5-2 mm.

[0033] Preferably, the spiral scanning speed of the laser used in the LCVD silicon carbide crystal growth is 10-100 mm / s.

[0034] Preferably, the laser used in the LCVD silicon carbide crystal growth rotates synchronously with the seed crystal.

[0035] As a preferred technical solution of the present invention, the growth temperature of the LCVD silicon carbide crystal growth is 1500-2000°C.

[0036] Preferably, the deposition rate of silicon carbide during the LCVD silicon carbide crystal growth is 1-5 nm / s.

[0037] Compared with the existing technical solutions, the present invention has the following beneficial effects:

[0038] (1) The laser optical path provided by the present invention adopts an annular layered laser distribution and cooperates with a homogenizing mirror and an X / Y galvanometer group so that the generated laser can be used to achieve large-area uniform single crystal growth and realize the uniform preparation of silicon carbide single crystal substrates.

[0039] (2) The growth method provided by the present invention, combined with the circular arrangement of lasers, spiral scanning and substrate rotation, and the design of adjustable laser power, can significantly improve the uniformity of single crystal growth, reduce defects and inhibit particle contamination, reduce growth defects of silicon carbide substrates, and reduce the roughness of the surface of silicon carbide substrates. The etch pit density EPD of the obtained silicon carbide crystal is ≤4389 / cm 2 , microtubule density ≤ 0.28 / cm 2 , under the preferred solution, the etching pit density EPD≤3358 / cm 2 , microtubule density ≤ 0.18 / cm 2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of a laser optical path for growing a silicon carbide substrate using an LCVD method according to an embodiment of the present invention;

[0041] Figure 2 It is a schematic diagram of a growth device for growing a silicon carbide substrate using an LCVD method according to an embodiment of the present invention.

[0042] In the figure: 100 is the laser optical path, 110 is the laser generator group, 120 is the attenuator, 130 is the beam expander, 140 is the homogenizer, 150 is the collimator, 160 is the beam splitter, 170 is the X / Y galvanometer group, and 180 is the F-θ lens;

[0043] 200 is a furnace body, 210 is a crystal growth chamber, 211 is a growth platform, 212 is an air inlet, 213 is an entrance lens, 221 is a seal, 222 is a quartz tube, 231 is a support platform, and 241 is a motor.

[0044] The present invention is further described in detail below. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0045] To better illustrate the present invention and facilitate understanding of the technical solutions of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0046] Currently, when growing silicon carbide substrates using the LCVD method, uneven heating due to laser scanning causes uneven heating, which leads to silicon carbide growth defects and uneven surfaces, which is not conducive to the preparation of high-quality silicon carbide substrates. Based on this, the present invention optimizes the laser optical path to improve the energy uniformity of the supplied laser, and further optimizes the growth method of the LCVD method for growing silicon carbide substrates to further improve the uniformity of the obtained silicon carbide substrates, thereby improving the performance of the silicon carbide substrates, as follows:

[0047] 1. This embodiment provides a laser optical path for growing a silicon carbide substrate using an LCVD method, such as Figure 1 As shown, the laser optical path 100 includes:

[0048] The laser generator group 110, the attenuator 120, the beam expander 130, the homogenizer 140, the collimator 150, the beam splitter 160, the X / Y galvanometer group 170 and the F-θ lens 180 are connected in sequence.

[0049] In the present invention, the laser light path homogenizes the laser energy distribution through beam shaping to form a flat-top beam, thereby achieving uniform surface heating during substrate growth. The laser generator is preferably an ultraviolet pulsed laser, which is the optimal choice for growing silicon carbide single crystal substrates. Its short wavelength and high energy density can accurately control the reaction area and reduce thermal damage. At the same time, it cooperates with the galvanometer scanning and homogenized light path of the rear mold to achieve large-area uniform single crystal growth.

[0050] The laser generator group 110 includes: N layers of annularly distributed lasers, N = 3-6, for example, 3 layers, 4 layers, 5 layers or 6 layers, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0051] Among them, in the laser with N layers of annular distribution, the distance between the I+1th ring and the Ith ring in the radial direction starting from the center is 60-80% of the distance between the I-1th ring and the Ith ring, 2≤I<N, for example, it can be 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78% or 80%, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0052] For example, from the center outward, there are the 1st ring (innermost layer), the 2nd ring, ... the Nth ring (outermost layer), N = 3-6. At this time, the 1st ring spacing: the radial distance between the 2nd ring and the 1st ring (S1), this spacing is defined as the initial inner layer spacing; the 2nd ring spacing: the radial distance between the 3rd ring and the 2nd ring (S2), which must satisfy S2 = 60-80% × S1; the 3rd ring spacing: the radial distance between the 4th ring and the 3rd ring (S3), which must satisfy S3 = 60-80% × S2, and so on.

[0053] The attenuator 120 is used to adjust the laser power to prevent subsequent optical components or substrates from being damaged due to excessive energy.

[0054] The beam expander 130 is used to expand the beam diameter, reduce the divergence angle, and improve the subsequent focusing quality, with a magnification of 2-5 times.

[0055] Among them, the homogenizer 140 is used to convert the Gaussian beam into a uniform flat-top beam to preliminarily eliminate the energy gradient. The size of the microlens unit of the homogenizer 140 is 0.1-0.5mm; the focal length f of the homogenizer 140 ranges from 50-200mm, which matches the beam diameter obtained after expansion by the beam expander, f>2D, where D is the beam diameter obtained after expansion by the beam expander.

[0056] The collimator 150 is used to adjust the parallelism of the light beam.

[0057] Among them, the beam splitter 160 is used to split and superimpose light beams. By splitting a single beam of light into multiple beams through the beam splitter 160, and refocusing or superimposing them through different paths, the coverage area of ​​the light spot can be expanded; at the same time, the beam splitter 160 can separate a small amount of light for real-time power feedback to ensure growth stability.

[0058] Among them, the X / Y galvanometer group 170 adjusts the incident angle of the light beam in real time through the high-speed deflection of the galvanometer reflector to achieve scanning or local energy control, and adopts X / Y dual galvanometers to achieve two-dimensional scanning.

[0059] Among them, the reflector in the X / Y galvanometer group 170 makes the incident angle of each layer of laser beam tilted 5-10°, for example, it can be 5°, 6°, 7°, 8°, 9° or 10°, etc., but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0060] Among them, the F-θ lens 180 is used to cooperate with the X / Y galvanometer group 170 to ensure that the spot size at different scanning positions is stable and consistent. The scanning field diameter of the F-θ lens 180 needs to be consistent with the size of the growth platform 211, and the lens scanning field diameter is ≥200mm.

[0061] 2. This embodiment provides a growth device for growing a silicon carbide substrate using an LCVD method. The growth device includes: using a laser light path 100 as a laser light source.

[0062] The laser optical path 100 includes: a laser generator group 110, an attenuator 120, a beam expander 130, a homogenizer 140, a collimator 150, a beam splitter 160, an X / Y galvanometer group 170 and an F-θ lens 180 connected in sequence.

[0063] The laser generator group 110 includes: N layers of annularly distributed lasers, N = 3-6, for example, 3 layers, 4 layers, 5 layers or 6 layers, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0064] Among them, in the laser with N layers of annular distribution, the distance between the I+1th ring and the Ith ring in the radial direction starting from the center is 60-80% of the distance between the I-1th ring and the Ith ring, 2≤I<N, for example, it can be 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78% or 80%, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0065] For example, from the center outward, there are the 1st ring (innermost layer), the 2nd ring, ... the Nth ring (outermost layer), N = 3-6. At this time, the 1st ring spacing: the radial distance between the 2nd ring and the 1st ring (S1), this spacing is defined as the initial inner layer spacing; the 2nd ring spacing: the radial distance between the 3rd ring and the 2nd ring (S2), which must satisfy S2 = 60-80% × S1; the 3rd ring spacing: the radial distance between the 4th ring and the 3rd ring (S3), which must satisfy S3 = 60-80% × S2, and so on.

[0066] The attenuator 120 is used to adjust the laser power to prevent subsequent optical components or substrates from being damaged due to excessive energy.

[0067] The beam expander 130 is used to expand the beam diameter, reduce the divergence angle, and improve the subsequent focusing quality, with a magnification of 2-5 times.

[0068] Among them, the homogenizer 140 is used to convert the Gaussian beam into a uniform flat-top beam to preliminarily eliminate the energy gradient. The size of the microlens unit of the homogenizer 140 is 0.1-0.5mm; the focal length f of the homogenizer 140 ranges from 50-200mm, which matches the beam diameter obtained after expansion by the beam expander, f>2D, where D is the beam diameter obtained after expansion by the beam expander.

[0069] The collimator 150 is used to adjust the parallelism of the light beam.

[0070] Among them, the beam splitter 160 is used to split and superimpose light beams. By splitting a single beam of light into multiple beams through the beam splitter 160, and refocusing or superimposing them through different paths, the coverage area of ​​the light spot can be expanded; at the same time, the beam splitter 160 can separate a small amount of light for real-time power feedback to ensure growth stability.

[0071] Among them, the X / Y galvanometer group 170 adjusts the incident angle of the light beam in real time through the high-speed deflection of the galvanometer reflector to achieve scanning or local energy control, and adopts X / Y dual galvanometers to achieve two-dimensional scanning.

[0072] Among them, the reflector in the X / Y galvanometer group 170 makes the incident angle of each layer of laser beam tilted 5-10°, for example, it can be 5°, 6°, 7°, 8°, 9° or 10°, etc., but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0073] Among them, the F-θ lens 180 is used to cooperate with the X / Y galvanometer group 170 to ensure that the spot size at different scanning positions is stable and consistent. The scanning field diameter of the F-θ lens 180 needs to be consistent with the size of the growth platform 211, and the lens scanning field diameter is ≥200mm.

[0074] The crystal growth chamber 210 in the growth device is a gradually narrowing structure along the laser direction, and the size of the gradually narrowing structure can be reasonably designed according to the volume design requirements of the crystal growth chamber 210 .

[0075] Among them, two axially symmetrical air inlets 212 are set on the side of the crystal growth chamber 210 at a position that is (1 / 2 to 2 / 3) the height of the crystal growth chamber 210 away from the growth platform 211. For example, it can be 1 / 2, 8 / 15, 17 / 30, 3 / 5, 19 / 30 or 2 / 3, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0076] In the present invention, the axial direction refers to the axial direction of the growth device.

[0077] The growth platform 211 is an axially rotating growth platform 211 .

[0078] For example, a silicon carbide crystal growth device, such as Figure 2 As shown, the furnace body 200 includes a quartz tube 222 with double-sided openings. The upper and lower open ends of the quartz tube 222 are sealed with sealing members 221; the sealing member 221 includes a flange.

[0079] A laser emitter is fixedly mounted at the bottom open end of the furnace body 200. A crucible assembly, i.e., a crystal growth chamber 210, is disposed within the growth chamber of the quartz tube 222. The crucible assembly is coaxially mounted on a support platform 231, with the end of the support platform 231 away from the crucible assembly being fixed to the sealing member 221. An insulation structure is provided on the outer surface of the crucible assembly, which is a graphite felt. The insulation structure wraps around the crucible.

[0080] An entrance lens 213 is provided at the bottom of the crucible. The diameter of the lens matches the area of ​​the laser ring distribution of the laser emitter, ensuring that all laser beams can pass through the lens to heat the low-temperature seed crystal surface of the crucible and ensure smooth growth of the silicon carbide substrate.

[0081] Two axially symmetrical gas inlets 212 are provided near the side of the crucible, communicating with the interior of the crucible and used to guide the reaction gas into the crucible;

[0082] The graphite crucible from the crucible gas inlet 212 to the bottom of the crucible forms a gradually narrowing internal crucible structure, which helps the reaction gas to enter the seed crystal surface for reaction;

[0083] The top of the crucible is provided with a connecting shaft tube that can rotate around the axial direction. The connecting shaft tube axially passes through the seal 221, the support platform 231, the crucible structure and the bottom of the crucible; the upper end of the connecting shaft tube is provided with a radially arranged growth platform 211, which is fixedly connected to the connecting pump tube. The growth platform 211 is used to bond and fix the silicon carbide seed crystal and grow the silicon carbide substrate; the lower end of the connecting shaft tube is connected to the motor 241, and the rotation speed is set to ensure that the growth platform 211 can rotate along the axis. The diameter of the growth platform 211 matches the diameter of the lens to ensure that the laser can fully cover the surface of the seed crystal.

[0084] The top of the crucible is also provided with an air outlet and an air outlet channel. The air outlet channel and the inside of the crucible are used to discharge excess gas. The air outlet end of the air outlet channel is connected to a vacuum pump.

[0085] 3. This embodiment provides a method for growing a silicon carbide substrate using an LCVD method, comprising:

[0086] The silicon carbide seed crystal is subjected to LCVD silicon carbide crystal growth using the laser light generated by the laser optical path 100 to obtain a silicon carbide single crystal substrate.

[0087] The laser optical path 100 includes: a laser generator group 110, an attenuator 120, a beam expander 130, a homogenizer 140, a collimator 150, a beam splitter 160, an X / Y galvanometer group 170 and an F-θ lens 180 connected in sequence.

[0088] The laser generator group 110 includes: N layers of annularly distributed lasers, N = 3-6, for example, 3 layers, 4 layers, 5 layers or 6 layers, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0089] Among them, in the laser with N layers of annular distribution, the distance between the I+1th ring and the Ith ring in the radial direction starting from the center is 60-80% of the distance between the I-1th ring and the Ith ring, 2≤I<N, for example, it can be 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78% or 80%, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0090] For example, from the center outward, there are the 1st ring (innermost layer), the 2nd ring, ... the Nth ring (outermost layer), N = 3-6. At this time, the 1st ring spacing: the radial distance between the 2nd ring and the 1st ring (S1), this spacing is defined as the initial inner layer spacing; the 2nd ring spacing: the radial distance between the 3rd ring and the 2nd ring (S2), which must satisfy S2 = 60-80% × S1; the 3rd ring spacing: the radial distance between the 4th ring and the 3rd ring (S3), which must satisfy S3 = 60-80% × S2, and so on.

[0091] The attenuator 120 is used to adjust the laser power to prevent subsequent optical components or substrates from being damaged due to excessive energy.

[0092] The beam expander 130 is used to expand the beam diameter, reduce the divergence angle, and improve the subsequent focusing quality, with a magnification of 2-5 times.

[0093] Among them, the homogenizer 140 is used to convert the Gaussian beam into a uniform flat-top beam to preliminarily eliminate the energy gradient. The size of the microlens unit of the homogenizer 140 is 0.1-0.5mm; the focal length f of the homogenizer 140 ranges from 50-200mm, which matches the beam diameter obtained after expansion by the beam expander, f>2D, where D is the beam diameter obtained after expansion by the beam expander.

[0094] The collimator 150 is used to adjust the parallelism of the light beam.

[0095] Among them, the beam splitter 160 is used to split and superimpose light beams. By splitting a single beam of light into multiple beams through the beam splitter 160, and refocusing or superimposing them through different paths, the coverage area of ​​the light spot can be expanded; at the same time, the beam splitter 160 can separate a small amount of light for real-time power feedback to ensure growth stability.

[0096] Among them, the X / Y galvanometer group 170 adjusts the incident angle of the light beam in real time through the high-speed deflection of the galvanometer reflector to achieve scanning or local energy control, and adopts X / Y dual galvanometers to achieve two-dimensional scanning.

[0097] Among them, the reflector in the X / Y galvanometer group 170 makes the incident angle of each layer of laser beam tilted 5-10°, for example, it can be 5°, 6°, 7°, 8°, 9° or 10°, etc., but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0098] Among them, the F-θ lens 180 is used to cooperate with the X / Y galvanometer group 170 to ensure that the spot size at different scanning positions is stable and consistent. The scanning field diameter of the F-θ lens 180 needs to be consistent with the size of the growth platform 211, and the lens scanning field diameter is ≥200mm.

[0099] The purity of the silicon carbide seed crystal is ≥5N5, for example, it can be 5N5, 6N or 6N5, etc., but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0100] The silicon carbide seed crystal is cleaned before LCVD silicon carbide crystal growth.

[0101] The cleaning method includes: organic solvent cleaning, water cleaning, acid cleaning or alkaline cleaning, or a combination of at least two of them.

[0102] The organic solvent used in the organic solvent cleaning may be one of acetone, ethanol or isopropanol, or a combination of at least two of them.

[0103] The acid medium used in the pickling can be selected from one of nitric acid, hydrofluoric acid, sulfuric acid, hydrochloric acid, etc., or a combination of at least two thereof.

[0104] The alkaline medium used in the alkaline washing may be ammonia water and / or tetramethylammonium hydroxide.

[0105] Among them, the cleaning process is supplemented by means of enhancing the cleaning effect such as microwaves and / or ultrasound to further improve the cleaning effect.

[0106] Among them, the volume ratio of silicon source gas and carbon source gas in the gas precursor used in LCVD silicon carbide crystal growth is (1-3):1, for example, it can be 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1 or 3:1, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0107] In the present invention, the silicon source gas used in the growth includes: silane and other commonly used silicon sources in the art, and the carbon source gas used includes: acetylene and / or methane and other commonly used carbon source gases in the art.

[0108] Among them, the flow rate of the gas precursor in the LCVD silicon carbide crystal growth is 50-200sccm, for example, it can be 50sccm, 60sccm, 70sccm, 80sccm, 90sccm, 100sccm, 110sccm, 120sccm, 130sccm, 140sccm, 150sccm, 160sccm, 170sccm, 180sccm, 190sccm or 200sccm, etc., but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0109] Among them, the pressure of the gas precursor in LCVD silicon carbide crystal growth is 50-200Pa, for example, it can be 50Pa, 60Pa, 70Pa, 80Pa, 90Pa, 100Pa, 110Pa, 120Pa, 130Pa, 140Pa, 150Pa, 160Pa, 180Pa, 190Pa or 200Pa, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0110] The single-layer power density of the laser used in LCVD silicon carbide crystal growth is 10-50kW / cm 2 , for example, it can be 10kW / cm 2 、15kW / cm 2 , 20kW / cm 2 , 25kW / cm 2 、30kW / cm 2 、35kW / cm 2 、40kW / cm 2 、45kW / cm 2 or 50kW / cm 2 The above values ​​are not limited to the listed values, and other values ​​not listed in the range also meet the requirements.

[0111] Among them, the spot diameter of the laser used in LCVD silicon carbide crystal growth is 0.5-2mm, for example, it can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm or 2mm, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0112] Among them, the spiral scanning speed of the laser used in LCVD silicon carbide crystal growth is 10-100 mm / s, for example, it can be 10 mm / s, 20 mm / s, 30 mm / s, 40 mm / s, 50 mm / s, 60 mm / s, 70 mm / s, 80 mm / s, 90 mm / s or 100 mm / s, etc., but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0113] Among them, the laser used in LCVD silicon carbide crystal growth rotates synchronously with the seed crystal.

[0114] Among them, the growth temperature of LCVD silicon carbide crystal growth is 1500-2000℃, for example, it can be 1500℃, 1550℃, 1600℃, 1650℃, 1700℃, 1750℃, 1800℃, 1850℃, 1900℃, 1950℃ or 2000℃, but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0115] Among them, the deposition rate of silicon carbide in LCVD silicon carbide crystal growth is 1-5nm / s, for example, it can be 1nm / s, 1.5nm / s, 2nm / s, 2.5nm / s, 3nm / s, 3.5nm / s, 4nm / s, 4.5nm / s or 5nm / s, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0116] In the present invention, after the LCVD silicon carbide crystal growth is completed, the sample can be slowly cooled to avoid stress concentration and defect formation caused by rapid cooling.

[0117] Furthermore, in order to illustrate the effects that can be achieved by the laser optical path and growth method provided by the present invention, the following practical examples are used for illustration, as follows:

[0118] Example 1

[0119] This embodiment provides a specific implementation process of growing a silicon carbide substrate using an LCVD method, which is as follows:

[0120] performing LCVD silicon carbide crystal growth on the silicon carbide seed crystal to obtain a silicon carbide single crystal substrate;

[0121] Wherein, the purity of the silicon carbide seed crystal is 5N5 grade; the silicon carbide seed crystal is washed with ethanol before LCVD silicon carbide crystal growth;

[0122] The laser used in the LCVD silicon carbide crystal growth is formed by the following laser optical path, including: a laser generator group, an attenuator, a beam expander, a homogenizer, a collimator, a beam splitter, an X / Y galvanometer group and an F-θ lens connected in sequence; the laser generator group includes: N layers of annularly distributed lasers, N = 5; in the N layers of annularly distributed lasers, the radial spacing between the I+1 ring and the I ring with the center as the starting point is 75% of the spacing between the I-1 ring and the I ring, 2≤I<N, the radial distance between the first ring and the second ring is 20mm, at this time I takes the value of 2, 3, 4, 5, and the radial spacing of the rings is stepped with the center as the starting point. The diameter of the original beam is 5mm. The magnification of the beam expander is 4 times, and the beam diameter D obtained after the beam expander is 20mm. The microlens unit size of the homogenizer is 0.4mm, and the focal length f range is 150mm, which matches the beam diameter obtained after the beam expander is expanded. f>2D, D is the beam diameter obtained after the beam expander is expanded. The reflector in the X / Y galvanometer group makes the incident angle of the laser beam of each layer tilted by 8°. The scanning field diameter of the F-θ lens must be consistent with the size of the growth platform, and the lens scanning field diameter is 200mm.

[0123] The single-layer power density of the laser used is 40kW / cm 2 , the spot diameter is 1.5 mm, the spiral scanning speed is 70 mm / s, and the laser used rotates synchronously with the seed crystal;

[0124] The crystal growth chamber of the growth device used in LCVD silicon carbide crystal growth is a gradually narrowing structure along the laser direction; two axially symmetrical air inlets are provided on the side of the crystal growth chamber at a distance of 3 / 5 of the crystal growth chamber height from the growth platform; the growth platform is an axially rotating growth platform;

[0125] The volume ratio of silicon source gas (silane) and carbon source gas (methane) in the gas precursor used in LCVD silicon carbide crystal growth is 2.5:1, the flow rate of the gas precursor is 150sccm, the pressure is 150Pa, the growth temperature is 1600℃, and the deposition rate is 3nm / s.

[0126] Example 2

[0127] This embodiment provides a specific implementation process of growing a silicon carbide substrate using an LCVD method, which is as follows:

[0128] performing LCVD silicon carbide crystal growth on the silicon carbide seed crystal to obtain a silicon carbide single crystal substrate;

[0129] Wherein, the purity of the silicon carbide seed crystal is 6N grade; the silicon carbide seed crystal is washed with water before LCVD silicon carbide crystal growth;

[0130] The laser used in the LCVD silicon carbide crystal growth is formed by the following laser optical path, including: a laser generator group, an attenuator, a beam expander, a homogenizer, a collimator, a beam splitter, an X / Y galvanometer group and an F-θ lens connected in sequence; the laser generator group includes: N layers of annularly distributed lasers, N = 4; in the N layers of annularly distributed lasers, the radial spacing between the I+1 ring and the I ring with the center as the starting point is 70% of the spacing between the I-1 ring and the I ring, 2≤I<N, the radial distance between the first ring and the second ring is 25mm, at this time I takes the value of 2,3, and the radial spacing of the rings starts from the center The diameters are gradually reduced to 25mm, 17.5mm, and 12.25mm respectively; the original beam diameter is 5mm; the magnification of the beam expander is 3 times, and the beam diameter D obtained after the beam expander is 15mm; the microlens unit size of the homogenizer is 0.3mm, and the focal length f range is 100mm, which matches the beam diameter obtained after the beam expander is expanded, f>2D, and D is the beam diameter obtained after the beam expander is expanded; the reflector in the X / Y galvanometer group makes the incident angle of the laser beam of each layer tilted by 6°; the F-θ lens scanning field diameter must be consistent with the size of the growth platform, and the lens scanning field diameter is 250mm;

[0131] The single-layer power density of the laser used is 30kW / cm 2 , the spot diameter is 1 mm, the spiral scanning speed is 50 mm / s, and the laser used rotates synchronously with the seed crystal;

[0132] The crystal growth chamber of the growth device used in LCVD silicon carbide crystal growth is a gradually narrowing structure along the laser direction; two axially symmetrical air inlets are provided on the side of the crystal growth chamber at a distance of 17 / 30 of the crystal growth chamber height from the growth platform; the growth platform is an axially rotating growth platform;

[0133] The volume ratio of silicon source gas (silane) and carbon source gas (acetylene) in the gas precursor used in LCVD silicon carbide crystal growth is 2:1, the flow rate of the gas precursor is 100 sccm, the pressure is 100 Pa, the growth temperature is 1800°C, and the deposition rate is 2 nm / s.

[0134] Example 3

[0135] This embodiment provides a specific implementation process of growing a silicon carbide substrate using an LCVD method, which is as follows:

[0136] performing LCVD silicon carbide crystal growth on the silicon carbide seed crystal to obtain a silicon carbide single crystal substrate;

[0137] Wherein, the purity of the silicon carbide seed crystal is 6N5 grade; the silicon carbide seed crystal is washed with water before LCVD silicon carbide crystal growth;

[0138] The laser used in the LCVD silicon carbide crystal growth is formed by the following laser optical path, including: a laser generator group, an attenuator, a beam expander, a homogenizer, a collimator, a beam splitter, an X / Y galvanometer group and an F-θ lens connected in sequence; the laser generator group includes: N layers of annularly distributed lasers, N = 6; in the N layers of annularly distributed lasers, the radial spacing between the I+1 ring and the I ring with the center as the starting point is 80% of the spacing between the I-1 ring and the I ring, 2≤I<N, the radial distance between the first ring and the second ring is 10mm, at this time I takes the value of 2, 3, 4, 5, and the radial spacing of the rings is stepped with the center as the starting point. The diameter of the original beam is 5mm; the magnification of the beam expander is 5 times, and the beam diameter D obtained after the beam expander is 25mm; the microlens unit size of the homogenizer is 0.5mm, and the focal length f range is 200mm, which matches the beam diameter obtained after the beam expander is expanded, f>2D, D is the beam diameter obtained after the beam expander is expanded; the reflector in the X / Y galvanometer group makes the incident angle of each layer of the laser beam tilted by 10°; the scanning field diameter of the F-θ lens must be consistent with the size of the growth platform, and the lens scanning field diameter is 400mm;

[0139] The single-layer power density of the laser used is 50kW / cm 2 , the spot diameter is 2 mm, the spiral scanning speed is 100 mm / s, and the laser used rotates synchronously with the seed crystal;

[0140] The crystal growth chamber of the growth device used in LCVD silicon carbide crystal growth is a gradually narrowing structure along the laser direction; two axially symmetrical air inlets are provided on the side of the crystal growth chamber at a position 1 / 2 the height of the crystal growth chamber from the growth platform; the growth platform is an axially rotating growth platform;

[0141] The volume ratio of silicon source gas (silane) and carbon source gas (methane) in the gas precursor used in LCVD silicon carbide crystal growth is 1:1, the flow rate of the gas precursor is 50sccm, the pressure is 200Pa, the growth temperature is 2000℃, and the deposition rate is 1nm / s.

[0142] Example 4

[0143] This embodiment provides a specific implementation process of growing a silicon carbide substrate using an LCVD method, which is as follows:

[0144] performing LCVD silicon carbide crystal growth on the silicon carbide seed crystal to obtain a silicon carbide single crystal substrate;

[0145] The purity of the silicon carbide seed crystal is 6N grade; the silicon carbide seed crystal is washed with ethanol before LCVD silicon carbide crystal growth;

[0146] The laser used in the LCVD silicon carbide crystal growth is formed by the following laser optical path, including: a laser generator group, an attenuator, a beam expander, a homogenizer, a collimator, a beam splitter, an X / Y galvanometer group and an F-θ lens connected in sequence; the laser generator group includes: N layers of annularly distributed lasers, N = 3; in the N layers of annularly distributed lasers, the radial spacing between the I+1 ring and the I ring with the center as the starting point is 60% of the spacing between the I-1 ring and the I ring, 2≤I<N, the radial distance between the first ring and the second ring is 30mm, at this time I is 2, and the radial spacing between the rings is The center is the starting point and the diameters decrease gradually, namely 30mm and 18mm respectively; the diameter of the original beam is 5mm; the magnification of the beam expander is 2 times, and the beam diameter D obtained after the beam expander is 10mm; the microlens unit size of the homogenizer is 0.1mm, and the focal length f range is 50mm, which matches the beam diameter obtained after the beam expander is expanded, f>2D, D is the beam diameter obtained after the beam expander is expanded; the reflector in the X / Y galvanometer group makes the incident angle of the laser beam of each layer tilted by 5°; the scanning field diameter of the F-θ lens must be consistent with the size of the growth platform, and the lens scanning field diameter is 300mm;

[0147] The single-layer power density of the laser used is 10kW / cm 2 , the spot diameter is 0.5 mm, the spiral scanning speed is 10 mm / s, and the laser used rotates synchronously with the seed crystal;

[0148] The crystal growth chamber of the growth device used in LCVD silicon carbide crystal growth is a gradually narrowing structure along the laser direction; two axially symmetrical air inlets are provided on the side of the crystal growth chamber at a distance of 2 / 3 of the crystal growth chamber height from the growth platform; the growth platform is an axially rotating growth platform;

[0149] The volume ratio of silicon source gas (silane) and carbon source gas (methane) in the gas precursor used in LCVD silicon carbide crystal growth is 3:1, the flow rate of the gas precursor is 200sccm, the pressure is 50Pa, the growth temperature is 1500℃, and the deposition rate is 5nm / s.

[0150] Comparative Example 1

[0151] The only difference from Example 1 is that the positions of the homogenizing mirror and the collimating mirror in the laser light path are swapped, that is, the laser first passes through the collimating mirror and then enters the homogenizing mirror.

[0152] Comparative Example 2

[0153] The only difference from Example 1 is that the beam splitter in the laser light path is removed.

[0154] Comparative Example 3

[0155] The only difference from Example 1 is that the F-θ lens in the laser light path is removed.

[0156] Comparative Example 4

[0157] The only difference from Example 1 is that the lasers of the N layers of annular distribution in the laser generator group in the laser light path are distributed at equal intervals.

[0158] Comparative Example 5

[0159] The only difference from Example 1 is that the laser generator group in the laser light path is a two-layer ring-distributed laser.

[0160] Comparative Example 6

[0161] The only difference from Example 1 is that the laser generator group in the laser light path is a 7-layer ring-distributed laser.

[0162] Comparative Example 7

[0163] The only difference from Example 1 is that in the N-layer annularly distributed laser, the radial distance between the I+1th ring and the Ith ring starting from the center is 90% of the distance between the I-1th ring and the Ith ring.

[0164] Comparative Example 8

[0165] The only difference from Example 1 is that in the N-layer annularly distributed laser, the radial distance between the I+1th ring and the Ith ring starting from the center is 50% of the distance between the I-1th ring and the Ith ring.

[0166] Example 5

[0167] The only difference from Example 1 is that the reflective mirror in the X / Y galvanometer group in the laser optical path causes the incident angle of the laser beam of each layer to be tilted by 2°.

[0168] Example 6

[0169] The only difference from Example 1 is that the reflective mirror in the X / Y galvanometer group in the laser optical path causes the incident angle of the laser beam of each layer to be tilted by 15°.

[0170] Example 7

[0171] The only difference from Example 1 is that the magnification of the beam expander is 1.5 times.

[0172] Example 8

[0173] The only difference from Example 1 is that the magnification of the beam expander is 6 times.

[0174] Example 9

[0175] The only difference from Example 1 is that the focal length of the homogenizer is f<2D, D is the diameter of the beam obtained after the beam is expanded by the beam expander, and f is 30 mm.

[0176] Example 10

[0177] The only difference from Example 1 is that the scanning field diameter of the F-θ lens is 100 mm.

[0178] Example 11

[0179] The only difference from Example 1 is that the crystal growth chamber in the growth device has a uniform width along the laser direction.

[0180] The silicon carbide crystals prepared in the above examples and comparative examples were tested, and the results are shown in Table 1 below.

[0181] Table 1

[0182]

[0183]

[0184] As can be seen from Table 1, in the solutions provided by the present invention, the EPD dislocation and micropipe density of the silicon carbide crystals prepared in Examples 1 to 4 are relatively small.

[0185] In Comparative Example 1, the order of the homogenizing mirror and the collimating mirror is swapped, resulting in the energy still being Gaussian, the temperature gradient on the surface of the seed crystal increases, and thermal stress dislocation is induced, resulting in an increase in the dislocation of the crystal.

[0186] In comparative example 2, the beam splitter is removed. The single laser beam cannot expand the coverage range through beam splitting and superposition, and the spot area is reduced. Multiple scans are required for compensation, resulting in a significant temperature difference between the overlapping area and the non-overlapping area. Microcracks are generated at the scanning junction due to repeated heating, resulting in an increase in crystal dislocations.

[0187] In comparative example 3, the F-θ lens was removed, and the scanning edge spot was distorted, the size was inconsistent, the energy density distribution was out of control, and unreacted particles were formed in the edge area due to insufficient energy, resulting in dislocation of the crystal.

[0188] In Comparative Example 4, the ring lasers are distributed at equal intervals, the spacing between the outer rings is not reduced, the edge spot density is insufficient, and the edge thermal stress causes an increase in dislocations; in Comparative Example 5, a two-layer ring laser is set, the coverage density is insufficient, the spot gap is large, the energy distribution is discontinuous, and dislocations are generated at the interface due to temperature fluctuations; in Comparative Example 6, a seven-layer ring laser is set, the energy superposition is excessive, the power of the single-layer tube is reduced, the local reaction is incomplete, the proportion of amorphous silicon carbide doping is increased, and the defects increase; in Comparative Example 7, the outer ring spacing is 90% of the inner ring, the outer laser distribution is sparse, the edge compensation effect is effective, resulting in an increase in the edge dislocation density; in Comparative Example 8, the outer laser distribution is too dense, the edge energy overlaps and transitions, and the dislocation density increases.

[0189] In Example 5, the galvanometer incident angle is tilted by 2°, the tilt angle is too small, the overlap rate of adjacent light spots is insufficient, and the dislocation density increases; in Example 6, the galvanometer incident angle is tilted by 15°, the angle is too large, resulting in too high a spot overlap rate, local energy accumulation, and thermal shock causing dislocations to increase; in Example 7, the beam expander magnification is less than 2 times, the beam expansion is insufficient, the homogenizer cannot effectively cover the light beam, some areas are thermally damaged, and crystal growth is affected; in Example 8, the beam expander magnification is greater than 5 times, the energy density is too low, the reaction rate decreases, the amorphous phase ratio increases, and defects increase; in Example 9, the focal length f of the homogenizer is less than 2D, the focal length is too short, resulting in insufficient mixing of the light beam in the focal plane, the energy distribution presents periodic stripes, the stripes are enriched with impurities, and the defects increase; in Example 10, the F-θ lens scanning field is less than 200 mm, the scanning field is insufficient to cover large-size substrates, the edge light spot is offset, the edge lattice is distorted, and the dislocations increase.

[0190] In Example 11, the graphite crucible from the crucible air inlet to the bottom of the crucible forms an internal crucible structure of equal width, and the airflow and water flow are unevenly distributed, which easily forms turbulence, impurity deposition, and increased defect density.

[0191] In summary, the laser optical path provided by the present invention, through the design of the laser optical path used in LCVD, achieves the uniformity of the obtained laser energy distribution with the help of the synergistic effect of the laser generator group, the homogenizing mirror and the X / Y galvanometer group, which is conducive to the uniform preparation of large-area silicon carbide single crystal substrates.

[0192] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0193] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0194] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A laser optical path for growing a silicon carbide substrate using an LCVD method, characterized in that: The laser light path includes: The laser generator group, attenuator, beam expander, homogenizer, collimator, beam splitter, X / Y galvanometer group and F-θ lens are connected in sequence; The laser generator group includes: N layers of lasers distributed in an annular pattern, N=3-6; In the N-layer annularly distributed laser, the radial distance between the I+1th ring and the Ith ring starting from the center is 60-80% of the distance between the I-1th ring and the Ith ring, 2≤I<N, and the radial distance between the first ring and the second ring is 10-30mm.

2. The laser light path according to claim 1, wherein: The magnification of the beam expander is 2-5 times; Preferably, the microlens unit size of the homogenizer is 0.1-0.5 mm; Preferably, the focal length f of the homogenizer is 50-200 mm, f>2D, and D is the diameter of the light beam obtained after expansion by the beam expander.

3. The laser light path according to claim 1 or 2, wherein: The reflector in the X / Y galvanometer group makes the incident angle of the laser beam of each layer tilted by 5-10°; Preferably, the scanning field diameter of the F-θ lens is ≥200 mm.

4. A growth device for growing a silicon carbide substrate using an LCVD method, characterized in that: The growth device includes: using the laser light path described in any one of claims 1 to 3 as a laser light source.

5. The growth device according to claim 4, wherein: The crystal growth chamber in the growth device is a gradually narrowing structure along the laser direction; Preferably, two axially symmetrical air inlets are provided on the side of the crystal growth chamber at a position that is (1 / 2 to 2 / 3) the height of the crystal growth chamber away from the growth platform; Preferably, the growth platform is an axially rotating growth platform.

6. A method for growing a silicon carbide substrate by LCVD, characterized in that: The growth method comprises: LCVD silicon carbide crystal growth is performed on a silicon carbide seed crystal using the laser generated by the laser optical path according to any one of claims 1 to 3 to obtain a silicon carbide single crystal substrate.

7. The growth method according to claim 6, wherein: The purity of the silicon carbide seed crystal is ≥5N5 grade; Preferably, the silicon carbide seed crystal is cleaned before LCVD silicon carbide crystal growth; Preferably, the cleaning method includes: organic solvent cleaning, water cleaning, acid cleaning or alkaline cleaning, or a combination of at least two of them.

8. The growth method according to claim 6 or 7, wherein: The volume ratio of silicon source gas to carbon source gas in the gas precursor used in the LCVD silicon carbide crystal growth is (1-3):1; Preferably, the flow rate of the gas precursor in the LCVD silicon carbide crystal growth is 50-200 sccm; Preferably, the pressure of the gas precursor during the LCVD silicon carbide crystal growth is 50-200 Pa.

9. The growth method according to any one of claims 6 to 8, characterized in that The single-layer power density of the laser used in the LCVD silicon carbide crystal growth is 10-50 kW / cm 2 ; Preferably, the spot diameter of the laser used in the LCVD silicon carbide crystal growth is 0.5-2 mm; Preferably, the spiral scanning speed of the laser used in the LCVD silicon carbide crystal growth is 10-100 mm / s; Preferably, the laser used in the LCVD silicon carbide crystal growth rotates synchronously with the seed crystal.

10. The growth method according to any one of claims 6 to 9, characterized in that: The growth temperature of the LCVD silicon carbide crystal growth is 1500-2000°C; Preferably, the deposition rate of silicon carbide during the LCVD silicon carbide crystal growth is 1-5 nm / s.

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