Auxiliary heater, heating element for thermal field, and crystal pulling system

Abstract

The application provides a sub-heater, a heating body for a thermal field and a crystal pulling system, and relates to the technical field of manufacturing crystalline silicon. The sub-heater comprises a heating area enclosed by at least two pairs of circumferential heating petals and at least two oppositely distributed U-shaped connecting heating petals; the U-shaped connecting heating petal has two legs, the two legs are connected to form the U-shaped connecting heating petal in the direction of the axis towards the heating area, and the part where the two legs are connected is the U-shaped end; the inside of the heating area is hollow except the area of at least one pair of first electrode foot plates and the at least two oppositely distributed U-shaped connecting heating petals. Each component is separately processed, waste is reduced, the heat preservation property of the bottom of the thermal field is good, the crystal pulling power consumption is reduced, the crystal pulling power is reduced, the stability of the thermal field is good, the success rate of crystal pulling and discharging is high, and the oxygen content in the single crystal silicon rod is reduced. The hollow area reduces cost, prolongs service life, reduces processing complexity, and reduces the oxygen content in the single crystal silicon rod.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crystal silicon manufacturing, in particular to a sub-heater, a heating body for a thermal field and a crystal pulling system. BACKGROUND

[0002] The sub-heater is an important device for providing heat in the crystal pulling system. The inventor found that the sub-heater in the prior art causes high power consumption in the crystal pulling process during the research on the sub-heater in the prior art. SUMMARY

[0003] The present application provides a sub-heater, a heating body for a thermal field and a crystal pulling system, and aims to solve the problem of high power consumption in the crystal pulling process caused by the sub-heater.

[0004] In the first aspect of the present application, a sub-heater is provided, comprising: a heating area, at least one pair of first electrode foot plates oppositely distributed, the heating area being conductively connected with electrodes through the at least one pair of first electrode foot plates; the heating area being formed by at least two pairs of circumferential heating petals and at least two oppositely distributed U-shaped connecting heating petals; each circumferential heating petal being distributed along the circumference of the heating area.

[0005] The U-shaped connecting heating petal has two legs, the two legs being connected to form the U-shaped connecting heating petal in the direction of the axis towards the heating area, and the part connected by the two legs being a U-shaped end.

[0006] The interior of the heating area is hollow except the at least one pair of first electrode foot plates and the at least two oppositely distributed U-shaped connecting heating petals.

[0007] In the embodiment of the present application, the heating area is formed by at least two pairs of circumferential heating petals and two oppositely distributed U-shaped connecting heating petals. Compared with the sub-heater formed by the hole formed in the embryo, each component of the embodiment of the present application is obtained by separate processing, which reduces the generation of waste and can reduce the cost of the sub-heater. The U-shaped connecting heating petal has two legs, and the two legs are connected to form a U-shaped connecting heating petal in the direction of the axis of the heating area. The part connected by the two legs is a U-shaped end, that is, the U-shaped connecting heating petal is not arranged along the axis direction of the heating area, but has a certain angle with the axis direction of the heating area, thereby saving more space in the axis direction of the heating area. In the case of adapting to the original components, the original assembly space and the original installation method of the heat field, more layers or thicker pressboard felt can be arranged, so that the heat preservation of the bottom of the heat field is good, the crystal pulling power consumption is reduced, the crystal pulling power is reduced, and the heat field stability is good, the crystal pulling success rate is high, and the crystal pulling is beneficial. At the same time, the crystal pulling power consumption is reduced, the area of the main heater and the sub-heater directly irradiating the crucible is reduced, the precipitation rate of silicon dioxide in the crucible can be reduced, and the oxygen content in the single crystal silicon rod can be reduced. In the internal of the heating area, in addition to at least one pair of first electrode foot plates and at least two oppositely distributed U-shaped connecting heating, the area is hollowed out, the area of the hollowed-out area does not use production materials, which can reduce the production cost of the sub-heater, and the area of the hollowed-out area does not set components, which can reduce the probability of failure of the sub-heater, and can improve the service life of the sub-heater. At the same time, part of the hollowed-out area does not set components, which can reduce the processing complexity. And the hollowed-out area does not provide heat to the crucible, so the heating area of the bottom of the crucible is relatively small, and the precipitation rate of silicon dioxide in the crucible opposite to the hollowed-out area is slow, which can reduce the oxygen content in the single crystal silicon rod. That is, the above-mentioned hollowed-out area can reduce the oxygen content in the single crystal silicon rod on the basis of reducing cost, prolonging service life and reducing processing complexity.

[0008] Optionally, the axis of the U-shaped connecting heating petal is perpendicular to the axis of the heating area.

[0009] Optionally, the first electrode foot plate is fixed on the circumferential heating petal by a first bolt;

[0010] The two legs of the U-shaped connecting heating petal are fixed on the adjacent circumferential heating petal by a second bolt;

[0011] At least one of the first bolts is provided with a thermal expansion release hole along the axial direction of the first bolt, and / or at least one of the second bolts is provided with a thermal expansion release hole along the axial direction of the second bolt;

[0012] And / or the at least one pair of first electrode foot plates and the at least two oppositely distributed U-shaped connecting heating petals are uniformly distributed along the circumference of the heating area.

[0013] Optionally, the thermal expansion release hole on the first bolt is a through hole, and / or the thermal expansion release hole on the second bolt is a through hole.

[0014] Optionally, the thermal expansion release hole is a cylindrical hole, and the diameter of the thermal expansion release hole is 5-7 mm.

[0015] Optionally, the first bolt is a carbon-carbon bolt, and / or the second bolt is a carbon-carbon bolt.

[0016] Optionally, the axis of the thermal expansion release hole on the first bolt coincides with the axis of the first bolt, and the axis of the thermal expansion release hole on the second bolt coincides with the axis of the second bolt.

[0017] In a second aspect, the present application provides a heating body for a thermal field, comprising: a main heater and any of the foregoing auxiliary heaters.

[0018] Optionally, the main heater comprises at least one pair of second electrode foot plates distributed oppositely; each of the second electrode foot plates is arranged in a hollow region surrounded by two legs of a U-shaped connecting heating lobe corresponding in position.

[0019] Optionally, the auxiliary heater further comprises a first electrode arranged on each first electrode foot plate, and the first electrode is arranged in a direction parallel to the axis of the heating area of the auxiliary heater.

[0020] The main heater further comprises a second electrode arranged on each second electrode foot plate, and the second electrode is arranged in a direction parallel to the axis of the heating area of the auxiliary heater.

[0021] At least one first electrode is internally provided with a first cavity, and the first cavity is filled with quartz sand and / or adhesive felt.

[0022] And / or, at least one second electrode is internally provided with a second cavity, and the second cavity is filled with quartz sand and / or adhesive felt.

[0023] Optionally, the first cavity and the second cavity are both cylindrical cavities, and the diameter of the first cavity is less than or equal to the diameter of the second cavity.

[0024] In a third aspect, the present application provides a crystal pulling system, comprising: a single crystal furnace and any of the foregoing heating bodies for a thermal field arranged inside the single crystal furnace.

[0025] Optionally, the distance between the bottom end of the first electrode foot plate of the auxiliary heater and the furnace bottom of the single crystal furnace is 245-275 mm, and the bottom end of the first electrode foot plate is the end of the first electrode foot plate close to the furnace bottom of the single crystal furnace. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A three-dimensional structural schematic diagram of the first type of auxiliary heater in an embodiment of the present invention is shown;

[0028] Figure 2 A three-dimensional structural schematic diagram of the second type of auxiliary heater in an embodiment of the present invention is shown.

[0029] Figure 3 A schematic diagram of the planar structure of an auxiliary heater according to an embodiment of the present invention is shown;

[0030] Figure 4 A three-dimensional structural schematic diagram of a portion of an auxiliary heater in an embodiment of the present invention is shown;

[0031] Figure 5 A three-dimensional structural schematic diagram of a first bolt or a second bolt in an embodiment of the present invention is shown;

[0032] Figure 6 A cross-sectional view of a first bolt or a second bolt according to an embodiment of the present invention is shown.

[0033] Figure 7 This invention illustrates a schematic diagram of the planar structure of a main heater and an auxiliary heater assembled in a thermal field according to an embodiment of the present invention.

[0034] Figure 8 A partial planar structure schematic diagram of a crystal pulling system according to an embodiment of the present invention is shown;

[0035] Figure 9 A schematic diagram of a planar structure of a first electrode according to an embodiment of the present invention is shown;

[0036] Figure 10 A schematic diagram of another planar structure of the first electrode in an embodiment of the present invention is shown;

[0037] Figure 11 A schematic diagram of a planar structure of another first electrode according to an embodiment of the present invention is shown;

[0038] Figure 12 A schematic diagram of a planar structure of a second electrode according to an embodiment of the present invention is shown.

[0039] Brief Description of Drawings

[0040] 101 - first electrode foot plate, 102 - circumferential heating lobe, 103 - U-shaped connecting heating lobe, 104 - first bolt, 105 - second bolt, 106 - first electrode, 1031 - leg, 1032 - U-shaped end, 1041 - thermal expansion release hole, 1061 - first cavity, 201 - second electrode foot plate, 202 - heating lobe of main heater, 203 - second electrode, 2031 - second cavity, 301 - bottom pressing plate, 302 - pressing felt, 303 - bottom fixing felt, 304 - bottom felt, 401 - quartz sand, 402 - adhesive felt, 501 - furnace bottom of single crystal furnace. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0042] Figure 1 A perspective structural schematic diagram of a first sub-heater in an embodiment of the present application is shown. Figure 2 It can be a perspective structural schematic diagram viewed from the top of the sub-heater. Figure 2 A perspective structural schematic diagram of a second sub-heater in an embodiment of the present application is shown. Figure 2 It can be a perspective structural schematic diagram viewed from the bottom of the sub-heater. Figure 3 A planar structural schematic diagram of a sub-heater in an embodiment of the present application is shown. Figure 3 It can be a top view of the sub-heater. Figure 4 A perspective structural schematic diagram of a sub-heater in an embodiment of the present application is shown. Referring to Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown in the drawings, the sub-heater comprises a heating area, at least one pair of first electrode foot plates 101 oppositely distributed, and the heating area is conductively connected with electrodes through the at least one pair of first electrode foot plates 101. The heating area is formed by enclosing at least two pairs of circumferential heating lobes 102 and at least two oppositely distributed U-shaped connecting heating lobes 103. In comparison with the sub-heater formed by hole digging from the embryo, each component in the embodiment of the present application is obtained by separate processing, which reduces the generation of waste and can reduce the cost of the sub-heater. The shape of the heating area can be a cylindrical structure. Each circumferential heating lobe 102 is distributed along the circumference of the heating area. The number of circumferential heating lobes 102 in the heating area is not specifically limited. For example, Figure 1 , Figure 2 , Figure 3, Figure 4 In some embodiments, the number of the circumferential heating petals 102 in the heating zone is 4. In other embodiments, the number of the circumferential heating petals 102 in the heating zone can be 6, or the like. The number of the U-shaped connecting heating petals 103 in the heating zone is not limited either.

[0043] Figure 1 , Figure 2 , Figure 3 The axis of the heating zone is shown by the dashed line L. The inventors have found that the main reason for the high power consumption in the crystal pulling process caused by the existing secondary heater is that the U-shaped connecting heating petals are arranged along the axis of the heating zone. In the direction of the axis of the heating zone, the U-shaped connecting heating petals occupy a large amount of space, so that the thickness of the setting felt is thin, the heat insulation at the bottom of the thermal field is poor, the power consumption in the crystal pulling is high, the stability of the thermal field is poor, the success rate of the crystal pulling is low, and the crystal pulling is not conducive. In the embodiments of the present application, the U-shaped connecting heating petals 103 have two legs 1031, and the two legs 1031 are connected to form a U-shaped connecting heating petal 103 in the direction towards the axis L of the heating zone. The part connected by the two legs 1031 is the U-shaped end 1032. That is, the U-shaped connecting heating petal 103 is not arranged along the axis L of the heating zone, but is arranged at an angle with the axis of the heating zone. Thus, in the direction along the axis L of the heating zone, a large amount of space is saved, and more layers or thicker felt can be arranged under the condition of adapting to the original components, original assembly space and original installation mode of the thermal field, so that the heat insulation at the bottom of the thermal field is good, the power consumption in the crystal pulling is reduced, the power for pulling the crystal is reduced, the stability of the thermal field is good, the success rate of the crystal pulling is high, and the crystal pulling is conducive. At the same time, the power consumption in the crystal pulling is reduced in the embodiments of the present application, the area of the primary heater and the secondary heater directly irradiating the crucible is reduced, the precipitation rate of silicon dioxide in the crucible can be reduced, and thus the oxygen content in the single crystal silicon rod can be reduced.

[0044] In the embodiments of the present application, the angle between the axis of the U-shaped connecting heating petal 103 and the axis L of the heating zone is greater than 0°, and the specific angle is not limited. For example, the angle between the axis of the U-shaped connecting heating petal 103 and the axis L of the heating zone is 45°. It should be noted that the larger the angle, the smaller the space occupied by the U-shaped connecting heating petal 103 in the direction along the axis L of the heating zone, and the more layers or thicker felt can be arranged, so that the heat insulation at the bottom of the thermal field is better, and the power consumption in the crystal pulling is further reduced.

[0045] The inner part of the heating area is hollowed out except for at least one pair of first electrode foot plates 101 and at least two oppositely distributed U-shaped connecting heating petals 103. The hollowed-out area does not use production materials, which can reduce the production cost of the auxiliary heater. The hollowed-out area does not have components, which reduces the probability of failure of the auxiliary heater and improves the service life of the auxiliary heater. At the same time, the hollowed-out area does not have components, which can reduce the processing complexity. The hollowed-out area does not provide heat to the crucible, so the heating area of the bottom of the crucible is relatively small, the precipitation rate of the silicon dioxide in the crucible opposite to the hollowed-out area is slow, and the oxygen content in the single crystal silicon rod can be reduced. That is, the above-mentioned hollowed-out area can reduce the oxygen content in the single crystal silicon rod on the basis of reducing cost, prolonging service life, and reducing processing complexity.

[0046] The following table is a statistical result of the auxiliary heater of the embodiment of the present application:

[0047] Number of platen felt layers and thickness of single platen felt layer Average seeding power (kW) 11 layers (110 ± 2 mm) 64

[0048] The above table is the result of statistical data of 96 crystal pulling of the hot field using the auxiliary heater as shown in any one of Figures 1-4 The U-shaped connecting heating petals 103 have two legs 1031 in the embodiment of the present application, the two legs 1031 are connected to form a U-shaped connecting heating petal 103 in the direction of the axis L of the heating area, and the part connected by the two legs 1031 is a U-shaped end 1032. That is, the U-shaped connecting heating petal 103 is not arranged along the axis direction of the heating area, thereby saving more space in the direction of the axis L of the heating area. Compared with the prior art, the number of layers of the press felt with a thickness of 80±2 mm is only 8, and in the embodiment of the present application, the number of layers of the press felt with a thickness of 110±2 mm can be 11. That is, the number of layers of the press felt can be increased by three, and the thickness of the press felt is thicker, and the average seeding power is 64 kw, which is 3 kw lower than 67 kw of the prior art.

[0049] Alternatively, the axis of the U-shaped connecting heating petal 103 is perpendicular to the axis L of the heating area, that is, the U-shaped connecting heating petal 103 is arranged transversely perpendicular to the axis direction of the heating area, thereby saving more space in the direction of the axis L of the heating area. More layers or thicker press felt can be arranged in the case of adapting to the original components, original assembly space and original installation method of the hot field, so that the heat preservation of the bottom of the hot field is good, the crystal pulling power consumption is reduced, the seeding power is reduced, and the stability of the hot field is good, the seeding success rate is high, and the crystal pulling is facilitated. At the same time, the crystal pulling power consumption is reduced in the embodiment of the present application, the temperature of the main heater and the auxiliary heater directly irradiating the crucible is reduced, the precipitation rate of the silicon dioxide in the crucible can be further reduced, and the oxygen content in the single crystal silicon rod can be further reduced.

[0050] Optionally, the first electrode foot plate 101 is fixed on the circumferential heating petal 102 by the first bolt 104, and the two legs 1031 of the U-shaped connecting heating petal 103 are fixed on the adjacent circumferential heating petal 102 by the second bolt 105. Figure 5 A perspective structural schematic diagram of the first bolt or the second bolt in the embodiment of the application is shown. Figure 6 A cross-sectional structural schematic diagram of the first bolt or the second bolt in the embodiment of the application is shown. Referring to Figure 5 、 Figure 6 As shown in the drawings, at least one first bolt 104 is provided with a thermal expansion release hole 1041 along the axial direction of the first bolt 104, and / or at least one second bolt 105 is provided with a thermal expansion release hole along the axial direction of the second bolt 105. The thermal expansion release hole can release the expansion caused by heat, which can prevent the first bolt 104 or the second bolt 105 from being stuck in the bolt hole, reduce the firing or short circuit of the furnace table, and facilitate replacement. On the other hand, the thermal expansion release hole can release the expansion caused by heat, reduce the cracks of the first electrode foot plate 101, the first bolt 104, the second bolt 105, the leg 1031, and the circumferential heating petal 102, and thus improve the service life of the auxiliary heater.

[0051] It should be noted that the number of first bolts provided with the thermal expansion release hole is not specifically limited, and the number of second bolts provided with the thermal expansion release hole is also not specifically limited. For example, all the first bolts can be provided with the thermal expansion release hole, and none of the second bolts can be provided with the thermal expansion release hole. Alternatively, all the first bolts and all the second bolts can be provided with the thermal expansion release hole.

[0052] Optionally, as shown in the drawings, Figure 1 、 Figure 2 、 Figure 3 At least one pair of first electrode foot plates 101 and at least two oppositely distributed U-shaped connecting heating petals 103 are uniformly distributed along the circumferential direction of the heating area, which can adapt to the original components in the heat field, the original assembly space, and the original installation mode, and the heating of the crucible is more uniform.

[0053] Optionally, as shown in the drawings, Figure 5 、 Figure 6 The thermal expansion release hole 1041 on the at least one first bolt 104 is a through hole, and / or the thermal expansion release hole on the at least one second bolt 105 is a through hole, which can release more thermal expansion, and thus can prevent the first bolt or the second bolt from being stuck in the bolt hole to a greater extent, reduce the firing or short circuit of the furnace table, and further improve the service life of the auxiliary heater. The number of first bolts provided with the through hole is not specifically limited, and the number of second bolts provided with the through hole is also not specifically limited.

[0054] Optionally, referring to Figure 5 , Figure 6 The heat expansion releasing hole 1041 is a cylindrical hole, and the diameter d1 of the heat expansion releasing hole 1041 is 5-7 mm. In the process of releasing the heat expansion, the heat expansion releasing hole 1041 with the above shape is relatively uniform in each direction. The heat expansion releasing hole 1041 with the above diameter range can sufficiently release the heat expansion and has a relatively small influence on the fastening degree of the bolt connection. For example, the diameter d1 of the heat expansion releasing hole 1041 can be 5 mm, 6 mm or 7 mm.

[0055] Optionally, the at least one first bolt 104 is a carbon-carbon bolt, and / or the at least one second bolt 105 is a carbon-carbon bolt. Compared with bolts made of other materials, the carbon-carbon bolt is not only suitable for a thermal field environment, but also has a relatively good heat expansion performance in each direction and is relatively firm, which is beneficial to releasing the heat expansion. The number of the carbon-carbon bolt is not specifically limited.

[0056] Optionally, referring to Figure 5 , Figure 6 The axis of the heat expansion releasing hole 1041 on the first bolt 104 coincides with the axis of the first bolt 104, and the axis of the heat expansion releasing hole on the second bolt 105 coincides with the axis of the second bolt 105. The heat expansion is more uniform in each direction, the bolt structure is symmetrical, the stress in each direction is relatively balanced, and the service life of the bolt can be improved.

[0057] The embodiment of the present application also provides a heating body for a thermal field, which comprises a main heater and any one of the foregoing auxiliary heaters. The heating body for the thermal field can refer to the foregoing description about the auxiliary heater, and can achieve the same or similar beneficial effects.

[0058] Figure 7 A planar structure schematic diagram of a main heater and an auxiliary heater assembled in a thermal field is shown. The structure schematic diagram can be a bottom view. Referring to Figure 7 The main heater comprises at least one pair of second electrode foot plates 201 which are oppositely distributed. Each second electrode foot plate 201 is arranged in a hollow region surrounded by two legs 1031 of a U-shaped connecting heating lobe 103 corresponding in position, so that the space can be saved. The number of the second electrode foot plates 201 comprised by the main heater is also not specifically limited.

[0059] Figure 8 A partial planar structure schematic diagram of a crystal pulling system is shown. The structure schematic diagram can be a front view. Figure 9 A planar structure schematic diagram of a first electrode is shown. The structure schematic diagram can be a front view. Figure 8301 is a bottom protection plate, 302 is a pressure plate felt, 303 is a bottom fixing felt, and 304 is a bottom felt. The bottom felt 304 is set on the furnace bottom 501 of the single crystal furnace. 106 is a first electrode in the auxiliary heater that is set on a first electrode foot plate 101. The first electrode 106 is set in a direction parallel to the axis L of the heating zone of the auxiliary heater. The height h1 of the first electrode 106 can be 260-280mm. For example, the height h1 of the first electrode 106 is 260mm, 270mm, or 280mm. Figure 8 In the design, 202 is the heating element of the main heater. The main heater also includes a second electrode 203 disposed on each second electrode foot plate 201. The second electrode 203 is disposed in a direction parallel to the axis L of the heating zone of the auxiliary heater, and the height of the second electrode 203 is equal to the height h1 of the first electrode 106. The number of first electrode feet 101 is equal to the number of first electrodes 106, and the number of second electrode feet 201 is equal to the number of second electrodes 203.

[0060] Figure 10 A schematic diagram of another planar structure of the first electrode in an embodiment of the present invention is shown. Figure 11 A schematic diagram of a planar structure of another first electrode according to an embodiment of the present invention is shown. Figure 10 , Figure 11 This can be a front view. (Refer to...) Figure 9 , Figure 10 , Figure 11 As shown, a first electrode 106 has a first cavity 1061 inside, which is filled with quartz sand 401 and / or adhesive felt 402. This can further reduce crystal pulling power consumption and crystal pulling power, and also has good thermal stability and high release success rate, which is beneficial for crystal pulling.

[0061] Figure 12 A schematic diagram of a planar structure of a second electrode according to an embodiment of the present invention is shown. Optionally, refer to... Figure 12 As shown, at least one second electrode 203 has a second cavity 2031 inside, and the second cavity 2031 is filled with quartz sand ( Figure 12 (not shown in the image), and / or, filled with adhesive felt ( Figure 12 (not shown in the image), which can further reduce crystal pulling power consumption and crystal pulling power, and has good thermal stability and high lead-out success rate, which is beneficial for crystal pulling.

[0062] Reference Figure 9 , Figure 10 , Figure 11 , Figure 12As shown, the first cavity 1061 and the second cavity 2031 are both cylindrical cavities, and the diameter d2 of the first cavity 1061 is less than or equal to the diameter d3 of the second cavity 2031. The above shape and size can further reduce the crystal pulling power consumption, further reduce the crystal pulling power, and the thermal field stability is good, the crystal pulling success rate is high, and the crystal pulling is facilitated.

[0063] For example, in the case that the first cavity 1061 and the second cavity 2031 are both cylindrical cavities and the first cavity and the second cavity are both filled with glue felt, based on the above, the crystal pulling data of 96 furnaces is counted, and the crystal pulling power can be reduced by 5kw compared with the prior art. Figures 1-4

[0064] The embodiment of the present application also provides a crystal pulling system, which comprises a single crystal furnace and the aforementioned any one heating body for thermal field located inside the single crystal furnace, the crystal pulling system can refer to the relevant description of the heating body for thermal field, and the same or similar beneficial effects can be achieved.

[0065] Optionally, referring to Figure 8 As shown, the distance h2 between the bottom end of the first electrode foot plate 101 of the sub-heater and the furnace bottom 501 of the single crystal furnace is 245-275mm, and the bottom end of the first electrode foot plate 101 of the sub-heater is the end of the first electrode foot plate 101 of the sub-heater close to the furnace bottom 501 of the single crystal furnace. In the prior art, the U-shaped connecting heating petals are arranged along the axis direction of the heating area, and therefore, the U-shaped connecting heating petals of the sub-heater are closer to the furnace bottom than the first electrode foot plate, that is, the U-shaped connecting heating petals in the prior art occupy a large size along the axis direction of the heating area. In the prior art, the distance between the bottom end of the U-shaped connecting heating petals of the sub-heater and the furnace bottom of the single crystal furnace is usually 200-235mm. In the present application, the U-shaped connecting heating petals 103 are not arranged along the axis direction of the heating area, so that the first electrode foot plate 101 of the sub-heater is closer to the furnace bottom 501 of the single crystal furnace than the U-shaped connecting heating petals 103, and the distance between the bottom end of the first electrode foot plate 101 of the sub-heater and the furnace bottom 501 of the single crystal furnace is 245-275mm, and therefore, more layers or thicker pressure plate felt 302 can be arranged between the bottom end of the first electrode foot plate 101 of the sub-heater and the furnace bottom 501 of the single crystal furnace, so that the heat preservation of the bottom of the thermal field is good, the crystal pulling power consumption is reduced, the crystal pulling power is reduced, the thermal field stability is good, the crystal pulling success rate is high, and the crystal pulling is facilitated.

[0066] ​It should be noted that, in this document, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0067] Those skilled in the art can clearly understand the above-mentioned embodiment method can be realized by means of software and necessary general hardware platform, of course, also can be realized by hardware, but in many cases, the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of software product, and the computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), including a plurality of instructions to make a terminal (may be a mobile phone, computer, server, air conditioner, or network equipment, etc.) execute the method described in various embodiments of the present application.

[0068] The embodiments of the present application are described above in conjunction with the drawings, but the present application is not limited to the above-mentioned specific embodiments, and the above-mentioned specific embodiments are only illustrative, not restrictive. Those skilled in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims.

Claims

1. An auxiliary heater characterized by, The heating body comprises: a heating area, at least one pair of first electrode foot plates oppositely distributed, the heating area being electrically connected with electrodes through the at least one pair of first electrode foot plates; the heating area being formed by at least two pairs of circumferential heating petals and at least two oppositely distributed U-shaped connecting heating petals, at least one circumferential heating petal being arranged between any two adjacent U-shaped connecting heating petals, no circumferential heating petal being arranged at the position of the U-shaped connecting heating petal, and an aperture being formed between the circumferential heating petals adjacent to the position of the U-shaped connecting heating petal; each circumferential heating petal being distributed along the circumference of the heating area; the U-shaped connecting heating petal having two legs connected to form the U-shaped connecting heating petal in the direction of the axis of the heating area, and the part where the two legs are connected being a U-shaped end; the interior of the heating area being hollow except the at least one pair of first electrode foot plates and the at least two oppositely distributed U-shaped connecting heating petals.

2. The sub-heater of claim 1, wherein the axis of the U-shaped connecting heating petal being perpendicular to the axis of the heating area.

3. The sub-heater of claim 1, wherein the first electrode foot plates being fixed on the circumferential heating petals by first bolts; the two legs of the U-shaped connecting heating petal being fixed on the adjacent circumferential heating petals by second bolts; at least one of the first bolts being provided with a thermal expansion release hole along the axial direction of the first bolt, and / or at least one of the second bolts being provided with a thermal expansion release hole along the axial direction of the second bolt; and / or the at least one pair of first electrode foot plates and the at least two oppositely distributed U-shaped connecting heating petals being uniformly distributed along the circumference of the heating area.

4. The sub-heater of claim 3, wherein the thermal expansion release hole on at least one of the first bolts being a through hole, and / or the thermal expansion release hole on at least one of the second bolts being a through hole.

5. The sub-heater according to claim 3 or 4, characterized in that the thermal expansion release hole being a cylindrical hole, and the diameter of the thermal expansion release hole being 5-7 mm.

6. The sub-heater according to claim 3 or 4, characterized in that at least one of the first bolts being a carbon-carbon bolt, and / or at least one of the second bolts being a carbon-carbon bolt.

7. The sub-heater according to claim 3 or 4, characterized in that the axis of the thermal expansion release hole on the first bolt coinciding with the axis of the first bolt, and the axis of the thermal expansion release hole on the second bolt coinciding with the axis of the second bolt.

8. A heating element for a hot field, characterized by the heating body comprising a main heater and a sub-heater according to any one of claims 1-7.

9. The heating element for a hot top according to claim 8, wherein the main heater comprising at least one pair of second electrode foot plates oppositely distributed; each of the second electrode foot plates being arranged in the hollow region enclosed by the two legs of the U-shaped connecting heating petal at the corresponding position.

10. The heating element for a thermal field according to claim 9, wherein the sub-heater further comprising a first electrode arranged on each first electrode foot plate, the first electrode being arranged in the direction parallel to the axis of the heating area of the sub-heater; the main heater further comprising a second electrode arranged on each second electrode foot plate, the second electrode being arranged in the direction parallel to the axis of the heating area of the sub-heater; at least one of the first electrodes being internally provided with a first cavity, the first cavity being filled with quartz sand and / or adhesive felt; and / or at least one of the second electrodes being internally provided with a second cavity, the second cavity being filled with quartz sand and / or adhesive felt.

11. The heating element for a hot zone according to claim 10, wherein The first cavity and the second cavity are cylindrical cavities, and the diameter of the first cavity is less than or equal to the diameter of the second cavity.

12. A crystal pulling system characterized by, Comprise: A single crystal furnace and a heating body for a thermal field as claimed in any one of claims 8-11 located inside the single crystal furnace.

13. The crystal pulling system of claim 12 wherein, The distance between the bottom end of the first electrode foot plate of the auxiliary heater and the furnace bottom of the single crystal furnace is 245-275 mm; and the bottom end of the first electrode foot plate is the end of the first electrode foot plate close to the furnace bottom of the single crystal furnace.

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