A silicon carbide crystal growth apparatus and crystal growth method

Abstract

This application discloses a silicon carbide crystal growth apparatus and method, including a crucible. The inner cavity of the crucible is divided into a raw material zone, a pre-reaction zone, and a growth zone from bottom to top. A seed crystal for crystal growth is provided in the growth zone. The pre-reaction zone includes a collision reaction chamber and a temperature difference sedimentation expansion chamber arranged from bottom to top. A porous baffle is provided in the collision reaction chamber. The internal temperature of the collision reaction chamber meets a first condition, whereby silicon carbide, silicon-rich clusters, and carbon-rich clusters are all maintained in the gas phase. The internal temperature of the temperature difference sedimentation expansion chamber meets a second condition, whereby silicon carbide is maintained in the gas phase, and silicon-rich clusters or carbon-rich clusters crystallize. The silicon carbide crystal growth apparatus disclosed in this application, by setting up a pre-reaction zone, allows the raw material vapor to undergo forced collision mixing and physical purification based on temperature difference sedimentation before reaching the growth interface, reducing the formation of inclusions and facilitating the acquisition of silicon carbide crystals with lower defect density.

Description

Technical Field

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

[0002] PVT (Physical Vapor Transport) is a method used to grow high-quality single crystals, especially wide-bandgap semiconductors such as silicon carbide. In a PVT system for growing silicon carbide crystals, the source material sublimates or decomposes in a high-temperature region into a mixture of various gaseous components, including silicon, disilicide, and disilicon carbide. This mixture is then transported to a lower-temperature seed crystal via a temperature gradient or carrier gas, where it recrystallizes and grows into a bulk single crystal. Inclusions are one of the main crystal defects. Inclusions refer to heterogeneous materials or phases, different from the crystal matrix (silicon carbide), that are accidentally captured and embedded within the crystal during single crystal growth. They severely affect the quality of the crystal and the performance of subsequent devices.

[0003] In existing technologies, methods for controlling inclusions mainly focus on optimizing thermal field design, improving raw material purity, using specially coated graphite components, and attempting to incorporate porous filters in the transport path. However, each of these methods has its limitations: thermal field optimization can only improve macroscopic distribution and is difficult to eliminate microscopic non-uniform reactions; improving raw material purity faces cost and technical bottlenecks; although porous filters can physically intercept some particles, they cannot solve the problem of chemical imbalance at the gas phase molecular scale. Chemically imbalanced carbon / silicon clusters are transported with the main gas flow to the seed crystal and crystallize, thus forming inclusions.

[0004] Therefore, how to reduce crystal defects during the growth of silicon carbide crystals using the PVT method has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to disclose a silicon carbide crystal growth apparatus to reduce crystal defects during the PVT process of growing silicon carbide crystals.

[0006] Another objective of this application is to disclose a crystal growth method using the aforementioned silicon carbide crystal growth apparatus.

[0007] A silicon carbide crystal growth apparatus includes a crucible, the inner cavity of which is divided into a raw material zone, a pre-reaction zone and a growth zone from bottom to top;

[0008] The raw material area is used to hold silicon carbide raw materials;

[0009] The growth region is provided with seed crystals for crystal growth;

[0010] The pre-reaction zone includes a collision reaction chamber and a temperature difference sedimentation expansion chamber arranged sequentially from bottom to top; the collision reaction chamber is equipped with a porous baffle; the internal temperature of the collision reaction chamber meets a first condition, the first condition being that silicon carbide, silicon-rich clusters and carbon-rich clusters are all kept in the gas phase;

[0011] The internal temperature of the temperature difference settling expansion chamber meets the second condition, which is that silicon carbide is maintained in the gas phase and silicon-rich clusters or carbon-rich clusters are crystallized, and the cross-sectional area of ​​the inner cavity at the outlet of the temperature difference settling expansion chamber is greater than the cross-sectional area of ​​the inner cavity at the inlet of the temperature difference settling expansion chamber.

[0012] In one possible implementation, the cross-sectional area of ​​the thermostatic sedimentation expansion chamber gradually increases in the direction from the collision reaction chamber to the thermostatic sedimentation expansion chamber.

[0013] In one possible implementation, the pre-reaction zone includes a combined inner liner that is detachably installed inside the crucible; the combined inner liner has an internal cavity, and the collision reaction chamber and the temperature difference sedimentation expansion chamber are disposed within the internal cavity.

[0014] In one possible implementation, a temperature control device is also included, which is an independently controllable heating unit and is arranged around the crucible. The temperature control device is configured to create an internal temperature that satisfies the second condition within the temperature difference settling expansion chamber.

[0015] In one possible implementation, the pre-reaction zone further includes a laminar flow guiding chamber located between the temperature difference settling expansion chamber and the growth zone. The laminar flow guiding chamber is provided with multiple baffles, which are parallel to each other and spaced apart. The extension direction of each baffle is perpendicular to the crystal growth surface of the seed crystal.

[0016] In one possible implementation, a collection tank is also included. The collection tank is an annular tank, with its outer ring connected to the inner wall of the crucible and its inner ring forming a channel for gas flow. The collection tank is located between the temperature difference settling expansion chamber and the collision reaction chamber and is used to collect sediments in the temperature difference settling expansion chamber.

[0017] In one possible implementation, the porous baffle has a circular cross-section and a diameter of 2 mm to 5 mm.

[0018] In one possible implementation, the perforated baffle has an opening ratio of 30% to 70%.

[0019] In one possible implementation, a plurality of porous baffles are stacked from bottom to top in the collision reaction chamber, each porous baffle having a different opening ratio, and the through holes of adjacent porous baffles being staggered on the horizontal projection plane.

[0020] In the operation of the silicon carbide crystal growth apparatus disclosed in this application, silicon carbide raw material is first loaded into the raw material area, and the seed crystal is fixed in the growth area. The entire crucible is sealed in the crystal growth furnace chamber, the furnace chamber is evacuated to a high vacuum, and then filled with inert gases such as high-purity argon as the growth atmosphere. Heating and temperature control are performed to establish and maintain a specific axial temperature gradient within the crucible.

[0021] After the silicon carbide raw material in the feed zone sublimates into a gaseous phase, the gaseous silicon carbide first passes upward through the porous baffles in the collision reaction chamber. As the vapor molecules pass through the channels, frequent collisions and primary reactions occur, and some high-saturation vapor pressure impurities or intermediate products polymerize or have altered transport characteristics during these collisions. Subsequently, the gas flow enters the thermostatic settling expansion chamber. Due to the spatial expansion, the gas flow velocity slows down; simultaneously, under the influence of the downward temperature gradient, silicon-rich or carbon-rich clusters in the vapor condense or settle, while the silicon carbide remains gaseous and is transported upward, thus achieving thermostatic settling purification.

[0022] The purified main gas flow continues to rise, reaching the lower surface of the seed crystal, where it becomes supersaturated and undergoes orderly crystal growth to form silicon carbide crystals. After growth is complete, the temperature is controlled to cool down, and finally the resulting silicon carbide crystals are removed.

[0023] Compared to related technologies, the silicon carbide crystal growth apparatus disclosed in this application, by setting up a pre-reaction zone with a specific temperature gradient, allows the raw material vapor to undergo a forced collision mixing and physical purification process based on temperature difference sedimentation before reaching the growth interface. High-melting-point impurities or non-target phases are effectively intercepted in the pre-reaction zone, significantly reducing the impurity concentration in the gaseous raw material reaching the seed crystal, reducing the formation of inclusions, and facilitating the acquisition of silicon carbide crystals with higher resistivity and lower defect density.

[0024] A crystal growth method, wherein the crystal growth method employs a silicon carbide crystal growth apparatus as described in any of the above possible implementations, the crystal growth method comprising:

[0025] S1: The silicon carbide raw material is loaded into the raw material zone of the crucible;

[0026] S2: Evacuate the growth chamber containing the crucible and fill it with inert gas;

[0027] S3: A preset temperature field is established along the axial direction of the crucible, decreasing from bottom to top, such that the temperature of the raw material zone is higher than the silicon carbide sublimation temperature, and the temperature of the growth zone is lower than the silicon carbide crystallization temperature, so that the silicon carbide raw material sublimates and is purified by the pre-reaction zone, and then crystallizes and grows at the seed crystal.

[0028] S4: Maintain the preset temperature field for a preset time to allow the crystal to continue growing;

[0029] S5: End growth, cool down and remove the crystal.

[0030] Since this silicon carbide crystal growth method uses the aforementioned silicon carbide crystal growth apparatus, it possesses all the technical effects of the aforementioned silicon carbide crystal growth apparatus, which will not be elaborated upon here. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the silicon carbide crystal growth apparatus disclosed in the embodiments of this application;

[0033] Figure 2 This is a schematic diagram of the structure of the porous baffle disclosed in an embodiment of this application.

[0034] The attached figures are labeled as follows:

[0035] 10. Crucible; 20. Silicon carbide raw material;

[0036] 100. Raw material area;

[0037] 200. Pre-reaction zone; 210. Collision reaction chamber; 211. Porous baffle; 220. Thermostatic settling expansion chamber; 230. Laminar flow guiding chamber; 231. Baffle;

[0038] 300. Growth zone;

[0039] 400, Seed Crystal;

[0040] 500, Seed Crystal Holder. Detailed Implementation

[0041] The purpose of this application is to disclose a silicon carbide crystal growth apparatus to reduce crystal defects during the PVT process of growing silicon carbide crystals.

[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0043] See Figure 1 The silicon carbide crystal growth apparatus disclosed in this application includes a crucible 10. The crucible 10 is typically made of high-temperature resistant materials such as graphite, is placed inside a crystal growth furnace, and is equipped with a main heating system for heating.

[0044] The inner cavity of crucible 10 is divided into a raw material zone 100, a pre-reaction zone 200, and a growth zone 300 from bottom to top. The raw material zone 100 is used to hold silicon carbide raw material 20, such as silicon carbide powder. The top of the growth zone 300 is provided with a seed crystal holder 500 to fix the seed crystal 400 so that its crystal growth surface is generally facing downwards.

[0045] The pre-reaction zone 200 is integrally formed on the inner wall of the crucible 10, or assembled inside the crucible 10 by independent components. Functionally, it is divided into two parts: the lower collision reaction chamber 210 and the upper temperature difference settling expansion chamber 220.

[0046] The collision reaction chamber 210 is mainly used to cause collisions, mixing, and preliminary reactions of silicon carbide vapor sublimated from the raw material zone 100. The internal temperature of the collision reaction chamber 210 must meet a first condition: its internal temperature must be higher than the condensation temperature of silicon-rich clusters or carbon-rich clusters, and simultaneously higher than the equilibrium crystallization temperature of pure silicon carbide, ensuring that silicon carbide, silicon-rich clusters, and carbon-rich clusters remain in the gas phase. In this embodiment, a horizontally arranged porous baffle 211 is provided inside the collision reaction chamber 210. The porous baffle 211 can be made of high-purity graphite, silicon carbide ceramic, or graphite coated with a refractory metal carbide coating to withstand high temperatures and prevent contamination. The porous baffle 211 can be detachably connected to the inner wall of the crucible 10 for easy replacement or cleaning after the growth cycle. The porous baffle 211 is densely covered with through-holes, which force the rising airflow through these holes, increasing the probability of collisions between gas molecules and between gas molecules and the pore walls, thus promoting the homogenization of gaseous substances and the generation of intermediate reactants.

[0047] The thermostatic settling expansion chamber 220 is located directly above the collision reaction chamber 210. Its internal temperature must meet a second condition: it must be within the condensation temperature range of silicon-rich or carbon-rich clusters, and simultaneously higher than the equilibrium crystallization temperature of pure silicon carbide, so that silicon carbide remains in the gaseous phase while the silicon-rich or carbon-rich clusters crystallize. In this embodiment, the internal temperature of the collision reaction chamber 210 is 2200°C to 2300°C, and the internal temperature of the thermostatic settling expansion chamber 220 can be set between 2100°C and 2150°C.

[0048] Silicon-rich clusters are atomic aggregates in which silicon atoms significantly outnumber carbon atoms. Carbon-rich clusters are atomic aggregates in which carbon atoms significantly outnumber silicon atoms. Their chemical composition deviates from the ideal stoichiometric ratio (Si:C=1:1), making them prone to forming inclusions during crystal growth. Temperature design ensures that the supersaturation of either silicon-rich or carbon-rich clusters increases sharply upon entering the temperature difference settling and expansion chamber at 220°C, leading to preferential condensation or precipitation, while pure silicon carbide remains in a gaseous state and is transported upwards, thus achieving online purification of the transported gas phase material.

[0049] It should be noted that the condensation temperature range of silicon-rich clusters or carbon-rich clusters will vary depending on the gas pressure inside the crucible 10. Those skilled in the art can set the internal temperature of the temperature difference settling expansion chamber 220 based on the actual process conditions.

[0050] The cross-sectional area of ​​the inner cavity at the outlet of the temperature difference settling expansion chamber 220 is larger than that at its inlet, wherein the cross-sectional area of ​​the inner cavity is the cross-sectional area perpendicular to the axis of the crucible 10. The increased cross-sectional area can reduce the gas flow velocity and prolong the gas phase residence time, providing sufficient settling time for the aforementioned condensed silicon-rich clusters or carbon-rich clusters, thereby separating them from the dominant growth gas phase.

[0051] The working process of the silicon carbide crystal growth apparatus disclosed in this application is as follows:

[0052] Silicon carbide raw material 20 is loaded into the raw material zone 100, and the seed crystal 400 is fixed in the growth zone 300. The entire crucible 10 is sealed in the crystal growth furnace chamber, the furnace chamber is evacuated to a high vacuum, and then filled with inert gases such as high-purity argon as the growth atmosphere. Heating and temperature control are performed to establish and maintain a specific axial temperature gradient within the crucible 10.

[0053] After the silicon carbide raw material 20 in the raw material zone 100 sublimates into a gaseous phase, the gaseous silicon carbide raw material 20 first passes upward through the porous baffle 211 of the collision reaction chamber 210. As the vapor molecules pass through the channels, frequent collisions and primary reactions occur, and some high-saturation vapor pressure impurities or intermediate products polymerize or change their transport characteristics during the collisions. Subsequently, the gas flow enters the temperature difference settling expansion chamber 220. Due to the spatial expansion, the gas flow velocity slows down; simultaneously, under the action of the temperature gradient, silicon-rich or carbon-rich clusters in the vapor condense or settle, while the silicon carbide remains in a gaseous state and is transported upward, thus achieving temperature difference settling purification.

[0054] The purified main gas flow continues to rise, reaching the lower surface of the seed crystal 400, where it becomes supersaturated and undergoes orderly crystal growth to form silicon carbide crystals. After growth is complete, the temperature is controlled to cool down, and finally the resulting silicon carbide crystals are removed.

[0055] Compared to related technologies, the silicon carbide crystal growth apparatus disclosed in this application, by setting a pre-reaction zone 200 with a specific temperature gradient, allows the raw material vapor to undergo a forced collision mixing and physical purification process based on temperature difference sedimentation before reaching the growth interface. High-melting-point impurities or non-target phases are effectively intercepted in the pre-reaction zone 200, significantly reducing the impurity concentration in the gaseous raw material reaching the seed crystal 400, reducing the formation of inclusions, and facilitating the acquisition of silicon carbide crystals with higher resistivity and lower defect density.

[0056] To guide a smooth transition in the airflow, the cross-sectional area of ​​the thermostatic settling expansion chamber 220 gradually increases from the collision reaction chamber 210 to the thermostatic settling expansion chamber 220, forming a gradually expanding funnel shape. When the airflow carrying the reaction products enters the thermostatic settling expansion chamber 220 from the lower collision reaction chamber 210, the gradual increase in the flow cross-sectional area significantly reduces the airflow velocity, effectively extending the residence time of the gaseous material within the thermostatic settling expansion chamber 220. This longer residence time provides sufficient time for the different vapor groups to undergo adequate gravity settling and diffusion separation, thereby improving the settling and separation effect of the thermostatic settling expansion chamber 220 on the raw material vapor and providing higher purity raw material transport to the growth interface. Furthermore, the gradually expanding structure guides the airflow to a smooth transition, effectively suppressing turbulent disturbances such as eddies or backflows that may occur due to abrupt changes in cross-section. This stabilization of the flow field ensures that the purified gaseous material can flow to the seed crystal in the growth zone in a more uniform and smoother manner.

[0057] To facilitate independent processing and replacement, the pre-reaction zone can adopt a modular inner liner structure. This modular inner liner is made of high-temperature resistant, high-purity materials that are compatible with silicon carbide growth processes (such as high-purity graphite, graphite coated with tantalum carbide, or high-purity refractory metals).

[0058] The combined inner liner is detachably installed within the inner cavity of the crucible 10, and its installation can be achieved through mechanical means. For example, a support ring or step can be provided at the junction of the inner wall of the crucible 10 and the raw material zone 100, and the combined inner liner can be placed entirely on this support structure; or it can be detachably fixed by means of threaded connection, pin positioning, etc., to ensure that it can maintain positional stability at high temperatures. The combined inner liner has a through internal cavity, which is longitudinally divided into a collision reaction chamber and a temperature difference settling expansion chamber.

[0059] The detachable design of the combined inner liner allows for easy replacement of the inner liner module with different impact reaction intensities (such as porous baffles 211 with different porosities) or different sizes of temperature difference sedimentation expansion chambers 220 during assembly, according to different crystal growth process requirements (such as different raw material particle sizes and different growth rates). During equipment maintenance, the combined inner liner can be removed individually for cleaning, high-temperature baking to remove deposits, or replaced entirely, without needing to replace the entire crucible, thus reducing maintenance costs and improving equipment efficiency.

[0060] Furthermore, the structure of the silicon carbide crystal growth apparatus of this application can be improved based on the existing crystal growth furnace. The pre-reaction zone 200 components can be integrated with the crucible 10, resulting in low modification costs. No complex additional chemical reactions or external filtration systems are required; purification and flow field control functions can be achieved solely through temperature field control, resulting in a simple and stable process.

[0061] To achieve precise and independent temperature control of the thermostatic settling expansion chamber 220, an independent temperature control device can be provided. This device is an independently controllable heating unit arranged around the crucible 10, such as a segmented graphite heating element nested in the outer wall of the crucible 10. Since the thermostatic settling expansion chamber 220 extends the gas transport path, to prevent the gas temperature from dropping too quickly during transport, which could lead to premature silicon carbide crystallization, the temperature control device actively heats the chamber 220, precisely maintaining its designed internal temperature and ensuring a stable and controllable temperature difference between it and the lower collision reaction chamber 210. This stable temperature gradient drives selective condensation and sedimentation of components with different saturated vapor pressures in the raw material vapor, allowing heavy impurities to precipitate and remain more fully and controllably within the expansion settling chamber. This achieves deep purification of the raw material vapor, fundamentally reducing the defect density in the crystal.

[0062] To further optimize the airflow state at the seed crystal 400, this embodiment adds a laminar flow guide chamber 230 in the pre-reaction zone 200. Specifically, the laminar flow guide chamber 230 is located between the thermostatic settling expansion chamber 220 and the growth zone 300. Multiple parallel and spaced baffles 231 are arranged inside the laminar flow guide chamber 230, thereby dividing the interior of the laminar flow guide chamber 230 into several parallel channels. The extending direction of the baffles 231 is set perpendicular to the crystal growth surface of the seed crystal 400. The rising airflow, purified by the thermostatic settling expansion chamber 220, enters the laminar flow guide chamber 230 and is forcibly divided into a series of parallel, uniform laminar flows. These flows are then vertically impacted onto the crystal growth surface of the seed crystal 400 by numerous parallel vertical baffles 231, providing extremely uniform material transport and heat exchange conditions across the entire growth surface. This process streamlines potentially turbulent airflow into parallel laminar flow with consistent direction and uniform velocity, significantly suppressing uneven undulations and defects at the growth interface. This promotes the formation of a smooth and stable growth interface, facilitating single-crystal growth. Together, these processes ensure extremely uniform material supply and heat distribution at the growth interface, effectively suppressing defects such as polymorphic inclusions and microtubes caused by excessively high or low local supersaturation, thus improving the overall quality and consistency of the crystal.

[0063] To facilitate the cleaning of deposits after the crystal growth cycle, the silicon carbide crystal growth apparatus also includes a collection tank. This collection tank is an annular tank located between the thermostatic sedimentation expansion chamber 220 and the collision reaction chamber 210. Its outer ring can be detachably installed on the inner wall of the crucible 10 via threaded connections or fasteners. The inner ring of the collection tank forms a gas flow channel, allowing gas exiting the collision reaction chamber 210 to enter the thermostatic sedimentation expansion chamber 220 through the inner ring of the collection tank. Deposits falling onto the wall of the thermostatic sedimentation expansion chamber 220 slide down the expanding inclined surface under gravity and eventually flow into this collection tank, thus being effectively collected and isolated, preventing them from falling back into the high-temperature collision reaction chamber 210 or being re-entrained by the gas flow, ensuring continuous gas-phase purification. Furthermore, the collection tank can be disassembled for cleaning after each crystal growth cycle, facilitating the use and maintenance of the apparatus.

[0064] In one specific embodiment, the cross-sectional shape of the channels on the porous baffle 211 can be circular. For example... Figure 2 As shown, the porous baffle 211 is a disc-shaped component with a circular through hole. The cross-section of the hole is a plane perpendicular to the axial direction of the porous baffle 211; in other words, the cross-section of the hole is perpendicular to the axial direction of the crucible 10. Specifically, when the diameter of the circular hole is controlled between 2 mm and 5 mm, an optimal balance can be achieved between airflow resistance, collision reaction efficiency, and prevention of hole blockage.

[0065] To achieve a balance between reaction efficiency and flow capacity, the porosity of the porous baffle 211 is designed to be between 30% and 70%. When the porosity is below 30%, the baffle is too dense. Although this increases the probability of collisions, it hinders the flow of raw material vapor, leading to insufficient transport rate of silicon carbide raw material 20, a shortage of supply in the growth zone, a significant decrease in crystal growth rate, and potentially an abnormal increase in pressure within the crucible 10. When the porosity is above 70%, the baffle is too sparse. Although the flow resistance is low, the collision reaction between the vapor flow and the solid surface is insufficient, resulting in poor filtration and decomposition of high-boiling-point impurities and gaseous byproducts, and weakening the purification function of the pre-reaction zone. Limiting the porosity to 30%-70% precisely balances the requirements for sufficient collision reaction and efficient vapor transport.

[0066] To further improve reaction efficiency, multiple porous baffles 211 can be stacked sequentially from bottom to top within the collision reaction chamber 210. Each porous baffle 211 is made of high-purity graphite or silicon carbide-coated graphite. The porosity of each porous baffle 211 is different, for example, the porosity gradually decreases from bottom to top or is distributed according to a preset gradient, and the through holes of adjacent porous baffles 211 are staggered on the horizontal projection plane, that is, the holes of each porous baffle 211 do not form a through channel in the axial direction.

[0067] For example, the first layer of porous baffles 211 at the bottom has a high opening ratio, mainly used for the initial distribution of the rising airflow from the raw material zone 100; the second layer of porous baffles 211 in the middle has a moderate opening ratio, and its through holes are offset from the through holes of the first layer of porous baffles 211; the third layer of porous baffles 211 at the top has a low opening ratio, and its through holes are again offset. A preset distance is maintained between each porous baffle 211 by washers or support bosses.

[0068] During the growth process, as the raw material steam passes through the porous baffles 211, the gradient changes in porosity and the staggered arrangement of the pores force it to change its flow direction multiple times and cause repeated collisions. This significantly increases the collision probability between gaseous precursors, promoting a thorough pre-reaction. Simultaneously, the staggered porosity structure effectively intercepts some of the condensed large particles, preventing them from being transported upwards with the airflow. Furthermore, the pre-reaction intensity and pressure drop can be flexibly controlled by adjusting the combination of porosity, the number of layers, and the spacing of the porous baffles 2, adapting to the process requirements under different raw material particle sizes, heating power, and growth rates. Moreover, the porous baffles 211 have a simple structure, are easy to manufacture and replace, and facilitate maintenance and process optimization.

[0069] Another aspect of this application discloses a method for growing silicon carbide crystals, employing the silicon carbide crystal growth apparatus in any of the above embodiments, the method comprising the following steps:

[0070] S1: Fill silicon carbide raw material 20 into the raw material area 100 of crucible 10, and clean and fix the seed crystal 400 on the seed crystal holder 500 in the growth area 300.

[0071] S2: Seal crucible 10 inside the crystal growth furnace and evacuate the furnace chamber to a high vacuum (e.g., up to 10). -5 (Pa) is used to remove moisture and impurity gases, and then high-purity argon and other inert gases are introduced as the growth environment atmosphere.

[0072] S3: Start the main heating system to establish a preset temperature field along the axial direction of crucible 10, so that the temperature of raw material zone 100 is the highest and higher than the silicon carbide sublimation temperature, serving as a sublimation source. The temperature of growth zone 300 is the lowest and lower than the silicon carbide crystallization temperature. Start the temperature control of pre-reaction zone 200, with the following control objectives: the temperature of collision reaction chamber 210 is set to T1, the temperature of temperature difference sedimentation expansion chamber 220 is set to T2, and the temperature at laminar flow guiding chamber 230 is set to T3. T1 satisfies the first condition, T2 satisfies the second condition, and T1 > T2 > T3, forming a decreasing temperature field from bottom to top.

[0073] S4: Once each region reaches and stabilizes at the preset temperature field, it enters the isothermal growth stage. This preset temperature field is maintained for a preset growth time (e.g., 80 to 120 hours). The silicon carbide raw material 20 continues to sublimate and, after collision, purification, and homogenization in the pre-reaction zone 200, it is epitaxially grown on the seed crystal 400.

[0074] S5: After the crystal grows to the target thickness, it is slowly cooled to room temperature according to a predetermined procedure, and the generated silicon carbide crystal is taken out.

[0075] Since this silicon carbide crystal growth method uses the aforementioned silicon carbide crystal growth apparatus, it possesses all the technical effects of the aforementioned silicon carbide crystal growth apparatus, which will not be elaborated upon here.

[0076] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order, and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units may include steps or units not listed, but rather steps or units not listed. Additionally, in the description of embodiments in this application, "a plurality of" means two or more.

[0077] In the description of this application, it should be understood that the terms "height," "thickness," "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and 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, and therefore should not be construed as a limitation of this application. In the description of this application, "a plurality of" means two or more, and "at least one" can mean one, two, or more, unless otherwise expressly specified.

[0078] 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. Specific technical means in some embodiments may be incorporated, in whole or in part, into another embodiment unless explicitly excluded by another embodiment. 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, Includes a crucible (10), the inner cavity of which is divided into a raw material zone (100), a pre-reaction zone (200) and a growth zone (300) from bottom to top. The raw material area (100) is used to hold silicon carbide raw material (20). The growth zone (300) is provided with a seed crystal (400) for crystal growth. The pre-reaction zone (200) includes a collision reaction chamber (210) and a temperature difference sedimentation expansion chamber (220) arranged sequentially from bottom to top; the collision reaction chamber (210) is provided with a porous baffle (211); the internal temperature of the collision reaction chamber (210) meets a first condition, the first condition being that silicon carbide, silicon-rich clusters and carbon-rich clusters are all kept in the gas phase; The internal temperature of the temperature difference settling expansion chamber (220) meets the second condition, which is that silicon carbide is kept in the gas phase and silicon-rich clusters or carbon-rich clusters are crystallized, and the cross-sectional area of ​​the inner cavity at the outlet of the temperature difference settling expansion chamber (220) is greater than the cross-sectional area of ​​the inner cavity at the inlet of the temperature difference settling expansion chamber (220).

2. The silicon carbide crystal growth apparatus as described in claim 1, characterized in that, In the direction from the collision reaction chamber (210) to the thermostatic settling expansion chamber (220), the cross-sectional area of ​​the inner cavity of the thermostatic settling expansion chamber (220) gradually increases.

3. The silicon carbide crystal growth apparatus as described in claim 1, characterized in that, The pre-reaction zone (200) includes a combined inner liner, which is detachably installed inside the crucible (10); the combined inner liner has an internal cavity, and the collision reaction chamber (210) and the temperature difference sedimentation expansion chamber (220) are disposed in the internal cavity.

4. The silicon carbide crystal growth apparatus as described in claim 1, characterized in that, It also includes a temperature control device, which is an independently controllable heating unit and is arranged around the crucible (10). The temperature control device is configured to form an internal temperature that satisfies the second condition within the temperature difference settling expansion chamber (220).

5. The silicon carbide crystal growth apparatus as described in claim 1, characterized in that, The pre-reaction zone (200) further includes a laminar flow guiding chamber (230), which is located between the temperature difference settling expansion chamber (220) and the growth zone (300). The laminar flow guiding chamber (230) is provided with a plurality of partitions (231), which are parallel to each other and spaced apart. The extension direction of each partition (231) is perpendicular to the crystal growth surface of the seed crystal (400).

6. The silicon carbide crystal growth apparatus as described in claim 1, characterized in that, It also includes a collection tank, which is an annular tank. The outer ring of the collection tank is connected to the inner wall of the crucible (10), and the inner ring of the collection tank forms a channel for gas flow. The collection tank is located between the temperature difference sedimentation expansion chamber (220) and the collision reaction chamber (210) and is used to collect sediment in the temperature difference sedimentation expansion chamber (220).

7. The silicon carbide crystal growth apparatus as described in claim 1, characterized in that, The porous baffle (211) has a circular cross-section and a diameter of 2 mm to 5 mm.

8. The silicon carbide crystal growth apparatus as described in claim 7, characterized in that, The perforated baffle (211) has an opening ratio of 30% to 70%.

9. The silicon carbide crystal growth apparatus as described in claim 1, characterized in that, The collision reaction chamber (210) is provided with multiple porous baffles (211) stacked from bottom to top. Each porous baffle (211) has a different opening ratio, and the through holes of adjacent porous baffles (211) are staggered on the horizontal projection plane.

10. A crystal growth method, characterized in that, The crystal growth method employs the silicon carbide crystal growth apparatus as described in any one of claims 1-9, and the crystal growth method includes: S1: The silicon carbide raw material (20) is filled into the raw material zone (100) of the crucible (10); S2: Evacuate the growth chamber containing the crucible (10) and fill it with inert gas; S3: A preset temperature field is established in the axial direction of the crucible (10) from bottom to top, so that the temperature of the raw material zone (100) is higher than the silicon carbide sublimation temperature and the temperature of the growth zone (300) is lower than the silicon carbide crystallization temperature, so that the silicon carbide raw material (20) is sublimated and purified by the pre-reaction zone (200) and then crystallized and grown at the seed crystal (400); S4: Maintain the preset temperature field for a preset growth time to allow the crystal to continue growing; S5: End growth, cool down and remove the crystal.

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