Guide cylinder and single crystal furnace
By designing a gradually decreasing lower opening and an inclined structure for the guide tube, the double reflection problem was solved, ensuring accurate calculation of the liquid outlet distance and improving the success rate of single-crystal silicon rod fabrication.
Patent Information
- Application Number
- CN202520267801.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-19
- Publication Date
- 2026-01-27
- Estimated Expiration
- 2035-02-19
AI Technical Summary
During the preparation of single-crystal silicon rods, as the diameter of the lower opening of the guide tube increases, a double reflection phenomenon occurs, affecting the calculation results of the liquid outlet distance and the success rate of single-crystal silicon rods.
Design a flow guide tube with a lower opening diameter that gradually decreases from top to bottom, and weaken the double reflection when the image monitoring device captures the image. The lower opening is made into a single reflection on the silicon liquid surface by using an inclined plane or inclined concave surface structure and a dark coating. The angular relationship between the image monitoring device and the furnace body central axis is combined to ensure that the reflection is within the viewing angle.
This improved the accuracy of liquid outlet distance calculation and increased the success rate of single-crystal silicon rod fabrication.
Smart Images
Figure CN223837636U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of single crystal silicon rod preparation technology, specifically to a flow guide tube and a single crystal furnace. Background Technology
[0002] In the process of preparing single-crystal silicon rods using a single-crystal furnace, obtaining the target liquid nozzle distance (the distance from the lower edge of the lower opening of the flow guide tube to the surface of the molten silicon) is crucial. Current techniques typically involve using a CCD camera to photograph the lower edge of the flow guide tube's lower opening and its reflection on the molten silicon surface, calculating the liquid nozzle distance using image processing techniques, and then adjusting the height of the flow guide tube and / or crucible based on the calculated distance to obtain the target liquid nozzle distance.
[0003] As the size of single-crystal silicon rods gradually increases, the diameter of the lower opening of the flow guide also gradually increases. After the lower opening diameter of the flow guide reaches a certain value, a double reflection phenomenon occurs in the reflection of the lower edge of the flow guide's lower opening on the molten silicon surface, as captured by a CCD camera. This double reflection affects the calculated liquid outlet distance and the adjustment height of the flow guide and / or crucible, thus impacting the success rate of single-crystal silicon rod fabrication. Utility Model Content
[0004] To address at least one of the problems mentioned in the background art, this utility model provides a flow guide tube and a single crystal furnace that can capture a single, clear reflection of the lower opening of the flow guide tube in the silicon liquid surface when positioning the target liquid outlet distance, without capturing a double reflection, thereby ensuring accurate positioning of the target liquid outlet distance and improving the success rate of pulling single crystal silicon rods.
[0005] The specific technical solution provided by this utility model is as follows:
[0006] In a first aspect, a guide tube is provided, comprising a tube body, an upper opening formed at the upper end of the tube body, and a lower opening formed on the bottom surface of the tube body, the diameter of the lower opening gradually decreasing from top to bottom.
[0007] As a preferred embodiment of the above scheme, an inclined plane is formed between the upper and lower edges of the lower opening.
[0008] As a preferred embodiment of the above scheme, an inclined concave surface is formed between the upper and lower edges of the lower opening.
[0009] As a preferred embodiment of the above solution, a dark coating is provided on the bottom of the cylinder.
[0010] As a preferred embodiment of the above scheme, the diameter of the upper opening is larger than the diameter of the lower opening.
[0011] By employing the above technical solution, the guide tube of this utility model sets the diameter of the lower opening to gradually decrease from top to bottom. In this way, in the image captured by the image monitoring device above the guide tube, the double reflection formed by the lower edge of the lower opening of the guide tube on the silicon liquid surface can be weakened, reducing the impact on the liquid outlet distance calculation results and improving the success rate of pulling single crystal silicon rods.
[0012] Secondly, a single crystal furnace is provided, comprising a furnace body and a crucible and a flow guide tube coaxially disposed within the furnace body.
[0013] The furnace body is equipped with image monitoring devices.
[0014] The crucible contained molten silicon.
[0015] The guide tube is positioned above the crucible and is the aforementioned guide tube. The image monitoring device captures images of the lower opening of the guide tube and its reflection on the surface of the silicon solution.
[0016] As a preferred embodiment of the above solution, the image monitoring device captures images of the lower opening of the guide tube and its reflection on the silicon liquid surface of the silicon solution. Only the reflection of the lower edge of the lower opening on the silicon liquid surface can be observed, while the reflection of the upper edge of the lower opening on the silicon liquid surface cannot be observed.
[0017] As a preferred embodiment of the above scheme, in the longitudinal section passing through the central axis of the image monitoring device and the furnace body, the acute angle formed by the line connecting the lower edge and the upper edge of the lower opening of the guide tube and the silicon liquid surface is less than or equal to the acute angle formed by the line connecting the reflection of the lower edge of the lower opening of the guide tube on the silicon liquid surface and the image monitoring device and the silicon liquid surface.
[0018] As a preferred embodiment of the above scheme, in the longitudinal section passing through the central axis of the image monitoring device and the furnace body, the acute angle formed by the line connecting the lower edge and the upper edge of the lower opening of the guide tube and the silicon liquid surface is less than or equal to the acute angle formed by the line connecting the reflection of the lower edge of the lower opening on the silicon liquid surface and the image monitoring device and the silicon liquid surface when the guide tube is closest to the silicon liquid surface.
[0019] As a preferred embodiment of the above scheme, in a longitudinal section passing through the central axis of the image monitoring device and the furnace body, the acute angle formed by the line connecting the lower edge and the upper edge of the lower opening of the guide tube and the silicon liquid surface satisfies the following formula:
[0020] tanA≤(D2+D4) / (D1+D3);
[0021] Where A is the acute angle formed by the line connecting the lower and upper edges of the lower opening of the guide tube and the silicon liquid surface; D1 is the vertical distance between the image monitoring device and the central axis; D2 is the vertical distance between the image monitoring device and the silicon liquid surface; D3 is the vertical distance between the lower edge of the lower opening of the guide tube and the central axis; and D4 is the minimum vertical distance between the lower edge of the lower opening of the guide tube and the silicon liquid surface.
[0022] By employing the above technical solution, the guide tube used in the furnace body of this utility model has its lower opening diameter gradually decreasing from top to bottom. In this way, the double reflection formed by the lower edge of the guide tube's lower opening on the silicon liquid surface can be weakened in the image captured by the image monitoring device above the guide tube, reducing the impact on the liquid outlet distance calculation results and improving the success rate of pulling single crystal silicon rods. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 This is a schematic diagram illustrating the principle of double reflection caused by enlarging the lower opening diameter of the guide tube in existing technology.
[0025] Figure 2 This is a double reflection image taken after the lower opening diameter of the guide tube in the prior art has been enlarged;
[0026] Figure 3 This is a single inverted image of the lower opening of the guide tube of this utility model;
[0027] Figure 4 This is a schematic diagram of the single crystal furnace of this utility model;
[0028] Figure 5 This is a schematic diagram of the structure of the guide tube of this utility model;
[0029] Figure 6 for Figure 5 An enlarged schematic diagram at point G, where the upper and lower edges of the lower opening of the guide tube form an inclined plane;
[0030] Figure 7 for Figure 5 An enlarged schematic diagram at point G, where the upper and lower edges of the lower opening of the guide tube form an inclined concave surface;
[0031] Figure 8 This is a longitudinal cross-sectional view of the image monitoring component and the central axis of the furnace body in this utility model;
[0032] Figure 9 This is a longitudinal cross-sectional view of the guide tube in this utility model, passing through the image monitoring device and the central axis of the furnace body when it is closest to the silicon liquid surface.
[0033] Figure 10 This is a schematic diagram illustrating the principle of determining the angle between the line connecting the lower and upper edges of the lower opening of the guide tube and the silicon liquid surface when the guide tube is closest to the silicon liquid surface in this utility model. Detailed Implementation
[0034] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0035] It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected to" another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "vertical," "horizontal," "left," "right," "upper," "lower," "inner," "outer," and "bottom," etc., used in this specification to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention 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 the present invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0036] As described in the background section, with the gradual increase in the diameter of single-crystal silicon rods, the diameter of the lower opening 33 of the guide tube also gradually increases. The lower opening 33 of existing guide tubes is generally of a straight-edge shape, that is, the lower opening of the guide tube is cylindrical. When the diameter of the lower opening 33 of such a guide tube increases to a certain value, such as... Figure 1 As shown, Figure 1 The cross-sectional view of one side of the guide tube shows the double reflection as follows: the dashed line shows the guide tube before the diameter of the lower opening 33 is enlarged, and the solid line shows the guide tube after the diameter of the lower opening 33 is enlarged. The horizontal plane M is the silicon liquid surface, the guide tube is above the silicon liquid surface, and the reflection 31 of the guide tube is below the silicon liquid surface.
[0037] Before the diameter of the lower opening 33 of the guide tube is enlarged, in the image captured by the image monitoring device 1 above the single crystal furnace, the distance between the upper edge 341 and the lower edge 342 of the lower opening 33 of the guide tube is d1, where d1 = L1 * sinα1, where L1 is the thickness between the upper edge 341 and the lower edge 342 of the lower opening 33 before the diameter of the lower opening 33 of the guide tube is enlarged, and α1 is the angle between the line connecting a point in the reflection of the upper edge 341 of the lower opening 33 of the guide tube in the silicon liquid surface and the image monitoring device and the vertical direction.
[0038] After the diameter of the lower opening 33 of the guide tube is enlarged, in the image captured by the image monitoring device 1 above the single crystal furnace, the distance between the upper edge 331 and the lower edge 332 of the lower opening 33 of the guide tube is d2, where d2 = L2*sinα2, where L2 is the distance between the upper edge 331 and the lower edge 332 of the lower opening 33 after the diameter of the lower opening 33 of the guide tube is enlarged, and α2 is the angle between the line connecting a point in the reflection of the upper edge 331 of the lower opening 33 in the silicon liquid surface and the image monitoring device 1 and the vertical direction.
[0039] Comparing the diameter of the lower opening 33 of the guide tube before and after its expansion, the thickness of the guide tube remains unchanged. This makes the distance L1 between the upper edge 341 and the lower edge 342 of the lower opening 33 before its expansion equal to the distance L2 between the upper edge 331 and the lower edge 332 of the lower opening 33 after its expansion. Since the diameter of the lower opening 33 of the guide tube has expanded, the angle α1 between the line connecting the reflection of the upper edge 341 of the lower opening 33 in the silicon liquid surface and the image monitoring device 1 before its expansion and the vertical direction is smaller than the angle α2 between the line connecting the reflection of the upper edge 331 of the lower opening 33 in the silicon liquid surface and the image monitoring device 1 after its expansion and the vertical direction. In other words, L1 = L2, α2 > α1, sinα2 > sinα1, which makes d2 > d1.
[0040] In other words, before the diameter of the lower opening 33 of the guide tube was enlarged, in the image captured by the image monitoring device 1 above the single crystal furnace, the distance d1 between the upper edge 341 and the lower edge 342 of the lower opening 33 of the guide tube was small, and the double reflection was not obvious; after the diameter of the lower opening 33 of the guide tube was enlarged, in the image captured by the image monitoring device 1 above the single crystal furnace, the distance d2 between the upper edge 331 and the lower edge 332 of the lower opening 33 of the guide tube became larger, and the double reflection became obvious, such as Figure 2 As indicated by the middle arrow.
[0041] Example 1
[0042] like Figure 4 , Figure 5 As shown, this utility model provides a flow guide tube, including a tube body 3, with an upper opening 32 formed at the upper end of the tube body 3 and a lower opening 33 formed on the bottom surface of the tube body 3, the diameter of the lower opening 33 gradually decreasing from top to bottom.
[0043] like Figure 6 As shown, in one embodiment, an inclined plane 333 is formed between the upper edge 331 and the lower edge 332 of the lower opening 33.
[0044] like Figure 7 As shown, in another embodiment, an inclined concave surface 334 is formed between the upper edge 331 and the lower edge 332 of the lower opening 33.
[0045] like Figure 6 , Figure 7 As shown, a dark coating 4, preferably black, is provided at the bottom of the cylinder 3. The dark coating 4 can make the lower opening 33 of the guide tube form a clearer image on the silicon liquid surface, the image edge is more distinct from the silicon liquid, and the data collected by the image monitoring device 1 is more accurate.
[0046] like Figure 5 , Figure 6 As shown, the diameter of the upper opening 32 of the guide tube is larger than the diameter of the lower opening 33. Specifically, the tube body 3 of the guide tube includes a coaxially arranged side wall portion 34, a transition portion 35, and a flat bottom 36. The side wall portion 34, the transition portion 35, and the flat bottom 36 are connected in sequence. An inclined plane 333 or an inclined concave surface 332 is provided on the inner edge of the flat bottom 36. The side wall portion 34, the transition portion 35, and the flat bottom 36 are all annular structures, and the diameter of the flat bottom 36 is smaller than the diameter of the side wall portion 34. The lower opening 33 of the guide tube is located in the middle of the flat bottom 36, and the bottom of the flat bottom 36 is coated with a dark coating 4.
[0047] like Figure 4 As shown, Figure 4 The arrow in the image indicates that the image monitoring device 1 captures the lower edge 332 of the lower opening 33 of the guide tube and its reflection on the silicon liquid surface. The guide tube of this utility model sets the diameter of the lower opening 33 to gradually decrease from top to bottom. In this way, the double reflection can be weakened in the image captured by the image monitoring device 1 above the guide tube, thereby making the target liquid outlet distance accurate and improving the success rate of pulling single crystal silicon rods.
[0048] Example 2
[0049] like Figure 4As shown, this utility model provides a single crystal furnace, including a furnace body 2 and a crucible 5, a flow guide tube, and a heating element (not shown) coaxially arranged inside the furnace body 2. An image monitoring device 1 is provided on the furnace body 2. The crucible 5 contains a silicon solution. The flow guide tube is arranged above the crucible 5 and is the flow guide tube of Embodiment 1. The image monitoring device 1 captures the lower opening 33 of the flow guide tube and the reflection of the lower opening 33 on the silicon liquid surface of the silicon solution. In this way, the double reflection can be weakened in the image captured by the image monitoring device 1 above the flow guide tube, thereby making the target liquid outlet distance accurate and improving the success rate of pulling single crystal silicon rods.
[0050] In one embodiment of the present invention, the image monitoring device 1 captures images of the lower opening 33 of the guide tube and its reflection on the silicon liquid surface of the silicon solution. Only the reflection of the lower edge of the lower opening on the silicon liquid surface can be observed, while the reflection of the upper edge of the lower opening on the silicon liquid surface cannot be observed. This avoids double reflections and improves the accuracy of the liquid outlet distance calculation.
[0051] like Figure 8 As shown, in the longitudinal section passing through the central axis E of the image monitoring device 1 and the furnace body 2, the acute angle α3 formed by the line connecting the lower edge 332 and the upper edge 331 of the lower opening 33 of the guide tube and the silicon liquid surface M is less than or equal to the acute angle α4 formed by the line connecting the reflection 31 of the lower edge 331 of the lower opening 33 of the guide tube on the silicon liquid surface M and the image monitoring device 1 and the silicon liquid surface M. That is, the image monitoring device 1 is located above the extension line C of the line connecting the reflection 31 of the lower edge 332 and the upper edge 331 of the lower opening 33 of the guide tube on the silicon liquid surface M. Therefore, the reflected light of the reflection of the upper edge 331 is not within the field of view of the image monitoring device 1, and the image monitoring device 1 cannot collect the double reflection, ensuring accurate positioning of the target liquid outlet distance and improving the success rate of pulling single crystal silicon rods.
[0052] like Figure 9 As shown, the distance between the guide tube and the molten silicon surface changes as the guide tube descends, and the distance between the lower opening of the guide tube and the molten silicon surface decreases. In one embodiment, when the guide tube is closest to the molten silicon surface M, the acute angle b4 formed by the line connecting the lower edge 332 and the upper edge 331 of the lower opening 33 of the guide tube and the molten silicon surface M through the longitudinal section of the central axis E of the image monitoring device 1 and the furnace body 2 is less than or equal to the acute angle b3 formed by the line connecting the lower edge 332 of the lower opening 33 on the molten silicon surface M and the image monitoring device 1 when the guide tube is closest to the molten silicon surface M and the molten silicon surface M. As the guide tube descends, the acute angle formed by the line connecting the lower edge 332 of the lower opening 33 on the molten silicon surface M and the image monitoring device 1 and the molten silicon surface M continuously decreases, as shown in the figure. Figure 9As shown, b1 > b2 > b3. This means that when the guide tube is closest to the silicon liquid surface M, the acute angle b3 formed by the line connecting the reflection of the lower edge 332 of the lower opening 33 on the silicon liquid surface M and the image monitoring component 1 with the silicon liquid surface M is the smallest. Therefore, as long as the acute angle formed by the line connecting the lower edge 332 and the upper edge 331 of the lower opening 33 of the guide tube with the silicon liquid surface M is less than or equal to the acute angle formed by the line connecting the reflection of the lower edge 332 of the lower opening 33 on the silicon liquid surface M and the image monitoring component 1 with the silicon liquid surface, it can be guaranteed that the guide tube will be positioned at the target liquid outlet distance. At any position of the flow tube relative to the silicon liquid surface M, the acute angle formed by the line connecting the lower edge 332 and the upper edge 331 of the lower opening 33 of the flow tube with the silicon liquid surface M is less than or equal to the acute angle formed by the line connecting the reflection of the lower edge 332 of the lower opening 33 on the silicon liquid surface M and the image monitoring device 1 with the silicon liquid surface M. That is, the image monitoring device 1 is always located above the extension line C of the line connecting the reflections of the lower edge 332 and the upper edge 331 of the lower opening 33 of the flow tube on the silicon liquid surface M. Therefore, during the process of locating the target liquid outlet distance, the reflected light from the reflection of the upper edge 331 is not within the field of view of the image monitoring device 1. Figure 3 As shown, image monitoring device 1 cannot capture double reflections, ensuring accurate positioning of the target liquid outlet distance and improving the success rate of pulling single crystal silicon rods.
[0053] like Figure 10The diagram shows the longitudinal section of the guide tube at its closest point to the silicon molten surface M, passing through the central axis E of the image monitoring device 1 and the furnace body 2. The vertical dashed line E represents the central axis E of the furnace body 2; the line connecting the reflection of the lower edge 332 to the image monitoring device 1 is F; the horizontal solid line M represents the silicon molten surface M; the intersection of F and M is O; the vertical dashed line N is a vertical line passing through point O; D1 is the vertical distance between the image monitoring device 1 and the central axis E; D2 is the vertical distance between the image monitoring device 1 and the silicon molten surface M; and D3 is the lower edge 33 of the lower opening 33 of the guide tube. The perpendicular distance between 32 and the central axis E, D4 is the minimum perpendicular distance between the lower edge 332 of the lower opening 33 of the guide tube and the silicon liquid surface M, D1, D2, D3, and D4 are all known. Let the perpendicular distance between the image monitoring device 1 and line N be x1, and the perpendicular distance between the lower edge 332 and line N be x2. Then we can get equation 1: x1 + x2 = D1 + D3, where B is the acute angle formed by F and M, and B1 is the acute angle formed by the line connecting the lower edge 332 of the lower opening 33 of the guide tube and point O and M. Since B and B1 are equal, we can obtain equation 2: tanB = D2 / x1 = tanB1 = D4 / x2. From equations 1 and 2, we get equation 3: x1 = D2(D1+D3) / (D2+D4). Therefore, we can obtain tanB = D2 / x1 = (D2+D4) / (D1+D3). Thus, we only need to ensure that the angle A between the line connecting the lower edge 332 and the upper edge 331 of the lower opening 33 of the guide tube and the silicon liquid surface satisfies tanA ≤ tanB, that is, A satisfies tanA ≤ (D2+D4). / (D1+D3) ensures that at any position of the guide tube from the silicon liquid surface M when positioning the target liquid outlet distance, the image monitoring device 1 is always located above the extension line C of the line connecting the lower edge 332 and the upper edge 331 of the guide tube on the silicon liquid surface M. Thus, during the positioning of the target liquid outlet distance, the reflected light of the upper edge 331 is always outside the field of view of the image monitoring device 1, and the image monitoring device 1 cannot collect the double reflection, ensuring accurate positioning of the target liquid outlet distance and improving the success rate of pulling single crystal silicon rods.
[0054] like Figure 4 As shown, in this embodiment, the image monitoring device 1 is connected to the control system (not shown). The image monitoring device 1 includes an imaging device, specifically, a camera. The crucible 5 includes a crucible body 51, a support member 52, and a lifting member 53. The support member 52 supports the crucible body 51, which contains silicon solution. The lifting member 53 is connected to the support member 52 and is used to drive the support member 52 and the crucible body 51 to rise and fall. The lifting member 53 is connected to the control system. During the positioning of the target liquid nozzle distance, the camera captures the lower edge 332 of the lower opening 33 of the guide tube and its reflection on the silicon solution surface. Image processing technology is used to calculate the liquid nozzle distance. Based on the feedback liquid nozzle distance, the control system controls the lifting member 53 to automatically adjust the rise and fall of the crucible body 51 so that the liquid nozzle distance reaches and remains at the target value.
[0055] When using the single crystal furnace of this utility model, silicon raw material is first filled into the crucible body 51, the heating element is activated, and the silicon raw material in the crucible body 51 is heated until the silicon raw material is completely melted to form a silicon melt. Then, the guide tube is lowered to the lower limit. When the guide tube is at the lowest position, the crucible body 21 is raised by the lifting element 53 to position the target liquid nozzle distance. During this process, the image monitoring element 1 collects the lower edge 332 of the lower opening 33 of the guide tube and its reflection on the silicon melt surface in real time. The rising position of the crucible body 51 is automatically adjusted by the image recognition and feedback control system to make the crucible body 51 reach and maintain the position of the target liquid nozzle distance. Next, the process of pulling single-crystal silicon rods, including crystal pulling, shoulder formation, and constant diameter growth, begins. During this process, as the silicon solution in the crucible body 51 gradually decreases, the crucible body 51 gradually increases to maintain the target liquid nozzle distance. When the single crystal growth reaches the preset length or quality requirement, the crucible body 51 stops rising, the heating element stops heating, and the single-crystal silicon rod is taken out after it has cooled to a suitable temperature, thus completing one growth cycle.
[0056] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.
[0057] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.
Claims
1. A flow guide tube, characterized in that, The device includes a cylindrical body with an upper opening at its upper end and a lower opening on its bottom surface, the diameter of which gradually decreases from top to bottom.
2. The guide tube according to claim 1, characterized in that, An inclined plane is formed between the upper and lower edges of the lower opening.
3. The guide tube according to claim 2, characterized in that, An inclined concave surface is formed between the upper and lower edges of the lower opening.
4. The guide tube according to claim 2 or 3, characterized in that, The bottom of the cylinder is coated with a dark color.
5. The guide tube according to claim 1, characterized in that, The diameter of the upper opening is larger than the diameter of the lower opening.
6. A single crystal furnace, characterized in that, Includes the furnace body and the crucible and guide tube coaxially arranged inside the furnace body. The furnace body is equipped with an image monitoring device. The crucible contains a silicon solution. The guide tube is disposed above the crucible and is a guide tube according to any one of claims 1-5. The image monitoring device captures the lower opening of the guide tube and the reflection of the lower opening on the silicon liquid surface of the silicon solution.
7. The guide tube according to claim 6, characterized in that, The image monitoring device captures images of the lower opening of the guide tube and its reflection on the silicon surface of the silicon solution. Only the reflection of the lower edge of the lower opening on the silicon surface can be observed, while the reflection of the upper edge of the lower opening on the silicon surface cannot be observed.
8. The single crystal furnace according to claim 7, characterized in that, In a longitudinal section passing through the central axis of the image monitoring device and the furnace body, the acute angle formed by the line connecting the lower edge and the upper edge of the lower opening of the guide tube and the silicon liquid surface is less than or equal to the acute angle formed by the line connecting the reflection of the lower edge of the lower opening of the guide tube on the silicon liquid surface and the image monitoring device and the silicon liquid surface.
9. The single crystal furnace according to claim 8, characterized in that, In a longitudinal section passing through the central axis of the image monitoring device and the furnace body, the acute angle formed by the line connecting the lower edge and the upper edge of the lower opening of the guide tube and the silicon liquid surface is less than or equal to the acute angle formed by the line connecting the reflection of the lower edge of the lower opening on the silicon liquid surface and the image monitoring device when the guide tube is closest to the silicon liquid surface.
10. The single crystal furnace according to claim 9, characterized in that, In a longitudinal section passing through the central axis of the image monitoring device and the furnace body, the acute angle formed by the line connecting the lower edge and the upper edge of the lower opening of the guide tube and the silicon liquid surface satisfies the following formula: tanA≤(D2+D4) / (D1+D3); Wherein, A is the acute angle formed by the line connecting the lower and upper edges of the lower opening of the guide tube and the silicon liquid surface; D1 is the vertical distance between the image monitoring device and the central axis; D2 is the vertical distance between the image monitoring device and the silicon liquid surface; D3 is the vertical distance between the lower edge of the lower opening of the guide tube and the central axis; and D4 is the minimum vertical distance between the lower edge of the lower opening of the guide tube and the silicon liquid surface.