An on-line charging apparatus for preparing silicon carbide ingot

Abstract

This utility model relates to the field of crystal preparation technology and discloses an online feeding device for preparing silicon carbide ingots. The device is connected to the bottom of a graphite container, the bottom wall of which has a longitudinally oriented through-hole. The feeding device includes a gas guide pipe, porous graphite, a feeding container, and an auxiliary heater. The gas guide pipe is longitudinally inserted into the through-hole of the graphite container, positioned at the bottom of the container and located at the upper end of the gas guide pipe. The porous graphite allows gas to pass through while preventing raw materials in the graphite container from falling into the gas guide pipe. The feeding container is located inside the furnace and at the bottom of the gas guide pipe. The lower end of the gas guide pipe is sealed and connected to the upper opening of the feeding container. The feeding container is filled with a material identical to the raw material. The auxiliary heater is connected around the outer periphery of the feeding container for heating it. This utility model can increase the height of silicon carbide ingots with lower cost and higher efficiency through online feeding.

Description

Technical Field

[0001] This utility model relates to the field of crystal preparation technology, and in particular to an online feeding device for preparing silicon carbide ingots. Background Technology

[0002] Currently, the physical vapor transport method (PVT) is the mainstream technology for preparing silicon carbide single crystals. The supporting equipment mostly adopts resistance heating, which has the advantages of simple structure, precise temperature control and high thermal efficiency. It can stably provide a high temperature environment above 2000℃ to meet the sublimation requirements of silicon carbide raw materials.

[0003] Currently, the PVT method for preparing silicon carbide single crystals mostly employs resistance heating equipment, such as... Figure 1 As shown, existing resistance heating equipment typically includes a furnace chamber 1, a main side heater 2, an inert material 3, a raw material 4, a graphite container 5, a main bottom heater 6, and a seed crystal 7. The main side heater 2 and the main bottom heater 6 are resistance heating structures, which are installed on the inner wall and bottom of the furnace chamber 1, respectively, to provide the high temperature and temperature gradient required for the sublimation of the raw material 4. The seed crystal 7 is fixed in the lower temperature area at the top of the graphite container 5. After the raw material 4 is heated, the temperature difference between the seed crystal 7 and the raw material 4 is used to form the desired crystals.

[0004] However, the current equipment has a key technical defect: its graphite container 5 is an industry standard container, and its loading capacity is limited. The total amount of raw materials is fixed, which leads to a strict constraint on the growth height of the seed crystal 7. The height of the silicon carbide ingot grown in a single furnace is usually no more than 50mm. Although the industry currently uses multiple furnaces to grow ingots in a unified manner and then splicing them together to obtain higher silicon carbide ingots, this also has problems such as complex processes, long production cycles and high costs. Moreover, defects such as dislocations and cracks are generated at the splicing points of the ingots, which leads to a decrease in the product qualification rate. Utility Model Content

[0005] This invention provides an online feeding device for preparing silicon carbide ingots, which can increase the height of silicon carbide ingots at a lower cost and higher efficiency through online feeding.

[0006] This utility model provides an online feeding device for preparing silicon carbide ingots, connected to the bottom of a graphite container. The bottom wall of the graphite container has a through hole along the longitudinal direction. The feeding device includes: a gas guide pipe, porous graphite, a feeding container, and an auxiliary heater. The gas guide pipe is inserted longitudinally into the through hole of the graphite container. The porous graphite has a disc-shaped porous structure and is placed at the bottom of the graphite container and located at the upper port of the gas guide pipe. The porous graphite is used for gas to pass through and to prevent the raw material in the graphite container from falling into the gas guide pipe. The feeding container is set in the furnace and located at the bottom of the gas guide pipe. The lower port of the gas guide pipe is sealed and connected to the upper opening of the feeding container. The feeding container is filled with a feed material of the same material as the raw material. The auxiliary heater is connected around the outer periphery of the feeding container for heating the feeding container.

[0007] Preferably, the inner bottom wall of the graphite container has a countersunk groove with the same center line as the through hole. The porous graphite is embedded and fixed in the countersunk groove, and the upper end of the gas guide tube is located below the countersunk groove.

[0008] Preferably, the upper periphery of the gas guide tube is detachably connected to the bottom wall of the graphite container.

[0009] Preferably, the through hole at the bottom of the graphite container is provided with a first internal thread, and the gas guide tube includes: an upper guide tube, a middle guide tube and a lower guide tube. The top of the upper guide tube is provided with a first external thread for threading with the first internal thread of the graphite container. The middle guide tube is connected to the lower port of the upper guide tube. The lower port of the middle guide tube is provided with a second external thread on its circumference. The lower guide tube is flared, and the inner wall of the smaller port is provided with a second internal thread for threading with the second external thread. The larger port of the lower guide tube is sealed and snapped into the upper opening of the feeding container.

[0010] Preferably, the middle guide tube and the upper guide tube are connected in a sealed manner, and an anti-detachment component is provided at the connection point between the two.

[0011] Preferably, the anti-detachment component includes an inner flange and an outer flange. The inner flange is fixedly connected to the inner side of the lower port of the upper guide tube, and the outer flange is sleeved and fixedly connected to the outer side of the upper port of the middle guide tube. As the middle guide tube slides away from the upper guide tube in a direction away from each other, the inner flange and the outer flange are sealed and engaged.

[0012] Preferably, the thickness of the porous graphite is 5 mm to 10 mm.

[0013] Preferably, the pore size of the porous graphite is 28 μm to 30 μm.

[0014] Preferably, the through hole is located at the very center of the bottom of the graphite container.

[0015] Preferably, the upper opening of the feeding container is provided with a slot, and the larger port of the lower guide pipe is provided with a snap-fit ​​groove for engaging with the slot.

[0016] Compared with the prior art, the beneficial effects of this utility model are as follows: by setting a gas guide pipe, porous graphite, a feeding container and an auxiliary heater at the bottom of the graphite container, the raw materials are replenished online during the ingot growth process. This breaks through the upper limit of ingot height caused by the limited amount of material in traditional PVT equipment, and can achieve a single furnace growth height of ≥80mm, increasing the single furnace capacity by more than 2 times. At the same time, it avoids defects such as ingot cracks and cost increases caused by splicing multiple furnaces. Specifically, after the main raw material is stably sublimated, the auxiliary heater is started, and the sublimation rate of the feed is adjusted by temperature control. The feed sublimation gas rises to the main raw material area through the gas guide pipe, mixes and migrates to the surface of the seed crystal for crystallization. Attached Figure Description

[0017] Figure 1 A schematic diagram of the structure of an existing resistance heating device;

[0018] Figure 2 A schematic diagram of an online feeding device for preparing silicon carbide ingots provided in an embodiment of this utility model;

[0019] Figure 3 A partial structural schematic diagram of an online feeding device for preparing silicon carbide ingots, provided as an embodiment of this utility model;

[0020] Figure 4 This is a partial structural schematic diagram of an online feeding device for preparing silicon carbide ingots, provided as an embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1. Furnace chamber; 2. Main side heater; 3. Inert material; 4. Raw material; 5. Graphite container; 51. Through hole; 52. Countersunk groove; 6. Main bottom heater; 7. Seed crystal; 8. Gas guide pipe; 81. Upper guide pipe; 82. Middle guide pipe; 83. Lower guide pipe; 9. Porous graphite; 10. Feeding container; 11. Auxiliary heater; 12. Feeding device. Detailed Implementation

[0023] The following describes a specific embodiment of the present invention in detail with reference to the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0024] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0025] refer to Figure 2 and Figure 3 This utility model provides an online feeding device for preparing silicon carbide ingots, connected to the bottom of a graphite container 5. The bottom wall of the graphite container 5 has a through hole 51 along the longitudinal direction. The feeding device includes: a gas guide pipe 8, porous graphite 9, a feeding container 10, and an auxiliary heater 11. The gas guide pipe 8 is inserted and connected to the through hole 51 of the graphite container 5 along the longitudinal direction. The porous graphite 9 has a disc-shaped porous structure and is placed at the bottom of the graphite container 5 and located at the upper port of the gas guide pipe 8. The porous graphite 9 is used for gas to pass through and to prevent the raw material 4 in the graphite container 5 from falling into the gas guide pipe 8. The feeding container 10 is set in the furnace 1 and located at the bottom of the gas guide pipe 8. The lower port of the gas guide pipe 8 is sealed and connected to the upper opening of the feeding container 10. The feeding container 10 is filled with a feed material 12 of the same material as the raw material 4. The auxiliary heater 11 is connected around the outer periphery of the feeding container 10 and is used to heat the feeding container 10.

[0026] In the above embodiments, by setting a gas guide pipe 8, porous graphite 9, a feeding container 10, and an auxiliary heater 11 at the bottom of the graphite container 5, the raw material 4 is supplemented online during the ingot growth process. This breaks through the upper limit of ingot height caused by the limited amount of material in traditional PVT equipment, and can achieve a single furnace growth height of ≥80mm, increasing the single furnace capacity by more than 2 times. At the same time, it avoids defects such as ingot cracks and cost increases caused by splicing multiple furnaces. Specifically, after the main raw material 4 is stably sublimated, the auxiliary heater 11 is started, and the sublimation rate of the feed 12 is adjusted by temperature control. The sublimation gas of the feed 12 rises to the main raw material 4 area through the gas guide pipe 8, mixes, and migrates to the surface of the seed crystal 7 for crystallization.

[0027] Specifically, since the gas guide pipe 8 exists for the purpose of guiding gas flow and also passes through the corresponding main bottom heater 6, the main bottom heater 6 is provided with a clearance opening at the position corresponding to the gas guide pipe 8, and does not come into contact with the gas guide pipe 8 or transfer heat.

[0028] Specifically, the graphite container 5 has an inner diameter of 320mm and a height of 280mm. The through hole 51 has a diameter of 160mm. The porous graphite 9 has a diameter of 180mm. The raw material 4 and the additive 12 are silicon carbide powder with a purity of ≥99.99% and a loose packing density of 1.2g / cm³ to 1.5g / cm³. The auxiliary heater 11 has a temperature control accuracy of ±5℃ and a heating power adjustment range of 10kW to 40kW.

[0029] Further, refer to Figure 4 The inner bottom wall of the graphite container 5 is provided with a countersunk groove 52 that is co-centered with the through hole 51. The porous graphite 9 is embedded and fixed in the countersunk groove 52, and the upper end of the gas guide pipe 8 is located below the countersunk groove 52.

[0030] In the above embodiments, the porous graphite 9 is precisely positioned and sealed by the countersunk groove 52, which avoids displacement or loosening caused by thermal expansion or vibration at high temperature, ensures the stability of the gas channel, and prevents the raw material 4 particles from entering the guide pipe, thereby improving the stability of equipment operation and product consistency. The diameter of the countersunk groove 52 is 181mm, and the gap between the diameter of the porous graphite 9 and the wall of the countersunk groove 52 is ≤1mm.

[0031] Further, refer to Figure 2 and Figure 3 The upper circumference of the gas guide tube 8 is detachably connected to the bottom wall of the graphite container 5.

[0032] The above embodiments facilitate equipment installation, maintenance, and cleaning, improve production flexibility and operational convenience, while ensuring the sealing of connections to prevent gas leakage from affecting the crystallization process.

[0033] Further, refer to Figure 3 The graphite container 5 has a through hole 51 at the bottom with a first internal thread. The gas guide tube 8 includes an upper guide tube 81, a middle guide tube 82, and a lower guide tube 83. The top of the upper guide tube 81 has a first external thread for engaging with the first internal thread of the graphite container 5. The middle guide tube 82 is connected to the lower port of the upper guide tube 81. The lower port of the middle guide tube 82 has a second external thread on its circumference. The lower guide tube 83 is flared. The inner wall of the smaller port has a second internal thread that engages with the second external thread. The larger port of the lower guide tube 83 is sealed and snapped into the upper opening of the feeding container 10.

[0034] In the above embodiments, threaded connections facilitate equipment installation, maintenance, and cleaning, improve production flexibility and operational convenience, and ensure the sealing of the connection to prevent gas leakage from affecting the crystallization process. They also feature a simple structure and convenient assembly and maintenance. Specifically, the threaded joints are sealed using sealing ligaments or sealing rings.

[0035] Further, refer toFigure 3 The middle guide tube 82 and the upper guide tube 81 are sealed and movable, and an anti-detachment component is provided at the connection between the two.

[0036] In the above embodiments, the overall length of the guide pipe is adjustable to accommodate feeding containers 10 of different heights, thereby improving the adaptability and versatility of the equipment.

[0037] Further, refer to Figure 3 The anti-detachment component includes an inner flange and an outer flange. The inner flange is fixedly connected to the inner side of the lower port of the upper guide tube 81, and the outer flange is sleeved and fixed to the outer side of the upper port of the middle guide tube 82. As the middle guide tube 82 slides away from the upper guide tube 81 in a direction away from each other, the inner flange and the outer flange are sealed and engaged.

[0038] In the above embodiments, under the premise of ensuring sealing, the guide tube is allowed to have a certain amount of movement during the assembly process, which facilitates the connection between the lower guide tube 83 and the feeding container 10, and prevents assembly difficulties or leakage caused by misalignment.

[0039] Further, refer to Figure 3 The thickness of porous graphite 9 is 5 mm to 10 mm.

[0040] In the above embodiments, by limiting the thickness of the porous graphite 9 to 5mm to 10mm, the thickness is moderate, which can effectively prevent the raw material 4 particles from sliding down without excessively hindering gas flow, thus balancing structural strength and gas permeability.

[0041] Further, refer to Figure 3 The pore size of porous graphite 9 is 28 μm to 30 μm.

[0042] In the above embodiments, the aperture design is precisely matched to the particle size of raw material 4 (≥0.4mm), which can effectively block raw material 4 particles while allowing sublimation gas to pass through smoothly, thus achieving the key function of "gas passage and material blockage".

[0043] Further, refer to Figure 3 The through hole 51 is located at the very center of the bottom of the graphite container 5.

[0044] In the above embodiments, the gas flow path is centrally symmetrical, which is conducive to the gas rising evenly to the raw material 4 region, thereby improving the uniformity and quality consistency of ingot growth.

[0045] Further, refer to Figure 3 The upper opening of the feeding container 10 is provided with a slot, and the larger port of the lower guide pipe 83 is provided with a snap-fit ​​groove for engaging with the slot.

[0046] In the above embodiments, the snap-fit ​​structure enables quick installation and disassembly, while the dynamic sealing ring ensures the sealing of the connection, facilitating the replacement and maintenance of the feeding container 10.

[0047] Usage and working principle:

[0048] Gas channel establishment: Gas guide pipe 8 serves as a closed channel to guide the sublimation gas of feed 12 in the feed container 10 below to the main raw material 4 area;

[0049] Material 4 barrier and gas conduction: Porous graphite 9, with its microporous structure (pore size 28μm to 30μm), blocks the slide of material 4 particles while allowing gas to pass through;

[0050] Temperature gradient driven crystallization: The main heater and the auxiliary heater 11 work together to form a temperature gradient from bottom to top, driving the gas to migrate to the seed crystal 7 at a lower temperature and crystallize.

[0051] Online controllable feeding: By adjusting the temperature of the auxiliary heater 11, the sublimation rate of the feed 12 can be controlled, realizing online replenishment of raw materials 4 during the growth process.

[0052] The specific steps are as follows: The porous graphite 9 is embedded in the countersunk groove 52 at the bottom of the graphite container 5. Then, the upper guide pipe 81 of the gas guide pipe 8 is threaded to the through hole 51 at the bottom of the graphite container 5. Next, the middle guide pipe 82 is movably connected to the upper guide pipe 81 and an anti-detachment component is installed. The lower guide pipe 83 is threaded to the middle guide pipe 82 and snapped onto the opening of the feeding container 10. The feed material 12 is loaded into the feeding container 10, and an auxiliary heater 11 is installed externally. At this time, the raw material 4 is loaded into the main graphite container 5, and the seed crystal 7 is fixed to the graphite. At the top of container 5, the main side heater 2 and the main bottom heater 6 are activated to form a temperature gradient. When online feeding is required, after the main raw material 4 has been stably sublimated, the auxiliary heater 11 is activated. The sublimation rate of the feed 12 is adjusted by temperature control. The sublimation gas of the feed 12 rises to the area of ​​the main raw material 4 through the gas guide pipe 8, mixes, and migrates to the surface of the seed crystal 7 for crystallization. The temperature of the auxiliary heater 11 is continuously controlled to keep the supply of raw material 4 in line with the growth rate. After the growth is completed, the gas guide pipe 8 and the feeding container 10 are disassembled in sequence, and the porous graphite 9 and the inside of the container are cleaned.

[0053] Specifically, the furnace chamber 1 is evacuated to a vacuum environment (vacuum degree ≥ 1×10⁻³ Pa), and the main side heater 2 and the main bottom heater 6 are energized to heat the furnace chamber 1, creating a temperature gradient of 50℃ / cm to 150℃ / cm. The raw material 4 is heated to a sublimation temperature of 2100℃ to 2400℃, forming silicon carbide gas. After the raw material 4 has stably sublimated (usually about 2 hours after heating), the auxiliary heater 11 is started. By adjusting its heating temperature (2000℃ to 2400℃), the sublimation rate of the feed material 12 is controlled, so that the feed material 12 sublimates synchronously to form gas.

[0054] The above-disclosed embodiments are only a few specific examples of the present utility model. However, the embodiments of the present utility model are not limited thereto. Any variations that can be conceived by those skilled in the art should fall within the protection scope of the present utility model.

Claims

1. An online feeding device for preparing silicon carbide ingots, connected to the bottom of a graphite container (5), characterized in that, The bottom wall of the graphite container (5) has a through hole (51) along the longitudinal direction, and the feeding device includes: A gas guide tube (8) is inserted longitudinally into the through hole (51) of the graphite container (5); Porous graphite (9), in the form of a disc-shaped porous structure, is placed at the bottom of the graphite container (5) and located at the upper port of the gas guide pipe (8). The porous graphite (9) is used for the passage of gas and to prevent the raw material (4) in the graphite container (5) from falling into the gas guide pipe (8). The feeding container (10) is located inside the furnace (1) and at the bottom of the gas guide pipe (8). The lower end of the gas guide pipe (8) is sealed and connected to the upper opening of the feeding container (10). The feeding container (10) is filled with additives (12) of the same material as the raw material (4). An auxiliary heater (11) is connected around the outer periphery of the feeding container (10) and is used to heat the feeding container (10).

2. The online feeding device for preparing silicon carbide ingots as described in claim 1, characterized in that, The graphite container (5) has a countersunk groove (52) on the inner bottom wall corresponding to the through hole (51) and the same center line as the through hole (51). The porous graphite (9) is embedded and fixed in the countersunk groove (52). The upper end of the gas guide pipe (8) is located below the countersunk groove (52).

3. The online feeding device for preparing silicon carbide ingots as described in claim 1, characterized in that, The upper periphery of the gas guide tube (8) is detachably connected to the bottom wall of the graphite container (5).

4. The online feeding device for preparing silicon carbide ingots as described in claim 3, characterized in that, The graphite container (5) has a through hole (51) at the bottom with a first internal thread, and the gas guide tube (8) includes: The upper guide tube (81) has a first external thread at the top for engaging with the first internal thread of the graphite container (5); The middle guide tube (82) is connected to the lower port of the upper guide tube (81), and a second external thread is provided on the circumferential side of the lower port of the middle guide tube (82); The lower guide tube (83) is flared, and a second internal thread that mates with the second external thread is provided on the inner wall of the smaller port. The larger port of the lower guide tube (83) is sealed and snapped into the upper opening of the feeding container (10).

5. The online feeding device for preparing silicon carbide ingots as described in claim 4, characterized in that, The middle guide tube (82) and the upper guide tube (81) are connected in a sealed manner, and an anti-detachment component is provided at the connection point between the two.

6. The online feeding device for preparing silicon carbide ingots as described in claim 5, characterized in that, The anti-detachment component includes an inner flange and an outer flange. The inner flange is fixedly connected to the inner side of the lower port of the upper guide tube (81), and the outer flange is sleeved and fixed to the outer side of the upper port of the middle guide tube (82). As the middle guide tube (82) slides away from the upper guide tube (81) in a direction away from each other, the inner flange and the outer flange are sealed and fastened.

7. The online feeding device for preparing silicon carbide ingots as described in claim 1, characterized in that, The thickness of the porous graphite (9) is 5 mm to 10 mm.

8. The online feeding device for preparing silicon carbide ingots as described in claim 1, characterized in that, The porous graphite (9) has a pore size of 28 μm to 30 μm.

9. The online feeding device for preparing silicon carbide ingots as described in claim 1, characterized in that, The through hole (51) is located at the center of the bottom of the graphite container (5).

10. The online feeding device for preparing silicon carbide ingots as described in claim 4, characterized in that, The upper opening of the feeding container (10) is provided with a slot, and the larger port of the lower guide pipe (83) is provided with a snap-fit ​​groove for engaging with the slot.

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