Silicon carbide crystal growth method and device

Abstract

The invention discloses a silicon carbide crystal growth method and device, and relates to the field of crystal growth, and the silicon carbide crystal growth device comprises a crucible, a cover plate, an expanding ring and a diversion assembly. The crucible is provided with a cavity for containing a silicon carbide raw material, and an opening is formed in the top of the cavity; the cover plate is used for covering the opening; the inner surface of the cover plate is used for fixing silicon carbide seed crystals; the expanding ring is fixed on the side wall of the cavity; in the first direction, the inner diameter of the expanding ring is linearly reduced from a first diameter D1 to a second diameter D2; when the cover plate covers the opening, the cover plate abuts against the top of the expanding ring. The flow guide assembly is arranged above the silicon carbide raw material and below the expanding ring, and is arranged in the middle of the cavity in the radial direction; the flow guide assembly comprises a circular bottom and a flow guide ring arranged around the circular bottom; the outer diameter of the flow guide ring increases in the first direction. The flow guide assembly is arranged on the surface of the silicon carbide raw material, so that the purposes of reducing silicon carbide crystal cracking and obtaining large-size silicon carbide crystals are achieved.

Description

Technical Field

[0001] This application relates to the field of crystal growth technology, and in particular to a method and apparatus for growing silicon carbide crystals. Background Technology

[0002] As silicon carbide growth technology and downstream silicon carbide-based device fabrication technology continue to mature, there is a growing demand to reduce the cost of silicon carbide-based devices. Therefore, it is necessary to increase the size of silicon carbide crystals to obtain a larger number of devices per wafer.

[0003] Currently, the effective technology for increasing the size of silicon carbide is the step-by-step diameter expansion technique. This involves first expanding the diameter to obtain a crystal of increased size, then processing this crystal to obtain a seed crystal of the corresponding size, and then further expanding the diameter to obtain the final crystal; this process is repeated iteratively until the target size crystal is obtained. However, to avoid edge polycrystalline defects or cracks that could lead to expansion failure, the crystal convexity is often controlled to be relatively large, inevitably increasing the internal stress of the crystal. As the crystal size increases, the internal stress also increases, leading to crystal cracking during crystal removal or slicing. Therefore, how to quickly obtain expanded diameter crystals while avoiding cracking remains a technical challenge for obtaining large-size crystals. Summary of the Invention

[0004] In view of the above problems, this application provides a method and apparatus for growing silicon carbide crystals to reduce cracking in silicon carbide crystals and obtain large-size silicon carbide crystals. The specific solution is as follows:

[0005] This application provides a silicon carbide crystal growth apparatus, comprising:

[0006] A crucible having a cavity for holding silicon carbide raw material, the top of which has an opening;

[0007] A cover plate is used to cover the opening; the inner surface of the cover plate is used to fix the silicon carbide seed crystal.

[0008] An expanding ring is fixed to the side wall of the cavity; in a first direction, the inner diameter of the expanding ring linearly decreases from a first diameter D1 to a second diameter D2, and the direction from the bottom of the cavity to the opening is the first direction; when the cover plate covers the opening, the cover plate abuts against the top of the expanding ring.

[0009] A flow guiding component is positioned above the silicon carbide raw material and below the diameter expansion ring, and is centrally located radially within the cavity. The flow guiding component includes a circular bottom and a flow guiding ring surrounding the circular bottom; the outer diameter of the flow guiding ring increases along a first direction. The flow guiding ring, with its self-defined shape, blocks and guides the sublimation gas source generated by the silicon carbide raw material during crystal growth, thereby improving the crystal preparation quality.

[0010] This application utilizes a flow-guiding component placed on the surface of silicon carbide raw material. The component includes a circular bottom and a flow-guiding ring surrounding the bottom. The outer diameter of the flow-guiding ring increases along a first direction, meaning the outer wall of the ring has a certain inclination angle. The circular bottom of the component prevents the high-concentration sublimation gas from directly diffusing vertically upwards from the central region of the silicon carbide raw material, allowing the gaseous components formed by the evaporation of the silicon carbide raw material to flow smoothly along the inclination direction of the flow-guiding ring towards the diameter-expanding ring region on the inner wall of the crucible. This directional guidance avoids disordered collisions and accumulation of gas at the crystal edge, suppressing the formation of polycrystalline and impurity crystals at the source, which is beneficial for increasing crystal size.

[0011] The flow guiding component ensures uniform gas distribution, significantly reducing the growth rate difference between the central and edge regions of the crystal. This avoids lattice compression caused by excessively rapid local growth, effectively reducing the generation and concentration of internal stress in the crystal, thereby reducing crystal cracking.

[0012] In some embodiments, in the first direction, the outer diameter of the guide ring is increased from a third diameter D3 to a fourth diameter D4;

[0013] Where, D2≥D4, and / or, D4≥ D2.

[0014] In some embodiments, in the first direction, the outer diameter of the guide ring increases linearly from a third diameter D3 to a fourth diameter D4.

[0015] In some embodiments, in the first direction, the inner diameter of the expansion ring linearly decreases from a first diameter D1 to a second diameter D2 based on a first linear relationship, and the outer diameter of the guide ring linearly increases from a third diameter D3 to a fourth diameter D4 based on a second linear relationship;

[0016] The first linear relationship has a first slope k1, the second linear relationship has a second slope k2, and |k1|>|k2|.

[0017] In some embodiments, in a first direction, the guide ring includes a first sub-guide ring to an Nth sub-guide ring distributed sequentially, where N is a positive integer greater than 1; the bottom outer diameter of the first sub-guide ring is D3; and the top outer diameter of the Nth sub-guide ring is D4.

[0018] The outer diameters of the first to the Nth sub-guide rings all increase linearly along the first direction;

[0019] The top of the i-th sub-guide ring and the bottom of the (i+1)-th sub-guide ring are on the same horizontal plane and are integrally connected based on a planar circular ring structure; the outer diameter of the top of the i-th sub-guide ring is smaller than the outer diameter of the bottom of the (i+1)-th sub-guide ring, where i is a positive integer less than N.

[0020] In some embodiments, the outer diameters of the first to Nth sub-guide rings increase linearly based on a third linear relationship;

[0021] Among the first to the Nth sub-guide rings, at least two of them have different slopes in their corresponding third linear relationships.

[0022] In some embodiments, the slope Ki of the third linear relationship corresponding to the i-th sub-guide ring and the slope K of the third linear relationship corresponding to the (i+1)-th sub-guide ring are... i+1 , | K i+1 |>| K i |

[0023] In some embodiments, in the first direction, the height of the i-th sub-guide ring is hi, and the height of the (i+1)-th sub-guide ring is hi+1, |h i |>|h i+1 |

[0024] In some embodiments, the angle between the inner wall of the expansion ring and the plane containing the bottom of the cavity is 30° to 60°.

[0025] In some embodiments, in the first direction, the outer diameter of the flow guide ring increases from a third diameter D3 to a fourth diameter D4, and the inner diameter of the crucible is D5, wherein the thickness of the flow guide assembly is 0.5 mm to 20 mm, and D3 ≥ D5, D4 < D5. In some embodiments, the diameter of the circular bottom of the flow guide assembly is... D4 to D4, the width of the guide ring remains consistent along the first direction.

[0026] In some embodiments, the loading height of the silicon carbide raw material is H1 relative to the bottom of the cavity, the bottom height of the expansion ring is H2, the top height of the expansion ring is H3, and the height difference between the bottom of the expansion ring and the top of the flow guiding assembly is ΔH.

[0027] in, (H2-H1) < ΔH < (H3-H2).

[0028] This application also provides a method for growing silicon carbide crystals, which can employ a silicon carbide crystal growth apparatus as described in any of the above embodiments, including:

[0029] Silicon carbide raw material is filled into the cavity of the crucible, and the top of the cavity has an opening;

[0030] The flow guiding component is placed in the center of the silicon carbide raw material surface;

[0031] Fix the expansion ring to the inner wall of the cavity;

[0032] Silicon carbide seed crystals are fixed on the inner surface of the cover plate to cover the opening;

[0033] The crucible is heated to sublimate the silicon carbide raw material and allow for crystal growth.

[0034] In some embodiments, the crystal growth process conditions include: the growth atmosphere is argon or a mixture of argon and hydrogen, the growth temperature is 2150°C to 2350°C, the growth pressure is 100Pa to 800Pa, and the growth time is 100h to 150h.

[0035] In some embodiments, the growth temperature is 2200°C to 2250°C, and the growth pressure is 500Pa to 800Pa. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0037] The structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and purposes that this application can produce, should still fall within the scope of the technical content disclosed in this application.

[0038] Figure 1 A diagram of a silicon carbide crystal growth apparatus provided in this application;

[0039] Figure 2 A diagram of another silicon carbide crystal growth apparatus provided in this application;

[0040] Figure 3 A flowchart of a silicon carbide crystal growth method provided in this application;

[0041] Figure 4 This is a diagram of a silicon carbide crystal growth apparatus;

[0042] Figure 5 This is a schematic diagram of silicon carbide crystal growth.

[0043] Figure 6 This is a schematic diagram of another type of silicon carbide crystal growth.

[0044] Figure label:

[0045] 10-Silicon carbide crystal growth apparatus; 11-Crucible; 12-Cover plate; 13-Expanding ring; 14-Flow guiding assembly; 15-Silicon carbide seed crystal; 16-Silicon carbide raw material; 141-Circular bottom; 142-Flow guiding ring; 1421-Sub-flow guiding ring; D5-Inner diameter of crucible; D6-Diameter of circular bottom; α-Included angle; T-First direction; 17-Planar circular ring structure. Detailed Implementation

[0046] The embodiments of this application will now be clearly and completely described with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are equally applicable to similar technical problems.

[0047] On the one hand, this application provides a silicon carbide crystal growth apparatus 10, such as Figure 1 As shown, the silicon carbide crystal growth apparatus 10 includes: a crucible 11, a cover plate 12, an expansion ring 13, and a flow guiding assembly 14.

[0048] The crucible 11 has a cavity for holding silicon carbide raw material 16, and the top of the cavity has an opening;

[0049] For example, the crucible 11 is integrally formed from graphite material, and its inner wall can be polished to reduce the adhesion and loss of gaseous components during the sublimation of raw materials.

[0050] The cover plate 12 is used to cover the opening; wherein, the inner surface of the cover plate 12 is used to fix the silicon carbide seed crystal 15;

[0051] Understandably, the cover plate 12 fits and covers the top opening of the crucible 11 to achieve a seal of the cavity. The material of the cover plate 12 is the same as that of the crucible 11, which is graphite, to ensure that the thermal expansion coefficients of the cover plate 12 and the crucible 11 are matched, thereby reducing the risk of seal failure at high temperatures.

[0052] For example, the silicon carbide seed crystal 15 is fixed to the inner surface of the cover plate 12, that is, the side close to the inside of the cavity. The size of the silicon carbide seed crystal 15 is 8 inches to 12 inches, and its growth surface faces the silicon carbide raw material 16 inside the cavity. The center of the silicon carbide seed crystal 15 is coaxially arranged with the center of the crucible 11 cavity. The silicon carbide seed crystal 15 can be connected to the cover plate 12 by bonding or embedding in a recessed fixing groove to ensure that the silicon carbide seed crystal 15 does not shift or loosen during the crystal growth process.

[0053] The expansion ring 13 is fixed to the side wall of the cavity; in the first direction T, the inner diameter of the expansion ring 13 is linearly reduced from the first diameter D1 to the second diameter D2, and the bottom of the cavity points to the opening in the first direction T; when the cover plate 12 covers the opening, the cover plate 12 abuts against the top of the expansion ring 13.

[0054] For example, after placing the silicon carbide raw material 16 in the cavity of the crucible 11, the diameter expansion ring 13 is located in the region between the opening and the silicon carbide raw material 16; in the first direction T, the inner diameter of the diameter expansion ring 13 linearly decreases from the first diameter D1 to the second diameter D2. The material of the diameter expansion ring 13 can be graphite, or graphite with a niobium (Nb) or tantalum (Ta) layer on the surface. The diameter expansion ring 13 is fixed to the side wall of the cavity to provide directional support and guidance for the silicon carbide crystal growth interface, so as to cause the silicon carbide crystal to gradually expand along the gradient contour of the diameter expansion ring 13, and suppress edge polycrystalline or crystal growth deviation.

[0055] When the cover plate 12 covers the opening, the inner surface of the cover plate 12, that is, the side of the cover plate 12 near the cavity, is in close contact with the top end face of the expansion ring 13, forming a continuous sealing fit, which prevents the growth atmosphere inside the cavity from leaking from the gap between the cover plate 12 and the expansion ring 13, and at the same time ensures the stability of the thermal field inside the cavity.

[0056] The flow guiding assembly 14 is disposed above the silicon carbide raw material 16 and below the diameter expansion ring 13, and is centrally located in the radial direction of the cavity; the flow guiding assembly 14 includes a circular bottom 141 and a flow guiding ring 142 disposed around the circular bottom 141; the outer diameter of the flow guiding ring 142 increases along the first direction T.

[0057] For example, the flow guiding component 14 is made of graphite or graphite with an Nb coating or a Ta coating on its surface. It has the characteristics of low volatility and structural stability at high temperatures, thus avoiding contamination of the silicon carbide raw material 16 and the silicon carbide crystal.

[0058] The flow guiding component 14 can actively interfere with and guide the natural convection path of the gaseous reactants generated by the sublimation of silicon carbide raw material 16. The airflow is redistributed as it flows over the surface of the flow guiding component 14, and diffuses in a directional manner from the central region to the edge region.

[0059] Through the aforementioned airflow regulation, the flow guiding component 14 can guide the reactant gas to be transported more evenly to the entire silicon carbide crystal growth interface, improving the phenomenon of insufficient reactant supply in the edge region of silicon carbide crystal growth that easily occurs in traditional methods. This is beneficial for balancing the growth interface between the center and edge of the silicon carbide crystal and reducing crystal defects caused by uneven growth rates.

[0060] This application places a flow guiding component 14 on the surface of silicon carbide raw material 16. The flow guiding component 14 includes a circular bottom 141 and a flow guiding ring 142 surrounding the circular bottom 141. The outer diameter of the flow guiding ring 142 increases along a first direction T, meaning that the outer wall of the flow guiding ring 142 has a certain tilt angle. The circular bottom 141 of the flow guiding component 14 can block the high-concentration sublimation gas source in the central region of the silicon carbide raw material 16 from directly diffusing vertically upwards, allowing the gas phase components formed by the evaporation of the silicon carbide raw material 16 to flow smoothly along the tilt direction of the flow guiding ring 142 to the diameter expansion ring 13 region on the inner wall of the crucible 11. This directional guidance avoids disordered collisions and accumulation of gas sources at the crystal edge, suppressing the generation of edge polycrystalline and impurity crystals from the source, which is beneficial to increasing the crystal size.

[0061] The flow guiding component 14 ensures uniform distribution of the gas source, significantly reducing the growth rate difference between the central and edge regions of the crystal. This avoids lattice compression caused by excessively rapid local growth, effectively reducing the generation and concentration of internal stress in the crystal, thereby reducing crystal cracking.

[0062] Meanwhile, the flow guiding component 14 has a simple structure, is easy to process, has a low cost, and does not increase environmental pollution inside the crucible cavity.

[0063] In some embodiments, reference Figure 1 In the silicon carbide crystal growth apparatus 10, along the first direction T, the outer diameter of the guide ring 142 increases from a third diameter D3 to a fourth diameter D4; wherein, D2 ≥ D4, and / or, D4 ≥ D2.

[0064] Specifically, in the first direction T, the outer diameter of the guide ring 142 increases from the third diameter D3 near the silicon carbide raw material 16 to the fourth diameter D4 near the diameter expansion ring 13, i.e., D4 > D3. This causes the outer wall of the guide ring 142 to form an inclined or curved surface that expands outward along the first direction T, which is beneficial for guiding the sublimation gas of the silicon carbide raw material 16 to diffuse towards the first direction T and towards the edge of the silicon carbide seed crystal 15 during subsequent heating.

[0065] D2≥D4 ensures that the maximum outer diameter D4 of the guide ring 142 near the expansion ring 13 does not exceed the minimum inner diameter D2 of the expansion ring 13. Therefore, the entire inner wall of the expansion ring 13 is completely exposed radially to the airflow and thermal field regulated by the guide assembly 14, preventing the critical growth interface of the crystal from being physically blocked. This ensures that the edge growth region of the crystal under the guidance of the expansion ring 13 receives sufficient and uniform reactant supply and heat transport, thereby ensuring the stability and consistency of crystal quality during the expansion process.

[0066] If D4 is too small, the radial dimension of the flow guiding component 14 is insufficient, and it cannot provide sufficient obstruction and regulation of the airflow in the central growth region below the silicon carbide seed crystal 15. D4 ≥ D2 ensures that the flow guiding component 14 has a sufficiently large effective area, thereby forming a sufficient and effective flow field and thermal field modulation on the entire growth surface of the silicon carbide seed crystal 15, which is conducive to achieving uniform crystal growth and avoiding imbalance between the growth rate of the center and the edge.

[0067] In some embodiments, in the first direction T, the outer diameter of the guide ring 142 increases linearly from a third diameter D3 to a fourth diameter D4.

[0068] The linear increase in the outer diameter of the guide ring 142 results in a continuous and smooth inclined expansion structure or arc-shaped expansion surface on the outer wall of the guide ring 142. This can guide the gaseous reactants generated by the sublimation of silicon carbide raw material 16 to diffuse smoothly and orderly in all directions along the inclined outer wall, avoiding local accumulation of gas flow at the edge of the guide ring 142. At the same time, it widens the radial range of gas source diffusion and promotes the transport of gaseous reactants to the edge region of crystal growth.

[0069] In some embodiments, in the first direction T, the inner diameter of the expansion ring 13 is linearly reduced from the first diameter D1 to the second diameter D2 based on a first linear relationship, and the outer diameter of the guide ring 142 is linearly increased from the third diameter D3 to the fourth diameter D4 based on a second linear relationship; wherein the first linear relationship has a first slope k1, the second linear relationship has a second slope k2, and |k1|>|k2|.

[0070] Specifically, the main function of the expansion ring 13 is to guide the expansion of the crystal growth interface. Its larger absolute slope value |k1| makes the inner wall of the expansion ring 13 steeper, which can strongly constrain the airflow and ensure that the crystal edge expands along the preset path. The guide ring is mainly used for uniform flow guidance. Its smaller absolute slope value |k2| makes the outer wall of the guide ring gentler, which can guide the gas source to diffuse slowly and orderly in the radial direction, avoiding sudden changes in airflow velocity due to excessively steep inclination. The combination of the two allows the airflow to flow smoothly into the constraint range of the expansion ring 13 after exiting the guide ring 142, reducing airflow impact and other phenomena, and ensuring the stability of airflow transport near the crystal growth interface.

[0071] The diffusion rate of the gas source from the sublimation of silicon carbide raw material 16 gradually decreases from the center to the edge. The relatively gentle tilt angle of the guide ring 142 can reduce the resistance of radial diffusion of the gas source, so that the edge area of ​​the silicon carbide seed crystal 15 can obtain sufficient gas supply. The larger tilt angle of the diameter expansion ring 13 can match the growth rate of the crystal edge, and ensure the crystal diameter expansion efficiency through the constraint effect, avoiding edge growth lag caused by the mismatch between gas source diffusion and growth rate.

[0072] In some embodiments, reference Figure 2The silicon carbide crystal growth apparatus 10 shown has a flow guide ring 142 in the first direction T, comprising a first sub-flow guide ring 1421 to an Nth sub-flow guide ring 1421 arranged sequentially, where N is a positive integer greater than 1; the bottom outer diameter of the first sub-flow guide ring 1421 is D3; and the top outer diameter of the Nth sub-flow guide ring 1421 is D4.

[0073] The outer diameters of the first sub-guide ring 1421 to the Nth sub-guide ring 1421 all increase linearly along the first direction T.

[0074] The top of the i-th sub-guide ring 1421 and the bottom of the (i+1)-th sub-guide ring 1421 are on the same horizontal plane and are integrally connected based on the planar circular ring structure 17; the outer diameter of the top of the i-th sub-guide ring 1421 is smaller than the outer diameter of the bottom of the (i+1)-th sub-guide ring 1421, where i is a positive integer less than N.

[0075] Specifically, the top outer diameter of the i-th sub-guide ring 1421 is smaller than the bottom outer diameter of the (i+1)-th sub-guide ring 1421. That is, at the connection of adjacent sub-guide rings 1421, there is a jump in the outer diameter, so that the outer wall of the entire guide ring 142 presents a segmented linear profile that expands upward in a stepped manner.

[0076] Each sub-guide ring 1421 can be independently designed with its linear slope, thereby enabling more precise and differentiated gradient control of airflow velocity, direction and thermal field intensity at different heights in the first direction T.

[0077] Compared to a single continuous inclined plane, the stepped structure can alleviate thermal stress concentration in segments and improve the structural reliability of the flow guiding component 14 at high temperatures.

[0078] The segmented structure of the flow guide ring 142 facilitates individual machining and replacement, providing greater flexibility for process tuning and optimization for different growth formulations without having to replace the entire flow guide assembly 14.

[0079] In some embodiments, the outer diameters of the first sub-guide ring 1421 to the Nth sub-guide ring 1421 increase linearly based on a third linear relationship; among the first sub-guide ring 1421 to the Nth sub-guide ring 1421, at least two of the corresponding third linear relationships have different slopes.

[0080] Specifically, the outer wall of the guide ring 142 is not a single slope, but a composite profile composed of multiple linear segments with different linear slopes.

[0081] By setting different slopes for different sub-circuit rings 1421, the heat flow inside the cavity can be more precisely shaped and redistributed, thereby more accurately controlling the convexity of crystal growth.

[0082] On the other hand, crystal growth is a dynamic process, and the requirements for conditions may differ at different thickness stages. The segmented structure of the sub-guide rings 1421 with different slopes is beneficial for growing large-sized crystals with higher uniformity and lower defect density.

[0083] In some embodiments, the slope K of the third linear relationship corresponding to the i-th sub-guide ring 1421 i The slope K of the third linear relationship corresponding to the (i+1)th sub-guide ring 1421 i+1 ,|K i+1 |>|K i |

[0084] The higher the elevation, the greater the slope and the higher the verticality. Higher elevations are farther from the silicon carbide raw material, resulting in relatively high airflow stability and no need for significant flow obstruction or buffering. Conversely, lower elevations are closer to the raw material, leading to greater airflow fluctuations and requiring smaller slopes and larger inclination sub-blocking rings to buffer the airflow.

[0085] Specifically, the temperature near silicon carbide raw material 16 is high, and the airflow originates from a violent sublimation process, resulting in large disturbances and low stability. The slope K of the sub-guide ring 1421... i The smaller size means that the sidewall of the sub-guide ring 1421 is relatively flat, which can reduce the disturbance to the thermal field, provide a wide buffer and rectification surface, and smoothly guide the unstable airflow to the first direction T.

[0086] Along the first direction T, away from the region of silicon carbide raw material 16, the thermal field is relatively stable, and the airflow, after passing through the lower buffer layer, tends to be stable and uniform. The slope K of the sub-guide ring 1421... i+1 The larger size, meaning the steeper sidewalls and higher verticality of the sub-guide ring 1421, provides strong guidance and applies a significant radial guiding force to the stabilized airflow, driving the reactants to be transported directionally to the crystal growth edge region to meet the higher demand for edge material supply during the diameter expansion process.

[0087] In some embodiments, the height of the i-th sub-guide ring 1421 in the first direction T is h. i The height of the (i+1)th sub-guide ring 1421 is h. i+1 ,|h i |>|h i+1 |

[0088] Specifically, the temperature near silicon carbide raw material 16 is high and the thermal field fluctuates greatly, and the height h of the sub-guide ring 1421 is... i The larger size provides a longer airflow path and a larger effective area, thus enabling more thorough buffering of strong initial airflow.

[0089] The thermal field is relatively stable in the region away from the silicon carbide raw material 16 along the first direction T. The thermal field tends to stabilize, the airflow disturbance is reduced, and there is no need for an excessively large buffer structure. The height h of the sub-guide ring 1421 i+1 The smaller size makes the flow guide ring 142 more compact, which meets the basic flow guidance requirements while avoiding excessive occupation of axial space and introduction of unnecessary thermal mass.

[0090] In some embodiments, reference Figure 1 The angle α between the inner wall of the expansion ring 13 and the plane containing the bottom of the cavity is 30° to 60°.

[0091] Specifically, if the included angle α < 30°, the inner sidewall of the expansion ring 13 is too flat, the radial expansion driving force is insufficient, and the crystal tends to grow preferentially along the first direction T, resulting in low expansion efficiency and difficulty in achieving rapid expansion of large-size crystals; at the same time, the flat sidewall tends to cause the gas source to stagnate near the sidewall surface, causing local oversaturation growth and generating impurity crystals.

[0092] If the included angle α > 60°, the inner sidewall of the expansion ring 13 is too steep, the radial expansion rate is too fast, the radial stress at the crystal growth interface increases sharply, which can easily cause problems such as crystal edge cracking and warping; and the steep sidewall will lead to the gas source diffusion path being too short, the uniformity of gas source supply at the growth interface will decrease, and the overall quality of the crystal will be affected.

[0093] Setting the included angle α to the range of 30° to 60° can achieve a balance between the radial growth rate and the growth rate in the first direction T, which can both ensure the diameter expansion efficiency of large-size crystals and effectively suppress radial stress accumulation, thereby reducing the risk of crystal cracking.

[0094] In some embodiments, in the first direction, the outer diameter of the flow guide ring 142 increases from a third diameter D3 to a fourth diameter D4, and the inner diameter of the crucible 11 is D5. The thickness of the flow guide assembly 14 is 0.5 mm to 20 mm, and D3 ≥ D5, D4 < D5. The flow guiding component 14 operates at high temperatures for extended periods, requiring it to withstand certain thermal stress and resist potential airflow impacts or minor displacements caused by the expansion of the silicon carbide raw material 16. Flow guiding components 14 with a thickness less than 0.5 mm are prone to warping, cracking, or even breakage, thereby losing their control function or contaminating the crystal growth environment.

[0095] An excessively thick flow guide component 14 will occupy too much space above the limited silicon carbide raw material 16 along the first direction T, which may interfere with the smooth transport of airflow or change the effective thermal field distribution of the chamber, thus having a negative impact on crystal growth.

[0096] The thickness of the flow guide component 14 ranges from 0.5 mm to 20 mm, ensuring sufficient mechanical strength and thermal stability while also exhibiting good thermal response characteristics.

[0097] The third diameter D3 of the guide ring 142 is greater than D5 ensures that the flow guiding component 14 has a sufficient effective area to effectively control the sublimation airflow from the central region of the silicon carbide raw material 16. If the third diameter D3 is too small, its effective range is limited to above the center of the silicon carbide raw material 16, and it cannot effectively affect the airflow flowing towards the edge region of the silicon carbide seed crystal 15, thereby weakening the ability to control the radial uniformity of the crystal growth interface and making it difficult to achieve low convexity and high-quality crystal diameter expansion.

[0098] The fourth diameter D4 of the flow guide ring 142 is smaller than D5 to avoid physical interference with the inner wall of the crucible 11. A certain gap is maintained between the outer wall of the flow guide assembly 14 and the inner wall of the crucible 11 to allow airflow and to reserve space for the thermal expansion of the flow guide assembly 14 at high temperatures.

[0099] In some embodiments, such as Figure 1 As shown, the diameter D6 of the circular bottom 141 of the flow guide assembly 14 is D4 to D4, the width of the flow guide ring 142 remains consistent along the first direction T. Specifically, the diameter D6 of the circular bottom 141 of the flow guide component 14 is the third diameter D3. If the diameter of the circular bottom 141 is too small, the coverage area of ​​the circular bottom 141 is too small, and the blocking effect on the gas source in the central area of ​​the silicon carbide raw material 16 is insufficient. The high-concentration gas source is likely to flow directly vertically to the center of the silicon carbide seed crystal 15, resulting in an excessively fast growth rate and excessive convexity in the crystal center, which leads to the accumulation of internal stress and the risk of cracking.

[0100] If the diameter D6 of the circular bottom 141 is too large, the radial width of the guide ring 142 will be excessively compressed, failing to provide sufficient radial flow space for the gas source. This results in insufficient gas supply at the edge and a significant decrease in crystal diameter expansion efficiency. At the same time, an excessively large bottom will exacerbate the local concentration of the thermal field and disrupt radial temperature uniformity.

[0101] D4 to The circular bottom 141 of D4, within the diameter D6 range, can achieve a balance between central flow obstruction and edge flow guidance. It can effectively block the strong gas source from rushing into the center of the silicon carbide raw material 16, while reserving sufficient radial flow guidance width for the flow guiding ring 142, ensuring a uniform matching of the growth rate between the crystal center and the edge.

[0102] The radial width of the guide ring 142 remains consistent along the first direction T. The constant width of the guide ring 142 results in better thermal expansion uniformity. At high temperatures, stress concentration will not occur due to local width changes, thus avoiding cracking or deformation of the sidewall of the guide ring 142, improving structural stability, and reducing the manufacturing difficulty and cost of the guide assembly 14, making it easier for mass production.

[0103] In some embodiments, reference Figure 1 Relative to the bottom of the cavity, the loading height of the silicon carbide raw material 16 is H1, the bottom height of the expansion ring 13 is H2, the top height of the expansion ring 13 is H3, and the height difference between the bottom of the expansion ring 13 and the top of the flow guiding assembly 14 is ΔH.

[0104] in, ×(H2-H1)<ΔH< ×(H3-H2)

[0105] Specifically, ΔH > × (H2-H1) ensures a minimum axial buffer zone between the top of the flow guide assembly 14 and the bottom of the diameter expansion ring 13. This prevents the flow guide assembly 14 from being positioned too low, which would cause the sublimation gas flow from the silicon carbide raw material 16 to prematurely or directly enter the growth guidance range defined by the diameter expansion ring 13 without sufficient buffering, homogenization, and radial guidance from the flow guide assembly 14. This ensures that the gas flow entering the region near the silicon carbide seed crystal 15 has a good flow pattern and distribution, which is beneficial to the diameter expansion growth of the crystal.

[0106] ΔH < × (H3-H2) limits the top of the flow guiding component 14 to a height that is not too high; that is, the distance between it and the bottom of the expansion ring 13 must be less than half the height of the expansion ring 13 itself. This ensures that the modulation effect of the flow guiding component 14 on the airflow and thermal field maintains sufficient strength as it propagates to the bottom of the expansion ring 13 and the entire growth guiding range, avoiding a weakening of the airflow control effect due to excessive axial distance, which would prevent it from effectively influencing the growth process at the crystal edge.

[0107] In the above embodiments, the flow guiding component 14 can be placed flat on the surface of the silicon carbide raw material 16. In this case, the height of the flow guiding component 14 will decrease as the silicon carbide raw material 16 is consumed. Alternatively, the flow guiding component can be fixed to the bottom of the crucible 11 by a bracket and placed above the silicon carbide raw material 16. In this case, the height of the flow guiding component 14 will not decrease as the silicon carbide raw material 16 is consumed.

[0108] This application also provides a method for growing silicon carbide crystals, which can employ the silicon carbide crystal growth apparatus 10 described in any of the above embodiments, such as... Figure 3 As shown, Figure 3 This is a flowchart of a silicon carbide crystal growth method provided in an embodiment of this application.

[0109] like Figure 3 As shown, the growth method includes the following steps S10 to S50:

[0110] Step S10: Fill the cavity of the crucible 11 with silicon carbide raw material 16, the top of the cavity has an opening.

[0111] For example, a preset mass of silicon carbide raw material 16 is filled into the cavity of crucible 11, and the top of the cavity has an opening.

[0112] Step S20: Place the flow guiding component 14 in the center of the surface of the silicon carbide raw material 16.

[0113] For example, the flow guiding component 14 is placed centrally on the upper surface of the silicon carbide raw material 16.

[0114] Step S30: Fix the expansion ring 13 to the inner wall of the cavity.

[0115] For example, the expansion ring 13 is fixed to a predetermined height on the inner side wall of the cavity of the crucible 11.

[0116] Step S40: Fix the silicon carbide seed crystal 15 on the inner surface of the cover plate 12 to cover the opening.

[0117] For example, the silicon carbide seed crystal 15 is fixed to the center area of ​​the inner surface of the cover plate 12. When the cover plate 12 covers the cavity opening, the inner surface of the cover plate 12 abuts against the top of the expansion ring 13 to form a seal. After the cavity is evacuated, an inert protective gas such as argon is filled into it to a preset pressure.

[0118] Step S50: Heat crucible 11 to sublimate silicon carbide raw material 16 and perform crystal growth.

[0119] For example, silicon carbide crystals can be grown using physical vapor transport (PVT). The crucible 11 is heated to the growth temperature using a preset heating program. Under the set temperature, pressure and atmosphere conditions, the silicon carbide raw material 16 is sublimated and deposited on the silicon carbide seed crystal 15. After a preset growth time, the crystal growth is completed and cooled to room temperature.

[0120] In some embodiments, the process conditions for silicon carbide crystal growth include: the growth atmosphere is argon or a mixture of argon and hydrogen, the growth temperature is 2150°C to 2350°C, the growth pressure is 100Pa to 800Pa, and the growth time is 100h to 150h.

[0121] The temperature range of 2150℃ to 2350℃ allows the silicon carbide raw material 16 to fully sublimate, generating highly active gaseous Si, SiC2 and other components, providing a sufficient source of material for crystal growth on the surface of the silicon carbide seed crystal 15.

[0122] Argon, as an inert gas, can isolate air and prevent the raw materials and seed crystals from oxidation; the mixture of argon and hydrogen can utilize the reducing properties of hydrogen to further remove trace oxide impurities on the surface of silicon carbide raw material 16 and improve the purity of the gas source.

[0123] The pressure range of 100Pa to 800Pa can reduce the collision probability of gas phase molecules, widen the mean free path of gaseous components, and enable the gas source to be uniformly and directionally transported to the growth surface of silicon carbide seed crystal 15 along the flow guiding component 14 and the expansion ring 13 of the device.

[0124] A growth time of 100 to 150 hours ensures that the silicon carbide crystal expands from the silicon carbide seed crystal 15 to a larger diameter.

[0125] In some embodiments, the growth temperature is 2200°C to 2250°C, and the growth pressure is 500Pa to 800Pa.

[0126] Within the relatively small high-temperature window of 2200℃ to 2250℃, a sufficient supply of silicon carbide raw material 16 can be guaranteed to meet the growth rate requirements of large-size diameter expansion, while effectively suppressing excessive decomposition of silicon carbide raw material 16 caused by excessive temperature and reducing crystal defects, which is conducive to the growth of crystals with high crystal integrity and low intrinsic defect density.

[0127] The relatively high pressure range of 500Pa to 800Pa can moderately shorten the mean free path of gas phase molecules, reduce the disordered diffusion of gas source during transmission, make it easier for gas source to be guided along the inclined sidewall of the flow guide component 14 to the expansion ring 13, and at the same time increase the collision probability of gas phase components, promote the uniform adsorption of gas source on the growth surface of silicon carbide seed crystal 15, avoid the imbalance of growth rate caused by excessively high or low local gas source concentration, ensure the uniform expansion of crystal along the expansion ring contour, and improve the shape regularity of large-size crystal.

[0128] To better illustrate the beneficial effects of this application, the following description is provided in conjunction with specific embodiments.

[0129] Example 1: The silicon carbide crystal growth apparatus has no current guiding components, such as... Figure 4 As shown, the silicon carbide crystal growth apparatus 10 includes: a cover plate 12, a silicon carbide seed crystal 15, a diameter expansion ring 13, a silicon carbide raw material 16, and a crucible 11.

[0130] Silicon carbide raw material 16 was grown by heating using the PVT method. The furnace pressure was controlled at 800 Pa, the temperature at 2200 °C, and the growth time was 150 h before growth was terminated. The silicon carbide crystals were then cooled to room temperature. Figure 5 As shown, Figure 5 To adopt Figure 4 The silicon carbide crystal grown by the silicon carbide crystal growth apparatus 10 shown can be seen to have a thickness that is mainly concentrated in the middle position, a large crystal convexity, a thinner crystal edge, and a low diameter expansion efficiency.

[0131] Example 2: A flow guiding component is added to the silicon carbide crystal growth apparatus, such as... Figure 1As shown, the silicon carbide crystal growth apparatus includes: a cover plate 12, a silicon carbide seed crystal 15, a diameter expansion ring 13, a silicon carbide raw material 16, a crucible 11, and a flow guiding component 14.

[0132] Silicon carbide raw material 16 was grown by heating using the PVT method. The furnace pressure was controlled at 800 Pa, the temperature at 2200 °C, and the growth time was 150 h before growth was terminated. The silicon carbide crystals were then cooled to room temperature. Figure 6 As shown, Figure 6 To adopt Figure 1 The silicon carbide crystal grown by the silicon carbide crystal growth apparatus 10 shown has a relatively uniform thickness at the middle and edge positions, a small crystal convexity, high diameter expansion efficiency, and is not prone to cracking.

[0133] Under the same supply of silicon carbide raw materials and the same crystal growth conditions, Figure 4 comparable Figure 3 The larger the crystal diameter (5mm-10mm), the more pronounced this effect becomes.

[0134] The various embodiments in this application are described in a progressive, parallel, or combined manner. Each embodiment focuses on its differences from other embodiments, and similar or identical parts between embodiments can be referred to interchangeably. The embodiments provided in this application can be combined with each other without contradiction.

[0135] It should be noted that, in the description of this application, the accompanying drawings and embodiments are illustrative rather than restrictive. The same reference numerals throughout the embodiments identify the same structures. Additionally, for understanding and ease of description, the thicknesses of some layers, films, panels, regions, etc., may be exaggerated in the drawings. It is also understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, the element may be directly on the other element or there may be intermediate elements. Furthermore, "on" means positioning an element on or below another element, but does not inherently mean positioning it above another element according to the direction of gravity.

[0136] The terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the middle.

[0137] It should also be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes the aforementioned element.

[0138] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A silicon carbide crystal growth apparatus, characterized in that, include: A crucible having a cavity for holding silicon carbide raw material, the top of the cavity having an opening; A cover plate for covering the opening; wherein the inner surface of the cover plate is used to fix the silicon carbide seed crystal; An expanding ring is fixed to the side wall of the cavity; in a first direction, the inner diameter of the expanding ring linearly decreases from a first diameter D1 to a second diameter D2, and the direction from the bottom of the cavity to the opening is the first direction; when the cover plate covers the opening, the cover plate abuts against the top of the expanding ring; A flow guiding assembly is disposed above the silicon carbide raw material and below the diameter expansion ring, and is centrally located in the radial direction of the cavity; the flow guiding assembly includes a circular bottom and a flow guiding ring disposed around the circular bottom; the outer diameter of the flow guiding ring increases along the first direction.

2. The silicon carbide crystal growth apparatus as described in claim 1, characterized in that, In the first direction, the outer diameter of the guide ring increases from the third diameter D3 to the fourth diameter D4; Where D2≥D4, and / or, D4≥ D2.

3. The silicon carbide crystal growth apparatus as described in claim 2, characterized in that, In the first direction, the outer diameter of the guide ring increases linearly from the third diameter D3 to the fourth diameter D4.

4. The silicon carbide crystal growth apparatus as described in claim 3, characterized in that, In the first direction, the inner diameter of the expanding ring is linearly reduced from the first diameter D1 to the second diameter D2 based on a first linear relationship, and the outer diameter of the guide ring is linearly increased from the third diameter D3 to the fourth diameter D4 based on a second linear relationship. Wherein, the first linear relationship has a first slope k1, the second linear relationship has a second slope k2, and |k1|>|k2|.

5. The silicon carbide crystal growth apparatus as described in claim 2, characterized in that, In the first direction, the flow guide ring includes a first sub-flow guide ring to an Nth sub-flow guide ring distributed sequentially, where N is a positive integer greater than 1; the bottom outer diameter of the first sub-flow guide ring is D3; and the top outer diameter of the Nth sub-flow guide ring is D4. The outer diameters of the first to the Nth sub-guide rings all increase linearly along the first direction; The top of the i-th sub-guide ring and the bottom of the (i+1)-th sub-guide ring are on the same horizontal plane and are integrally connected based on a planar circular ring structure; the outer diameter of the top of the i-th sub-guide ring is smaller than the outer diameter of the bottom of the (i+1)-th sub-guide ring, where i is a positive integer less than N.

6. The silicon carbide crystal growth apparatus as described in claim 5, characterized in that, The outer diameter of the first to the Nth sub-guide rings increases linearly based on the third linear relationship; Among the first to the Nth sub-guide rings, at least two of them have different slopes in their corresponding third linear relationships.

7. The silicon carbide crystal growth apparatus as described in claim 6, characterized in that, The slope K of the third linear relationship corresponding to the i-th sub-guide loop i The slope K of the third linear relationship corresponding to the (i+1)th sub-guide loop i+1 ,|K i+1 |>|K i | 8. The silicon carbide crystal growth apparatus as described in claim 6, characterized in that, In the first direction, the height of the i-th sub-guide ring is h. i The height of the (i+1)th sub-guide ring is h i+1 ,|h i |>|h i+1 | 9. The silicon carbide crystal growth apparatus as described in claim 1, characterized in that, The angle between the inner wall of the expanding ring and the plane containing the bottom of the cavity is 30° to 60°.

10. The silicon carbide crystal growth apparatus as described in claim 1, characterized in that, In the first direction, the outer diameter of the guide ring increases from a third diameter D3 to a fourth diameter D4; the inner diameter of the crucible is D5; The thickness of the flow guiding component is 0.5mm to 20mm, and D3 ≥ D5, D4 < D5.

11. The silicon carbide crystal growth apparatus as described in claim 2, characterized in that, The diameter of the circular bottom of the flow guiding component is D4 to D4, the width of the guide ring remains consistent along the first direction.

12. The silicon carbide crystal growth apparatus as described in claim 1, characterized in that, Relative to the bottom of the cavity, the loading height of the silicon carbide raw material is H1, the bottom height of the expansion ring is H2, the top height of the expansion ring is H3, and the height difference between the bottom of the expansion ring and the top of the flow guiding assembly is ΔH. in, (H2-H1) < ΔH < (H3-H2).

13. A method for growing silicon carbide crystals, characterized in that, The silicon carbide crystal growth apparatus according to any one of claims 1 to 12 comprises: Silicon carbide raw material is filled into the cavity of the crucible, and the top of the cavity has an opening; The flow guiding component is placed in the center of the surface of the silicon carbide raw material; The expansion ring is fixed to the inner wall of the cavity; A silicon carbide seed crystal is fixed on the inner surface of the cover plate, and the cover plate covers the opening; The crucible is heated to sublimate the silicon carbide raw material and allow for crystal growth.

14. The silicon carbide crystal growth method as described in claim 13, characterized in that, The crystal growth process conditions include: the growth atmosphere is argon or a mixture of argon and hydrogen, the growth temperature is 2150℃ to 2350℃, the growth pressure is 100Pa to 800Pa, and the growth time is 100h to 150h.

15. The silicon carbide crystal growth method as described in claim 14, characterized in that, The growth temperature is 2200℃ to 2250℃, and the growth pressure is 500Pa to 800Pa.

Images