A method for preparing a wafer level (100) face cubic silicon carbide single crystal

Abstract

The application provides a preparation method of a wafer-level (100) face cubic silicon carbide single crystal. The preparation method uses a (100) face 3C-SiC seed crystal, adopts a high-temperature liquid phase method (mainly a TSSG method), and obtains a wafer-level (100) face 3C-SiC single crystal through self-diameter expansion growth in a specified temperature field. In particular, through multiple iterative diameter expansion growths as required, wafer-level (100) face 3C-SiC single crystals of target sizes meeting requirements can be ensured. The preparation method has the advantages of easy diameter expansion, low growth cost, growth of different doped types of (100) face 3C-SiC single crystals, suitability for large-scale industrial production and the like.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials technology, and specifically to a method for preparing wafer-level (100)-plane cubic silicon carbide single crystals. Background Technology

[0002] Silicon carbide (SiC) possesses excellent properties such as wide bandgap, high breakdown field strength, high saturated electron drift velocity, and high thermal conductivity, making it crucial for applications in new energy vehicles, photovoltaics, 5G communications, rail transportation, and smart grids. Currently, SiC-based metal-oxide-semiconductor field-effect transistors (MOSFETs) are primarily fabricated on 4H-SiC single-crystal substrates. Compared to 4H-SiC, cubic silicon carbide (3C-SiC) exhibits higher carrier mobility, lower resistivity (3C-SiC has a resistivity of ~0.3 mΩ·cm; 4H-SiC has a resistivity of ~22 mΩ·cm), lower interface state density (Dit, two orders of magnitude lower), higher electron affinity (3.7 eV), and higher channel carrier mobility (3C-SiC has a channel carrier mobility of 100-370 cm⁻¹). 2 The channel carrier mobility of 4H-SiC is 20-180 cm⁻¹ / V·s. 2 / V·s). Using 3C-SiC to fabricate MOSFET devices can solve the technical bottlenecks of poor reliability and stability and low lifespan of SiC-based MOSFET devices caused by gate oxide interface defect states, and can also reduce energy consumption.

[0003] 3C-SiC, also known as β-SiC, has the space group [missing information]. (No. 216) has a face-centered cubic (FCC) structure, and its crystal plane families mainly include {100}, {110}, and {111}. The atomic arrangement, surface energy, chemical bonds, and other physical properties of different crystal plane families differ significantly, leading to different physical, chemical, and electrical properties. The formation energy of stacking faults and twins in 3C-SiC on the (111) crystal plane is much lower than that on the (100) crystal plane. Compared with the (100) crystal plane, the (111) crystal plane has a higher stacking fault density and twin defect density. Experimentally, it was found that the stacking fault density of the (100) plane 3C-SiC thin film was (2.47 ± 0.09) × 10⁻⁶ by epitaxial growth. 3 cm -1 The average length is 0.31 ± 0.01 mm, which is less than the stacking fault density of the (111) plane 3C-SiC thin film (7.16 ± 0.04) × 10⁻⁶. 3 cm -1The average length is 3.32 ± 0.35 mm. In 3C-SiC, the (100) facet exhibits higher electron and hole carrier mobilities compared to the (111) facet, when the doping concentration is 5 × 10⁻⁶ mm. 16 cm -3 The electron mobility of the (100) plane is 460 cm⁻¹. 2 The electron mobility of the (111) plane is only 200 cm⁻¹ / V·s. 2 / V·s. Compared to the (111) facet, the (100) facet has a higher activation energy. The activation energies of the (100) C and Si faces, and the (111) C and Si faces of 3C-SiC are 30.1 and 35.6, and 29.9 and 33.4 kJ / mol, respectively. The high activation energy indicates that the oxidation rate is slow at typical process temperatures, the oxide layer grows more smoothly and densely, and the oxidation stability is high. This is conducive to forming a more uniform SiC / SiO2 interface with fewer defect states, and also conducive to forming a smoother surface and reducing the requirements for the process. The (100) facet of 3C-SiC has fewer dangling bonds. Under normal circumstances, the dangling bond density of the (100) facet is only 50-60% of that of the (111) facet, which is also conducive to reducing the interface defect state density. Studies have found that the Dit of 3C-SiC (100) film / SiO2 can be as low as 4×10 10 cm -2 ·eV -1 The Dit is two orders of magnitude lower than that of 4H-SiC and 6H-SiC. It can be seen that among 3C-SiC, the (100) facet 3C-SiC has superior performance compared to the (111) facet, which helps to improve the performance of SiC-based devices.

[0004] Current reports indicate that the liquid-phase method, primarily Top Seeded Solution Growth (TSSG), has been used to grow 2-4 inch diameter, single-crystal, 4-10 mm thick 3C-SiC single crystals with (111) facets for the first time internationally. However, the maximum thickness of this ingot is only about 10 mm, making it impossible to obtain large-size 3C-SiC single crystal substrates with (100) facets. Therefore, there is an urgent need for a growth method capable of producing large-size, high-quality 3C-SiC single crystals with (100) facets, providing a material basis for high-performance devices. Summary of the Invention

[0005] To address the aforementioned problems, a method for preparing wafer-level (100)-plane cubic silicon carbide single crystals is provided to overcome or at least partially solve these problems.

[0006] One object of the present invention is to achieve the preparation of wafer-level, high-quality (100)-plane 3C-SiC single crystals.

[0007] A further objective of the present invention is to improve the ease of obtaining (100)-faceted 3C-SiC seed crystals.

[0008] Another further objective of the present invention is to achieve rapid diameter expansion growth of (100)-plane 3C-SiC single crystals.

[0009] Another further objective of the present invention is to achieve the growth of (100)-plane 3C-SiC single crystals with different doping types.

[0010] Specifically, the present invention provides a method for preparing wafer-level (100)-plane cubic silicon carbide (3C-SiC) single crystals, comprising the following steps:

[0011] S1: Obtain (100) plane 3C-SiC seed crystal;

[0012] S2: Place silicon and flux in a crucible, fix the (100) face 3C-SiC seed crystal on the lifting rod above the crucible, and heat the crucible with a heat source under a functional gas atmosphere and a set pressure, so that silicon and flux are completely melted to form a melt, and the melt is in a specified temperature field, wherein the composition of flux and the ratio of silicon to flux are selected so that the melt contains enough carbon to grow 3C-SiC single crystals;

[0013] S3: Push down the lifting rod to make the seed crystal contact the melt, and rotate and lift the seed crystal and crucible and dynamically adjust the relative position between the heat source, the crucible and the seed crystal so that the relative position between the crystal growth interface and the melt and the temperature of the crystal growth interface remain unchanged, so as to grow (100) plane 3C-SiC single crystal.

[0014] S4: If the size of the obtained (100)-plane 3C-SiC single crystal does not reach the target size, the (100)-plane 3C-SiC single crystal is cut along the direction parallel to the crystal growth plane of the (100)-plane 3C-SiC single crystal and then ground, polished, and cleaned to serve as a seed crystal; and

[0015] S5: Repeat steps S2 to S4 until the size of the obtained (100) plane 3C-SiC single crystal reaches the target size.

[0016] Optionally, the step of obtaining the (100)-plane 3C-SiC seed crystal includes:

[0017] A (111)-plane 3C-SiC crystal ingot with a certain thickness and diameter is cut to obtain a (100)-plane 3C-SiC single crystal substrate. The cut single crystal substrate is then ground, polished, and cleaned to obtain a (100)-plane 3C-SiC seed crystal.

[0018] Optionally, the step of cutting a (111)-plane 3C-SiC ingot with a certain thickness and diameter to obtain a (100)-plane 3C-SiC single crystal substrate includes:

[0019] Along the 3C-SiC ingot parallel to the (111) plane [ Cut the (100) plane 3C-SiC single crystal substrate at an angle of 54.74° to the (111) plane in the direction of ];

[0020] (111) The thickness of the 3C-SiC ingot is ≥1 mm and the diameter is ≥1 inch;

[0021] The thickness of the (100) facet 3C-SiC seed crystal is 0.2-1 mm and the width is ≥1 mm.

[0022] Optionally, the co-solvent includes transition metals and / or rare earth metals that have carbon solubility and a melting point lower than the growth temperature of 3C-SiC single crystals;

[0023] The transition metal is one or more of Fe, Co, Ni, Ti, Cu, Cr, and Mn;

[0024] Rare earth metals are one or more of La, Ce, Pr, Nd, and Y.

[0025] Optionally, the co-solvent also includes Al.

[0026] Optionally, the co-solvent includes Cr;

[0027] In the absence of Al as the flux, the atomic molar ratio of Si, Cr, transition metals other than Cr, and rare earth elements is (20-70): (30-60): (0-30): (0-50), which is used to achieve the growth of n-type doped 3C-SiC single crystals.

[0028] When the flux includes Al, the atomic molar ratio of Si, Cr, transition metals other than Cr, rare earth elements to Al is (20-70): (30-60): (0-30): (0-50): (0.5-10), which is used to achieve the growth of semi-insulating and p-type doped 3C-SiC single crystals.

[0029] Optionally, the specified temperature field includes the temperature at the crystal growth interface, the axial temperature gradient increasing from the crystal growth interface to the bottom of the crucible, and the radial temperature gradient increasing from the seed crystal region to the peripheral wall of the crucible.

[0030] Preferably, the temperature at the crystal growth interface is 1700-2100℃;

[0031] The axial temperature gradient is 0.5-15℃ / cm;

[0032] The radial temperature gradient is 0.5-10℃ / cm.

[0033] Optionally, the crucible is a graphite crucible;

[0034] The inner diameter of the graphite crucible is 1.4-30 times the length of the seed crystal;

[0035] The wall thickness of the graphite crucible is ≥10 mm.

[0036] Optionally, the functional gas is one or more selected from Ar, N2, Ar / N2, He, and He / N2;

[0037] Set the air pressure to 0.1-2 atm.

[0038] Optionally, when growing n-type doped 3C-SiC single crystals, the nitrogen partial pressure in the functional gas atmosphere is 5-100%;

[0039] In the case of growing semi-insulating and p-type doped 3C-SiC single crystals, the nitrogen partial pressure in the functional gas atmosphere is 0-10%.

[0040] Optionally, the rotation and lifting operations of the seed crystal and crucible in step S3 include:

[0041] The seed crystal and crucible are periodically rotated in both directions, as well as accelerated and decelerated, while the seed crystal and crucible are slowly pulled up.

[0042] The seed crystal rotates at a speed of ±0-200 r / min, and its rotational acceleration during acceleration and deceleration is 0.1-200 r / min. 2 ;

[0043] The crucible rotates at a speed of ±0-50 r / min, with rotational acceleration of 0.1-50 r / min during acceleration and deceleration. 2 ;

[0044] The pulling speed of the seed crystal and crucible is 1-3000 μm / h.

[0045] Optionally, the operation of fixing the (100)-faceted 3C-SiC seed crystal to the lifting rod above the crucible in step S2 includes:

[0046] The (100)-face 3C-SiC seed crystal is fixed on the graphite seed crystal holder connected to the lifting rod, with the seed crystal located in the middle or at the edge of the graphite seed crystal holder.

[0047] Optionally, the graphite seed holder is a circular seed holder with a flat surface for fixing the seed crystal; or

[0048] The graphite seed crystal holder is cross-shaped, with a protrusion at the end of the cross for fixing the seed crystal.

[0049] The method for preparing (100)-plane cubic silicon carbide single crystals provided by this invention utilizes (100)-plane 3C-SiC seed crystals and employs a high-temperature liquid phase method (mainly the TSSG method) to obtain wafer-level (100)-plane 3C-SiC single crystals through self-expansion growth at a specified temperature field. In particular, by performing multiple iterative expansion growth as required, wafer-level (100)-plane 3C-SiC single crystals meeting the target size requirements can be guaranteed to be obtained.

[0050] Furthermore, in the preparation method of the present invention, (100) facet 3C-SiC seed crystals are obtained by cutting (111) facet 3C-SiC ingots, which improves the convenience of obtaining (100) facet 3C-SiC seed crystals.

[0051] Furthermore, in the preparation method of the present invention, by selecting the composition of the co-solvent and the ratio of silicon to the co-solvent, sufficient carbon can be dissolved in the melt, thereby ensuring the normal and rapid growth of the crystal.

[0052] Furthermore, in the preparation method of the present invention, the inner diameter of the crucible is set to 1.4-30 times the length of the seed crystal to achieve rapid diameter expansion growth of (100) plane 3C-SiC single crystal.

[0053] Furthermore, in the preparation method of the present invention, the growth of (100)-plane 3C-SiC single crystals with different doping types is achieved by selecting different cosolvent components and / or controlling the nitrogen partial pressure in the functional gas atmosphere.

[0054] The preparation method of the present invention can realize rapid, stable, and diameter-expanding growth of wafer-level (100)-plane 3C-SiC single crystals. It has advantages such as easy diameter expansion, low growth cost, ability to grow (100)-plane 3C-SiC single crystals with different doping types, and suitability for large-scale industrial production.

[0055] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below.

[0056] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0057] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. The same reference numerals in the drawings denote the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0058] Figure 1 A schematic flowchart illustrating a method for preparing a wafer-level (100) plane 3C-SiC single crystal according to an embodiment of the present invention is shown below:

[0059] Figure 2 A schematic diagram of cutting a (111)-plane 3C-SiC crystal ingot with a certain thickness and diameter according to an embodiment of the present invention to obtain a (100)-plane 3C-SiC single crystal substrate;

[0060] Figure 3 The Raman spectrum of the (100)-plane 3C-SiC single crystal grown in Example 1 of this invention;

[0061] Figure 4 This is a schematic diagram of the circular graphite seed crystal holder used in Embodiment 2 of the present invention;

[0062] Figure 5 This is a photograph of a (100)-plane 3C-SiC single crystal polished wafer with a length greater than 29 mm and a width greater than 23 mm, obtained in Example 2 of the present invention.

[0063] Figure 6 This is an X-ray rocking curve of the (100)-faceted 3C-SiC single crystal polished wafer obtained in Example 2 of the present invention;

[0064] Figure 7 The electrical properties of the (100)-plane 3C-SiC single crystal polished wafer obtained in Example 2 of this invention are shown in the diagram.

[0065] Figure 8 This is a photograph of a (100)-plane 3C-SiC single crystal polished wafer with a length greater than 27 mm and a width greater than 25 mm, obtained in Example 3 of the present invention.

[0066] Figure 9 The powder X-ray diffraction patterns of the (100)-plane 3C-SiC single crystal substrate grown in Example 4 of this invention, in the unpolished and polished condition. Detailed Implementation

[0067] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0068] In view of the problems and deficiencies of the prior art, the present invention provides a method for preparing wafer-level (100)-plane 3C-SiC single crystals to solve the problem that (100)-plane 3C-SiC single crystals cannot be obtained in the prior art.

[0069] Figure 1 This is a schematic flowchart illustrating a method for preparing a wafer-level (100) plane 3C-SiC single crystal according to an embodiment of the present invention. See also... Figure 1 As shown, the method for preparing wafer-level (100) plane 3C-SiC single crystal of the present invention may include the following steps S1 to S5.

[0070] S1: Obtain (100) plane 3C-SiC seed crystal.

[0071] S2: Place silicon and flux in a crucible, fix the (100) face 3C-SiC seed crystal on the lifting rod above the crucible, and heat the crucible with a heat source under a functional gas atmosphere and a set pressure, so that silicon and flux are completely melted to form a melt, and the melt is in a specified temperature field, wherein the composition of flux and the ratio of silicon to flux are selected so that the melt contains enough carbon to grow 3C-SiC single crystals.

[0072] Specifically, in step S2, after placing silicon and flux into the crucible, the crucible is placed in the growth furnace, and the (100)-faceted 3C-SiC seed crystal is fixed on the lifting rod above the crucible. Then, the growth furnace is evacuated. After reaching the required vacuum level, functional gas is introduced into the growth furnace to form a functional gas atmosphere, and the gas pressure inside the growth furnace is controlled to the set pressure. Afterward, the crucible is heated so that the silicon and flux completely melt, and the flux dissolves carbon to form a high-temperature melt.

[0073] Specifically, the growth furnace can be an induction heating furnace or a resistance heating furnace equipped with a lifting device.

[0074] Silicon can be in the form of silicon blocks. The co-solvent can be in granular or block form.

[0075] S3: Push down the lifting rod to make the seed crystal contact the melt, and rotate and lift the seed crystal and crucible and dynamically adjust the relative positions between the heat source, crucible and seed crystal, so that the relative position between the crystal growth interface and the melt and the temperature of the crystal growth interface remain unchanged, so as to grow (100) plane 3C-SiC single crystal.

[0076] S4: If the size of the obtained (100) plane 3C-SiC single crystal does not reach the target size, the (100) plane 3C-SiC single crystal is cut along the direction parallel to the crystal growth plane of the (100) plane 3C-SiC single crystal and then ground, polished and cleaned to serve as a seed crystal.

[0077] S5: Repeat steps S2 to S4 until the size of the obtained (100) plane 3C-SiC single crystal reaches the target size.

[0078] Those skilled in the art will understand that if the size (specifically, length and width) of the (100)-plane 3C-SiC single crystal obtained by a single growth reaches the target size, then there is no need to repeat steps S2 to S4.

[0079] In the method for preparing (100)-plane 3C-SiC single crystals provided in this embodiment of the invention, (100)-plane 3C-SiC seed crystals are used, and a high-temperature liquid phase method (mainly TSSG method) is employed to obtain wafer-level (100)-plane 3C-SiC single crystals through self-expansion growth at a specified temperature field. In particular, by performing multiple iterative expansion growths as required, wafer-level (100)-plane 3C-SiC single crystals meeting the target size requirements can be guaranteed to be obtained.

[0080] In some optional embodiments, the step of obtaining (100)-faceted 3C-SiC seed crystals may include: cutting (111)-faceted 3C-SiC ingots with a certain thickness and diameter to obtain (100)-faceted 3C-SiC single crystal substrates, and grinding, polishing and cleaning the cut single crystal substrates to obtain (100)-faceted 3C-SiC seed crystals.

[0081] Preferably, the thickness of the (111)-faceted 3C-SiC ingot is ≥1 mm and the diameter is ≥1 inch.

[0082] Preferably, the obtained (100)-faceted 3C-SiC seed crystal is roughly in the shape of a cuboid, with a thickness of 0.2-1 mm and a width of ≥1 mm.

[0083] Figure 2 A schematic diagram of obtaining a (100)-plane 3C-SiC single crystal substrate by cutting a (111)-plane 3C-SiC ingot with a certain thickness and diameter according to an embodiment of the present invention. Figure 2As shown, the step of cutting a (111)-plane 3C-SiC crystal ingot with a certain thickness and diameter to obtain a (100)-plane 3C-SiC single crystal substrate may specifically include: cutting along a path parallel to the (111)-plane 3C-SiC crystal ingot... Cut the (100) plane 3C-SiC single crystal substrate at an angle of 54.74° to the (111) plane in the direction of ] to obtain the (100) plane 3C-SiC single crystal substrate.

[0084] In this embodiment, (100) facet 3C-SiC seed crystals are obtained by cutting (111) facet 3C-SiC ingots, which improves the convenience of obtaining (100) facet 3C-SiC seed crystals.

[0085] In some alternative embodiments, the cutting method can be one of single-wire cutting, multi-wire cutting, or laser cutting.

[0086] In some optional embodiments, the co-solvent may include a transition metal and / or rare earth metal with carbon-solubility and a melting point below the growth temperature of 3C-SiC single crystals. Preferably, a transition metal and / or rare earth metal with high carbon-solubility is used to ensure that the co-solvent can dissolve a sufficient amount of carbon.

[0087] Preferably, the transition metal can be one or more of Fe, Co, Ni, Ti, Cu, Cr, and Mn.

[0088] Preferably, the rare earth metal can be one or more of La, Ce, Pr, Nd, and Y.

[0089] In some alternative embodiments, the co-solvent may also include Al.

[0090] In some preferred embodiments, where the co-solvent does not include Al, the co-solvent composition includes Cr, and optionally other transition metals and / or rare earth elements other than Cr. The atomic molar ratio of Si, Cr, transition metals other than Cr, and rare earth elements can be (20-70): (30-60): (0-30): (0-50) to achieve the growth of n-type doped 3C-SiC single crystals.

[0091] In some other preferred embodiments, when the co-solvent includes Al, the co-solvent composition includes Cr, Al, and optionally other transition metals and / or rare earth elements other than Cr. The atomic molar ratio of Si, Cr, transition metals other than Cr, rare earth elements to Al can be (20-70): (30-60): (0-30): (0-50): (0.5-10) to achieve the growth of semi-insulating and p-type doped 3C-SiC single crystals.

[0092] In this embodiment, by selecting the composition of the flux and the ratio of silicon to the flux, sufficient carbon can be dissolved in the melt, thereby ensuring the normal and rapid growth of the crystal, and at the same time, the growth of (100) plane 3C-SiC single crystals with different doping types can also be achieved.

[0093] In some alternative embodiments, the crucible used for crystal growth is a graphite crucible.

[0094] Preferably, the graphite crucible is made of high-purity, high-density, and high-strength graphite.

[0095] In some preferred embodiments, the inner diameter of the crucible (specifically a graphite crucible) can be 1.4-30 times the length of the seed crystal to achieve rapid diameter expansion growth of (100)-plane 3C-SiC single crystals.

[0096] In some optional embodiments, the graphite crucible has a wall thickness of ≥10 mm to ensure its service life and prevent it from being burned through during crystal growth.

[0097] In some optional embodiments, the operation of fixing the (100)-faceted 3C-SiC seed crystal to the lifting rod above the crucible in step S2 includes fixing the (100)-faceted 3C-SiC seed crystal to a graphite seed crystal holder connected to the lifting rod. The seed crystal can be fixed in the middle of the graphite seed crystal holder or at the edge of the graphite seed crystal holder.

[0098] In some optional embodiments, the graphite seed holder can be a circular seed holder with a flat surface for fixing the seed crystal; in other words, the seed-fixing surface of the graphite seed holder is a flat surface, and the other side has a device for connecting to the seed crystal rod, for example... Figure 4 As shown.

[0099] In some alternative embodiments, the graphite seed holder can be cross-shaped, with a boss at one end for fixing the seed crystal and a device for connecting to the seed crystal rod on the other side.

[0100] In some alternative embodiments, the functional gas may be one or more selected from Ar, N2, Ar / N2, He, and He / N2.

[0101] In some alternative embodiments, the set pressure can be in the range of 0.1-2 atm, for example 0.2, 0.3, 0.5, 0.8, 1.0, 1.2, 1.5, 1.8, 2.0 atm.

[0102] Preferably, the air pressure can be set in the range of 0.2-1.2 atm.

[0103] In some alternative embodiments, when growing n-type doped 3C-SiC single crystals, the nitrogen partial pressure in the functional gas atmosphere can be 5-100%.

[0104] In some alternative embodiments, when growing semi-insulating and p-type doped 3C-SiC single crystals, the nitrogen partial pressure in the functional gas atmosphere can be 0-10%.

[0105] In this embodiment, the growth of (100)-plane 3C-SiC single crystals with different doping types can be achieved by controlling the nitrogen partial pressure in the functional gas atmosphere.

[0106] In some embodiments, the specified temperature field includes the temperature at the crystal growth interface, an axial temperature gradient increasing from the crystal growth interface towards the bottom of the crucible, and a radial temperature gradient increasing from the seed crystal region towards the periphery of the crucible. In other words, during crystal growth, the temperature at the crystal growth interface between the crucible and the seed crystal is kept to be the lowest, with the temperature gradually increasing axially from the crystal growth interface towards the bottom of the crucible, and simultaneously increasing radially from the inside to the outside of the seed crystal region.

[0107] In some preferred embodiments, the temperature at the crystal growth interface is controlled at 1700-2100°C, for example, 1700, 1750, 1800, 1850, 1900, 1950, 2000, 2050, 2100°C.

[0108] In some preferred embodiments, the axial temperature gradient is 0.5-15℃ / cm, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15℃ / cm.

[0109] In some preferred embodiments, the radial temperature gradient is 0.5-10℃ / cm, for example 1, 2, 3, 4, 5, 6, 7, 8, 9, 10℃ / cm.

[0110] In some embodiments, the operation of rotating and pulling the seed crystal and crucible in step S3 may include: periodically rotating the seed crystal and crucible in both forward and reverse directions, as well as accelerating and decelerating the rotation, while slowly pulling the seed crystal and crucible.

[0111] Specifically, for example, the lifting rod can drive the seed crystal to rotate forward at a set first rotation speed for a first time, then decelerate to 0 with a fixed acceleration, then accelerate in the opposite direction to the first rotation speed with a fixed acceleration, and then rotate in the opposite direction at the first rotation speed for the first time, wherein the acceleration and deceleration times are both second times.

[0112] Similarly, for example, the crucible can first rotate forward at a set second rotational speed for a first time, then decelerate to 0 with a fixed acceleration, then accelerate in the opposite direction to the second rotational speed with a fixed acceleration, and then rotate in the opposite direction at the second rotational speed for a first time, wherein the acceleration and deceleration times are both the second time.

[0113] In some optional embodiments, the rotational speed of the seed crystal (i.e., the rotational speed of the lifting rod) is ±0-200 r / min, and the rotational acceleration during acceleration and deceleration is 0.1 – 200 r / min. 2 .

[0114] In some optional embodiments, the crucible rotates at a speed of ±0-50 r / min, with rotational acceleration of 0.1-50 r / min during acceleration and deceleration. 2 .

[0115] In some optional embodiments, the pulling speed of the seed crystal and the crucible is 1-3000 μm / h.

[0116] The above describes various implementation methods of the preparation method of the present invention. The present invention will be further described in detail below through specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0117] Example 1

[0118] Adopting such Figure 2 The method shown involves using a single-wire dicing machine to cut a (111)-plane 3C-SiC ingot with a diameter of 4 inches and a thickness of 10 mm to obtain a (100)-plane 3C-SiC single crystal substrate. The cut (100)-plane 3C-SiC single crystal substrate is then ground, polished, and cleaned to obtain a substrate with dimensions of 10 × 30 mm. 2 A rectangular 3C-SiC seed crystal with a (100) facet was used. Graphite paper was used as a buffer layer to fix the (100) facet 3C-SiC seed crystal onto a cross-shaped graphite seed crystal support protrusion or a circular seed crystal support. Then, the graphite seed crystal support was fixed onto a graphite lifting rod with a length of 500 mm and a diameter of 20 mm. The raw materials were weighed according to the molar ratio Si:Cr:Ti:La = 55:35:5:5. The weighed raw materials were placed in a graphite crucible with an inner diameter of 200 mm, an outer diameter of 220 mm, and a height of 200 mm. The graphite crucible and the graphite lifting rod were placed in the growth furnace. The vacuum in the growth furnace was evacuated to 1×10⁻⁶ using a mechanical pump and a molecular pump. -4 Below Pa, fill with 2×10 4 Pa of N2 and 2×10 4 Ar at Pa, to the furnace pressure 4 × 10 4Stop gas filling at Pa. Heat the graphite crucible and seed crystal, stabilizing the temperature at the seed crystal at 1800℃. After the flux has melted and stabilized for 2 hours, push the graphite lifting rod down to contact the molten flux, then slowly pull the graphite lifting rod to grow the crystal. During growth, maintain the lowest temperature at the interface between the graphite crucible and the seed crystal, and the highest temperature at the bottom of the graphite crucible, with an axial temperature gradient of 10℃ / cm and a radial temperature gradient of 10℃ / cm. Rotate the graphite lifting rod in both directions at 120 r / min for 20 min each, then slowly decelerate to 0 rpm, then accelerate back to 120 r / min in the opposite direction for 5 min each, repeating this cycle until growth is complete. During the growth process, the graphite lifting rod was slowly pulled upwards at a speed of 50 μm / h, while the crucible was rotated in both directions at a speed of 20 r / min for 20 min each. Then, the speed was slowly reduced to 0 rpm, and then accelerated in the opposite direction to 20 r / min for 5 min each. After a growth time of 144 h, the graphite lifting rod was pulled upwards at a speed of 10 mm / h until the grown crystal was completely separated from the liquid surface of the melt, at which point the pulling and heating were stopped. After the temperature inside the crucible stabilized to room temperature, high-purity N2 was introduced until the pressure inside the single crystal growth furnace reached atmospheric pressure. The furnace lid of the single crystal growth furnace was opened, the graphite lifting rod and graphite crucible were removed, and the (100)-plane 3C-SiC single crystal with diameter expansion was taken out. The diameter expansion rate of the crystal reached 30%. Subsequently, the substrate is cut along the direction parallel to the growth plane to obtain a (100)-plane 3C-SiC single crystal substrate. After grinding, polishing and cleaning, a (100)-plane 3C-SiC seed crystal is obtained. After two diameter expansion growths in the same manner, a wafer-level (100)-plane 3C-SiC single crystal is obtained.

[0119] Figure 3 The image shown is the Raman diagram of the (100) plane 3C-SiC single crystal grown in this embodiment, proving that it is 3C-SiC.

[0120] Example 2

[0121] Adopting such Figure 2 The method shown yields a size of 10 × 20 mm. 2 (100)-plane 3C-SiC seed crystal. Graphite paper was used as a buffer layer to fix the (100)-plane 3C-SiC seed crystal to a position such as... Figure 4The graphite seed crystal is placed on the graphite seed holder, which is then fixed to a graphite lifting rod. This graphite lifting rod is 500 mm long and 20 mm in diameter. The raw materials are weighed in a molar ratio of Si:Cr:Fe:Pr = 50:35:5:10 and placed in a graphite crucible with an inner diameter of 150 mm, an outer diameter of 170 mm, and a height of 200 mm. The graphite crucible and graphite lifting rod are then placed in a single crystal growth furnace. The furnace vacuum is evacuated to 1 × 10⁻⁶ using a mechanical pump and a molecular pump. -4 Below Pa, filled with 4×10 4 Pa of N2 and 3×10 4 Ar at Pa, to the furnace pressure 7 × 10 4 Pa, stop gas filling. Heat the graphite crucible and seed crystal, stabilizing the temperature at the seed crystal at 1750℃. After the flux has melted and stabilized for 2 hours, push the graphite lifting rod down to contact the molten flux, then slowly pull the graphite lifting rod to grow the crystal. During growth, maintain the lowest temperature at the interface between the graphite crucible and the seed crystal, and the highest temperature at the bottom of the graphite crucible, with an axial temperature gradient of 10℃ / cm and a radial temperature gradient of 10℃ / cm. Rotate the graphite lifting rod in both directions at 180 r / min for 20 min each, then slowly decelerate to 0 rpm, then accelerate back to 180 r / min in the opposite direction for 5 min each, repeating this cycle until growth is complete. During the growth process, the graphite lifting rod was slowly pulled upwards at a speed of 10 μm / h, and the crucible was rotated in both directions at a speed of 10 r / min for 20 min each. Then, the speed was slowly reduced to 0 rpm, and then accelerated in the opposite direction to 10 r / min for 5 min each. After the growth time of 144 h was reached, the graphite lifting rod was pulled upwards at a speed of 10 mm / h until the growth crystal was completely separated from the liquid surface of the flux. The pulling and heating were then stopped. After the temperature inside the crucible reached room temperature, high-purity N2 was introduced until the pressure inside the single crystal growth furnace reached atmospheric pressure. The furnace lid of the single crystal growth furnace was opened, the graphite lifting rod and graphite crucible were removed, and the (100)-plane 3C-SiC single crystal with diameter expansion was removed. Then, it was cut along the direction parallel to the growth plane to obtain the (100)-plane 3C-SiC single crystal substrate. After grinding, polishing and cleaning, the (100)-plane 3C-SiC seed crystal was obtained. Following the above method, a wafer-level (100)-plane 3C-SiC single crystal was obtained through two diameter-expansion growth processes. An optical photograph of the polished wafer is shown below. Figure 5 As shown.

[0122] from Figure 5 As can be seen, the dimensions of the (100)-plane 3C-SiC wafer are better than 29×23 mm. 2 . Figure 6The full width at half maximum (FWHM) of the X-ray rocking curve of the polished wafer shown is 36 arcsec, indicating that the grown (100)-plane 3C-SiC single crystal has high crystal quality. Figure 7 The resistivity versus temperature curve and Hall effect test results for the (100)-sided polished wafer are shown. It can be seen that the carrier concentration of the (100)-sided polished wafer is 2.62 × 10⁻⁶. 20 cm -3 The room temperature resistivity is 0.49 mΩ·cm, and the room temperature carrier mobility is 49 cm⁻¹. 2 V -1 s -1 .

[0123] Example 3

[0124] Adopting such Figure 2 The method shown yields a size of 10 × 20 mm. 2 (100)-faceted 3C-SiC seed crystals were used. Graphite paper was used as a buffer layer to fix the (100)-faceted 3C-SiC seed crystals onto a graphite seed crystal holder. Then, the bonded graphite seed crystal holder was fixed onto a graphite lifting rod, which was 500 mm long and 30 mm in diameter. The raw materials were weighed according to the molar ratio Si:Cr:Co:Pr = 40:30:20:10 and placed in a graphite crucible with an inner diameter of 150 mm, an outer diameter of 170 mm, and a height of 250 mm. The graphite crucible and the graphite lifting rod were placed in a single crystal growth furnace. The vacuum inside the furnace was evacuated to 1×10⁻⁶ using a mechanical pump and a molecular pump. -4 Below Pa, fill with 3×10 4 Pa of N2 and 5×10 4 Ar at Pa, to the furnace pressure 8 × 10 4Stop gas filling at Pa. Heat the graphite crucible and seed crystal, stabilizing the temperature at the seed crystal at 1900℃. After the flux has melted and stabilized for 2 hours, push the graphite lifting rod down to contact the molten flux, then slowly pull the graphite lifting rod to grow the crystal. During growth, maintain the lowest temperature at the interface between the graphite crucible and the seed crystal, and the highest temperature at the bottom of the graphite crucible, with an axial temperature gradient of 5℃ / cm and a radial temperature gradient of 5℃ / cm. Rotate the graphite lifting rod in both directions at 100 r / min for 20 min each, then slowly decelerate to 0 rpm, then accelerate back to 100 r / min in the opposite direction for 5 min each, repeating this cycle until growth is complete. During the growth process, the graphite lifting rod was slowly pulled upwards at a speed of 50 μm / h, and the crucible was rotated in both directions at a speed of 10 r / min for 20 min each. Then, it was slowly decelerated to 0 rpm and then accelerated in the opposite direction to 10 r / min for 5 min each. After the growth time of 168 h was reached, the graphite lifting rod was pulled upwards at a speed of 20 mm / h until the growth crystal was completely separated from the liquid surface of the flux melt, and the pulling and heating were stopped. After the temperature inside the crucible reached room temperature, Ar was introduced until the pressure inside the single crystal growth furnace reached atmospheric pressure. The furnace lid of the single crystal growth furnace was opened, the graphite lifting rod and graphite crucible were taken out, and the (100)-plane 3C-SiC single crystal with diameter expansion was taken out. Then, it was cut along the direction parallel to the growth plane to obtain the (100)-plane 3C-SiC single crystal substrate. After grinding, polishing and cleaning, the (100)-plane 3C-SiC seed crystal was obtained. Following the above method, a wafer-level (100)-plane 3C-SiC single crystal was obtained through two diameter-expansion growth processes. The (100)-plane 3C-SiC single crystal was then cut along a direction parallel to the growth plane to obtain a wafer. After chemical mechanical polishing, the wafer's optical photograph is shown below. Figure 8 As shown, the wafer obtained after cutting and polishing has a size better than 27×25 mm. 2 .

[0125] Example 4

[0126] Adopting such Figure 2 The method shown yields a size of 10 × 25 mm. 2 (100)-plane 3C-SiC seed crystal. Graphite paper was used as a buffer layer to fix the (100)-plane 3C-SiC seed crystal to a position such as... Figure 4The graphite seed crystal holder is then attached to a graphite lifting rod, which is 400 mm long and 40 mm in diameter. Raw materials are weighed in a molar ratio of Si:Ti:Ce:Al = 65:30:4:1 and placed in a graphite crucible with an inner diameter of 150 mm, an outer diameter of 170 mm, and a height of 200 mm. The graphite crucible and lifting rod are then placed in a single crystal growth furnace. The furnace vacuum is evacuated to 1 × 10⁻⁶ using a mechanical pump and a molecular pump. -4 Below Pa, fill with 2×10 4 Pa of N2 and 4×10 4 Ar at Pa, to the furnace pressure 6×10 4 Pa, stop gas filling. Heat the graphite crucible and seed crystal, stabilizing the temperature at the seed crystal at 1850℃. After the flux melts and stabilizes for 2 hours, push the graphite lifting rod down to contact the molten flux, then slowly pull the graphite lifting rod to grow the crystal. During growth, maintain the lowest temperature at the interface between the graphite crucible and the seed crystal, and the highest temperature at the bottom of the graphite crucible, with an axial temperature gradient of 4℃ / cm and a radial temperature gradient of 8℃ / cm. Rotate the graphite lifting rod in both directions at 30 r / min for 20 min each, then slowly decelerate to 0 rpm, then accelerate back to 30 r / min in the opposite direction for 5 min each, repeating this cycle until growth is complete. During growth, slowly pull the graphite lifting rod upward at 10 μm / h, rotating the crucible in both directions at 10 r / min for 20 min each, then slowly decelerate to 0 rpm, then accelerate back to 10 r / min in the opposite direction for 5 min each. After a growth time of 120 hours, the graphite pull rod is pulled upwards at a speed of 20 mm / h until the growth crystal is completely separated from the surface of the flux. Pulling and heating are then stopped. Once the crucible reaches room temperature, high-purity Ar is introduced until the pressure inside the single crystal growth furnace reaches atmospheric pressure. The furnace lid is then opened, the graphite pull rod and graphite crucible are removed, and the (100)-plane 3C-SiC single crystal grown by diameter expansion is taken off. It is then cut along a direction parallel to the growth plane to obtain a (100)-plane 3C-SiC single crystal substrate. After grinding, polishing, and cleaning, a (100)-plane 3C-SiC seed crystal is obtained. Following the above method, two diameter expansion growth cycles are performed to obtain a wafer-level (100)-plane 3C-SiC single crystal. The obtained single crystal is then cut and polished to obtain cut wafers and polished wafers. Figure 9 The powder X-ray diffraction pattern shown indicates that both the cut and polished wafers are (100) plane 3C-SiC single crystals.

[0127] Example 5

[0128] Adopting such Figure 2 The method shown yields a size of 10 × 30 mm. 2 The (100)-faceted 3C-SiC seed crystal was fixed to the graphite seed crystal holder using graphite paper as a buffer layer. The graphite seed crystal holder was then fixed to the graphite lifting rod, which was 500 mm long and 20 mm in diameter. The raw materials were weighed according to the molar ratio Si:Cr:Ti:Al = 55:39:5:1. The weighed materials were placed in a graphite crucible with an inner diameter of 200 mm, an outer diameter of 220 mm, and a height of 200 mm. The graphite crucible and the graphite lifting rod were placed in the growth furnace. The vacuum inside the growth furnace was evacuated to 1×10⁻⁶ using a mechanical pump and a molecular pump. -4 Below Pa, fill with 5×10 3 Pa of N2 and 5×10 4 Ar at Pa, to a furnace pressure of 5.5 × 10⁻⁶. 4 Pa, stop gas filling. Heat the graphite crucible and seed crystal, stabilizing the temperature at the seed crystal at 1850℃. After the flux has melted and stabilized for 3 hours, push the graphite lifting rod down to contact the molten flux, then slowly pull the graphite lifting rod to grow the crystal. During growth, maintain the lowest temperature at the interface between the graphite crucible and the seed crystal, and the highest temperature at the bottom of the graphite crucible, with an axial temperature gradient of 15℃ / cm and a radial temperature gradient of 10℃ / cm. Rotate the graphite lifting rod in both directions at 180 r / min for 20 min each, then slowly decelerate to 0 rpm, then accelerate back to 180 r / min in the opposite direction for 5 min each, repeating this cycle until growth is complete. During the growth process, the graphite lifting rod was slowly pulled upwards at a speed of 60 μm / h, while the crucible was rotated in both directions at a speed of 25 r / min for 20 min each. Then, the speed was slowly reduced to 0 rpm, and then accelerated in the opposite direction to 25 r / min for 5 min each. After the growth time of 120 h was reached, the graphite lifting rod was pulled upwards at a speed of 20 mm / h until the grown crystal was completely separated from the liquid surface of the melt, at which point the pulling and heating were stopped. After the temperature inside the crucible stabilized to room temperature, high-purity Ar was introduced until the pressure inside the single crystal growth furnace reached atmospheric pressure. The furnace lid of the single crystal growth furnace was opened, the graphite lifting rod and graphite crucible were removed, and the (100)-plane 3C-SiC single crystal grown by the first diameter expansion was taken out to obtain a semi-insulating (100)-plane 3C-SiC single crystal.

[0129] Example 6

[0130] (100)-plane 3C-SiC grown with diameter expansion was used as the seed crystal, with a seed crystal size of 20 × 20 mm. 2The (100)-faceted 3C-SiC seed crystal was fixed onto the graphite seed crystal holder, and then the graphite seed crystal holder was fixed onto the graphite lifting rod. The length of the graphite lifting rod was 500 mm and the diameter was 20 mm. The raw materials were weighed according to the molar ratio Si:Cr:Mn:Al = 55:35:5:5. The weighed raw materials were placed in a graphite crucible with an inner diameter of 200 mm, an outer diameter of 220 mm, and a height of 200 mm. The graphite crucible and the graphite lifting rod were placed into the growth furnace. The vacuum in the growth furnace was evacuated to 1×10⁻⁶ using a mechanical pump and a molecular pump. -4 Below Pa, fill with 5×10 4 Ar in Pa was used to stop gas filling. The graphite crucible and seed crystal were heated, and the temperature at the seed crystal was stabilized at 1850℃. After the flux melted and stabilized for 4 hours, the graphite lifting rod was pushed down to contact the molten flux, and then the graphite lifting rod was slowly pulled up to carry out crystal growth. During the growth process, the temperature at the interface between the graphite crucible and the seed crystal was kept the lowest, and the temperature at the bottom of the graphite crucible was the highest. The axial temperature gradient was 5℃ / cm, and the radial temperature gradient was 10℃ / cm. The graphite lifting rod was rotated in both directions at a speed of 100 r / min for 20 min each, then slowly decelerated to 0 rpm, and then accelerated in the opposite direction to 100 r / min for 5 min each. This cycle was repeated until the growth was completed. During the growth process, the graphite lifting rod was slowly pulled upwards at a speed of 20 μm / h, while the crucible was rotated in both directions at a speed of 10 r / min for 20 min each. Then, the speed was slowly reduced to 0 rpm, and then accelerated in the opposite direction to 10 r / min for 5 min each. After a growth time of 60 h, the graphite lifting rod was pulled upwards at a speed of 30 mm / h until the grown crystal was completely separated from the liquid surface of the melt, at which point the pulling and heating were stopped. After the temperature inside the crucible stabilized to room temperature, high-purity Ar was introduced until the pressure inside the single crystal growth furnace reached atmospheric pressure. The furnace lid of the single crystal growth furnace was opened, the graphite lifting rod and graphite crucible were removed, and the (100)-plane 3C-SiC single crystal with one diameter expansion growth was taken out to obtain a p-type doped (100)-plane 3C-SiC single crystal.

[0131] Comparative Example 1

[0132] Adopting such Figure 2 The method shown yields a size of 10 × 30 mm. 2(100)-faceted 3C-SiC seed crystals were used. Graphite paper was used as a buffer layer to fix the (100)-faceted 3C-SiC seed crystals onto a graphite seed crystal holder, which was then fixed onto a graphite lifting rod. The length of the graphite lifting rod was 500 mm and the diameter was 20 mm. The raw materials were weighed according to the molar ratio Si:Cr:Ce = 85:5:10 and placed in a graphite crucible with an inner diameter of 200 mm, an outer diameter of 220 mm, and a height of 200 mm. The graphite crucible and the graphite lifting rod were placed in a single crystal growth furnace. The vacuum inside the furnace was evacuated to 1×10⁻⁶ using a mechanical pump and a molecular pump. -4 Below Pa, then immediately fill with 2×10 4 Pa of N2 and 2×10 4 Ar at Pa, to the furnace pressure 4 × 10 4 Pa, stop gas filling. Heat the graphite crucible and seed crystal, stabilizing the temperature at the seed crystal at 1800℃. After the flux has melted and stabilized for 2 hours, push the graphite lifting rod down to contact the molten flux, then slowly pull the graphite lifting rod to grow the crystal. During growth, maintain the lowest temperature at the interface between the graphite crucible and the seed crystal, and the highest temperature at the bottom of the graphite crucible. The axial temperature gradient is 10℃ / cm, and the radial temperature gradient is 10℃ / cm. Rotate the graphite lifting rod in both directions at 120 r / min for 20 min each, then slowly decelerate to 0 rpm, and then accelerate back to 120 r / min in the opposite direction for 5 min each. Repeat this cycle until growth is complete. During growth, the graphite lifting rod was slowly pulled upwards at a speed of 50 μm / h, while the crucible was rotated in both directions at 20 r / min for 20 min each. The rotation was then slowly decelerated to 0 rpm, followed by acceleration in the opposite direction to 20 r / min for 5 min each. After 144 h of growth, the graphite lifting rod was pulled upwards at 10 mm / h until the grown crystal completely separated from the flux melt. Pulling and heating were then stopped. After the crucible reached room temperature, Ar was introduced until the pressure inside the single crystal growth furnace reached atmospheric pressure. The furnace lid was opened, and the graphite lifting rod and crucible were removed. The growth rate was found to be too low, only 1 μm / h, due to the low carbon content in the flux caused by its composition and formulation.

[0133] Comparative Example 2

[0134] Adopting such Figure 2 The method shown yields a size of 10 × 25 mm. 2(100)-faceted 3C-SiC seed crystals were used. Graphite paper was used as a buffer layer to fix the (100)-faceted 3C-SiC seed crystals onto a graphite seed crystal holder. Then, the bonded graphite seed crystal holder was fixed onto a graphite lifting rod, which was 500 mm long and 30 mm in diameter. The raw materials were weighed according to the molar ratio Si:Cr:Co:Pr = 40:30:20:10 and placed in a graphite crucible with an inner diameter of 150 mm, an outer diameter of 170 mm, and a height of 250 mm. The graphite crucible and the graphite lifting rod were placed in a single crystal growth furnace. The vacuum inside the furnace was evacuated to 1×10⁻⁶ using a mechanical pump and a molecular pump. -4 Below Pa, then immediately fill with 3×10 4 Pa of N2 and 5×10 4 Ar at Pa, to the furnace pressure 8 × 10 4 Stop gas filling at Pa. Heat the graphite crucible and seed crystal, stabilizing the temperature at the seed crystal at 1900℃. After the flux has melted and stabilized for 2 hours, push the graphite lifting rod down to contact the molten flux, then slowly pull the graphite lifting rod to grow the crystal. During growth, maintain the lowest temperature at the interface between the graphite crucible and the seed crystal, and the highest temperature at the bottom of the graphite crucible, with an axial temperature gradient of 30℃ / cm and a radial temperature gradient of 50℃ / cm. Rotate the graphite lifting rod in both directions at 100 r / min for 20 min each, then slowly decelerate to 0 rpm, then accelerate back to 100 r / min in the opposite direction for 5 min each, repeating this cycle until growth is complete. During the growth process, the graphite lifting rod was slowly pulled upwards at a speed of 50 μm / h, while the crucible was rotated in both directions at a speed of 10 r / min for 20 min each. Then, the speed was slowly reduced to 0 rpm, and then accelerated in the opposite direction to 10 r / min for 5 min each. After a growth time of 168 h, the graphite lifting rod was pulled upwards at a speed of 20 mm / h until the growth crystal was completely separated from the liquid surface of the flux melt. The pulling and heating were then stopped. After the temperature inside the crucible stabilized to room temperature, Ar was introduced until the pressure inside the single crystal growth furnace reached atmospheric pressure. The furnace lid was then opened, and the graphite lifting rod and graphite crucible were removed. The (100)-plane 3C-SiC single crystal with diameter expansion was then taken out. It was observed that due to the excessively high growth temperature gradient, a large number of grooves appeared on the surface of the single crystal.

[0135] Comparative Example 3

[0136] Adopting such Figure 2 The method shown yields a size of 10 × 25 mm. 2(100)-faceted 3C-SiC seed crystals were used. Graphite paper was used as a buffer layer to fix the (100)-faceted 3C-SiC seed crystals onto a graphite seed crystal holder. Then, the bonded graphite seed crystal holder was fixed onto a graphite lifting rod, which was 400 mm long and 40 mm in diameter. The raw materials were weighed according to the molar ratio Si:Ti:Ce:Al = 65:30:4:1 and placed in a graphite crucible with an inner diameter of 150 mm, an outer diameter of 170 mm, and a height of 200 mm. The graphite crucible and the graphite lifting rod were placed in a single crystal growth furnace. The vacuum inside the furnace was evacuated to 1×10⁻⁶ using a mechanical pump and a molecular pump. -4 Below Pa, fill with 2×10 4 Pa of N2 and 4×10 4 Ar at Pa, to the furnace pressure 6×10 4 Stop gas filling at Pa. Heat the graphite crucible and seed crystal, stabilizing the temperature at the seed crystal at 1850℃. After the flux has melted and stabilized for 2 hours, push the graphite lifting rod down to contact the molten flux, then slowly pull the graphite lifting rod to grow the crystal. During growth, maintain the lowest temperature at the interface between the graphite crucible and the seed crystal, and the highest temperature at the bottom of the graphite crucible, with an axial temperature gradient of 4℃ / cm and a radial temperature gradient of 4℃ / cm. Rotate the graphite lifting rod in both directions at 30 r / min for 20 min each, then slowly decelerate to 0 rpm, then accelerate back to 30 r / min in the opposite direction for 5 min each, repeating this cycle until growth is complete. During growth, slowly pull the graphite lifting rod upward at 10 μm / h, rotating the crucible in both directions at 10 r / min for 20 min each, then slowly decelerate to 0 rpm, then accelerate back to 10 r / min in the opposite direction for 5 min each. After a growth time of 120 h, the graphite lifting rod was pulled upwards at a speed of 20 mm / h until the grown crystal was completely separated from the surface of the flux melt. Pulling and heating were then stopped. The temperature at the seed crystal in the crucible was heated again to a stable 1850 ℃ using the same method. The graphite lifting rod was then pushed down to immerse 3 mm below the liquid surface, and a second growth was performed at the aforementioned growth rate and time. After growth was complete, the expanded crystal was removed. Observation revealed that due to the second extension experiment, there were more inclusions and bubbles at the extension point, resulting in a lower quality crystal.

[0137] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0138] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A method for preparing a wafer-level (100)-plane cubic silicon carbide (3C-SiC) single crystal, comprising the following steps: S1: Obtain (100) plane 3C-SiC seed crystal; S2: Place silicon and flux in a crucible, fix the (100) face 3C-SiC seed crystal on a lifting rod above the crucible, and heat the crucible with a heat source under a functional gas atmosphere and a set pressure, so that silicon and flux are completely melted to form a melt, and the melt is in a specified temperature field, wherein the composition of the flux and the ratio of silicon to the flux are selected such that the melt contains enough carbon to grow 3C-SiC single crystals; S3: Push down the lifting rod to make the seed crystal contact the melt, and rotate and lift the seed crystal and the crucible and dynamically adjust the relative position between the heat source, the crucible and the seed crystal so that the relative position between the crystal growth interface and the melt and the temperature of the crystal growth interface remain unchanged, so as to grow (100) plane 3C-SiC single crystal. S4: If the size of the obtained (100)-plane 3C-SiC single crystal does not reach the target size, the (100)-plane 3C-SiC single crystal is cut along the direction parallel to the crystal growth plane of the (100)-plane 3C-SiC single crystal and then ground, polished, and cleaned to serve as a seed crystal; and S5: Repeat steps S2 to S4 until the size of the (100) plane 3C-SiC single crystal reaches the target size; The specified temperature field includes the temperature at the crystal growth interface, an axial temperature gradient increasing from the crystal growth interface to the bottom of the crucible, and a radial temperature gradient increasing from the seed crystal region to the peripheral wall of the crucible. The temperature at the crystal growth interface is 1700-2100℃, the axial temperature gradient is 0.5-15℃ / cm, and the radial temperature gradient is 0.5-10℃ / cm.

2. The preparation method according to claim 1, wherein, The step of obtaining (100) plane 3C-SiC seed crystals includes: A (111)-plane 3C-SiC crystal ingot with a certain thickness and diameter is cut to obtain a (100)-plane 3C-SiC single crystal substrate. The cut single crystal substrate is then ground, polished, and cleaned to obtain the (100)-plane 3C-SiC seed crystal.

3. The preparation method according to claim 2, wherein, The step of cutting a (111)-plane 3C-SiC crystal ingot with a certain thickness and diameter to obtain a (100)-plane 3C-SiC single crystal substrate includes: Along the 3C-SiC ingot parallel to the (111) plane [ Cut the (100) plane 3C-SiC single crystal substrate at an angle of 54.74° to the (111) plane in the direction of ]; The thickness of the (111) facet 3C-SiC ingot is ≥1 mm and the diameter is ≥1 inch; The thickness of the (100) plane 3C-SiC seed crystal is 0.2-1 mm, and the width is ≥1 mm.

4. The preparation method according to claim 1, wherein, The co-solvent includes transition metals and / or rare earth metals with carbon-solubilizing ability and melting points lower than the growth temperature of 3C-SiC single crystals. The transition metal is one or more selected from Fe, Co, Ni, Ti, Cu, Cr, and Mn; The rare earth metal is one or more of La, Ce, Pr, Nd, and Y.

5. The preparation method according to claim 4, wherein, The co-solvent also includes Al.

6. The preparation method according to claim 5, wherein, The co-solvent includes Cr; When the flux does not include Al, the atomic molar ratio of Si, Cr, transition metals other than Cr and rare earth elements is (20-70): (30-60): (0-30): (0-50), which is used to achieve the growth of n-type doped 3C-SiC single crystals. When the co-solvent includes Al, the atomic molar ratio of Si, Cr, transition metals other than Cr, rare earth elements to Al is (20-70): (30-60): (0-30): (0-50): (0.5-10), which is used to achieve the growth of semi-insulating and p-type doped 3C-SiC single crystals.

7. The preparation method according to claim 1, wherein, The crucible is a graphite crucible; The inner diameter of the graphite crucible is 1.4-30 times the length of the seed crystal; The graphite crucible has a wall thickness of ≥10 mm.

8. The preparation method according to claim 1, wherein, The functional gas is selected from one or more of Ar, N2, Ar / N2, He, and He / N2; The set air pressure is 0.1-2 atm.

9. The preparation method according to claim 8, wherein, When growing n-type doped 3C-SiC single crystals, the nitrogen partial pressure in the functional gas atmosphere is 5-100%. In the case of growing semi-insulating and p-type doped 3C-SiC single crystals, the nitrogen partial pressure in the functional gas atmosphere is 0-10%.

10. The preparation method according to claim 1, wherein, Step S3, which involves rotating and pulling the seed crystal and the crucible, includes: The seed crystal and the crucible are periodically rotated in both directions, as well as accelerated and decelerated, while the seed crystal and the crucible are slowly lifted. The seed crystal rotates at a speed of ±0-200 r / min, and its rotational acceleration during acceleration and deceleration is 0.1-200 r / min. 2 ; The crucible rotates at a speed of ±0-50 r / min, with rotational acceleration of 0.1-50 r / min during acceleration and deceleration. 2 ; The pulling speed of the seed crystal and the crucible is 1-3000 μm / h.

11. The preparation method according to claim 1, wherein, The operation of fixing the (100)-faceted 3C-SiC seed crystal to the lifting rod above the crucible in step S2 includes: The (100)-faceted 3C-SiC seed crystal is fixed on a graphite seed crystal holder connected to the lifting rod, and the seed crystal is located in the middle or at the edge of the graphite seed crystal holder.

12. The preparation method according to claim 11, wherein, The graphite seed crystal holder is a circular seed crystal holder with a flat surface for fixing the seed crystal; or The graphite seed crystal holder is cross-shaped, with a protrusion at the end of the cross for fixing the seed crystal.

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