Single crystal furnace and cooling method

Abstract

The invention relates to the technical field of single crystal furnace cooling, and discloses a single crystal furnace cooling method which comprises the following steps: in a first gap between a heat preservation cover and a furnace body and a second gap between a crucible and a heat preservation cylinder, lifting a guide cylinder to a first height, lifting the heat preservation cover to a second height, and lifting the guide cylinder to a second height; a third gap is formed between the guide cylinder and the heat-insulating cover, and a fourth gap is formed between the heat-insulating cover and the heat-insulating cylinder; cooling gas is downwards injected into the middle of the crucible through the guide cylinder and continuously introduced for a period of time, and meanwhile gas in the heat preservation cylinder is pumped away through the suction opening. According to the cooling method, under the cooperation of the first gap, the second gap, the third gap and the fourth gap, the airflow trend in the furnace can be changed, and the cooling efficiency is improved. Meanwhile, the invention also provides the single crystal furnace for implementing the cooling method.

Description

Technical Field

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

[0002] The Czochralski crystal growth furnace, also known as a single crystal furnace, is a device used for single crystal growth. It is based on the Czochralski method and achieves high-quality growth of single crystal materials through precise thermal management and pulling speed. The core of the entire process lies in temperature control, seed selection and crystal pulling speed adjustment, which together determine the quality and performance of the final crystal.

[0003] After the existing single crystal furnace is shut down, the heat field needs to be cooled and cleaned before it can be restarted. Since the heat field structure of the existing crystal growth furnace is coated with carbon-based insulation materials, although it can ensure that the heat is lost as little as possible during the entire production process, it will cause the single crystal furnace to have a long waiting time for cooling down after the furnace is shut down. For example, CN114574943A discloses a single crystal furnace and a single crystal, which mainly discloses a single crystal furnace, including a furnace body and a furnace cover, in which a crucible, an insulation tube, an annular insulation platform, and an isolation tube are provided in the furnace body. The insulation tube includes an upper insulation tube, which is located at the top of the crucible, and the crucible is connected to the upper insulation tube; the annular insulation platform is arranged at the top of the upper insulation tube; the isolation tube is arranged on a plane of the annular insulation platform away from the crucible, and there is a preset gap between the top of the isolation tube and the furnace cover.

[0004] However, in the above technical solution, only the guide tube can be raised and lowered, and the annular insulation table cannot be separated from the insulation tube. The airflow can only enter and exit the crucible area from the gap between the guide tube and the annular insulation table. Therefore, after the furnace is stopped and the heating element is turned off, the heat of the insulation structure in the furnace and the remaining material in the crucible dissipates slowly, the cooling waiting time is long, and the production efficiency is low. Summary of the invention

[0005] The purpose of the present application is to solve the above-mentioned problem, and a cooling method for a single crystal furnace is provided. The cooling method is to raise the guide tube to a first height and the insulation cover to a second height, so that there is a third gap between the insulation cover and the guide tube, and a fourth gap between the insulation cover and the insulation tube, and the first gap between the insulation cover and the furnace body and the second gap between the crucible and the insulation tube are matched to change the direction of the airflow in the furnace and improve the cooling efficiency. At the same time, the present invention also provides a single crystal furnace for implementing the cooling method.

[0006] To achieve the above objectives, this application provides the following technical solutions:

[0007] A cooling method for a single crystal furnace, the method involving:

[0008] Single crystal furnace: comprising a furnace body, in which a heat preservation tube, a crucible and a liftable flow guide tube are arranged, a heat preservation cover is detachably placed on the heat preservation tube, a furnace opening is arranged on the top of the furnace body, an air exhaust port is arranged on the bottom of the furnace body, and the air exhaust port is located in the heat preservation tube; a first gap is provided between the heat preservation cover and the furnace body; a second gap is provided between the crucible and the heat preservation tube;

[0009] The cooling method is:

[0010] Lifting the guide tube to a first height and the insulation cover to a second height, so that a third gap exists between the guide tube and the insulation cover, and a fourth gap exists between the insulation cover and the insulation tube;

[0011] The cooling gas is injected downward into the middle of the crucible through the guide tube and the cooling gas is continuously introduced for a period of time, and at the same time, the gas in the insulation tube is extracted through the exhaust port.

[0012] The cooling gas used may be an inert gas, and preferably, the cooling gas used is argon.

[0013] Preferably, a liftable cooling water pipe is provided on the furnace body, the cooling water pipe is connected to the guide cylinder, and the cooling water pipe is used to drive the guide cylinder to be lifted to the first height.

[0014] Preferably, a conical portion is provided at the bottom end of the guide tube, and when the guide tube is at the first height, the conical portion is located above the heat preservation tube;

[0015] When the heat-insulating cover is located at the second height, the lowest point of the tapered portion is located between the top and the bottom of the heat-insulating cover.

[0016] Preferably, a ratio among the width of the first gap, the width of the second gap, the width of the third gap and the width of the fourth gap is 11:9:7-13:5-11.

[0017] Wherein, the width of the first gap, the width of the second gap, the width of the third gap and the width of the fourth gap are all defined by a vertical cross section of the single crystal furnace;

[0018] Specifically:

[0019] In the vertical section, the distance from the perpendicular line of the outer wall of the insulation cover to the inner wall of the furnace body is defined as the width of the first gap;

[0020] In the vertical section, the distance from the vertical line of the top of the crucible edge to the insulation tube is defined as the width of the second gap;

[0021] In the vertical section, the distance from the perpendicular line of the outer wall of the tapered portion of the guide tube to the top of the minimum inner diameter of the thermal insulation cover is defined as the width of the third gap;

[0022] In the vertical section, the vertical distance from the bottom of the thermal insulation cover to the top of the thermal insulation cylinder is defined as the width of the fourth gap.

[0023] In actual use, because the width of the first gap and the width of the second gap are fixed values ​​of the furnace body, it can be known that when the width of the third gap decreases, the width of the fourth gap will increase; and when the width of the third gap increases, the width of the fourth gap will decrease. Therefore, the ratio between the width of the first gap, the width of the second gap, the width of the third gap and the width of the fourth gap can be 11:9:13:5, that is, the third gap is smaller than the fourth gap. Of course, 11:9:7:11 can also be used, that is, the third gap is larger than the fourth gap. 11:9:9:9 can also be used, that is, the third gap is equal to the fourth gap. However, the present application is not limited to the listed values, and other values ​​not listed within this numerical range are applicable.

[0024] Preferably, the cooling method further relates to a lifting device, which comprises a lifting rod, and a plurality of bracket assemblies are provided at the bottom of the lifting rod; the bracket assemblies can swing from a vertical contracted state to a horizontal expanded state;

[0025] The lifting rod is driven downward into the furnace body by the external lifting mechanism until the support assembly in the retracted state passes through the guide tube and swings to the expanded state, and then the lifting rod is driven upward by the external lifting mechanism to make the support assembly contact with the insulation cover and lift the insulation cover to the second height.

[0026] Preferably, the lifting device also includes a tube body, which is provided with a flange. The tube body can be placed at the furnace mouth through the flange, and the tube body completely passes through the guide tube. The bracket assembly can be placed in the tube body in a retracted state and driven downward along the length of the tube body by an external lifting mechanism until the bracket assembly passes through the tube body. The bracket assembly can swing to the expanded state under its own weight.

[0027] Preferably, a rod body is further provided at the top of the tube body, and a through hole is provided on the rod body for the lifting rod to pass through;

[0028] The external lifting mechanism drives the lifting rod and the pipe body to move downward together, until the pipe body is placed on the furnace mouth through the flange, and then the external lifting mechanism drives the bracket assembly to move downward along the length of the pipe body.

[0029] Preferably, the bracket assembly includes a fixed block, a movable block, a plurality of support rods and a connecting rod, the fixed block is connected to the bottom of the lifting rod, the movable block is slidably connected to the lifting rod, the plurality of support rods are hinged to the side of the fixed block and arranged along the circumference of the lifting rod, the plurality of connecting rods correspond to the support rods one by one, and one end of the connecting rod is hinged to the support rod, and the other end is hinged to the movable block;

[0030] The free end of the support rod is provided with a convex block which is perpendicular to the top of the support rod; when the lifting rod moves upward, the convex block contacts the heat preservation cover and drives the heat preservation cover to move upward.

[0031] At the same time, the present application also provides a single crystal furnace, including a furnace body, a heat preservation tube, a crucible and a liftable guide tube are arranged in the furnace body, a heat preservation cover is detachably placed on the heat preservation tube, a furnace opening is arranged on the top of the furnace body, an air exhaust port is arranged on the bottom of the furnace body, and the air exhaust port is located in the heat preservation tube; a first gap is provided between the heat preservation cover and the furnace body; a second gap is provided between the crucible and the heat preservation tube;

[0032] It also includes a lifting module: used to lift the guide tube to a first height and lift the insulation cover to a second height, so that there is a third gap between the guide tube and the insulation cover, and there is a fourth gap between the insulation cover and the insulation tube;

[0033] The guide tube is used to continuously inject the cooling gas downward into the middle of the crucible;

[0034] The exhaust port is used to extract the gas in the insulation cylinder.

[0035] Preferably, the lifting module includes a cooling water pipe for lifting the guide tube and a lifting device for lifting the thermal insulation cover, the lifting device includes a lifting rod and a pipe body, and a plurality of bracket assemblies are provided at the bottom of the lifting rod; the bracket assemblies can swing from a vertical contracted state to a horizontal expanded state;

[0036] A rod body is also provided on the top of the tube body, and a through hole is provided on the rod body for the lifting rod to pass through; the bracket assembly can be placed in the tube body in a retracted state, and the rod body is used to limit the bracket assembly from detaching from the top of the tube body; a flange is also provided on the tube body, and the tube body can be placed at the furnace mouth through the flange.

[0037] Compared with the prior art, the beneficial effects of this application are:

[0038] The present invention raises the guide tube to a first height and the insulation cover to a second height, so that there is a third gap between the insulation cover and the guide tube, and a fourth gap between the insulation cover and the insulation tube, and cooperates with the first gap between the insulation cover and the furnace body and the second gap between the crucible and the insulation tube to change the direction of the airflow in the furnace and improve the cooling efficiency. At the same time, the present invention also provides a single crystal furnace for implementing the cooling method. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of a single crystal furnace of the present invention;

[0040] Figure 2 It is a structural schematic diagram of the lifting device of the present invention;

[0041] Figure 3 It is a working schematic diagram of the present invention;

[0042] Figure 4 is a schematic diagram of the first gap, the second gap, the third gap, and the fourth gap of the present invention;

[0043] Figure 5 It is a schematic diagram of gas flow of the present invention;

[0044] The reference numerals are as follows:

[0045] Furnace body 1; insulation tube 11; crucible 12; guide tube 13; furnace mouth 14; exhaust port 15; lifting device 16; cooling water pipe 17; insulation cover 111; tapered portion 131; lifting rod 161; bracket assembly 162; tube body 163; fixed block 1621; movable block 1622; support rod 1623; connecting rod 1624; protrusion 1625; flange 1631; rod body 1632; through hole 1633; first gap a; second gap b; third gap c; fourth gap d. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] Before describing the embodiments of the present invention, in order to compare the cooling efficiency between the prior art and the cooling method of the present invention, the cooling time of the single crystal furnace is recorded by using the cooling method of the prior art;

[0048] Specifically, after the single crystal furnace is shut down, the guide tube is driven to rise to a first height through the cooling water pipe, and argon gas is injected downward into the middle of the crucible through the guide tube and continuously introduced for a period of time, while the gas in the insulation tube is extracted through the exhaust port.

[0049] The cooling gas introduced in the following embodiments is also argon gas, and the duration, pressure, flow rate and temperature of the introduced argon gas are the same and are not limited in the embodiments.

[0050] The time for the crucible residue in the single crystal furnace to cool from 1400°C to 800°C is measured to be 4.2h;

[0051] The time for the remaining material in the crucible in the single crystal furnace to cool from 800°C to 200°C was measured to be 5.1h.

[0052] Example 1

[0053] refer to Figures 1 to 4A single crystal furnace comprises a furnace body 1, wherein a heat preservation tube 11, a crucible 12 and a guide tube 13 which can be raised and lowered are arranged in the furnace body 1, a heat preservation cover 111 is detachably placed on the heat preservation tube 11, a furnace opening 14 is arranged on the top of the furnace body 1, an air exhaust port 15 is arranged on the bottom of the furnace body 1, and the air exhaust port 15 is located in the heat preservation tube 11; a first gap a is formed between the heat preservation cover 111 and the furnace body 1; a second gap b is formed between the crucible 12 and the heat preservation tube 11;

[0054] It also includes a lifting module: used to lift the guide tube 13 to a first height and the insulation cover 111 to a second height, so that there is a third gap c between the guide tube 13 and the insulation cover 111, and there is a fourth gap d between the insulation cover 111 and the insulation tube 11;

[0055] The guide tube 13 is used to continuously inject the cooling gas downward into the middle of the crucible 12;

[0056] The exhaust port 15 is used to extract the gas in the heat preservation tube 11.

[0057] During operation, the guide tube 13 and the insulation cover 111 are in a close fit state to maintain the thermal field in the furnace body 1 and reduce heat dissipation and heat loss in the furnace. During the crystal pulling process, the cooling water pipe 17 drives the guide tube 13 to gradually rise to a first height, at which time the tapered portion 131 of the guide tube 13 is located above the insulation tube 11, until the crystal is completely pulled out, and the furnace body 1 enters the cooling stage.

[0058] In order to improve the cooling efficiency, during the cooling stage, the lifting device 16 lifts the insulation cover 111 to the second height so that the lowest point of the conical portion 131 is located between the top and bottom of the insulation cover 111. At this time, there is a third gap c between the insulation cover 111 and the guide tube 13, and a fourth gap d between the insulation cover 111 and the insulation tube 11, which cooperates with the first gap a between the insulation cover 111 and the furnace body 1, and the second gap b between the crucible 12 and the insulation tube 11; the airflow direction in the furnace is changed to improve the cooling efficiency.

[0059] It should also be noted that the width of the first gap a, the width of the second gap b, the width of the third gap c and the width of the fourth gap d are all defined by the vertical cross section of the single crystal furnace;

[0060] Specifically:

[0061] In the vertical section, the distance from the perpendicular line of the outer wall of the insulation cover 111 to the inner wall of the furnace body 1 is defined as the width of the first gap a;

[0062] In the vertical section, the distance from the vertical line of the top of the edge of the crucible 12 to the insulation tube 11 is defined as the width of the second gap b;

[0063] In the vertical section, the distance from the perpendicular line of the outer wall of the tapered portion 131 of the guide tube 13 to the top of the minimum inner diameter of the insulation cover 111 is defined as the width of the third gap c;

[0064] In the vertical section, the vertical distance from the bottom of the heat-insulating cover 111 to the top of the heat-insulating cylinder 11 is defined as the width of the fourth gap d.

[0065] The ratios of the widths of the first gap a, the second gap b, the third gap c and the fourth gap d are 11:9:7 to 13:5 to 11. It can be seen that when the width of the third gap c decreases, the width of the fourth gap d increases; and when the width of the third gap c increases, the width of the fourth gap d decreases.

[0066] Therefore, the ratio between the width of the first gap a, the width of the second gap b, the width of the third gap c and the width of the fourth gap d can be 11:9:13:5, that is, the third gap c is smaller than the fourth gap d. Of course, 11:9:7:11 can also be adopted, that is, the third gap c is larger than the fourth gap d. 11:9:9:9 can also be adopted, that is, the third gap c is equal to the fourth gap d.

[0067] In this embodiment, the lifting device 16 includes a lifting rod 161, and a plurality of bracket assemblies 162 are provided at the bottom of the lifting rod 161; the bracket assemblies 162 can swing from a vertical contracted state to a horizontal expanded state;

[0068] Specifically, the lifting rod 161 is driven downward into the furnace body 1 by an external lifting mechanism until the support assembly 162 in the retracted state passes through the guide tube 13 and swings to the expanded state, and then the lifting rod 161 is driven upward by the external lifting mechanism to make the support assembly 162 contact with the insulation cover 111 and lift the insulation cover 111 to the second height.

[0069] The advantage of this method is that there is no need to perform additional modifications on the furnace body 1 to add modules, and the same lifting mechanism is used as for crystal pulling, that is, after crystal pulling is completed, the crystal is taken out from the lifting mechanism, and the lifting rod 161 is connected to the lifting mechanism to perform the above-mentioned lifting operation. Of course, the lifting device 16 can also be lifted by connecting the power output end of the oil cylinder to the insulation cover 111, or by connecting the power output end of the screw rod to the insulation cover 111.

[0070] Furthermore, the lifting device 16 also includes a tube body 163, which is provided with a flange 1631. The tube body 163 can be placed at the furnace mouth 14 through the flange 1631, and the tube body 163 completely passes through the guide tube 13. The bracket assembly 162 can be placed in the tube body 163 in a retracted state and driven downward along the length of the tube body 163 by an external lifting mechanism until the bracket assembly 162 passes through the tube body 163. The bracket assembly 162 can swing to the expanded state under its own weight.

[0071] In actual use, the tube body 163 can ensure that the support assembly remains in a contracted state during the process of descending into the furnace body 1, thereby avoiding collision and friction between the support assembly and the guide tube 13. At the same time, after the tube body 163 is placed on the furnace mouth 14 through the flange 1631, it can guide the cooling air flow directly into the crucible 12 to contact the residual material in the crucible 12 and take away the heat of the residual material.

[0072] As a further optimization of this embodiment, a rod body 1632 is further provided on the top of the tube body 163, and a through hole 1633 is provided on the rod body 1632 for the lifting rod 161 to pass through;

[0073] Specifically, the external lifting mechanism drives the lifting rod 161 and the tube body 163 downward together, until the tube body 163 passes through the flange 1631 and rests on the furnace mouth 14, and then the external lifting mechanism drives the bracket assembly 162 downward along the length of the tube body 163. In this way, it can be ensured that the initial state of the bracket assembly is the retracted state, and the bracket assembly will swing to the expanded state only after it is separated from the tube body 163.

[0074] In this embodiment, the bracket assembly 162 includes a fixed block 1621, a movable block 1622, a plurality of support rods 1623 and a connecting rod 1624. The fixed block 1621 is connected to the bottom of the lifting rod 161, the movable block 1622 is slidably connected to the lifting rod 161, the plurality of support rods 1623 are hinged to the side of the fixed block 1621 and arranged along the circumference of the lifting rod 161, the plurality of connecting rods 1624 correspond to the support rods 1623 one by one, and one end of the connecting rod 1624 is hinged to the support rod 1623, and the other end is hinged to the movable block 1622.

[0075] During the process of swinging from the contracted state to the expanded state, the distance between the movable block 1622 and the fixed block 1621 gradually decreases, and the support rod 1623 gradually swings from the vertical state to the horizontal state, until the movable block 1622 and the fixed block 1621 contact each other, and the support rod 1623 is fixed in a horizontal state under the limitation of the connecting rod 1624.

[0076] Furthermore, the free end of the support rod 1623 is provided with a protrusion 1625 perpendicular to the top of the support rod 1623; when the lifting rod 161 moves upward, the protrusion 1625 contacts the insulation cover 111 and drives the insulation cover 111 upward. By adding the protrusion 1625, the support rod 1623 can more easily lift the insulation cover 111.

[0077] Example 2

[0078] A cooling method for a single crystal furnace, the method relates to the single crystal furnace of embodiment 1;

[0079] The cooling method is:

[0080] Lift the guide tube 13 to a first height, and lift the insulation cover 111 to a second height, so that there is a second gap b between the guide tube 13 and the insulation cover 111, and there is a third gap c between the insulation cover 111 and the insulation tube 11;

[0081] Argon gas is injected downward into the middle of the crucible 12 through the tube body 163 and continues to be introduced for a period of time, while the gas in the heat preservation tube 11 is extracted through the exhaust port 15.

[0082] refer to Figure 5 During the process of introducing argon gas, the argon gas contacts the residual material in the middle of the crucible 12 and moves toward the inner wall of the crucible 12, and under the action of the exhaust port 15, a first airflow flowing toward the second gap b and a second airflow upward are generated near the crucible 12;

[0083] The first airflow will be directly drawn out of the furnace body 1 by the air outlet 15, while the second airflow and the cooling airflow are relative airflows. When the second airflow rises to the top of the heat preservation tube 11, the continuous and rapid introduction of argon gas will cause a low-pressure area to be generated below the guide tube 13; the low-pressure area is caused by the high flow rate of argon gas, resulting in low pressure in the nearby area. Under the action of the low-pressure area, the furnace body 1 will generate three airflows;

[0084] The first is the third airflow generated at the top of the furnace body 1. The third airflow will pass through the third gap c from the top of the furnace body 1 into the heat preservation tube 11 and flow downward with the argon gas.

[0085] The second is that the rising second airflow will generate the first branch airflow flowing toward the low pressure area under the influence of the low pressure area;

[0086] The third is that the rising second airflow generates a second branch airflow passing through the third gap c and the first gap a;

[0087] Because the third airflow will make it difficult for the second airflow to pass through the third gap c to replenish gas for the top of the furnace body 1, the second airflow will be more inclined to generate a second branch airflow passing through the third gap c and the first gap a to replenish gas for the furnace body 1, thereby forming a circulating airflow in the furnace body 1 that comes out of the insulation tube 11, passes through the fourth gap d, the first gap a, and the third gap c in sequence, and then returns to the insulation tube 11.

[0088] In this embodiment, the ratio of the width of the first gap a, the width of the second gap b, the width of the third gap c and the width of the fourth gap d is 11:9:13:5.

[0089] The time for the crucible residue in the single crystal furnace to cool from 1400°C to 800°C was measured to be 3.2h;

[0090] The time taken for the remaining material in the crucible in the single crystal furnace to cool from 800°C to 200°C was measured to be 4 hours.

[0091] Example 3

[0092] It is basically the same as Example 2, except that the ratios among the width of the first gap a, the width of the second gap b, the width of the third gap c and the width of the fourth gap d are 11:9:7:11.

[0093] The time for the crucible residue in the single crystal furnace to cool from 1400°C to 800°C was measured to be 2.6h;

[0094] The time taken for the remaining material in the crucible in the single crystal furnace to cool from 800°C to 200°C was measured to be 3.6 hours.

[0095] Example 4

[0096] It is basically the same as Example 2, except that the ratio among the width of the first gap a, the width of the second gap b, the width of the third gap c and the width of the fourth gap d is 11:9:9:9.

[0097] The time for the crucible residue in the single crystal furnace to cool from 1400°C to 800°C was measured to be 2.9h;

[0098] The time taken for the remaining material in the crucible in the single crystal furnace to cool from 800°C to 200°C was measured to be 3.8 hours.

[0099] Result analysis: From the results of Examples 2 to 4, it can be seen that the heat dissipation efficiency of improving the insulation cover and the guide tube is significantly higher than that of only improving the guide tube, because with the cooperation of the first gap, the second gap, the third gap, and the fourth gap, a circulating airflow is formed in the furnace body, which comes out of the insulation tube, passes through the fourth gap, the first gap, and the third gap in sequence, and then returns to the insulation tube, making the airflow smoother, especially Example 3 with the highest heat dissipation efficiency. Example 3 adopts a method in which the width of the third gap is smaller than the width of the fourth gap. This method makes the third airflow passing through the third gap faster and enters the negative pressure area faster, while the second airflow is more inclined to generate a second branch airflow passing through the third gap and the first gap. Therefore, the results of Examples 2 and 4 are slightly worse than those of Example 3, but the difference is not obvious.

[0100] Compared with the prior art method of only lifting the guide tube, although there will be a first gap, a second gap, and a third gap, due to the lack of the fourth gap, the airflow can only enter and exit through the third gap, and a smooth airflow circulation cannot be formed, resulting in low heat dissipation efficiency.

[0101] In summary, the present invention changes the direction of the airflow in the furnace by lifting the guide tube to a first height and lifting the insulation cover to a second height so that there is a third gap between the insulation cover and the guide tube, and a fourth gap between the insulation cover and the insulation tube, in conjunction with the first gap between the insulation cover and the furnace body, and the second gap between the crucible and the insulation tube. Experiments have shown that when the width of the third gap is smaller than the width of the fourth gap, the cooling efficiency is highest.

[0102] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A cooling method for a single crystal furnace, characterized in that: The method involves: Single crystal furnace: comprising a furnace body, wherein a heat preservation tube, a crucible and a liftable flow guide tube are arranged in the furnace body, a heat preservation cover is detachably placed on the heat preservation tube, a furnace opening is arranged on the top of the furnace body, an air exhaust port is arranged on the bottom of the furnace body, and the air exhaust port is located in the heat preservation tube; a first gap is provided between the heat preservation cover and the furnace body; a second gap is provided between the crucible and the heat preservation tube; The cooling method is: Lifting the guide tube to a first height and the insulation cover to a second height, so that a third gap exists between the guide tube and the insulation cover, and a fourth gap exists between the insulation cover and the insulation tube; The cooling gas is injected downward into the middle of the crucible through the guide tube and the cooling gas is continuously introduced for a period of time, and at the same time, the gas in the insulation tube is extracted through the exhaust port.

2. The cooling method according to claim 1, characterized in that: The furnace body is provided with a lifting cooling water pipe, the cooling water pipe is connected to the guide cylinder, and the cooling water pipe is used to drive the guide cylinder to be lifted to a first height.

3. The cooling method according to claim 1, characterized in that: A conical portion is provided at the bottom end of the guide tube, and when the guide tube is located at the first height, the conical portion is located above the heat preservation tube; When the heat-insulating cover is located at the second height, the lowest point of the conical portion is located between the top and the bottom of the heat-insulating cover.

4. The cooling method according to claim 1, characterized in that: The ratio of the width of the first gap, the width of the second gap, the width of the third gap and the width of the fourth gap is 11:9:7-13:5-11.

5. The cooling method according to claim 1, characterized in that: The cooling method further relates to a lifting device, which comprises a lifting rod, and a plurality of bracket assemblies are provided at the bottom of the lifting rod; the bracket assemblies can swing from a vertical contracted state to a horizontal expanded state; The lifting rod is driven downward into the furnace body by an external lifting mechanism until the support assembly in the retracted state passes through the guide tube and swings to the expanded state, and then the lifting rod is driven upward by the external lifting mechanism to make the support assembly contact with the insulation cover and lift the insulation cover to the second height.

6. The cooling method according to claim 5, characterized in that: The lifting device also includes a tube body, which is provided with a flange. The tube body can be placed at the furnace mouth through the flange, and the tube body completely passes through the guide tube. The bracket assembly can be placed in the tube body in a retracted state and driven downward along the length of the tube body by an external lifting mechanism until the bracket assembly passes through the tube body. The bracket assembly can then swing to an expanded state under its own weight.

7. The cooling method according to claim 6, characterized in that: A rod body is also provided on the top of the tube body, and a through hole is provided on the rod body for the lifting rod to pass through; The external lifting mechanism drives the lifting rod and the tube body to move downward together, until the tube body is placed on the furnace mouth through the flange, and then the external lifting mechanism drives the bracket assembly to move downward along the length of the tube body.

8. The cooling method according to claim 5, characterized in that: The bracket assembly includes a fixed block, a movable block, a plurality of support rods and a connecting rod, the fixed block is connected to the bottom of the lifting rod, the movable block is slidably connected to the lifting rod, the plurality of support rods are hinged to the side of the fixed block and arranged along the circumference of the lifting rod, the plurality of connecting rods correspond to the support rods one by one, and one end of the connecting rod is hinged to the support rod, and the other end is hinged to the movable block; The free end of the support rod is provided with a convex block which is perpendicular to the top of the support rod; when the lifting rod moves upward, the convex block contacts the heat-insulating cover and drives the heat-insulating cover to move upward.

9. A single crystal furnace, characterized in that: The furnace body comprises a heat preservation tube, a crucible and a flow guide tube which can be raised and lowered. A heat preservation cover is detachably placed on the heat preservation tube. A furnace opening is arranged on the top of the furnace body. An air exhaust port is arranged on the bottom of the furnace body. The air exhaust port is located in the heat preservation tube. A first gap is provided between the heat preservation cover and the furnace body. A second gap is provided between the crucible and the heat preservation tube. It also includes a lifting module: used to lift the guide tube to a first height and lift the insulation cover to a second height, so that there is a third gap between the guide tube and the insulation cover, and there is a fourth gap between the insulation cover and the insulation tube; The guide tube is used to continuously inject cooling gas downward into the middle of the crucible; The exhaust port is used to extract the gas in the heat preservation cylinder.

10. The single crystal furnace according to claim 9, characterized in that: The lifting module includes a cooling water pipe for lifting the guide tube and a lifting device for lifting the thermal insulation cover. The lifting device includes a lifting rod and a tube body. A plurality of bracket assemblies are provided at the bottom of the lifting rod. The bracket assemblies can swing from a vertical contracted state to a horizontal expanded state. A rod body is also provided on the top of the tube body, and a through hole is provided on the rod body for the lifting rod to pass through; the bracket assembly can be placed in the tube body in a retracted state, and the rod body is used to limit the bracket assembly from detaching from the top of the tube body; a flange is also provided on the tube body, and the tube body can be placed at the furnace mouth through the flange.

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