A single crystal furnace liquid level distance target point detection device

Abstract

The utility model relates to monocrystal silicon rod production field relates to a single crystal furnace liquid level distance target point detection device, the utility model discloses: target point main part, the target point main part upper end is installed on the flow guide cylinder support ring, the target point main part one end towards liquid level is provided with counterbore, through target point main part as physical reference target point, the on -the -spot operator can refer to the target point and carry out initial liquid mouth distance judgement, avoided the subjective difference judgement of artificial, the counterbore design of target point main part bottom, can enhance its reflection imaging definition and contrast ratio to improve the feature extraction precision of visual inspection, realize higher liquid level distance measurement accuracy finally.

Description

Technical Field

[0001] This utility model relates to the field of monocrystalline silicon rod production, and specifically to a device for detecting the distance between the liquid level and the target point in a monocrystalline furnace. Background Technology

[0002] Monocrystalline silicon rods are essential raw materials for the semiconductor and photovoltaic industries, and their usage is very large in the production of photovoltaic modules. Currently, the main methods for manufacturing monocrystalline silicon rods are the Czochralski method and the zone melting method. The Czochralski method grows high-quality monocrystalline silicon rods by pulling them from molten silicon. Due to its high maturity and controllable cost, it is the dominant technology for monocrystalline silicon preparation. The main process flow of the Czochralski method includes: Loading and melting: Polycrystalline silicon is loaded into a quartz crucible and placed in a graphite heater. It is heated to the melting point of silicon in an argon atmosphere, and the temperature is precisely controlled to ensure that the silicon melt is uniform and to avoid excessive temperature fluctuations that could cause lattice defects.

[0003] Seed crystal welding: After the melting process is complete and the temperature stabilizes, the crucible needs to be raised to maintain a suitable distance from the guide tube. A high-purity single-crystal silicon seed crystal is fixed on a rotating hammer. Once the temperature of the molten silicon in the furnace is suitable, the seed crystal is slowly brought into contact with the liquid surface. The temperature is controlled by adjusting the power, allowing the part of the seed crystal in contact with the molten silicon to melt and recrystallize, ensuring lattice matching.

[0004] Necking and crystal pulling: After the furnace temperature is suitable, the seed crystal is quickly pulled up to reduce the crystal diameter to about 5mm. Then, the pulling is continuously controlled to a certain extent according to the 5mm diameter, usually between 200 and 250mm, in order to eliminate dislocation defects.

[0005] Shoulder formation: Reduce the pulling speed to gradually increase the crystal diameter to the target diameter. During the shoulder formation process, temperature step control is required, and the crucible lifting speed needs to be adjusted to maintain a relatively stable liquid outlet position, ensuring uniform crystal growth and avoiding stress-induced cracking.

[0006] Constant diameter growth: The pulling speed, temperature and liquid outlet distance are adjusted by feedback such as diameter measurement to maintain the constant diameter growth of the crystal.

[0007] Finishing: Increase the pulling speed and gradually reduce the diameter to form a conical tail to avoid dislocation multiplication caused by thermal stress.

[0008] To improve temperature control efficiency and output in the production of monocrystalline silicon rods, it is necessary to ensure accurate detection and control of the liquid gate distance throughout the entire pulling process. In monocrystalline silicon growth, stable control of the liquid gate distance directly affects crystal quality. Currently, the industry commonly uses horizontal or oblique measurement of the pixel distance between the edge of the guide tube and its reflection to determine whether the liquid surface movement position is appropriate. However, this control process has significant bottlenecks. High dependence on human intervention: Before automatic control, the initial liquid outlet distance needs to be confirmed manually. There are no actual physical reference marks, and the initial liquid outlet distance is determined by human experience, which is greatly affected by subjective factors. Systemic deviations in newly started furnaces: The need to clean the hot zone and reinstall the guide tube during the initial furnace start-up process can lead to installation differences, causing a certain offset in the visual measurement position. The original technology had poor precision and large fluctuations, making it impossible to accurately control the liquid level. There were also significant differences between different furnace platforms, and disassembling and reinstalling the furnace platform resulted in deviations. Utility Model Content

[0009] This invention provides a device for detecting the distance between the liquid surface and the target point in a single crystal furnace, in order to solve the problems of the prior art.

[0010] The purpose of this utility model can be achieved through the following technical solution: A single crystal furnace liquid level distance target detection device includes: a target body, the upper end of the target body is installed on the guide tube support ring, and a countersink is provided at the end of the target body facing the liquid surface.

[0011] In a further improvement, the target body includes a horizontal part and a vertical part, the vertical part is integrally fixed to the lower end of the horizontal part, the outer diameter of the vertical part is smaller than the inner diameter of the horizontal part, and the countersunk hole is located at the lower end of the vertical part.

[0012] In a further improvement, the target body is made of a material with high-temperature reflective properties.

[0013] In a further improvement, the target body may be selected from one of tantalum alloy, molybdenum alloy or tungsten alloy.

[0014] Compared with existing technologies, the advantages of this novel single-crystal furnace liquid level distance target detection device are as follows: By using the target body as a physical reference target, on-site operators can refer to the target to make initial liquid outlet distance judgments, avoiding subjective human judgment differences; the countersunk hole design at the bottom of the target body can enhance the clarity and contrast of its reflection imaging, thereby improving the feature extraction accuracy of visual inspection and ultimately achieving higher accuracy in liquid surface distance measurement. Attached Figure Description

[0015] Figure 1 This is a structural schematic diagram of the present invention. In the figure, 1-target body, 11-sinkhole, 12-horizontal part, 13-vertical part. Detailed Implementation

[0016] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing 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, and therefore should not be construed as a limitation of this utility model; unless otherwise expressly specified and limited, the terms "installed," "connected," and "joined" should be interpreted broadly, for example, they can refer to fixed connections or detachable connections, etc. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0017] The following is a description of the embodiments and appendices. Figure 1 The technical solution of this utility model will be further described below.

[0018] Example 1 A single crystal furnace liquid level distance target detection device includes: a target body 1, the upper end of which is mounted on a guide tube support ring, a countersunk hole 11 provided at the end of the target body 1 facing the liquid surface, the target body 1 including a horizontal part 12 and a vertical part 13, the vertical part 13 being integrally fixed to the lower end of the horizontal part 12, the outer diameter of the vertical part 13 being smaller than the inner diameter of the horizontal part 12, and the countersunk hole 11 being provided at the lower end of the vertical part 13.

[0019] During the growth of single-crystal silicon rods, the distance between the bottom of the rod cooling device and the surface of the raw silicon molten material (i.e., the nozzle distance) must remain stable, as this directly affects the crystal quality. As the rod length increases, the rod lifting device will lift the rod to achieve continuous growth. However, the movement speed of the silicon molten material surface may not match the rod growth speed. Therefore, it is necessary to monitor and adjust the surface position in real time to ensure that the nozzle distance is always within the optimal range.

[0020] To achieve the above functions, before production feeding, a liquid level distance measuring target device (i.e., target body 1) is installed on the guide tube support ring. The purpose of the countersunk hole 11 on the target body 1 is to make the target device form a clear reflection with holes on the silicon liquid surface, so as to facilitate computer vision measurement.

[0021] After the hot zone of the single crystal furnace is disassembled and reassembled, the material is refilled and melting is completed. Before the first temperature adjustment, in order to determine the optimal liquid level position, the liquid level distance calibration needs to be performed: the crucible is slowly raised manually until the edge of the guide tube is tangent to the reflection edge of the target body 1. At this time, the system performs the first (near distance) calibration and records the calibration value "16". After the calibration is completed, the crucible is lowered by 12mm and the second (far distance) calibration is performed and the calibration value "28" is recorded. At this time, the liquid level position has reached the target temperature adjustment position.

[0022] Compared to traditional methods of measuring liquid surface distance, this solution employs adaptive angle vision measurement technology. The specific operation process is as follows: Image acquisition and area marking: Images of the silicon liquid surface area are captured using an industrial camera, and the target measurement range is marked to ensure that the detection is focused on the effective area; Target Reflection Recognition: Within the marked area, the black circular hole reflection of the target body 1 on the silicon liquid surface (i.e., the reflection of the sink hole 11) is located using a feature recognition algorithm. This reflection has high contrast due to the sink hole design and is easy to capture accurately. Angle measurement area generation: Based on the center coordinates of the black circular hole, a measurement area with a specific angle is generated to narrow the detection range and improve recognition efficiency; Intersection point identification: Within the aforementioned angular area, the intersection point between the guide tube support ring and the liquid surface is accurately identified through feature analysis such as edge detection, serving as another reference point for distance measurement; Pixel distance calculation: Calculate the pixel distance between the above intersection point and the center coordinates of the black circular hole, and convert the physical distance into quantifiable image parameters; Physical distance conversion: The calculated pixel distance is input into a pre-calibrated vision system model, and the corresponding actual physical distance is output, thus completing the conversion from image information to physical quantity.

[0023] The physical distance calculated by the vision system is transmitted to the PLC (Programmable Logic Controller). The PLC compares it with the set optimal liquid level distance and adjusts the liquid level position by controlling the lifting and lowering of the crucible, ultimately achieving precise control of the liquid outlet distance.

[0024] The advantages of this solution are as follows: by using the target body 1 as a physical reference target, on-site operators can directly refer to the target to judge the initial liquid outlet distance, avoiding the subjective differences of traditional manual judgment; the design of the countersunk hole 11 enhances the clarity and contrast of the reflection imaging, improves the feature extraction accuracy of visual detection, and thus improves the accuracy of liquid surface distance measurement; the secondary calibration method combined with coefficient calibration ensures the accuracy of the conversion of pixel distance to actual physical distance, providing reliable data support for PLC precise control.

[0025] As a further preferred embodiment, the target body 1 is made of a material with high-temperature reflective properties, specifically one of tantalum alloy, molybdenum alloy, or tungsten alloy. The crystal growth environment temperature is extremely high (silicon melt temperature approximately 1450℃). The aforementioned materials maintain stable chemical and physical properties at high temperatures, and compared to graphite or carbon-carbon composite materials, their reflective properties on the silicon liquid surface are superior, significantly improving the accuracy of the vision system in capturing the target reflection and ensuring the accuracy of liquid surface distance measurement. Using other materials with equivalent high-temperature reflective properties to achieve the same effect falls within the scope of equivalent substitution in this solution.

[0026] The preferred embodiments of this utility model have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of this utility model without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of this utility model through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A device for detecting the distance between the liquid level and the target point in a single crystal furnace, characterized in that, include: The target body (1) is mounted on the upper end of the guide tube support ring, and a sinkhole (11) is provided on the end of the target body (1) facing the liquid surface.

2. The single crystal furnace liquid level distance target detection device according to claim 1, characterized in that, The target body (1) includes a horizontal part (12) and a vertical part (13). The vertical part (13) is integrally fixed to the lower end of the horizontal part (12). The outer diameter of the vertical part (13) is smaller than the inner diameter of the horizontal part (12). The countersunk hole (11) is located at the lower end of the vertical part (13).

3. The single crystal furnace liquid level distance target detection device according to claim 1, characterized in that, The target body (1) is made of a material with high temperature reflective properties.

4. The single crystal furnace liquid level distance target detection device according to claim 3, characterized in that, The target body (1) is made of one of tantalum alloy, molybdenum alloy or tungsten alloy.

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