Exhaust structure, single crystal furnace and crystal growth method

Abstract

The invention relates to an exhaust structure, a single crystal furnace and a crystal growth method.The exhaust structure is applied to the single crystal furnace and comprises an exhaust pipeline, one end of the exhaust pipeline is connected to the bottom of the single crystal furnace, the other end of the exhaust pipeline is connected with a vacuum pump, and at least part of the exhaust pipeline is a double-layer pipeline in the extension direction of the exhaust pipeline; the double-layer pipeline comprises an inner-layer pipeline and an outer-layer pipeline, and the inner-layer pipeline and the outer-layer pipeline are arranged in a spaced mode so that a containing space can be formed between the outer-layer pipeline and the inner-layer pipeline; a plurality of through holes are formed in the side wall of the inner-layer pipeline so that the interior of the inner-layer pipeline can communicate with the containing space. A gas inlet is formed in the side wall of the outer layer pipeline and communicates with the gas supply structure through a connecting pipe so as to supply compressed gas to the containing space. Compressed gas is introduced into the containing space through the gas inlet, and oxide attached to the inner wall of the exhaust pipeline can be impacted into the exhaust pipeline, so that discharge of the oxide is facilitated, and accumulation of the oxide in the exhaust pipeline is avoided.

Description

Technical Field

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

[0002] When growing a single crystal ingot, polysilicon is loaded into the quartz crucible of the crystal pulling furnace, and then the polysilicon is melted. The temperature of the melt is stable, and then the seed crystal is brought into contact with the melt to pull the crystal ingot. This method is widely used to pull single crystal ingots. The crystal pulling furnace will produce oxides in the process of melting polysilicon. An exhaust pipe is provided at the bottom of the existing crystal pulling furnace, and the generated oxides are evacuated from the furnace chamber (chamber) through the main pump to the exhaust pipe, and then discharged through the exhaust pipe. At present, due to the use of water cooling inside the exhaust pipe (the exhaust pipe adopts a double-layer pipe, and cooling water is contained between the double-layer pipes), due to the large temperature difference of the cold and heat exchange, the particles will be crystallized and attached to the inner wall of the pipe. In the long run, the pipe diameter will become smaller, the air extraction volume will become smaller, and the furnace pressure will be affected. The oxides produced in the crystal pulling furnace are of particle type, which will induce ingot dislocation during the growth of the ingot. If the pipe is over-accumulated, the generated oxides cannot be extracted in time, which will affect the quality of the ingot and the success rate of seeding. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides an exhaust structure, a single crystal furnace and a crystal growth method to solve the problem of oxide accumulation in the exhaust pipe and failure to discharge in time.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted in the embodiment of the present invention is: an exhaust structure applied to a single crystal furnace, comprising:

[0005] An exhaust pipe, one end of which is connected to the bottom of the single crystal furnace, and the other end of which is connected to a vacuum pump, and in the extension direction of the exhaust pipe, at least part of the exhaust pipe is a double-layer pipe;

[0006] The double-layer pipe comprises an inner pipe and an outer pipe, wherein the inner pipe and the outer pipe are arranged at an interval to form a receiving space between the outer pipe and the inner pipe;

[0007] A plurality of through holes are provided on the side wall of the inner layer pipe to connect the interior of the inner layer pipe with the accommodation space;

[0008] A gas inlet is arranged on the side wall of the outer layer pipe, and the gas inlet is connected with the gas supply structure through a connecting pipe to provide compressed gas to the accommodating space.

[0009] Optionally, the plurality of through holes are evenly distributed on the side wall of the inner layer pipe.

[0010] Optionally, the spacing between adjacent through holes is 2.5-3.5 mm.

[0011] Optionally, the through hole has a size of 1-2 mm.

[0012] Optionally, the through hole has a shape of circular, square, or polygonal.

[0013] Optionally, the distance between the inner layer pipe and the outer layer pipe is 0.4-0.6 mm.

[0014] Optionally, the length of the double-layer pipe is less than 3m.

[0015] Optionally, the compressed gas is cooling gas.

[0016] Optionally, the exhaust structure further includes:

[0017] A temperature sensor is disposed on the exhaust duct to measure the temperature inside the exhaust duct;

[0018] A solenoid valve is arranged on the connecting pipe;

[0019] The control unit is used to control the opening of the solenoid valve according to the temperature measured by the temperature sensor.

[0020] An embodiment of the present invention further provides a single crystal furnace, comprising a furnace body, and an exhaust structure arranged at the bottom of the furnace body, wherein the exhaust structure is the exhaust structure described above.

[0021] The embodiment of the present invention further provides a crystal growth method, which is applied to the above-mentioned single crystal furnace, comprising:

[0022] Immersing the seed crystal into silicon melt to seed the crystal to form a crystal rod;

[0023] Growing the crystal rods with equal diameter;

[0024] Finish and cool;

[0025] When cooling the crystal rod, cooling compressed gas is introduced into the accommodation space between the inner layer pipe and the outer layer pipe through the gas inlet.

[0026] The beneficial effects of the present invention are as follows: in the exhaust structure provided by the embodiment of the present invention, at least part of the exhaust pipe is set as a double-layer pipe, the double-layer pipe includes an inner pipe and an outer pipe, a gap is set between the inner pipe and the outer pipe to form a holding space, a plurality of through holes are set on the side wall of the inner pipe to connect the inside of the inner pipe with the holding space, a gas inlet is set on the side wall of the outer pipe, and the gas inlet is connected to the gas supply structure through a connecting pipe to provide compressed gas to the holding space. Through the gas inlet, compressed gas is introduced into the holding space, and the oxides attached to the inner wall of the exhaust pipe can be impacted into the exhaust pipe, so as to facilitate the discharge of the oxides and avoid the accumulation of oxides in the exhaust pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram showing an exhaust structure in an embodiment of the present invention;

[0028] Figure 2 for Figure 1 Enlarged schematic diagram of part A.

[0029] Figure 3 A schematic diagram showing an exhaust structure in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] refer to Figure 1-Figure 3 This embodiment provides an exhaust structure, which is applied to a single crystal furnace, including:

[0035] An exhaust pipe, one end of which is connected to the bottom 101 of the single crystal furnace, and the other end of which is connected to a vacuum pump 7. In the extension direction of the exhaust pipe, at least part of the exhaust pipe is a double-layer pipe 1;

[0036] The double-layer pipe 1 comprises an inner layer pipe 11 and an outer layer pipe 12, wherein the inner layer pipe 11 and the outer layer pipe 12 are arranged at intervals to form a receiving space between the outer layer pipe 12 and the inner layer pipe 11;

[0037] A plurality of through holes 111 are provided on the side wall of the inner layer pipe 11 to connect the interior of the inner layer pipe 11 with the accommodation space;

[0038] A gas inlet is provided on the side wall of the outer layer pipe 12, and the gas inlet is connected to the gas supply structure through the connecting pipe 2 to provide compressed gas to the accommodating space.

[0039] By introducing compressed gas into the containing space through the gas inlet, the oxides ( Figure 1 The small circle M in the figure represents oxide particles) impacts the exhaust pipe. Through the exhaust operation of the vacuum pump 7, the oxides in the exhaust pipe can be sucked out to avoid the accumulation of oxides in the exhaust pipe.

[0040] In an exemplary embodiment, the exhaust structure further includes an oxide collecting portion 6, which is disposed between the vacuum pump 7 and the gas inlet and is used to collect oxides exhausted from the exhaust pipe.

[0041] It should be noted that at least part of the exhaust pipe is constructed as the double-layer pipe 1. In the part of the double-layer pipe 1, the oxide is attached to the inner wall of the inner pipe 11. By continuously introducing compressed gas into the containing space, the oxide attached to the inner wall of the inner pipe 11 can be impacted into the interior of the inner pipe 11, that is, the interior of the exhaust pipe, so as to be sucked out by the vacuum pump 7.

[0042] In an exemplary embodiment, the temperature difference between the exhaust duct and the furnace chamber is large, and the closer to the furnace body, the more obvious it is. The double-layer pipe 1 is located at one end of the exhaust duct close to the bottom 101 of the furnace body, which can effectively prevent oxides from accumulating on the inner wall of the exhaust duct.

[0043] In an exemplary embodiment, a plurality of exhaust holes 1011 are disposed at the bottom 101 of the single crystal furnace. Corresponding to the plurality of exhaust holes 1011 , the exhaust duct includes a plurality of branch pipes 4 connected to the plurality of exhaust holes 1011 in a one-to-one correspondence.

[0044] The multiple branch pipes 4 can be arranged independently or combined. In some embodiments, the exhaust duct also includes a main pipe 5. The multiple branch pipes 4 are connected at one end away from the furnace body and connected to the main pipe 5. The other end of the main pipe 5 is connected to an external vacuum pump 7.

[0045] In an exemplary embodiment, along a direction away from the furnace body, the branch pipeline 4 includes a vertical portion and a curved portion, and the vertical portions of a plurality of the branch pipelines 4 are arranged in parallel.

[0046] In an exemplary embodiment, at least a portion of the vertical portion is constructed as the double-layer pipe 1 .

[0047] In an exemplary embodiment, the vertical portion is configured as the double-layer pipe 1 , and the curved portion includes a first region adjacent to the vertical portion, the first region being configured as the double-layer pipe 1 .

[0048] Due to the curved shape of the curved portion, oxides are more likely to accumulate in the curved portion. Therefore, in some embodiments, at least a portion of the curved portion is constructed as the double-layer pipe 1.

[0049] In an exemplary embodiment, the branch pipeline 4 is entirely constructed as the double-layer pipeline 1 .

[0050] In an exemplary embodiment, the plurality of through holes 111 are evenly distributed on the side wall of the inner layer pipe 11 .

[0051] In an exemplary embodiment, the curved portion is more likely to cause oxide accumulation, and therefore, the distribution density of the through holes 111 in the curved portion is greater than the distribution density of the through holes 111 in the vertical portion.

[0052] In an exemplary embodiment, the spacing between adjacent through holes 111 is 2.5-3.5 mm. For example, the spacing between adjacent through holes 111 may be 3 mm.

[0053] In an exemplary embodiment, the size of the through hole 111 is 1-2 mm. For example, the size of the through hole 111 may be 2 mm, but is not limited thereto.

[0054] It should be noted that the spacing between adjacent through holes 111 and the size of the through holes 111 can be set according to actual needs and are not limited to the above. The smaller the size of the through holes 111 and the smaller the spacing between adjacent through holes 111, the more conducive it is to remove the oxides attached to the inner wall of the exhaust pipe (it should be noted that in the part constructed as a double-layer pipe 1, the oxides are attached to the inner wall of the inner pipe 11).

[0055] In an exemplary embodiment, the through hole 111 has a shape of a circle, a square, or a polygon.

[0056] In an exemplary embodiment, the distance between the inner layer pipe 11 and the outer layer pipe 12 is 0.4-0.6 mm. In some embodiments, the distance between the inner layer pipe 11 and the outer layer pipe 12 is 0.5 mm, but not limited thereto.

[0057] The spacing between the inner layer pipe 11 and the outer layer pipe 12 is arranged as described above, which facilitates the control of the flow rate and pressure of the gas entering the containing space and can save costs.

[0058] In an exemplary embodiment, the length of the double-layer pipe 1 is less than 3 m.

[0059] The total length of the double-layer pipeline 1 should not be too long, because if the length of the double-layer pipeline 1 is too long, the flow rate of the gas ejected from the through hole 111 is difficult to control, which affects the effect of removing oxides.

[0060] In some embodiments, the length of the double-layer pipe 1 is greater than 1.5 m and less than 3 m, but is not limited thereto.

[0061] In an exemplary embodiment, the gas inlet is disposed at an end of the double-layer pipe 1 away from the bottom 101 of the furnace body, but the present invention is not limited thereto.

[0062] In the flow direction of the gas, the farther the through hole 111 is from the gas inlet, the greater the influence on the corresponding injected gas flow rate. In some embodiments, the gas inlet is arranged in the middle of the double-layer pipe 1 in its extension direction to reduce the difference in flow rate of the gas ejected from the multiple through holes 111.

[0063] In some embodiments, the distribution density of the plurality of through holes 111 on the side wall of the inner layer pipe 11 gradually increases along the direction away from the gas inlet, so as to effectively remove the oxides attached to the inner wall of the exhaust pipe.

[0064] In an exemplary embodiment, the compressed gas is a cooling gas.

[0065] After the single crystal ingot is grown in the single crystal furnace, it needs to be cooled to remove the ingot. During the cooling process, the compressed gas between the outer layer pipe 12 and the inner layer pipe 11 is the cooling gas, which can improve the cooling efficiency of the single crystal furnace and shorten the production time of the single crystal ingot.

[0066] It should be noted that, during the growth of a single crystal ingot, the compressed gas may be a high-temperature gas (the temperature of the high-temperature gas is lower than the temperature inside the furnace body, and the difference between the temperature of the high-temperature gas and the temperature inside the furnace body is less than a preset value), which can shorten the temperature difference between the exhaust duct and the furnace body's furnace chamber, and reduce the temperature difference between the inner and outer walls of the exhaust duct (the high-temperature gas discharged from the furnace body's furnace chamber enters the exhaust duct, resulting in a large temperature difference between the inner and outer walls of the exhaust duct). While effectively removing oxides attached to the inner wall of the exhaust duct, it can also prevent oxides from attaching to the inner wall of the exhaust duct.

[0067] In an exemplary embodiment, the exhaust structure further comprises:

[0068] A temperature sensor 3 is provided on the exhaust pipe to measure the temperature inside the exhaust pipe;

[0069] A solenoid valve is arranged on the connecting pipe 2;

[0070] The control unit is used to control the opening of the solenoid valve according to the temperature measured by the temperature sensor 3.

[0071] When a crystal ingot is produced by a single crystal furnace, after the crystal ingot has gone through the growth stages of seeding, shouldering, equal diameter growth, and tailing to form a crystal ingot, the crystal ingot needs to be cooled to remove the crystal ingot. In some embodiments, during the cooling stage of the crystal ingot, cooling compressed gas is introduced into the accommodation space between the outer layer pipe 12 and the inner layer pipe 11 through the gas inlet, which can effectively prevent oxides from accumulating in the exhaust pipe, improve cooling efficiency, and shorten cooling time.

[0072] In an exemplary embodiment, the temperature sensor 3 is a thermocouple temperature sensor, which includes an annular body and a probe exposed from the annular body. The annular body is sleeved on the outside of the exhaust pipe, and the probe is inserted into the interior of the exhaust pipe to measure the temperature inside the exhaust pipe.

[0073] Exemplarily, when the exhaust pipe includes a plurality of branch pipes 4 , the temperature sensor 3 is disposed on each branch pipe 4 .

[0074] In an exemplary embodiment, the compressed gas is an inert gas, such as nitrogen, but is not limited thereto.

[0075] In an exemplary embodiment, the gas in the furnace body and furnace chamber is discharged from the exhaust duct. In order not to affect the discharge of the gas in the furnace body and furnace chamber, the flow rate of the compressed gas entering the accommodating space from the gas inlet is lower than the flow rate of the gas discharged from the furnace body and furnace chamber into the exhaust duct.

[0076] In an exemplary embodiment, the flow rate of the compressed gas introduced into the accommodation space from the gas inlet is 30%-40% of the flow rate of the gas discharged from the furnace body and furnace chamber into the exhaust duct, but the present invention is not limited thereto.

[0077] In an exemplary embodiment, the pressure of the compressed gas introduced into the accommodation space from the gas inlet is lower than the pressure of the gas exhausted from the furnace body and furnace chamber into the exhaust duct.

[0078] In some embodiments, the pressure of the compressed gas introduced into the accommodation space from the gas inlet is 0.1-0.2 MPa, and the pressure of the gas discharged from the furnace body and furnace chamber into the exhaust duct is 0.4 MPa, but the present invention is not limited thereto.

[0079] An embodiment of the present invention further provides a single crystal furnace, comprising a furnace body, and an exhaust structure arranged at the bottom of the furnace body, wherein the exhaust structure is the exhaust structure described above.

[0080] The single crystal furnace specifically comprises:

[0081] a furnace body, the furnace body defining a chamber;

[0082] A crucible assembly is arranged in the inner cavity of the furnace body, the crucible assembly comprises a sleeved quartz crucible and a graphite crucible, and the quartz crucible contains a silicon solution;

[0083] A guide tube, the guide tube is used to guide the inert gas to the top of the silicon melt, wherein the guide tube is arranged on the periphery of the water cooling jacket;

[0084] 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.

[0085] 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;

[0086] 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.

[0087] The embodiment of the present invention further provides a crystal growth method, which is applied to the above-mentioned single crystal furnace, comprising:

[0088] Immersing the seed crystal into silicon melt to seed the crystal to form a crystal rod;

[0089] Growing the crystal rods with equal diameter;

[0090] Finish and cool;

[0091] When cooling the crystal rod, cooling compressed gas is introduced into the accommodation space between the inner layer pipe 11 and the outer layer pipe 12 through the gas inlet.

[0092] By adopting the above solution, the cooling efficiency can be improved during the cooling stage of the crystal rod, and the oxides can be effectively prevented from accumulating in the exhaust pipe.

[0093] Specifically, the crystal growth method includes:

[0094] First, the crystal raw material is placed in the crucible assembly and melted by the high temperature generated by the heating component.

[0095] Then, the molten silicon solution is slightly cooled to produce a certain degree of supercooling.

[0096] Then, a silicon single crystal (called a seed crystal) fixed on the seed crystal axis is inserted into the melt surface. After the seed crystal and the melt are melted, the seed crystal is slowly pulled upwards, and the crystal will grow at the lower end of the seed crystal.

[0097] Next, the seed crystal is controlled to grow a thin neck with a length of about 100 mm and a diameter of 3 mm to 5 mm to eliminate the dislocation of atomic arrangement caused by the strong thermal shock of the high-temperature solution on the seed crystal. This process is called seeding.

[0098] Subsequently, the crystal diameter is enlarged to the size required by the process, generally 75mm to 300mm. This process is called shoulder release.

[0099] Next, suddenly increase the pulling speed to perform the shoulder rotation operation so that the shoulder is approximately at a right angle.

[0100] Then, the equal-diameter process is entered, and single crystal columns of a certain size are grown by controlling the thermal field temperature and the crystal lifting speed.

[0101] Finally, when most of the silicon solution has completed crystallization, the crystals are gradually shrunk to form a tail-shaped cone, which is called the finishing process.

[0102] In this way, the single crystal pulling process is basically completed and it can be taken out after a certain period of insulation and cooling.

[0103] There are a few points to note:

[0104] (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.

[0105] (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.

[0106] (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.

[0107] 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. An exhaust structure, applied to a single crystal furnace, characterized in that: include: An exhaust pipe, one end of which is connected to the bottom of the single crystal furnace, and the other end of which is connected to a vacuum pump, and in the extension direction of the exhaust pipe, at least part of the exhaust pipe is a double-layer pipe; The double-layer pipe comprises an inner pipe and an outer pipe, wherein the inner pipe and the outer pipe are arranged at an interval to form a receiving space between the outer pipe and the inner pipe; A plurality of through holes are provided on the side wall of the inner layer pipe to connect the interior of the inner layer pipe with the accommodation space; A gas inlet is arranged on the side wall of the outer layer pipe, and the gas inlet is connected with the gas supply structure through a connecting pipe to provide compressed gas to the accommodating space.

2. The exhaust structure according to claim 1, characterized in that: The plurality of through holes are evenly distributed on the side wall of the inner layer pipe.

3. The exhaust structure according to claim 1, characterized in that: The distance between adjacent through holes is 2.5-3.5 mm.

4. The exhaust structure according to claim 1, characterized in that: The size of the through hole is 1-2 mm.

5. The exhaust structure according to claim 1, characterized in that: The through hole has a shape of a circle, a square or a polygon.

6. The exhaust structure according to claim 1, characterized in that: The distance between the inner layer pipe and the outer layer pipe is 0.4-0.6 mm.

7. The exhaust structure according to claim 1, characterized in that: The length of the double-layer pipe is less than 3m.

8. The exhaust structure according to claim 1, characterized in that: The compressed gas is cooling gas.

9. The exhaust structure according to claim 1, characterized in that: Also includes: A temperature sensor is disposed on the exhaust duct to measure the temperature inside the exhaust duct; A solenoid valve is arranged on the connecting pipe; The control unit is used to control the opening of the solenoid valve according to the temperature measured by the temperature sensor.

10. A single crystal furnace, characterized in that: It comprises a furnace body and an exhaust structure arranged at the bottom of the furnace body, and the exhaust structure is the exhaust structure according to any one of claims 1 to 9.

11. A crystal growth method, applied to the single crystal furnace according to claim 10, characterized in that: include: Immersing the seed crystal into silicon melt to seed the crystal to form a crystal rod; Growing the crystal rods with equal diameter; Finish and cool; When cooling the crystal rod, cooling compressed gas is introduced into the accommodation space between the inner layer pipe and the outer layer pipe through the gas inlet.

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