Protection device and method for preventing heat shield of single crystal furnace from being immersed in silicon liquid

Abstract

The invention discloses a protection device and method for preventing a heat shield of a single crystal furnace from being immersed into silicon liquid. The silicon liquid is contained in a crucible body; the crucible tray is located at the bottom where the crucible body is located, and a moving shaft moving in the vertical direction is arranged in the center of the bottom of the crucible tray. The heater wraps the periphery of the crucible body and continuously heats a silicon solution contained in the crucible body; the heat shield is located at the top of the crucible body, crystallization forming of a silicon solution is achieved through the heat shield, lifting movement of the crucible tray is synchronously achieved by controlling lifting of the movement shaft, and crystal pulling forming on the heat shield is achieved; and a gap is formed between the lower edge of the heat shield and the upper surface of the silicon solution of the crucible body. According to the protection device, the height of the silicon liquid is compared with a set protection parameter value, necessary early warning or alarm crucible stopping and lifting actions are achieved, accidents caused by the fact that a heat shield is immersed into the silicon liquid are prevented, and the safety coefficient of equipment is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of protective devices for silicon liquid, and in particular relates to a protective device and a method for preventing a single crystal furnace heat shield from being immersed in silicon liquid. Background Art

[0002] In a single crystal furnace, the heat shield is a key component. Its function is to keep the heat insulated, stabilize the temperature field in the furnace, improve the direction of the airflow in the furnace, and reduce the heat radiation from the heater to the crystal. The design of the heat shield directly affects the growth speed and quality of the single crystal. In the design and operation of the single crystal furnace, the protection device of the heat shield immersed in the silicon liquid is crucial, because it not only involves the service life and maintenance cost of the heat shield, but also the growth efficiency and quality of the single crystal silicon.

[0003] The heat shield is installed on the inside of the guide tube. There is cooling water inside the heat shield. When the heat shield is immersed in high-temperature silicon liquid due to employee misoperation or other reasons, the temperature of the heat shield body will rise rapidly, and the internal cooling water will vaporize at high temperature, causing the heat shield to explode and rupture. A large amount of internal cooling water will flow from the heat shield into the quartz crucible. The cooling water will vaporize instantly when it comes into contact with the high-temperature silicon liquid, causing the single crystal furnace pressure to be too high, resulting in the explosion of the single crystal furnace.

[0004] With the improvement of safety awareness, the market pays more and more attention to the safety of single crystal furnace equipment operation. When the single crystal furnace equipment is running, if the process parameters are not set correctly or there is a human error in operation, there is a certain probability that the heat shield will be immersed in the silicon solution. There is circulating cooling water inside the heat shield. The high-temperature silicon solution will cause the temperature of the heat shield to rise rapidly, the internal cooling water will vaporize instantly, and the internal pressure will be too high, causing the heat shield to explode and rupture, and the cooling water will overflow. When water encounters the silicon solution, it will vaporize rapidly, causing the single crystal furnace to explode, seriously affecting personal safety.

[0005] In the Chinese patent application announcement number CN107523869B, a water-cooled heat shield device for a single crystal furnace is disclosed, which includes a heat shield lifting device, a water-cooled heat shield, a heat shield upper ring, a heat shield lower ring, a heat shield outer ring, a heat field upper insulation cover, a quick-release nut, and an immersion protection device, which is used to be arranged above the quartz crucible in the single crystal furnace body. However, due to the irregular structure of the single crystal furnace, this method cannot effectively control the uniform lifting of the heat shield in the actual operation link, which will cause uneven crystallization of single crystal silicon and affect its purity. Summary of the invention

[0006] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a protective device and method for preventing the heat shield of a single crystal furnace from being immersed in silicon liquid, thereby solving the above-mentioned technical problems existing in the prior art.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A protective device for preventing a single crystal furnace heat shield from being immersed in silicon liquid, comprising a crucible body, a crucible tray, a heater, and a heat shield;

[0009] The crucible body contains a silicon solution;

[0010] The crucible tray is located at the bottom where the crucible body is located, and a movement axis that moves in an up-and-down direction is arranged at the bottom center of the crucible tray;

[0011] The heater forms a wrap around the periphery of the crucible body and continuously heats the silicon solution contained in the crucible body;

[0012] The heat shield is located on the top of the crucible body, and the silicon solution is crystallized by the heat shield. The lifting and lowering of the crucible tray is synchronously achieved by controlling the lifting and lowering of the motion axis, so that the crystal is pulled on the heat shield.

[0013] At the same time, a gap is formed between the lower edge of the heat shield and the upper surface of the silicon solution of the crucible body.

[0014] Further, the following steps are included:

[0015] S1. First, before the single crystal furnace is put into production, the lifting position of the crucible body is calibrated to the zero crucible position, so that the upper edge of the crucible body is flush with the upper edge of the main heater, which is used as the zero position of the motion axis;

[0016] S2, setting protection parameters, including the pre-alarm height of the silicon solution contained in the crucible body and the silicon solution height alarm stop crucible position;

[0017] S3, input the crucible body size parameters, and calculate the volume of each part of the crucible body in turn;

[0018] S4, input the density of the silicon solution ρ, and calculate the actual height of the silicon solution in the crucible body according to the volume dimensions of each part of the crucible body and the weight of the silicon material;

[0019] S5, subdividing the middle and lower parts of the crucible body into N equal parts in the height direction, and calculating the corresponding weights of the silicon solution at different silicon solution depths in the middle and lower parts of the crucible body, m1 and m2 respectively;

[0020] S6. The actual weight of the silicon solution carried in the crucible body is M, and is compared with the corresponding fully loaded silicon solution weights m1 and m2 at different silicon solution depths in the middle and lower parts of the crucible body 1;

[0021] When M≤m2, the system determines that the silicon solution in the crucible body is at the lower position, and at the same time determines the specific depth of the silicon solution;

[0022] When m2≤M≤m1+m2, the system determines that the silicon solution in the crucible body is in the middle position, and at the same time determines the specific depth of the silicon solution;

[0023] When M>m1+m2, the system determines that the silicon solution in the crucible body is at the upper position, and at the same time determines the specific depth of the silicon solution;

[0024] S7. Determine the real-time height of the silicon solution and issue an alarm or take action.

[0025] Furthermore, the crucible body in S3 includes a cylinder whose upper part is composed of a circle with a diameter of d, a frustum-like cone-shaped arc whose middle part is composed of a circular arc with a radius of r, and a spherical segment whose lower part is composed of a circular arc with a radius of R, and the volumes of respective parts of the crucible body are calculated as V1, V2, and V3 respectively.

[0026] Further, the volume of V1 is expressed as:

[0027]

[0028] Wherein, d represents the diameter of the upper cylinder, and h1 represents the vertical height of the upper cylinder.

[0029] Further, the volume of V2 is expressed as:

[0030]

[0031] Wherein, h2 represents the height of the sector-shaped ring shape in the vertical direction.

[0032] Further, the volume of V3 is expressed as:

[0033]

[0034] Among them, h3 represents the vertical height of the spherical part.

[0035] Furthermore, in S5, N equal parts are less than 1000 equal parts.

[0036] Furthermore, the step S7 specifically includes the following steps:

[0037] When the real-time silicon solution height is less than the preset alarm position of the silicon solution height, the distance between the bottom of the heat screen and the silicon solution is in the preset safety area, and the system does not give any prompts;

[0038] When the silicon liquid height alarm stop position > real-time silicon liquid height > silicon liquid height pre-alarm position, the system will give a pre-alarm prompt but will not take any substantial action;

[0039] When the real-time silicon liquid height is greater than the silicon liquid height alarm stop position, the system will give an alarm prompt and at the same time the system will stop the crucible from rising to achieve the detachment of the heat shield and direct contact with the upper part of the silicon solution.

[0040] Beneficial effects of the present invention:

[0041] 1. The present invention is a protection method for preventing the heat shield of a single crystal furnace from being immersed in silicon liquid. An alarm can be issued before the heat shield is immersed in silicon liquid during the crystal pulling process of the single crystal furnace to prevent major accidents from occurring.

[0042] 2. The present invention calculates the specific value of the silicon liquid height, and the system compares this value with the set pre-alarm position parameters and alarm shutdown position parameters to achieve early warning before the heat shield is immersed in the silicon solution, ultimately achieving the protection of preventing the single crystal furnace heat shield from being immersed in the silicon liquid.

[0043] 3. The present invention can effectively avoid the occurrence of heat shield immersion in silicon solution due to incorrect process parameters or human factors by adding a silicon solution height protection method in the electric control system. When the height of the silicon solution exceeds the set value, the system will promptly issue an early warning or alarm to stop the crucible lifting action, reminding the operator to handle it and avoid accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0045] Figure 1 is a schematic diagram of the overall cross-sectional structure of an embodiment of the present invention;

[0046] Figure 2 It is a partial structural schematic diagram of an embodiment of the present invention;

[0047] Figure 3 It is a schematic diagram of the size structure of the crucible body according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The technical scheme in the embodiment of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiment of the present invention. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] like Figure 1 , Figure 2 As shown, an embodiment of the present invention provides a protective device for preventing a single crystal furnace heat shield from being immersed in silicon liquid, comprising a crucible body 1, a crucible tray 2, a heater 3, and a heat shield 4;

[0050] The crucible body 1 contains silicon solution;

[0051] The crucible tray 2 is located at the bottom of the crucible body 1, and a moving shaft 21 for moving in the up and down direction is arranged at the bottom center of the crucible tray 2; the moving shaft 21 can realize the vertical movement of the crucible tray 2.

[0052] The heater 3 wraps around the outer circumference of the crucible body 1 and continuously heats the silicon solution contained in the crucible body 1 .

[0053] The heat shield 4 is located at the top of the crucible body 1, and the silicon solution is crystallized by the heat shield 4. The lifting and lowering of the crucible tray 2 is synchronously realized by controlling the lifting and lowering of the motion shaft 21, so that the crystal is pulled on the heat shield 4.

[0054] At the same time, a gap is formed between the lower edge of the heat shield 4 and the upper surface of the silicon solution in the crucible body 1 .

[0055] In addition, the present application also provides a method for preventing a single crystal furnace heat shield from being immersed in silicon liquid, comprising the following steps:

[0056] S1. First, before the single crystal furnace is put into production, the lifting position of the crucible body 1 is calibrated to the zero crucible position, so that the upper edge of the crucible body 1 is flush with the upper edge of the main heater, which serves as the zero position of the moving axis 21;

[0057] S2, setting protection parameters, including the pre-alarm height of the silicon solution contained in the crucible body 1 and the silicon solution height alarm stop crucible position;

[0058] S3, inputting the size parameters of the crucible body 1, and calculating the volume of each part in the crucible body 1 in sequence;

[0059] The crucible body 1 in S3 includes a cylinder with a circle of diameter d at the top, a truncated cone-like shape formed by an arc of radius r in the middle, and a spherical segment formed by an arc of radius R at the bottom. The volumes of the respective parts of the crucible body 1 are calculated as V1, V2, and V3.

[0060] like Figure 3 As shown, according to the similar triangle theorem, the basic parameters required to calculate the volume can be obtained.

[0061] The volume formula of a spherical segment is:

[0062] Trigonometric formula: sinA = opposite side / hypotenuse;

[0063] The volume formula of a truncated cone is:

[0064] Cylinder volume formula: V = πr 2 h;

[0065] Torus volume formula: V = 2π2 r 2 R;

[0066]

[0067] Wherein, d represents the diameter of the upper cylinder, and h1 represents the vertical height of the upper cylinder.

[0068] The volume of V2 is expressed as:

[0069]

[0070] Wherein, h2 represents the height of the sector-shaped ring shape in the vertical direction.

[0071] The volume of V3 is expressed as:

[0072]

[0073]

[0074] Among them, h3 represents the vertical height of the spherical part.

[0075] S4, input the density ρ of the silicon solution, and calculate the actual height of the silicon solution in the crucible body 1 according to the volume dimensions of each part of the crucible body 1 and the weight of the silicon material;

[0076] S5, subdividing the middle and lower parts of the crucible body 1 into N equal parts in the height direction (N equal parts are less than 1000 equal parts, the larger N is, the more precise the calculation result is, but when N is too large, too much system memory will be occupied, so this involving method of the present application can meet the memory requirements while ensuring the accuracy of its height subdivision), and calculating the corresponding weights of the silicon solution at different silicon solution depths in the middle and lower parts of the crucible body 1 are m1 and m2 respectively;

[0077] At this time, m=ρ*V; wherein ρ is the density of the silicon solution, and V is the volume occupied by the silicon solution. The weight of the silicon solution at different positions in the middle and lower parts of the crucible body 1 can be calculated separately according to the above formula.

[0078] S6. The actual weight of the silicon solution carried in the crucible body 1 is M, and is compared with the corresponding weights m1 and m2 of the silicon solution at different silicon solution depths in the middle and lower parts of the crucible body 1;

[0079] When M≤m2, the system retrieves the data of the array at the bottom of the crucible body 1 in the computer memory, finds the silicon liquid depth value corresponding to M, and uses this value as the final silicon liquid depth.

[0080] When m2≤M≤m1+m2, the system retrieves the data of the middle array of the crucible body 1 in the computer memory and finds the silicon liquid depth value corresponding to M. This value + the height of the lower part of the quartz crucible is used as the final silicon liquid depth.

[0081] When M>m1+m2, the system calculates the depth of the silicon solution above the crucible body 1 according to the volume calculation formula of the upper cylinder where the crucible body 1 is located.

[0082] S7. Determine the real-time height of the silicon solution and issue an alarm or take action.

[0083] The specific steps include:

[0084] When the real-time silicon solution height is less than the preset alarm position of the silicon solution height, the distance between the bottom of the heat shield 4 and the silicon solution is large and is in the preset safety area, and the system does not give any prompts.

[0085] When the silicon liquid height alarm stop position > real-time silicon liquid height > silicon liquid height pre-alarm position, the distance between the bottom of the heat screen 4 and the silicon solution is small, but it is still in a relatively safe position. The system gives a pre-alarm prompt but does not take any substantial action.

[0086] When the real-time silicon liquid height is greater than the silicon liquid height alarm stop position, the distance between the heat shield and the silicon liquid surface is small and is in a dangerous area. The system will give an alarm prompt and stop the crucible from rising to achieve heat shield 4 being out of direct contact with the upper part of the silicon solution.

[0087] In this application, according to the size of the quartz crucible installed in the thermal field of the equipment and the zero crucible position of the quartz crucible, according to the density of the silicon liquid after the silicon material is melted at high temperature, the height of the silicon liquid in the quartz crucible based on the zero crucible position is finally obtained through system calculation. When the height of the silicon liquid is greater than the set warning value, a pre-alarm is performed. When the height of the silicon liquid is greater than the set protection value, the crucible stops rising and an alarm is sounded.

[0088] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A protective device for preventing a single crystal furnace heat shield from being immersed in silicon liquid, characterized in that: It comprises a crucible body (1), a crucible tray (2), a heater (3), and a heat shield (4); The crucible body (1) contains a silicon solution; The crucible tray (2) is located at the bottom of the crucible body (1), and a moving shaft (21) that moves in an up-and-down direction is provided at the bottom center of the crucible tray (2); The heater (3) forms a wrap around the outer periphery of the crucible body (1) and continuously heats the silicon solution contained in the crucible body (1); The heat shield (4) is located on the top of the crucible body (1), and the silicon solution is crystallized by the heat shield (4). The lifting and lowering of the crucible tray (2) is synchronously achieved by controlling the lifting and lowering of the motion shaft (21), so that the crystal is pulled on the heat shield (4); At the same time, a gap is formed between the lower edge of the heat shield (4) and the upper surface of the silicon solution in the crucible body (1).

2. The method for preventing a single crystal furnace heat shield from being immersed in silicon liquid according to claim 1, characterized in that: The following steps are involved: S1. First, before the single crystal furnace is put into production, the lifting position of the crucible body (1) is calibrated to a zero crucible position, so that the upper edge of the crucible body (1) is flush with the upper edge of the heater (3), which serves as the zero position of the moving axis (21); S2, setting protection parameters, including the pre-alarm height of the silicon solution contained in the crucible body (1) and the silicon solution height alarm stop position; S3, inputting the dimension parameters of the crucible body (1), and calculating the volume of each part in the crucible body (1) in sequence; S4, inputting the density ρ of the silicon solution, and calculating the actual height of the silicon solution in the crucible body (1) according to the volume dimensions of each part of the crucible body (1) and the weight of the silicon material; S5, subdividing the middle and lower parts of the crucible body (1) into N equal parts in the height direction, and calculating the corresponding weights of the silicon solution at different silicon solution depths in the middle and lower parts of the crucible body (1), which are m1 and m2 respectively; S6, the actual weight of the silicon solution carried in the crucible body (1) is M, and is compared with the corresponding full-load silicon solution weights m1 and m2 at different silicon solution depths in the middle and lower parts of the crucible body (1); When M≤m2, the system determines that the silicon solution in the crucible body (1) is at the lower position, and at the same time determines the specific depth of the silicon solution; When m2≤M≤m1+m2, the system determines that the silicon solution in the crucible body (1) is in the middle position, and at the same time determines the specific depth of the silicon solution; When M>m1+m2, the system determines that the silicon solution in the crucible body (1) is at the upper position, and at the same time determines the specific depth of the silicon solution; S7. Determine the real-time height of the silicon solution and issue an alarm or take action.

3. The method for preventing a single crystal furnace heat shield from being immersed in silicon liquid according to claim 1, characterized in that: The crucible body (1) in S3 comprises a cylinder whose upper part is formed by a circle with a diameter of d, a sector-shaped ring body whose middle part is formed by an arc with a radius of r, and a spherical segment whose lower part is formed by an arc with a radius of R. The volumes of the respective parts of the crucible body (1) are calculated as V1, V2, and V3.

4. The method for preventing a single crystal furnace heat shield from being immersed in silicon liquid according to claim 3, characterized in that: The volume of V1 is expressed as: Wherein, d represents the diameter of the upper cylinder, and h1 represents the vertical height of the upper cylinder.

5. The method for preventing a single crystal furnace heat shield from being immersed in silicon liquid according to claim 3, characterized in that: The volume of V2 is expressed as: Wherein, h2 represents the height of the sector-shaped ring shape in the vertical direction.

6. The method for preventing a single crystal furnace heat shield from being immersed in silicon liquid according to claim 3, characterized in that: Said Among them, h3 represents the vertical height of the spherical part.

7. The method for preventing a single crystal furnace heat shield from being immersed in silicon liquid according to claim 2, characterized in that: In S5, N equal parts is less than 1000 equal parts.

8. The method for preventing a single crystal furnace heat shield from being immersed in silicon liquid according to claim 2, characterized in that: The S7 specifically includes the following steps: When the real-time silicon solution height is less than the preset alarm position of the silicon solution height, the distance between the bottom of the heat shield (4) and the silicon solution is in the preset safety area, and the system does not give any prompt; When the silicon liquid height alarm stop position > real-time silicon liquid height > silicon liquid height pre-alarm position, the system will give a pre-alarm prompt but will not take any substantial action; When the real-time silicon liquid height is greater than the silicon liquid height alarm stop position, the system will give an alarm prompt and at the same time the system will stop the crucible from rising to achieve the heat shield (4) being out of direct contact with the upper part of the silicon solution.

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