A feeding system for a czochralski furnace

Abstract

The utility model discloses a straight pull single crystal manufacturing field's a kind of straight pull single crystal furnace feeding system, to solve the technical problem of the temperature difference inside and outside double-layer crucible caused by continuous feeding when continuous straight pull single crystal.The system includes furnace body and the silicon material feeding device located at the outside of the furnace body, and the silicon material feeding device is extended to the inside of the furnace body by discharging pipeline;Double-layer crucible is installed in the inside of the furnace body, and the double-layer crucible includes outer layer crucible and inner layer crucible, and the outer layer crucible and inner layer crucible form feeding interlayer;The discharging pipeline is equipped with discharging port, and the discharging port corresponds the opening of the feeding interlayer;The silicon material feeding device is equipped with multiple microwave heating devices, to heat granular silicon passing through the microwave heating device, so as to reduce the temperature difference between the granular silicon and the silicon liquid in the double-layer crucible.The utility model can reduce the breakage rate of inner layer crucible, and avoid the generation of silicon rod temperature gradient.

Description

Technical Field

[0001] This utility model relates to a feeding system for a Czochralski single crystal furnace, belonging to the field of Czochralski single crystal manufacturing technology. Background Technology

[0002] In the field of Czochralski single crystal manufacturing, granular polycrystalline silicon is widely used as a raw material in the feeding process. However, when adding granular silicon to molten silicon, a significant temperature difference exists between the two, which can easily lead to thermal shock. This thermal shock not only causes silicon molten metal to splash, increasing the risk of impurity introduction, but also creates a large temperature gradient between the inner and outer layers of silicon molten metal in a double-layer crucible, affecting the stability of the thermal field. Excessive temperature difference will exacerbate the thermal stress in the inner crucible, leading to a higher crucible breakage rate. It may also allow the cooler silicon molten metal from the outer layer to enter the inner layer, further causing uneven temperature distribution in the inner layer, ultimately affecting the pulling quality of the single crystal silicon rod and resulting in lattice defects or crystal breakage.

[0003] In existing technologies, microwave radiation heating is commonly used to treat granular polycrystalline silicon, or a combination of high-temperature pyrolysis and ozone oxidation is employed to reduce the carbon content in granular silicon. The former utilizes the difference in microwave absorption capacity between micro / nano-sized silicon powder and larger particles, making the micro-silicon powder easier to melt and adhere to the surface of larger particles, thereby reducing dust dispersion. This process is typically carried out under a vacuum or inert atmosphere. By controlling the microwave power and heating rate, the turbidity of the silicon material can be effectively reduced with low energy consumption. The latter, on the other hand, uses microwave heating to create microcracks in the granular silicon, exposing internal carbon impurities. Ozone gas is then used to react with these impurities, reducing the carbon impurity content to a low level, preventing silicon oxidation, and improving the purity of the final product.

[0004] While the aforementioned technologies each have their advantages in dust and impurity removal, they do not effectively solve the problems of thermal shock, crucible life, and single crystal growth quality stability caused by excessive temperature differences between granular silicon and molten silicon during continuous feeding. Therefore, a feeding system solution that can effectively control temperature differences, improve thermal field distribution, and thus enhance crystal pulling efficiency and silicon rod quality is still needed. Utility Model Content

[0005] The purpose of this invention is to provide a feeding system for a Czochralski single crystal furnace that can reduce the breakage rate of the inner crucible and avoid the generation of temperature gradients in the silicon rod, thereby improving the crystal pulling quality.

[0006] To solve the above-mentioned technical problems, the present invention is implemented using the following technical solution.

[0007] On the one hand, this utility model provides a Czochralski single crystal furnace feeding system, including a furnace body and a silicon material feeding device located outside the furnace body, wherein the silicon material feeding device extends through a feeding pipe into the interior of the furnace body; The furnace body is equipped with a double-layer crucible, which includes an outer crucible and an inner crucible, and a feeding jacket is formed between the outer crucible and the inner crucible; the feeding pipe is provided with a feeding port, which corresponds to the opening of the feeding jacket; The silicon material feeding device integrates multiple microwave heating devices for preheating the granular silicon, which heat the granular silicon before it enters the feeding jacket, thereby reducing the temperature difference between the granular silicon and the molten silicon in the double-layer crucible.

[0008] Preferably, a support structure is provided below the double-layer crucible. The support structure includes, from top to bottom, a graphite heating element, a tray, and a support rod. The top of the support rod supports the tray, and the graphite heating element is mounted on the tray.

[0009] Preferably, one end of the drag bar is connected to the tray, and the other end is disposed through the bottom of the furnace body.

[0010] Preferably, a heater is also provided on the outer periphery of the double-layer crucible. The heater is connected to a heating electrode that penetrates through the bottom of the furnace body and is connected to a power source outside the furnace body.

[0011] Preferably, both the double-layered crucible and the heater are cylindrical structures.

[0012] Preferably, a flow guide tube is provided directly above the double-layer crucible, and the flow guide tube is fixed to the top of the furnace body.

[0013] Preferably, an inverted flow guide shroud is provided around the outer periphery of the open end of the flow guide tube.

[0014] Preferably, a stretching device is provided above the guide tube for stretching the molten silicon in the inner crucible to form a single crystal silicon rod. The stretching device is provided with an inert gas inlet, which is connected to an inert gas source. The inert gas source enters the guide tube through the stretching device and moves towards the inner crucible under the guidance of the guide hood.

[0015] Preferably, an inert gas intake port is provided on the lower side of the furnace body, and the inert gas intake port is connected to a negative pressure device.

[0016] Preferably, the inner wall of the furnace is provided with a heat insulation layer, and its bottom is provided with a reflective layer.

[0017] Compared with the prior art, the beneficial effects achieved by this utility model are as follows: This invention preheats the granular silicon before it enters the double-layer crucible using microwave heating. The granular silicon is heated rapidly and uniformly, effectively reducing the temperature difference between it and the molten silicon in the double-layer crucible. This significantly reduces the thermal shock to the crucible during feeding, preventing the inner crucible from breaking due to excessive temperature difference. It also suppresses the temperature gradient caused by the outer layer of molten silicon entering the inner layer, ultimately improving the pulling quality and yield of single-crystal silicon rods. It has good prospects for industrial application. The feeding port corresponds to the opening of the feeding jacket, enabling precise feeding of granular silicon. Attached Figure Description

[0018] Figure 1 The diagram shown is a structural schematic of a Czochralski single crystal furnace feeding system provided in an embodiment of this utility model; In the diagram: 1. Furnace body; 2. Double-layer crucible; 201. Outer crucible; 202. Inner crucible; 203. Feeding jacket; 3. Graphite heating element; 4. Tray; 5. Trailing rod; 6. Flow guide tube; 7. Flow guide hood; 8. Feeding and silicon adding device; 9. Stretching device; 10. Inert gas inlet; 11. Insulation layer; 12. Reflective layer; 13. Heater; 14. Inert gas outlet; 15. Microwave heating device; 16. Heating electrode; 17. Feeding pipe; 18. Feeding port. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features therein are detailed descriptions of the present invention, rather than limitations thereof. In the absence of conflict, the embodiments of the present invention and the technical features therein can be combined with each other.

[0020] The term "and / or" simply describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Additionally, the character " / " generally indicates that the preceding and following related objects have an "or" relationship. Example 1

[0021] See Figure 1This embodiment describes a Czochralski single crystal furnace feeding system, including a furnace body 1 and a silicon material feeding device 8 located outside the furnace body 1. The silicon material feeding device 8 extends through a feeding pipe 17 into the interior of the furnace body 1. Inside the furnace body 1 is a cylindrical double-layer crucible 2, comprising an outer crucible 201 and an inner crucible 202, forming a feeding interlayer 203 for receiving granular silicon. The feeding pipe 17 has a feeding port 18, the outlet of which corresponds to the opening (inlet) of the feeding interlayer 203, allowing granular silicon to be accurately fed into the feeding interlayer 203. This feeding interlayer serves as an intermediate layer to temporarily store or guide granular silicon into the inner crucible 202. The entire conveying process is controlled by valves on the feeding pipe 17, ensuring that the amount of added granular silicon is controllable and stable.

[0022] To further optimize the process, multiple microwave heating devices 15 are integrated into the silicon feeding device 8. These devices preheat the silicon particles before they enter the feeding jacket 203 (microwave radiation heating power of 100-6000W, heating rate of 5-300℃ / min). This preheating process effectively reduces the temperature difference between the solid silicon particles and the existing molten silicon in the double-layer crucible 2, thereby mitigating thermal shock during the feeding process, stabilizing the thermal environment, improving the growth quality of the single crystal silicon rod, and extending the crucible's lifespan. Example 2

[0023] See Figure 1 Based on Example 1, the feeding system of the Czochralski single crystal furnace is further refined as follows: A support structure is provided below the double-layer crucible 2. The support structure includes, from top to bottom, a graphite heating element 3, a tray 4, and a support rod 5. The top of the support rod 5 supports the tray 4, and the graphite heating element 3 is installed on the tray 4, directly acting on the bottom of the double-layer crucible 2, serving both as a support and as a heat source.

[0024] In a further embodiment of this utility model, one end of the drag rod 5 is connected to and supports the tray 4, and the other end is inserted through the bottom of the furnace body 1 and connected to an external lifting mechanism. The lifting mechanism controls the raising and lowering of the drag rod 5, thereby adjusting the height of the double-layer crucible 2 inside the furnace body 1 to ensure that it is in the optimal heating zone. A heater 13 with the same shape as the double-layer crucible 2 (cylindrical) is also provided on the outer periphery of the double-layer crucible 2. The heater 13 is connected to a heating electrode 16, which penetrates through the bottom of the furnace body 1 and is connected to a power source outside the furnace body 1 to achieve auxiliary uniform heating of the double-layer crucible 2.

[0025] In a further embodiment of this utility model, a guide tube 6 is provided directly above the double-layer crucible 2. The guide tube 6 is fixed at the top position inside the furnace body 1, and an inverted guide shroud 7 is also provided around the outer periphery of the open end of the guide tube 6. A stretching device 9 is provided above the guide tube 6 for stretching the silicon liquid in the inner crucible 202 to form a single crystal silicon rod. The stretching device 9 is provided with an inert gas inlet 10, which is connected to an inert gas source. In actual operation, the inert gas source enters the stretching device 9 from the inert gas inlet 10, is guided downward through the stretching device 9 to the guide tube 6, and moves along the direction of the inner crucible 202 under the guidance of the guide shroud 7, thereby effectively suppressing the upward escape of inert gas and allowing it to continuously scour the surface of the growing single crystal silicon rod to remove volatile impurities such as silicon oxide and reduce crystal defects.

[0026] To further control the atmosphere inside the furnace, an inert gas intake port 14 is provided on the lower side of the bottom of the furnace body 1. The inert gas intake port 14 is connected to a negative pressure device to discharge the inert gas inside the furnace body 1.

[0027] To improve the efficiency of the thermal field, an insulation layer 11 is arranged on the inner wall of the furnace body 1, and a reflective layer 12 is set at its bottom. The two work together to reduce heat loss and maintain a stable high-temperature environment.

[0028] In a further embodiment of this invention, the upper part of the silicon material feeding device 8 is provided with multiple downward-facing microwave heating devices 15, preferably two; the lower part is provided with multiple upward-facing microwave heating devices 15, preferably two. In actual operation, the silicon particles pass through the channel formed between the upper and lower sets of microwave heating devices 15 during the conveying process. This opposing arrangement allows the silicon particles to be uniformly irradiated by microwaves from different directions during movement, thereby achieving rapid and uniform preheating. Furthermore, by setting multiple microwave heating devices 15, the power of a single microwave heating device 15 is reduced, while making the microwave heating more uniform. The preferred heating power is set to 500-5000W, and the heating rate is set to 25-250℃ / min.

[0029] The embodiments of the present utility model have been described above with reference to the accompanying drawings. However, the present utility model is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present utility model without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present utility model.

Claims

1. A feeding system for a Czochralski single crystal furnace, characterized in that, It includes a furnace body (1) and a silicon material feeding device (8) located outside the furnace body (1), the silicon material feeding device (8) extending through a feeding pipe (17) into the interior of the furnace body (1); The furnace body (1) is equipped with a double-layer crucible (2), which includes an outer crucible (201) and an inner crucible (202), and a feeding jacket (203) is formed between the outer crucible (201) and the inner crucible (202); the feeding pipe (17) is provided with a feeding port (18), which corresponds to the opening of the feeding jacket (203); The silicon material feeding device (8) is internally integrated with multiple microwave heating devices (15) for preheating the granular silicon. The granular silicon is heated before entering the feeding jacket (203), thereby reducing the temperature difference between the granular silicon and the silicon liquid in the double-layer crucible (2).

2. The feeding system for the Czochralski single crystal furnace according to claim 1, characterized in that, The double-layer crucible (2) is provided with a support structure below it. The support structure includes a graphite heating element (3), a tray (4) and a drag rod (5) from top to bottom. The top of the drag rod (5) supports the tray (4), and the graphite heating element (3) is installed on the tray (4).

3. The feeding system for the Czochralski single crystal furnace according to claim 2, characterized in that, One end of the drag bar (5) is connected to the tray (4), and the other end is disposed at the bottom of the furnace body (1).

4. The feeding system for a Czochralski single crystal furnace according to claim 1, characterized in that, A heater (13) is also provided on the outer periphery of the double-layer crucible (2). The heater (13) is connected to a heating electrode (16). The heating electrode (16) penetrates the bottom of the furnace body (1) and is connected to a power source outside the furnace body (1).

5. The feeding system for a Czochralski single crystal furnace according to claim 4, characterized in that, Both the double-layer crucible (2) and the heater (13) are cylindrical structures.

6. The feeding system for a Czochralski single crystal furnace according to claim 1, characterized in that, A guide tube (6) is provided directly above the double-layer crucible (2), and the guide tube (6) is fixed to the top inside the furnace body (1).

7. The feeding system for a Czochralski single crystal furnace according to claim 6, characterized in that, The outer periphery of the opening end of the guide tube (6) is provided with an inverted guide shroud (7).

8. The feeding system for a Czochralski single crystal furnace according to claim 7, characterized in that, Above the guide tube is a stretching device (9) for stretching the molten silicon in the inner crucible (202) to form a single crystal silicon rod. The stretching device (9) is provided with an inert gas inlet (10), which is connected to an inert gas source. The inert gas source enters the guide tube (6) through the stretching device (9) and moves toward the inner crucible (202) under the guidance of the guide hood (7).

9. The feeding system for a Czochralski single crystal furnace according to claim 1, characterized in that, An inert gas intake port (14) is provided on the lower side of the furnace body (1), and the inert gas intake port (14) is connected to a negative pressure device.

10. The Czochralski single crystal furnace feeding system according to claim 1, characterized in that, The furnace body (1) has an insulation layer (11) on its inner wall and a reflective layer (12) at its bottom.

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