A bell-shaped reactor and a method for preparing silicon crystal materials for deposition.

Abstract

This invention relates to the field of ultra-high purity silicon crystal materials technology, specifically to a bell-shaped reactor and a method for preparing silicon crystal materials by deposition. In this invention, the hollow carrier is configured with an internal hollow channel through which gas can be introduced. During peeling, the interior simultaneously cools down, achieving drastic thermal expansion and contraction, making the deposit easier to peel off. A collection hopper is located at the bottom of the bell-shaped reactor chassis. After all the powder remaining on the reactor chassis enters the hopper, the discharge valve is closed, and the hopper is purged with inert gas. Then, the conveyor belt at the bottom of the hopper is activated to dynamically transport the collected silicon carbide powder out of the hopper for packaging, achieving automation.

Description

Technical Field

[0001] This invention belongs to the field of silicon crystal material technology, specifically relating to a bell-shaped reactor and a method for preparing silicon crystal materials for deposition. Background Technology

[0002] Ultra-high purity silicon crystal materials are the core raw materials for integrated circuit substrates, with a purity of 7N or higher. They are mainly composed of polycrystalline silicon and silicon carbide, and the current mainstream process is vapor deposition in a bell-type reactor. Taking silicon carbide as an example, methyltrichlorosilane and hydrogen are used as raw materials. In the vapor deposition reactor, methyltrichlorosilane reacts with hydrogen on a high-temperature carrier to deposit silicon carbide. Once a certain thickness is reached, feeding is stopped, and after the inert gas is properly replaced, the bell is opened, the silicon carbide rod is physically broken and packaged. Then, the bell-type reactor is reloaded with the deposition carrier, replaced, heated, and fed again. This is an intermittent reaction, meaning the system cannot operate continuously, resulting in low production efficiency. Furthermore, each time the furnace is shut down and restarted, a clean and inert reaction environment needs to be reconstructed, which is time-consuming and costly. Frequent opening of the deposition furnace can easily introduce contaminants, leading to a decrease in product quality.

[0003] Existing technologies have the following drawbacks: they are all intermittent preparation methods. After the substrate reaches a certain thickness, the feeding is stopped, and after the inert gas is used for purging, the deposited silicon carbide is crushed, cleaned in the deposition furnace, and a new substrate is installed. After the inert gas is purged again, the furnace is started for growth, and the cycle is repeated, which is not continuous. The system requires frequent purging to create a clean atmosphere, which is time-consuming and costly. At the same time, frequent opening of the bell jar can easily introduce external impurities for contamination, resulting in substandard quality. The deposited crystals are mostly large rod-shaped, which end users need to crush before use. Silicon carbide has extremely high hardness, second only to diamond, making it difficult to crush. The introduction of impurities and losses during the mechanical crushing process can also cause quality problems and material waste. Summary of the Invention

[0004] This invention provides a bell-shaped reactor and a method for preparing silicon crystal materials by deposition. It can be used to prepare silicon crystal materials such as ultra-high purity polycrystalline silicon and silicon carbide. A hollow deposition carrier is installed on the bottom of the bell-shaped reactor. The hollow carrier is hollow and has a regular ridge grid pattern on its surface. The size can be set according to the particle size of ultra-high purity polycrystalline silicon, silicon carbide and other silicon crystal materials.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a bell-shaped reactor, comprising a bell-shaped furnace cylinder, a sealed reaction chamber, a chassis, an electrode assembly, a hollow carrier, a feed nozzle, a gas outlet, a collection funnel, and a cold source inlet and outlet; The furnace cylinder sidewall is provided with a gas purging port to introduce purging gas for cooling the sealed reaction chamber; The hollow carrier is used to deposit silicon crystal material to form a silicon crystal material deposition layer. The surface of the hollow carrier is provided with raised ridges to form a ridge grid. The inlet and outlet of the cold source realize the cooling of the hollow carrier. Through the cooling of the sealed reaction chamber and the hollow carrier, when a temperature gradient is formed between the temperature of the hollow carrier and the temperature of the silicon crystal material deposition layer, the silicon crystal material deposition layer falls off, causing the silicon crystal material deposition layer to pulverize and form silicon crystal material powder, which is collected by the collection funnel.

[0006] Preferably, the diameter of the hollow carrier is 1~10mm, the raised ridges form a ridge grid, the spacing of the ridge grid is 1~20mm, and the height of the raised ridges is 0.1~5mm.

[0007] Preferably, it also includes a collection hopper; the electrode assembly is evenly distributed on the chassis, and a control valve is provided in the lower channel of the collection funnel; the collection hopper is located at the bottom of the chassis, and a flange is also provided on the chassis for connecting the collection hopper; a conveyor belt is provided at the bottom of the collection hopper to dynamically transport the silicon crystal material powder collected in the collection hopper out of the collection hopper for packaging.

[0008] Preferably, the silicon crystal material is silicon carbide or polycrystalline silicon.

[0009] Preferably, the upper opening size of the collecting funnel is 1~30cm; the side wall of the furnace cylinder is provided with a gas purging port, which includes a bottom gas purging port, a middle gas purging port and a top gas purging port.

[0010] Preferably, the bottom gas purge port is tilted towards the chassis at an angle of 10 to 45 degrees.

[0011] Preferably, the hollow carrier is selected from at least one of graphite, tungsten metal, or their alloys.

[0012] Secondly, the present invention provides a method for preparing silicon crystal materials by depositing a bell-shaped reactor, comprising the following steps: The hollow carrier is heated by applying electricity through the electrode assembly, and the raw material gas is introduced through the feed nozzle. The raw material gas is continuously deposited on the surface of the hollow carrier to grow into a silicon crystal material deposition layer. Once the deposited layer reaches the preset size, the cold source inlet and outlet connected to the bottom of the hollow carrier are opened to introduce cooling gas into the hollow carrier for circulation, thereby cooling the hollow carrier. At the same time, the gas purging port on the side wall of the furnace is opened to introduce purging gas for cooling the sealed reaction chamber, thereby cooling the silicon crystal material deposited layer. When a temperature gradient is formed between the temperature of the hollow carrier and the temperature of the silicon crystal material deposition layer, the silicon crystal material deposition layer falls off, causing the silicon crystal material deposition layer to pulverize and form silicon crystal material powder, which is collected by the collection funnel.

[0013] Preferably, the process further includes: the silicon crystal material is silicon carbide, and the sealed reaction chamber is purged with nitrogen; after the nitrogen purging is completed, hydrogen is purged at room temperature; after the hydrogen purging is completed, the hollow carrier is energized through the electrode assembly to generate heat and reach the reaction temperature. A constant flow rate of hydrogen and methyltrichlorosilane is introduced into a closed reaction chamber to allow them to react continuously and deposit continuously on the surface of a hollow carrier, growing into a silicon crystal material deposition layer, resulting in a rod with a deposition layer on a hollow carrier. Once the deposited layer reaches the preset size, the flow of methyltrichlorosilane and hydrogen is stopped after the rod diameter reaches the set size, thereby rapidly reducing the current of the electrode assembly and reducing the heat generation of the hollow carrier. Open the valve connected to the bottom of the hollow carrier to introduce inert gas into the inlet and outlet of the cold source for internal circulation and internal cooling of the hollow carrier. Open the gas valve on the side wall of the furnace cylinder, open the gas purging port, and introduce purging gas to cool the sealed reaction chamber, thereby cooling the silicon crystal material deposition layer. Open the gas inlet valve near the chassis, open the bottom gas purge port to blow the silicon carbide powder that has fallen on the chassis into the collection funnel, open the control valve at the bottom of the collection funnel, and the silicon carbide powder falls into the collection hopper. After all the powder remaining on the chassis has entered the collection hopper, close the discharge valve, use inert gas to replace the collection hopper, and start the conveyor belt at the bottom of the collection hopper to dynamically transport the silicon carbide powder collected in the collection hopper out of the collection hopper for packaging.

[0014] Preferably, the reaction temperature in the sealed reaction chamber is 1000~1600℃.

[0015] Preferably, the flow rate of the hydrogen is 1~100 kg / h, the flow rate of the methyltrichlorosilane is 10~1000 kg / h, the temperature of the hydrogen is ≥100℃, and the temperature of the methyltrichlorosilane is ≥100℃.

[0016] Preferably, the inert gas is selected from nitrogen and / or argon, the temperature after cooling is 25℃~500℃, and the inert gas flow rate is 1~50kg / h.

[0017] Preferably, the furnace cylinder sidewall is provided with a gas purging port, and the introduced gas is nitrogen with a temperature of 25℃~500℃.

[0018] The beneficial effects of this invention are as follows: In this invention, the hollow carrier is designed with an internal hollow channel that allows gas to pass through. During peeling, the internal cooling system works in conjunction with external cooling to achieve rapid thermal expansion and contraction, making the deposits easier to peel off. The external surface features raised, regular ridges, forming an easy-to-peel structure. The ridge design effectively reduces interfacial bonding forces. The size of the ridge grid can be adjusted by setting the spacing as needed, allowing for customized powder size removal and reducing subsequent crushing. Simultaneously, the small-sized silicon carbide powder has good flowability, facilitating its entry into the collection hopper for automated collection. Furthermore, a collection hopper is installed at the bottom of the bell-shaped reactor chassis. After all the powder remaining on the reactor chassis enters the hopper, the discharge valve is closed, and the hopper is purged with inert gas. Then, the conveyor belt at the bottom of the hopper is activated to dynamically transport the collected silicon carbide powder out of the hopper for packaging, achieving continuous and automated production. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the bell-shaped reactor provided in an embodiment of the present invention; Explanation of reference numerals in the attached figures: 1. Furnace cylinder; 2. Chassis; 3. Electrode assembly; 4. Hollow carrier; 41. Ridge; 7. Collection bin; 9. Flange; 10. Conveyor belt; 110. Bottom gas purging port; 111. Middle gas purging port; 112. Top gas purging port; 13. Sealed reaction chamber; 14. Deposition layer; 15. Cold source inlet and outlet; 16. Discharge port; 17. Collection bin door. Detailed Implementation

[0021] In this invention, unless otherwise stated, directional terms such as "up," "down," "left," and "right" are generally understood in conjunction with the accompanying drawings and the directions shown in actual applications.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the ranges, the endpoint values ​​of the ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. The terms "optional" and "discretionary" mean that they may or may not be included (or may or may not be present).

[0025] The applicant of this invention discovered that silicon crystal materials are prepared by vapor deposition in a bell-shaped reactor. After a certain thickness is reached in the hollow carrier, the feeding is stopped, and after the inert gas is used to replace the silicon carbide, the deposited silicon carbide is crushed, cleaned in the deposition furnace, and a new hollow carrier is installed. After the inert gas is replaced, the furnace is started for growth. This cycle is repeated, which is not continuous and will reduce the purity, making it impossible to prepare ultra-high purity silicon crystal materials.

[0026] To address the aforementioned problems, this invention provides a bell-shaped reactor, such as... Figure 1 As shown, it includes a furnace cylinder 1, a chassis 2, an electrode assembly 3, a hollow carrier 4, a feed nozzle, a collection funnel, and a collection bin 7. The furnace cylinder 1 has a bell-shaped structure and is integrated with the chassis 2. The electrode assembly 3, the hollow carrier 4, the feed nozzle, the collection funnel, and the collection bin 7 are arranged in the accommodating space formed by the furnace cylinder 1 and the chassis 2.

[0027] Electrode assemblies 3 are evenly distributed on the chassis 2. The electrode assemblies 3 are connected to both ends of the hollow carrier 4. After being energized, the electrode assemblies 3 are used to heat the hollow carrier 4. The hollow carrier 4 is arranged in an inverted U-shape. The two ends of the hollow carrier 4 are provided with discharge ports 16 near the electrode assemblies 3. The discharge ports 16 are connected to one end of the collection funnel. The other end of the collection funnel is connected to the collection hopper. The collection funnel and the collection hopper 7 are located at the bottom of the chassis 2. The bottom of the collection hopper 7 is provided with a conveyor belt 10 for conveying the collected silicon carbide powder. The furnace cylinder 1 and the base flange 9 form a sealed reaction chamber. The surface of the hollow carrier 4 has raised ridges 41, on which the CVD reaction zone, i.e., the silicon carbide deposition layer 14 formed by the reaction in the sealed reaction chamber 13, is deposited. The diameter of the hollow carrier 4 is 1~10mm, and the raised ridges 41 form a ridge grid with a grid spacing of 1~20mm and a raised height of 0.1~5mm. The raised ridges 41 are designed for the peeling and collection of the deposition layer 14, making the deposition process more efficient.

[0028] A control valve is installed in the lower channel of the collection funnel. This valve is used to collect silicon carbide powder after opening. The upper opening size of the collection funnel is 1-30 cm. Low-temperature inert gas is introduced through the cold source inlet / outlet 15 to cool the hollow carrier 4. The furnace cylinder 1 has a top gas purging port 112, a bottom gas purging port 110, and a middle gas purging port 111 on its upper, middle, and lower side walls, respectively, to purge the silicon carbide deposited on the hollow carrier 4. This creates a temperature difference on the hollow carrier 4, allowing the silicon carbide powder to peel off and be better collected through the collection funnel. The silicon carbide powder collected in the collection hopper 7 is dynamically conveyed out of the collection hopper 7 for packaging through the outlet 16 and the receiving hopper door 17.

[0029] This invention utilizes a bell-type reactor for the continuous preparation of silicon crystal materials. A collection funnel is installed at the bottom of the bell-type reactor, and a hopper is located at the bottom. After one production cycle, the bell-type reactor does not open, allowing direct production to the next stage. This shortens the time required for connection and furnace shutdown, achieving continuous production. Simultaneously, it avoids frequent bell opening, which can introduce external impurities and lead to quality defects. The hollow carrier is designed with internal hollow channels, allowing gas to pass through. During peeling, the interior cools simultaneously, achieving dramatic thermal expansion and contraction, making the deposits easier to peel off. The external surface features raised, regular ridges, forming an easy-to-peel structure. The ridge design effectively reduces interfacial bonding forces. The size of the ridge grid can be adjusted by setting the spacing as needed, allowing for customized powder size peeling, reducing subsequent breakage. Furthermore, the small-sized silicon carbide powder has good flowability, facilitating entry into the collection funnel for automated collection. A collection hopper is set at the bottom of the bell-shaped reactor chassis. After all the powder remaining on the bell-shaped reactor chassis enters the hopper, the conveyor belt at the bottom of the hopper is activated to dynamically transport the collected silicon carbide powder out of the hopper for packaging, thus achieving automation.

[0030] Optionally, in one embodiment, the diameter of the hollow carrier is 1 to 10 mm, preferably 1 to 10 mm, and can be one or any two of the following values: 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm. By using a suitable diameter, the efficient circulation cooling process of the cold source gas in the hollow carrier can be realized, improving the controllability of cooling and facilitating the precise control of the temperature difference transformation process of the deposition layer.

[0031] The raised ridges form a ridge grid, which can be a regular shape to control the shape and size of powder particles, thereby avoiding excessive particle fluctuation. The spacing of the ridge grid is 1~20mm, and can be one or any combination of 1mm, 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, and 20mm. The height of the raised ridges is 0.1~5mm, and can be 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, or 2mm. The range of values ​​is 0.5mm, 3mm, 3.5mm, 4mm, 4.5mm, and 5mm, or any combination thereof. Regular, raised ridges are set on the surface of the hollow carrier to form an easily peelable structure. During cooling, due to the difference in thermal expansion coefficients between the deposited layer and the hollow carrier, the resulting shear thermal stress concentrates on the ridges, transforming into tensile peeling stress. This causes the deposited layer to peel off starting from the ridges and break off at the ridge valleys and ridges. This mechanism can focus the originally uniformly distributed interfacial stress to specific locations, significantly reducing the overall energy required for peeling. Appropriate ridge protrusions in a suitable blast furnace alter the surface gas flow field, placing the sidewalls in a region with lower reactant concentrations (shading effect). The deposition rate is lower than that of the top windward side, promoting the formation of a relatively loose deposition zone on the sidewalls and a relatively dense deposition zone at the top. By controlling the difference through the height of the protrusions, the ease of peeling of the deposited layer is improved.

[0032] Optionally, in one embodiment, the upper opening size of the collection funnel is 1~30cm, which can be one or any two of the following values: 1cm, 5cm, 10cm, 15cm, 20cm, 25cm, and 30cm; the collection funnel has a conical structure and is evenly distributed on the base plate for collecting silicon carbide powder.

[0033] Secondly, the present invention provides a method for preparing silicon crystal materials by depositing a bell-shaped reactor, comprising the following steps: (1) Install a hollow carrier in the bell-shaped reactor, connect the furnace cylinder 1 and the flange 9 to form a closed reaction chamber 13, and perform nitrogen replacement; taking silicon carbide as an example, install the deposited hollow carrier on the bottom plate of the bell-shaped reactor.

[0034] (2) After nitrogen replacement is completed, hydrogen replacement is carried out at room temperature; after hydrogen replacement is completed, the hollow carrier is energized to generate heat and reach the reaction temperature. (3) Start by introducing a constant flow of hydrogen and methyltrichlorosilane into the reactor to allow it to react continuously and obtain rods; (4) When the diameter of the rod is deposited to the set size, stop the introduction of methyltrichlorosilane and hydrogen, quickly reduce the electrode current, and reduce the heat generation of the hollow carrier; (5) Open the valve connecting the hollow carrier to the hollow carrier and introduce inert gas to circulate inside the hollow carrier and cool the hollow carrier internally. (6) Open the gas valve on furnace cylinder 1 to cool the outer surface of the hollow substrate. (7) Open the gas port valve near the chassis 2 and blow the silicon carbide powder that has fallen on the deposition furnace chassis 2 into the collection funnel on the chassis 2. Open the control valve at the bottom of the collection funnel and the silicon carbide powder falls into the collection hopper 7. After all the powder remaining on the chassis 2 enters the collection hopper 7, close the discharge valve and use inert gas to replace the collection hopper 7. Open the conveyor belt 10 at the bottom of the collection hopper 7 and dynamically transport the silicon carbide powder collected in the collection hopper 7 out of the collection hopper 7 for packaging.

[0035] In this embodiment, the hollow substrate is heated by electrodes, and silicon carbide is deposited on the high-temperature hollow substrate using methyltrichlorosilane and hydrogen. After the deposited silicon carbide grows to a predetermined thickness, the flow of methyltrichlorosilane and hydrogen is stopped, the electrode current is rapidly reduced to decrease the heat generated by the hollow substrate, and the valve connecting the hollow substrate is opened to allow inert gas to circulate and cool the interior of the hollow substrate. Simultaneously, the gas valve on the furnace side is opened to cool the outer surface of the deposited hollow substrate. This simultaneous rapid cooling of the interior and exterior of the hollow substrate increases the temperature gradient, causing thermal expansion and contraction, which allows the deposited silicon carbide to separate from the hollow substrate and fall onto the deposition furnace chassis and a collection funnel located on the chassis. At this point, the gas port valve near the chassis is opened to blow the silicon carbide powder that has fallen onto the deposition furnace chassis into the collection funnel on the chassis. Open the control valve at the bottom of the collection funnel, and silicon carbide powder falls into the collection hopper. After all the powder remaining on the bottom of the bell-shaped reactor has entered the hopper, close the discharge valve and purge the hopper with inert gas. Then, start the conveyor belt at the bottom of the hopper to dynamically transport the collected silicon carbide powder out of the hopper for packaging. Reheat the electrodes of the bell-shaped reactor, raise the temperature, and introduce methyltrichlorosilane and hydrogen to re-form the hollow carrier. No further purging of the bell-shaped reactor is required. This cycle is repeated to achieve continuous production. Silicon carbide is extremely hard, second only to diamond, making it a superhard material that is difficult to break. Large-sized silicon carbide requires further crushing. To further reduce the size of silicon carbide powder and minimize subsequent crushing steps, the hollow carrier is made of high-temperature resistant metals such as graphite or tungsten, or their alloys. Hollow channels are machined inside to allow gas to enter for cooling. Simultaneously, raised, regular ridges are created on the surface of the hollow carrier to form an easy-to-peel structure. The ridge design effectively reduces interfacial bonding forces. At the raised ridges, there are more interfacial defects in the deposited material, and stress concentration points are introduced. When the deposit is peeled from the hollow carrier surface, it will preferentially concentrate at the edges of the raised ridges, making cracks more likely to initiate and propagate. The size of the ridge grid can be set according to the required spacing, allowing for customized peeled powder size and reducing subsequent crushing.

[0036] In this embodiment, the preparation method is applicable to bell-shaped reactors with different logarithmic deposition hollow carriers, such as 12 pairs, 24 pairs, 36 pairs, 48 ​​pairs, etc.

[0037] Optionally, in one embodiment, the hollow carrier is selected from graphite, high-temperature resistant tungsten metal, or their alloys. Due to differences in materials and cooling rates, the thermal expansion and contraction of the deposited silicon crystal material and the hollow carrier differ greatly during cooling, resulting in significant shear thermal stress at the interface. The regular ridge structure can concentrate this stress and convert it into tensile peel stress. When the stress exceeds the interfacial bonding strength, the deposited layer automatically detaches. The core advantage of the easy-peel structure is that the hollow carrier can be reused multiple times. The high-temperature stability and mechanical durability of graphite and tungsten metal allow the ridge structure to maintain its function after dozens or even hundreds of process cycles, avoiding the cost of frequent replacement of the hollow carrier.

[0038] The furnace cylinder 1 is provided with gas purging ports on its sidewall, including a bottom gas purging port 110, a middle gas purging port 111, and a top gas purging port 112. The multiple inlets at different heights on the sidewall of the furnace cylinder 1 increase the cooling rate of the sealed reaction chamber 13 and the cooling rate of the deposited layer 14, facilitating rapid cooling and quickly achieving temperature difference changes in the deposited layer 14, which is beneficial for the pulverization of the deposited layer. The bottom gas purging port 110 is inclined towards the chassis 2 at an angle of 10-45 degrees. This facilitates rapid purging and collection of powder and rapid cooling of the deposited layer on the hollow carrier 4 at the bottom.

[0039] Optionally, in one embodiment, the reaction temperature of the above-mentioned vapor deposition is 1000~1600℃, which can be one or any two of 1000℃, 1100℃, 1200℃, 1300℃, 1400℃, 1500℃, and 1600℃; this ensures that the precursor is fully pyrolyzed, achieves high-purity deposition, and avoids over-reaction.

[0040] Optionally, in one embodiment, the hydrogen flow rate is 1~100 kg / h, which can be one or any two of the following values: 1 kg / h, 10 kg / h, 20 kg / h, 30 kg / h, 40 kg / h, 50 kg / h, 60 kg / h, 70 kg / h, 80 kg / h, 90 kg / h, and 100 kg / h. A relatively high hydrogen flow rate can enhance MTS reduction and increase the deposition rate. The accelerated deposition will also facilitate the generation of defects, such as a large number of carbon vacancies and silicon antisite defects in the SiC lattice. These defects are enriched at the edge protrusions, which is conducive to the formation of microcrack sources, weakens the interface strength, and improves the peelability of the deposited layer. The MTS flow rate is 10~1000 kg / h, which can be one or any two of the following values: 10 kg / h, 50 kg / h, 100 kg / h, 200 kg / h, 300 kg / h, 400 kg / h, 500 kg / h, 600 kg / h, 700 kg / h, 800 kg / h, 900 kg / h, and 1000 kg / h. The MTS flow rate needs to be moderate to avoid gas phase pre-reaction and keep the deposition in the surface reaction control zone. Due to the gas shielding effect, a loose porous layer is formed on the edge sidewall, which forms a differential interface with the top dense layer, reducing the exfoliation energy. The hydrogen temperature is ≥100℃, and can be any value within the range of 100℃, 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, or any two of these ranges. The MTS temperature is ≥100℃, and can be any value within the range of 100℃, 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, or any two of these ranges. A slightly higher feed gas temperature facilitates the complete vaporization of MTS and uniform mixing with H2. This homogenization of the deposited layer thickness allows for the simultaneous release of thermal stress at various points along the ridge grid during rapid cooling, resulting in regular crack propagation along the grid and more controllable powder size. Simultaneously, the preheated reactants are more conducive to rapid deposition at the top of the ridges, forming a relatively dense layer. The sidewalls, due to the shielding effect, form relatively loose areas, increasing the differences near the ridges, which helps reduce the exfoliation energy and improve the exfoliation effect.

[0041] Optionally, in one embodiment, the inert gas is selected from nitrogen and / or argon, and the temperature after cooling is 25°C to 500°C, which can be one or any two of 25°C, 50°C, 100°C, 200°C, 300°C, 400°C, and 500°C; the inert gas flow rate is 1 to 50 kg / h, which can be one or any two of 1 kg / h, 10 kg / h, 20 kg / h, 30 kg / h, 40 kg / h, and 50 kg / h; the flow rate control is to increase the gas flow velocity, achieve rapid heat exchange and cooling, increase the temperature difference between the inside and outside of the deposited layer, and thus achieve peeling due to thermal expansion and contraction.

[0042] Optionally, in one embodiment, the above-mentioned cooling of the outer surface of the hollow substrate is performed using nitrogen gas, and the temperature is 25°C to 500°C, which can be one or any two of 25°C, 50°C, 100°C, 200°C, 300°C, 400°C, and 500°C. Optionally, in one embodiment, the collected silicon carbide powder is obtained from the first rod deposition layer stripping. After the growth layer stripping is completed, a second feeding growth begins, and the same preparation method steps are repeated to obtain the silicon carbide powder for the second rod growth. Continuous production can be achieved.

[0043] In this invention, the hollow carrier is designed with an internal hollow channel through which gas can be introduced. During peeling, the interior cools down simultaneously, resulting in drastic thermal expansion and contraction, which makes the deposits easier to peel off. The outer surface of the hollow carrier is provided with raised, regular ridges, forming an easy-to-peel structure. The ridge design can effectively reduce the interfacial bonding force. The size of the ridge grid can be set according to the required spacing, allowing for customized peeled powder size and reducing subsequent breakage. At the same time, the small-sized silicon carbide powder has good flowability, which is conducive to entering the collection funnel for automated collection. A collection funnel is installed on the chassis of the bell-shaped reactor to collect the deposits detached from the hollow carrier. At the same time, gas purging ports are set at different positions in the bell of the bell-shaped reactor. On the one hand, this allows for rapid cooling of the outer surface of the hollow carrier when the reactor is shut down. On the other hand, it blows the remaining deposits on the chassis into the collection funnel. A collection hopper is set at the bottom of the bell-shaped reactor chassis. After all the powder remaining on the chassis of the bell-shaped reactor has entered the hopper, the discharge valve is closed, and the hopper is purged with inert gas. Then, the conveyor belt at the bottom of the hopper is activated to dynamically transport the silicon carbide powder collected in the hopper out of the hopper for packaging, thus achieving automation.

[0044] The present invention will be described in detail below through embodiments.

[0045] Example 1 A method for preparing silicon crystal materials by depositing a bell-shaped reactor, comprising the following steps: (1) Install a hollow carrier in the bell-shaped reactor, connect the furnace cylinder and the flange to form a closed reaction chamber, and perform nitrogen replacement; taking silicon carbide as an example, install the deposited hollow carrier on the bottom plate of the bell-shaped reactor. The hollow carrier is hollow and has regular textures on its surface. The size can be set according to the particle size of the silicon carbide material at the end. Graphite is selected as the hollow carrier.

[0046] (2) After nitrogen replacement, hydrogen replacement is carried out at room temperature; after hydrogen replacement, the hollow carrier is energized to generate heat and reach the reaction temperature; the reaction temperature is 1500℃.

[0047] (3) Start by introducing a constant flow of hydrogen and methyltrichlorosilane into the reactor to allow it to react continuously and obtain rods; the hydrogen flow rate is 80 kg / h, the MTS flow rate is 500 kg / h, the hydrogen temperature is 200℃, and the MTS temperature is 300℃. (4) When the diameter of the rod is deposited to the set size, stop the introduction of methyltrichlorosilane and hydrogen, quickly reduce the electrode current, and reduce the heat generation of the hollow carrier; (5) Open the valve connecting the hollow carrier to the hollow carrier and introduce inert gas to circulate inside the hollow carrier and cool the hollow carrier internally; the inert gas is selected from nitrogen, the temperature after cooling is 100℃, and the flow rate is 20kg / h.

[0048] (6) Open the gas valve on the furnace cylinder side to cool the outer surface of the hollow substrate in the deposition; the gas is nitrogen and the temperature is 60°C.

[0049] (7) Open the gas port valve near the chassis to blow the silicon carbide powder that has fallen on the chassis of the deposition furnace into the collection funnel on the chassis. Open the control valve at the bottom of the collection funnel so that the silicon carbide powder falls into the collection hopper. After all the powder remaining on the chassis enters the collection hopper, close the discharge valve and use inert gas to replace the collection hopper. Open the conveyor belt at the bottom of the collection hopper to dynamically transport the silicon carbide powder collected in the collection hopper out of the collection hopper for packaging.

[0050] (8) The collected silicon carbide powder is the first rod deposition layer stripped off. After the growth layer is stripped off, the second feeding growth begins. The same preparation method steps are repeated to obtain the second rod growth silicon carbide powder.

[0051] (9) The purity of silicon carbide powder was tested by glow discharge mass spectrometry (GD-MS) and was 7.6N.

[0052] Example 2 The difference from Example 1 is that in step (1), the hollow carrier is selected from tungsten metal.

[0053] The silicon carbide powder was tested using glow discharge mass spectrometry (GD-MS), and the purity was 7.4N. The increased tungsten metal impurity content was due to the diffusion of elements from the hollow tungsten metal carrier into the deposition layer at high temperatures.

[0054] Example 3 The difference from Example 1 is that in step (2), the reaction temperature is 1200°C.

[0055] As the deposition temperature decreases, the MTS decomposition efficiency decreases, and with the same raw material supply, the weight of collected silicon carbide powder decreases by 10%.

[0056] Example 4 The difference from Example 1 is that in step (3), the hydrogen flow rate is 50 kg / h, the MTS flow rate is 600 kg / h, the hydrogen temperature is 150°C, and the MTS temperature is 400°C.

[0057] When the hydrogen to MTS feed ratio decreases, the deposited layer becomes less dense, and the particle size of the silicon carbide obtained by stripping increases.

[0058] Example 5 The difference from Example 1 is that in step (5), the inert gas is selected from argon, the temperature after cooling is 50°C, and the flow rate is 25 kg / h.

[0059] The temperature was 50°C lower than in the previous example. The temperature was reduced to 50°C by gas purging, which increased the amount of gas used and the replacement time. In addition, argon is more expensive than nitrogen, making it uneconomical overall.

[0060] Example 6 The difference from Example 1 is that in step (6), the gas used to cool the outer surface of the hollow substrate is nitrogen, and the temperature is 25°C.

[0061] The purging time required to cool down to 25°C in a high-temperature furnace is more than doubled, and the amount of nitrogen used also increases, resulting in reduced production efficiency and economy.

[0062] Comparative Example 1 The difference from Example 1 is that in step (5), no inert gas was introduced for internal circulation of the hollow carrier.

[0063] Without gas circulation cooling inside the hollow carrier, the temperature of the hollow carrier and the deposition layer are the same. When the hollow carrier is purged and cooled outside, the deposition layer is prone to sticking to the hollow carrier, causing the graphite hollow carrier surface to peel off and form pits or fractures, reducing the number of furnaces that can be continuously operated. The same batch of hollow carriers can only be continuously operated for 2 to 4 furnaces.

[0064] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A bell jar reactor characterized by, It includes a bell-shaped furnace tube (1), a sealed reaction chamber (13), a chassis (2), an electrode assembly (3), a hollow carrier (4), a feed nozzle, an outlet, a collection funnel, and a cold source inlet and outlet (15). The furnace cylinder (1) is provided with a gas purging port on its side wall, and purging gas is introduced to cool the sealed reaction chamber (13). The hollow carrier (4) is used to deposit silicon crystal material to form a silicon crystal material deposition layer (14). The surface of the hollow carrier (4) is provided with raised ridges (41) to form a ridge grid. The cold source inlet and outlet (15) realizes the cooling of the hollow carrier (4). Through the cooling of the sealed reaction chamber (13) and the hollow carrier (4), when the temperature of the hollow carrier (4) and the temperature of the silicon crystal material deposition layer (14) form a temperature gradient, the silicon crystal material deposition layer (14) falls off, causing the silicon crystal material deposition layer (14) to pulverize and form silicon crystal material powder, which is collected by the collection funnel. The electrode assembly (3) is connected to the hollow carrier (4) at both ends. After the electrode assembly (3) is powered on, it is used to heat the hollow carrier (4). The hollow carrier (4) is set in an inverted U-shape. The two ends of the hollow carrier (4) are provided with discharge ports (16) near the electrode assembly (3). The discharge ports (16) are connected to one end of the collection funnel, and the other end of the collection funnel is connected to the collection bin. The hollow carrier (4) is configured as an internal hollow channel. When the deposition layer (14) reaches the preset size, the cold source inlet and outlet (15) connected to the bottom of the hollow carrier (4) is opened to introduce cooling gas into the hollow carrier (4) for circulation, thereby cooling the hollow carrier (4). At the same time, the gas purging port set on the side wall of the furnace cylinder (1) is opened to introduce purging gas for cooling the sealed reaction chamber (13), thereby cooling the silicon crystal material deposition layer (14). The diameter of the hollow carrier (4) is 1~10mm, the spacing of the ridge grid is 1~20mm, and the height of the ridge (41) protrusion is 0.1~5mm; It also includes a collection hopper (7); the electrode assembly (3) is evenly distributed on the chassis (2), and a control valve is provided in the lower channel of the collection funnel; the collection hopper (7) is located at the lower part of the chassis (2), and a flange (9) is also provided on the chassis (2) for connecting the collection hopper (7); a conveyor belt (10) is provided at the bottom of the collection hopper (7) to dynamically transport the silicon crystal material powder collected in the collection hopper (7) out of the collection hopper (7) for packaging; The gas purging port includes a bottom gas purging port (110), a middle gas purging port (111), and a top gas purging port (112).

2. The bell reactor of claim 1, wherein, The silicon crystal material is silicon carbide or polycrystalline silicon.

3. The bell-shaped reactor according to claim 1, characterized in that, The opening size of the upper part of the collecting funnel is 1~30cm.

4. The bell-shaped reactor according to claim 1, characterized in that, The bottom gas purge port (110) is tilted toward the chassis (2) at an angle of 10~45°.

5. The bell-shaped reactor for depositing silicon crystal materials according to claim 1, characterized in that, The hollow carrier (4) is selected from at least one of graphite, tungsten metal or their alloy materials.

6. A method for preparing silicon crystal materials by depositing a bell-shaped reactor, characterized in that, The preparation using the bell-shaped reactor according to any one of claims 1 to 5 includes the following steps: The hollow carrier (4) is heated by electric current through the electrode assembly (3), and the raw material gas is introduced through the feed nozzle. The raw material gas is continuously deposited on the surface of the hollow carrier (4) to grow into a silicon crystal material deposition layer (14). When the temperature of the hollow carrier (4) and the temperature of the silicon crystal material deposition layer (14) form a temperature gradient, the silicon crystal material deposition layer (14) falls off, causing the silicon crystal material deposition layer (14) to pulverize and form silicon crystal material powder, which is collected by the collection funnel.

7. The method for preparing silicon crystal materials by depositing a bell-shaped reactor according to claim 6, characterized in that, It also includes: the silicon crystal material is silicon carbide, and the sealed reaction chamber (13) is replaced with nitrogen; after the nitrogen replacement is completed, hydrogen is replaced at room temperature; after the hydrogen replacement is completed, the hollow carrier (4) is energized through the electrode assembly (3) to generate heat and reach the reaction temperature; A constant flow of hydrogen and methyltrichlorosilane material is introduced into the sealed reaction chamber (13) to allow it to react continuously and deposit continuously on the surface of the hollow carrier (4) to grow into a silicon crystal material deposition layer (14), thus obtaining a rod with a deposition layer (14) on the hollow carrier (4). When the deposition layer (14) reaches the preset size, the flow of methyltrichlorosilane and hydrogen is stopped after the rod diameter is deposited to the set size, the current of the electrode assembly (3) is quickly reduced, and the heat generated by the hollow carrier (4) is reduced. Open the valve connected to the bottom of the hollow carrier (4) and introduce inert gas into the inlet and outlet of the cold source (15) to circulate the hollow carrier (4) internally and cool the hollow carrier (4) internally. Open the gas valve on the side wall of the furnace cylinder (1), open the gas purging port, and introduce purging gas to cool the sealed reaction chamber (13) to achieve cooling of the silicon crystal material deposition layer (14); Open the gas port valve near the chassis (2), open the bottom gas purging port (110) to blow the silicon carbide powder that fell on the chassis (2) into the collection funnel, open the control valve at the bottom of the collection funnel, and the silicon carbide powder fell into the collection hopper (7). After all the powder remaining on the chassis (2) entered the collection hopper (7), close the discharge valve, use inert gas to replace the collection hopper (7), open the conveyor belt (10) at the bottom of the collection hopper (7), and dynamically transport the silicon carbide powder collected in the collection hopper (7) out of the collection hopper (7) for packaging.

8. The method for preparing silicon crystal materials by depositing a bell-shaped reactor according to claim 6 or 7, characterized in that, In the closed reaction chamber (13), the reaction temperature is 1000~1600℃.

9. The method for preparing silicon crystal materials by depositing a bell-shaped reactor according to claim 7, characterized in that, The flow rate of the hydrogen is 1~100 kg / h, the flow rate of the methyltrichlorosilane is 10~1000 kg / h, the temperature of the hydrogen is ≥100℃, and the temperature of the methyltrichlorosilane is ≥100℃.

10. The method for preparing silicon crystal materials by depositing a bell-shaped reactor according to claim 7, characterized in that, The inert gas is argon, and the temperature after cooling is 25℃~500℃. The flow rate of the inert gas is 1~50kg / h.

11. The method for preparing silicon crystal materials by depositing a bell-shaped reactor according to claim 7, characterized in that, The furnace cylinder (1) has a gas purging port on its side wall, and the introduced gas is nitrogen with a temperature of 25℃~500℃.

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