Single crystal furnace

Abstract

The invention relates to a single crystal furnace which comprises a furnace body and a crucible assembly located in the furnace body, a guide cylinder is arranged above the crucible assembly and comprises a cylinder body, the cylinder body is provided with a top end close to the top of the furnace body, the top end is provided with a flange, and a plurality of through holes are formed in the flange in the circumferential direction of the cylinder body; a supporting ring is further arranged on the side wall of the furnace body and used for supporting the guide cylinder in the furnace body, a plurality of supporting columns in one-to-one correspondence with the through holes are arranged on the supporting face of the supporting ring, the lifting structure comprises a lifting rod connected with the flange, and the lifting rod is used for controlling the guide cylinder to move so as to be switched between a first state and a second state. In the first state, the supporting column is inserted into the through hole and located at the first position in the axial direction of the furnace body, and in the second state, the supporting column is supported on the flange and located at the second position in the axial direction of the furnace body, and the second position is located on the side, close to the top of the furnace body, of the first position.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor product manufacturing, and in particular to a single crystal furnace. Background Art

[0002] At present, the most widely used single crystal silicon production technology is to grow single crystal silicon rods in a crystal pulling furnace by the Czochralski method. In this method, the solid polysilicon raw material is placed in a crucible and heated by a heater to melt the polysilicon raw material in the crucible, and then goes through the process of temperature testing, seeding, shoulder release, shoulder rotation, equal diameter and finishing to finally complete the pulling of dislocation-free single crystal silicon rods.

[0003] A commonly used crystal pulling furnace has a guide tube, which is used to guide the inert gas entering the crystal pulling furnace so that the inert gas can be used to carry away the heat on the crystal surface and the silicon melt surface during the growth of polysilicon, so as to adjust the longitudinal and radial temperature gradients of the thermal field, and to facilitate the inert gas to carry away the silicon vapor in the crystal pulling process to avoid impurities affecting the quality of the single crystal silicon rod.

[0004] During the charging and mixing process of single crystal silicon production, in order to prevent the solid material pile from contacting the guide tube or the silicon melt from splashing onto the guide tube, the guide tube needs to be lifted to keep a certain distance from the surface of the silicon melt. However, during the charging process, the guide tube may shake under the purge of inert gas, causing the water cooling jacket adjacent to the guide tube to break due to collision with the guide tube. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a single crystal furnace to solve the problem of guide tube shaking.

[0006] In order to achieve the above object, the technical solution adopted in the embodiment of the present invention is: a single crystal furnace, comprising a furnace body and a crucible assembly located in the furnace body, wherein a guide tube is arranged above the crucible assembly,

[0007] The guide tube comprises a cylinder, the cylinder has a top end close to the top of the furnace body, the top end has a flange extending outward along the radial direction of the cylinder, and a plurality of through holes are arranged on the flange along the circumferential direction of the cylinder;

[0008] A support ring is also provided on the side wall of the furnace body, and the support ring is used to support the guide tube in the furnace body. A plurality of support columns corresponding to the plurality of through holes are provided on the support surface of the support ring.

[0009] The lifting structure includes a lifting rod connected to the flange, the lifting rod is used to control the movement of the guide tube to switch between a first state and a second state. In the first state, the support column is inserted into the through hole, and the guide tube is located at a first position in the axial direction of the furnace body. In the second state, the support column is supported on the flange, and the guide tube is located at a second position in the axial direction of the furnace body. The second position is located on the side of the first position close to the top of the furnace body.

[0010] Optionally, along the circumferential direction of the cylinder, a plurality of through holes are evenly arranged on the flange;

[0011] Along the circumferential direction of the support ring, a plurality of support columns are evenly arranged on the support surface.

[0012] Optionally, the support column is made of graphite.

[0013] Optionally, when the guide tube is located at the first position, there is a gap between the flange and the support ring.

[0014] Optionally, the lifting rod is in a Z-shaped structure, and the lifting rod includes a first connecting rod, a second connecting rod and a third connecting rod;

[0015] The extending direction of the first connecting rod is parallel to the axial direction of the furnace body;

[0016] An extension direction of the second connecting rod is perpendicular to an extension direction of the first connecting rod, and one end of the second connecting rod is connected to the first connecting rod;

[0017] The extension direction of the third connecting rod is parallel to the extension direction of the first connecting rod, one end of the third connecting rod is connected to an end of the second connecting rod away from the first connecting rod, and the other end of the third connecting rod is connected to the flange.

[0018] Optionally, the single crystal furnace further includes a rotating structure for rotating the lifting rod to drive the cylinder to rotate, so that the supporting column and the corresponding through hole are staggered.

[0019] Optionally, the lifting structure includes at least two lifting rods, and each of the lifting rods is connected to the flange via a connecting piece.

[0020] Optionally, the single crystal furnace further includes a displacement sensor for measuring the lifting distance of the guide tube.

[0021] Optionally, a quartz pin is provided at the bottom of the cylinder.

[0022] Optionally, the cylinder is conical, and the radial cross-sectional area of ​​the top of the cylinder is larger than the radial cross-sectional area of ​​the bottom of the cylinder.

[0023] The beneficial effects of the present invention are as follows: the single crystal furnace provided in this embodiment includes a guide tube, the guide tube includes a cylinder, the cylinder has a top end close to the top of the furnace body, the top end has a flange extending outward along the radial direction of the cylinder, and a plurality of through holes are arranged on the flange along the circumferential direction of the cylinder; a support ring is also arranged on the side wall of the furnace body, the support ring is used to support the guide tube in the furnace body, and a plurality of support columns corresponding to the plurality of through holes are arranged on the support surface of the support ring, and the guide tube can be converted between a first state and a second state under the control of a lifting structure, wherein, in the second state, the single crystal furnace is in a feeding and chemical stage, at this time, the support column is supported on the flange, so as to improve the stability of the guide tube, prevent the guide tube from shaking, and reduce the possibility of the guide tube colliding with the water cooling jacket due to shaking. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram showing a single crystal furnace in an embodiment of the present invention;

[0025] Figure 2 A schematic diagram showing a flow guide tube in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0027] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, similar words such as "one", "one" or "the" do not indicate quantity restrictions, but indicate that there is at least one. Similar words such as "include" or "comprise" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Similar words such as "connect" or "connected" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0028] The features such as "parallel", "perpendicular", and "same" used in the embodiments of the present disclosure include the features such as "parallel", "perpendicular", and "same" in a strict sense, as well as the cases where "approximately parallel", "approximately perpendicular", "approximately the same", etc. include certain tolerances, taking into account the tolerances associated with the measurement of specific quantities (e.g., the limitations of the measurement system), and represent the acceptable deviation range for a specific value determined by ordinary technicians in the field. For example, "approximately" can mean within one or more standard deviations, or within 3% or 5% of the value.

[0029] In addition, in this document, unless otherwise defined, the terms "substantially", "substantially", "approximately" and "about" are used to describe and explain small changes. When used with an event or situation, these terms can cover situations where the event or situation occurs exactly, and can also cover situations where the event or situation occurs approximately. For example, when used with a numerical value, these terms can include a range of variation of less than or equal to 10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, less than or equal to ±0.05%. The term "substantially coplanar" can refer to two surfaces being arranged along the same plane in the micrometer range, for example, arranged along the same plane within 40μm, 30μm, 20μm, 10μm or 1μm.

[0030] In the process of pulling the crystal rod through the seed crystal, a guide tube is arranged around the crystal rod. The guide tube is located above the crucible and is specifically in the shape of an inverted truncated cone with a large top and a small bottom. Its main function is to isolate the heat radiation of the heater to the crystal rod, ensure the temperature gradient required for the growth of the crystal rod, and increase the pulling speed of the growth of the single crystal silicon rod. In addition, it can also ensure the flow direction of the protective gas in the single crystal furnace, accelerate the gas flow rate of the silicon melt liquid surface, and take away volatile impurities, such as quickly taking away volatile oxygen, effectively reducing the oxygen content of the single crystal silicon rod and improving the quality of the single crystal silicon rod.

[0031] During the crystal pulling process, the guide tube is placed on the top ring in the furnace body and is supported and limited by the top ring. In the early stage of preparation, the solid polysilicon raw material (hereinafter referred to as silicon material) contained in the crucible may accumulate high, causing the silicon material to contact the guide tube. In addition, as the crystal pulling process progresses, the liquid level of the molten silicon in the crucible gradually decreases, and the crucible needs to be recharged in time. Moreover, when recharging, the silicon material is poured into the crucible from above, and the falling silicon material may cause the molten silicon to splash onto the surface of the guide tube. After the molten silicon condenses on the surface of the guide tube, it is difficult to clean and damages the surface of the guide tube.

[0032] In order to protect the guide tube, during the feeding stage, the guide tube needs to rise relative to the top ring so that the guide tube is at a certain distance from the surface of the silicon melt. However, after rising, the guide tube loses the support of the top ring. Since the molybdenum pendant connection method of the guide tube has a certain tolerance, the guide tube may shake under the purge of inert gas. Since the guide tube and the water cooling jacket are close, the shaking of the guide tube will increase the possibility of collision and rupture of the water cooling jacket. In addition, there is also a risk of the guide tube falling as a whole.

[0033] refer to Figure 1 and Figure 2 In view of the above problems, this embodiment provides a single crystal furnace, including a furnace body, a furnace cover 5 is arranged on the top of the furnace body, a crucible assembly 6 is arranged in the chamber in the furnace body, and a guide tube 1 is arranged above the crucible assembly 6.

[0034] The guide tube 1 comprises a cylinder, the cylinder has a top end close to the top of the furnace body, the top end has a flange 11 extending outward along the radial direction of the cylinder, and a plurality of through holes 101 are arranged on the flange 11 along the circumferential direction of the cylinder;

[0035] A support ring 2 is also provided on the side wall of the furnace body, and the support ring 2 is used to support the guide tube 1 in the furnace body. A plurality of support columns 3 corresponding to the plurality of through holes 101 are provided on the support surface of the support ring 2.

[0036] The lifting structure includes a lifting rod 4 connected to the flange 11, and the lifting rod 4 is used to control the movement of the guide tube 1 to switch between a first state and a second state. In the first state, the support column 3 is inserted into the through hole 101, and in the axial direction of the furnace body, the guide tube 1 is located in a first position. In the second state, the support column 3 is supported on the flange 11, and in the axial direction of the furnace body, the guide tube 1 is located in a second position, and the second position is located on the side of the first position close to the top of the furnace body.

[0037] In the first state, the support column 3 is inserted into the through hole 101. Compared with the related art, the guide tube 1 is only placed on the top ring, which improves the stability of the guide tube 1. The support column 3 and the through hole 101 cooperate to limit the guide tube 1 in the radial direction of the guide tube 1.

[0038] In the second state, the guide tube 1 rises to separate from the support column 3 and is supported on the flange 11 by the support column 3. Under the support of the support column 3, the stability of the guide tube 1 is improved to prevent the guide tube 1 from shaking.

[0039] In an exemplary embodiment, in the first state, the guide tube 1 may be in contact with the top ring and supported by the top ring.

[0040] It should be noted that, if the guide tube 1 is supported only by the support ring 2, the support ring 2 may be deflected due to assembly deviation or thermal expansion in a high temperature environment, thereby causing the guide tube 1 supported by the support ring 2 to be deflected or causing the bottom of the guide tube 1 to be not level, that is, not level on the plane where the radial direction of the bottom is located, that is, not centered in the vertical direction.

[0041] However, during the crystal pulling process, the lifting position of the crucible needs to be determined according to the liquid level of the silicon melt, and the liquid level of the silicon melt is usually measured by means of a quartz pin arranged at the bottom of the guide tube 1. Therefore, when the bottom of the guide tube 1 is not horizontal, the position of the quartz pin used to measure the liquid level is deflected, resulting in inaccurate measurement of the silicon melt level. In this case, the position of the crucible determined based on the silicon melt level will be inaccurate, resulting in differences in the lifting position of the crucible in different rounds of production, which ultimately affects the stability of single crystal silicon growth.

[0042] To solve the above problem, when the guide tube 1 is located at the first position, the pressure between the flange 11 and the support ring 2 is zero, there is a gap between the flange 11 and the support ring 2, or there is zero pressure contact between the flange 11 and the support ring 2.

[0043] The guide tube 1 moves to the first position under the action of the lifting structure, and is maintained at the first position under the lifting action of the lifting structure.

[0044] In an exemplary embodiment, when the guide tube 1 is located at the first position, it is suspended by the lifting structure, replacing the prior art of using the top ring to provide support for the guide tube 1 after it is lowered. In the present disclosure, the lifting force provided by the at least two lifting rods 4 can be used as the support force to keep the guide tube 1 in the first position, so that the guide tube 1 after it is lowered no longer relies on the support of the top ring, thereby preventing it from being affected by the deflection of the top ring. At this time, the support column 3 is inserted into the through hole 101, that is, the support column 3 and the through hole 101 cooperate to limit the guide tube 1 to prevent the guide tube 1 from shaking.

[0045] It should be noted that, regarding the setting of the first position and the second position, it can be imagined that the second position can be a position with a suitable distance from the crucible to ensure that the guide tube 1 is not affected by the silicon material during the feeding process. The first position can be a position that is just not in contact with the support ring 2, and there is a gap between the suspended guide tube 1 and the support ring 2. Alternatively, the first position can be a position that is just in contact with the support ring 2 but does not subject the support ring 2 to the pressure of the guide tube 1. Both the second position and the first position can be set in advance based on experience.

[0046] In an exemplary embodiment, along the circumferential direction of the cylinder, a plurality of through holes 101 are evenly arranged on the flange 11;

[0047] Along the circumferential direction of the support ring 2, a plurality of support columns 3 are evenly arranged on the support surface.

[0048] By adopting the above solution, the guide tube 1 can be subjected to uniform force, thereby preventing the guide tube 1 from being deflected.

[0049] In an exemplary embodiment, the support column 3 is made of graphite.

[0050] In an exemplary embodiment, the shape of the through hole 101 matches the cross-sectional shape of the support column 3. In the radial direction of the cylinder, the cross-sectional shape of the support column 3 can be square, circular, polygonal, etc., which is not limited here.

[0051] In a preferred embodiment, in the radial direction of the cylinder, the cross-sectional shape of the support column 3 is a square, and the shape of the through hole 101 is a square that matches the cross-sectional shape of the support column 3, so as to facilitate the insertion of the support column 3. The square arrangement effectively prevents the guide cylinder 1 from shaking.

[0052] In an exemplary embodiment, the lifting rod 4 is in a Z-shaped structure, and the lifting rod 4 includes a first connecting rod 41, a second connecting rod 42 and a third connecting rod 43;

[0053] The extending direction of the first connecting rod 41 is parallel to the axial direction of the furnace body, and one end of the first connecting rod 41 extends out of the furnace body to be connected to the driving structure;

[0054] The extension direction of the second connecting rod 42 is perpendicular to the extension direction of the first connecting rod 41, and one end of the second connecting rod 42 is connected to the first connecting rod 41;

[0055] The extension direction of the third connecting rod 43 is parallel to the extension direction of the first connecting rod 41 , one end of the third connecting rod 43 is connected to an end of the second connecting rod 42 away from the first connecting rod 41 , and the other end of the third connecting rod 43 is connected to the flange 11 .

[0056] Exemplarily, the lifting structure includes at least two lifting rods 4 arranged opposite to each other, and the lifting rods 4 adopt the above-mentioned Z-shaped structure. After the support column 3 is detached from the corresponding through hole 101, the first connecting rod 41 can be rotated so that the first connecting rod 41 rotates around its axial center line, thereby driving the cylinder body to rotate, thereby making the through hole 101 and the support column 3 staggered, that is, the support column 3 is supported on the area of ​​the flange 11 where the through hole 101 is not set, thereby supporting the cylinder body and preventing the guide tube 1 from shaking.

[0057] It should be noted that the rotation of the lifting rod 4 can be achieved manually or automatically. In an exemplary embodiment, the single crystal furnace also includes a rotating structure for automatically rotating the lifting rod 4 (rotating the part of the first connecting rod 41 exposed outside the furnace body) to drive the cylinder to rotate, so that the support column 3 and the corresponding through hole 101 are staggered.

[0058] It should be noted that the lifting structure includes at least two lifting rods 4 , and each of the lifting rods 4 is connected to the flange 11 via a connecting piece.

[0059] In the case of using the at least two lifting rods 4 of the present disclosure, before recharging the crucible, in order to prevent the solid or liquid silicon material in the crucible from contacting the guide tube 1, it is necessary to raise the guide tube 1. At this time, the two lifting rods 4 move upward in the vertical direction at the same time, thereby applying a lifting force upward in the vertical direction to the guide tube 1 by means of the connection points between the two lifting rods 4 and the guide tube 1, thereby pulling the guide tube 1 to rise with the two lifting rods 4.

[0060] After the addition of materials is completed, the guide tube 1 needs to be lowered to start the crystal pulling process. At this time, at least two of the lifting rods 4 move downward along the axial direction of the cylinder at the same time, thereby driving the guide tube 1 to descend along the axial direction of the cylinder, and finally making the guide tube 1 reach the second position. It should be understood that the second position to which the guide tube 1 descends can be the initial position (i.e., the first position) before the guide tube 1 rises.

[0061] In order to achieve the staggered setting of the through hole 101 and the corresponding support column 3, that is, to make the support column 3 supported on the area of ​​the flange 11 where the through hole 101 is not set, to achieve the support of the cylinder, it is necessary to control the lifting rod 4 to rotate to drive the cylinder to rotate. At this time, at least two of the lifting rods 4 are rotating at the same time and in the same direction.

[0062] In an exemplary embodiment, the single crystal furnace further includes a displacement sensor for measuring the lifting distance of the guide tube.

[0063] By setting the displacement sensor, the moving distance of the guide tube from the first position to the second position, or the distance from the second position to the first position can be measured and recorded, so as to serve as a reference standard for the lifting distance in the subsequent lifting process, saving time and improving efficiency.

[0064] In an exemplary embodiment, a quartz pin is disposed at the bottom of the cylinder, and the quartz pin forms a reflection on the liquid surface of the silicon melt.

[0065] Exemplarily, the single crystal furnace further includes a distance measuring structure, and the distance measuring structure is used to measure the distance between the bottom of the quartz pin and the reflection of the bottom;

[0066] Exemplarily, the single crystal furnace further includes a processing structure for controlling the position of the liquid level of the silicon melt to be at a preset position according to the distance between the bottom of the quartz pin and the reflection of the bottom.

[0067] In an exemplary embodiment, in order to avoid measurement deviation of the distance measuring structure due to liquid level fluctuation, at least two quartz pins are arranged at the bottom of the cylinder. The distance measuring structure is used to measure the distance between the bottom of each quartz pin and the reflection of the bottom; the processing structure obtains an average value based on multiple measurement results, and controls the position of the liquid level of the silicon melt to be at a preset position based on the average value. The control accuracy of the liquid level position of the silicon melt is improved, the influence of the liquid level change of the silicon melt on the growth of the crystal rod is reduced, and a higher quality single crystal silicon rod is obtained.

[0068] In an exemplary embodiment, the cylinder is conical, and the radial cross-sectional area of ​​the top of the cylinder is larger than the radial cross-sectional area of ​​the bottom of the cylinder.

[0069] In an exemplary embodiment, the crucible assembly is disposed in the inner cavity of the furnace body, and the crucible assembly includes a quartz crucible and a graphite crucible that are nested, and the quartz crucible contains a silicon solution.

[0070] In an exemplary embodiment, the single crystal furnace further includes:

[0071] A water cooling jacket is disposed between the guide tube and the crystal rod and partially overlaps with the guide tube in the axial direction of the furnace body to cool the drawn crystal rod;

[0072] A heating component is arranged around the crucible assembly and is used to heat the crucible assembly. The heating component is fixed to the bottom of the furnace body through electrode bolts and is connected to the heating electrode at the bottom of the furnace body.

[0073] A heat-insulating layer, disposed between the heating component and the side wall of the furnace body, for preventing the heat of the heating component from radiating to the outside of the furnace body;

[0074] A support shaft is supported and connected to the bottom of the graphite crucible; a crucible tray is arranged at the upper end of the support shaft, and the lower end of the support shaft passes through the bottom of the furnace body.

[0075] There are a few points to note:

[0076] (1) The drawings of the embodiments of the present disclosure only relate to the structures related to the embodiments of the present disclosure, and other structures may refer to the general design.

[0077] (2) For the sake of clarity, in the drawings used to describe the embodiments of the present disclosure, the thickness of layers or regions is exaggerated or reduced, that is, these drawings are not drawn according to the actual scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being "on" or "under" another element, the element may be "directly" "on" or "under" the other element or there may be intermediate elements.

[0078] (3) In the absence of conflict, the embodiments of the present disclosure and the features therein may be combined with each other to obtain new embodiments.

[0079] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A single crystal furnace, comprising a furnace body and a crucible assembly located in the furnace body, wherein a guide tube is arranged above the crucible assembly, characterized in that: The guide tube comprises a cylinder, the cylinder has a top end close to the top of the furnace body, the top end has a flange extending outward along the radial direction of the cylinder, and a plurality of through holes are arranged on the flange along the circumferential direction of the cylinder; A support ring is also provided on the side wall of the furnace body, and the support ring is used to support the guide tube in the furnace body. A plurality of support columns corresponding to the plurality of through holes are provided on the support surface of the support ring. The lifting structure includes a lifting rod connected to the flange, the lifting rod is used to control the movement of the guide tube to switch between a first state and a second state. In the first state, the support column is inserted into the through hole, and the guide tube is located at a first position in the axial direction of the furnace body. In the second state, the support column is supported on the flange, and the guide tube is located at a second position in the axial direction of the furnace body. The second position is located on the side of the first position close to the top of the furnace body.

2. The single crystal furnace according to claim 1, characterized in that: Along the circumferential direction of the cylinder, a plurality of through holes are evenly arranged on the flange; Along the circumferential direction of the support ring, a plurality of support columns are evenly arranged on the support surface.

3. The single crystal furnace according to claim 1, characterized in that: The support column is made of graphite.

4. The single crystal furnace according to claim 1, characterized in that: When the guide tube is located at the first position, there is a gap between the flange and the support ring.

5. The single crystal furnace according to claim 1, characterized in that: The lifting rod is in a Z-shaped structure, and comprises a first connecting rod, a second connecting rod and a third connecting rod; The extending direction of the first connecting rod is parallel to the axial direction of the furnace body; An extension direction of the second connecting rod is perpendicular to an extension direction of the first connecting rod, and one end of the second connecting rod is connected to the first connecting rod; The extension direction of the third connecting rod is parallel to the extension direction of the first connecting rod, one end of the third connecting rod is connected to an end of the second connecting rod away from the first connecting rod, and the other end of the third connecting rod is connected to the flange.

6. The single crystal furnace according to claim 5, characterized in that: It also includes a rotating structure for rotating the lifting rod to drive the cylinder to rotate, so that the support column and the corresponding through hole are staggered.

7. The single crystal furnace according to claim 1, characterized in that: The lifting structure includes at least two lifting rods, and each of the lifting rods is connected to the flange via a connecting piece.

8. The single crystal furnace according to claim 1, characterized in that: A displacement sensor is also included to measure the lifting distance of the guide tube.

9. The single crystal furnace according to claim 1, characterized in that: A quartz pin is arranged at the bottom of the cylinder.

10. The single crystal furnace according to claim 1, characterized in that: The cylinder is conical, and the radial cross-sectional area of ​​the top end of the cylinder is larger than the radial cross-sectional area of ​​the bottom end of the cylinder.

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