Heater and single crystal casting furnace

Abstract

The invention provides a heater and a single crystal casting furnace, and belongs to the technical field of single crystal casting equipment, the heater comprises a top heater and side heaters arranged around the top heater; the top heater comprises a plurality of heating belts which are connected with one another, and a circular area is defined by the plurality of heating belts; the heating belt comprises a plurality of bent sections which are connected with one another, and the bent sections are distributed in the circular area in a staggered mode. In the first direction, the distance between every two adjacent bent sections is larger than or equal to 30 mm and smaller than or equal to 50 mm. In the second direction, the distance between every two adjacent bent sections is larger than or equal to 8 mm and smaller than or equal to 12 mm. The first direction is perpendicular to the second direction. By means of the heater and the single crystal casting furnace, the uniformity of thermal field temperature distribution in the furnace body can be improved, and then the growth quality of crystals is improved.

Description

Technical Field

[0001] The present application relates to the technical field of single crystal casting equipment, and in particular to a heater and a single crystal casting furnace. Background Art

[0002] In the photovoltaic industry, the technology of multi-crystalline ingot casting is already very mature, and its thermal field structure is basically a simple amplification or power expansion based on the GT furnace. Some of them maintain the single power supply structure design of the GT furnace, and some of them are improved to dual power supply or multi-power supply structure. From the development history of multi-crystalline technology, with the increase of ingot casting feed or the amplification of thermal field, the improvement of dual power supply control mode is more conducive to the development of process and good control of crystal growth. The ingot casting single crystal adopts the technology of multi-crystalline dual power supply. The top and side heaters can be controlled separately, which is more diversified and refined than the control of single power supply.

[0003] However, existing single crystal ingot manufacturers, while still using multi-crystalline ingot furnaces, generally focus more on research and improvement of the side and bottom heaters, while ignoring the impact of the top heater on the thermal field, resulting in uneven temperature distribution of the entire thermal field, thereby affecting the overall crystal growth quality. It not only affects the increase in crystal dislocation density defects in the later stages of crystal growth, but the uneven coupling and superposition of the top heater temperature extends to the bottom, affecting the temperature distribution in the entire thermal field. Summary of the invention

[0004] The present application is to provide a heater and a single crystal casting furnace, aiming to improve the uniformity of the temperature distribution of the thermal field in the furnace body, thereby improving the growth quality of the crystal.

[0005] A first aspect of the present application provides a heater, comprising: a top heater and side heaters disposed around the top heater; The top heater comprises a plurality of mutually connected heating belts, and the plurality of heating belts enclose a circular area; The heating belt comprises a plurality of mutually connected bending sections, and the plurality of bending sections are staggeredly distributed in the circular area; Wherein, in the first direction, the distance between two adjacent bending segments is greater than or equal to 30 mm and less than or equal to 50 mm; In the second direction, the distance between two adjacent bending segments is greater than or equal to 8 mm and less than or equal to 12 mm; The first direction and the second direction are perpendicular to each other.

[0006] Optionally, the heater further comprises a plurality of side electrodes connected to the side heaters, wherein the side electrodes are used to be connected to a circuit and a copper electrode.

[0007] Optionally, the plurality of side electrodes are all located within the circular region, and the side electrodes and the heating belt are at the same position in the third direction; The third direction is perpendicular to both the first direction and the second direction.

[0008] Optionally, a graphite electrode is provided on the end of the heating belt, and the graphite electrode is threadedly connected to the heating belt.

[0009] Optionally, the top heater includes three heating belts, and the distribution area of ​​each heating belt within the circular area is the same.

[0010] Optionally, each of the heating belts has the same length.

[0011] Optionally, the top heater is configured as a symmetrical structure.

[0012] Optionally, the shape of the bending section is set to be U-shaped or arc-shaped.

[0013] A second aspect of an embodiment of the present application provides a single crystal casting furnace, comprising a furnace body and a heater provided in the first aspect of an embodiment of the present application and arranged in the furnace body.

[0014] Beneficial effects: The present application provides a heater and a single crystal casting furnace. A top heater and a side heater located around the top heater are provided. The top heater includes a plurality of heating belts connected to each other, and the plurality of heating belts form a circular area. The heating belts include a plurality of bending segments connected to each other, and the plurality of bending segments are staggered in the circular area. Meanwhile, in a first direction, a distance between two adjacent bending segments is greater than or equal to 30 mm and less than or equal to 50 mm. In a second direction, a distance between two adjacent bending segments is greater than or equal to 8 mm and less than or equal to 12 mm. In this way, by using a top heater with a plurality of staggered heating belts, the horizontal and vertical staggering density of the top heater can be increased, thereby better balancing the heat distribution and further improving the quality of crystal generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0016] Figure 1 is a structural schematic diagram of a heater proposed in one embodiment of the present application; Figure 2It is a schematic diagram of the planar structure of a top heater in a heater proposed in one embodiment of the present application; Figure 3 1 is a temperature distribution diagram of an axial cross section of a heater in the related art (left) and a heater proposed in an embodiment of the present application (right); Figure 4 1 is a heating temperature curve diagram of a heater in the related art and a heater proposed in an embodiment of the present application.

[0017] Explanation of the accompanying drawings: 1. Top heater; 11. Heating belt; 111. Bending section; 12. Graphite electrode; 13. First heating belt; 14. Second heating belt; 15. Third heating belt; 2. Side heater; 3. Side electrode; X, first direction; Y, second direction; Z, third direction. DETAILED DESCRIPTION

[0018] 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 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.

[0019] Reference Figure 1 As shown, a heater disclosed in an embodiment of the present application includes a top heater 1 and a side heater 2 arranged around the top heater 1 .

[0020] Specifically, the top heater 1 includes a plurality of mutually connected heating belts 11, that is, the plurality of heating belts 11 are connected end to end. Exemplarily, when the top heater 1 includes three heating belts 11, the tail end of the first heating belt 11 is connected to the start end of the second heating belt 11, the tail end of the second heating belt 11 is connected to the start end of the third heating belt 11, and the tail end of the third heating belt 11 is connected to the start end of the first heating belt 11. When the top heater 1 includes a greater number of heating belts 11, the heating belts 11 are also connected in this manner.

[0021] In the related art, the top heater 1 roughly presents a square structure after assembly, but since the furnace body structure of the single crystal casting furnace is circular, the distance between the four corners of the top heater 1 and the furnace body is quite different from the distance between the center position of the top heater 1 and the furnace body, that is, the four corners are closer to the furnace body, and the center position is more rounded to the furnace body, resulting in a large difference in heat distribution between the four corners and the center position. Specifically, the temperature of the four corners will be higher than the temperature of the center position, resulting in the balanced distribution of the entire heat field being affected.

[0022] For this purpose, refer to Figure 1 As shown, in the embodiment of the present application, a plurality of heating belts 11 surround a circular area, that is, after the plurality of heating belts 11 are connected to each other, the outer edges of the plurality of heating belts 11 will form a roughly circle, so that the top heater 1 and the furnace body can form a concentric circle structure, that is, the distance between each position of the top heater 1 and the furnace body is roughly the same, so that the temperature of each position on the top heater 1 is roughly the same, thereby improving the balance of the thermal field distribution.

[0023] It is understandable that the material of the heating belt 11 is graphite, and the heating belt 11 can generate heat when current is passed through the heating belt 11. Of course, the heating belt 11 can also include other materials, which is not specifically limited in the embodiment of the present application.

[0024] In the related art, the current trend in the square-structured top heater 1 is mostly horizontal (which can also be understood as a straight line direction), and the structural density layout and distribution of the top heater 1 are unbalanced, resulting in uneven heat distribution in the thermal field, affecting the debugging of the process technology and the growth quality of the crystal.

[0025] Reference Figure 1 As shown, in order to make the heat generated by the top heater 1 more uniform, in the embodiment of the present application, each heating belt 11 includes a plurality of bending segments 111, and the plurality of bending segments 111 are staggeredly distributed in the circular area.

[0026] Specifically, the shape of the bending section 111 may include a U-shape or an arc shape. In the embodiment of the present application, most of the bending sections 111 are U-shaped, and some of the bending sections 111 are arc-shaped. A heating belt 11 may be composed of a plurality of U-shaped bending sections 111, or a plurality of arc-shaped bending sections 111, or a plurality of U-shaped bending sections 111 and a plurality of arc-shaped bending sections 111.

[0027] In the embodiment of the present application, the top heater includes three heating belts 11 in total, and the three heating belts 11 are respectively a first heating belt 13, a second heating belt 14 and a third heating belt 15. The head end of the first heating belt 13 is connected to the tail end of the third heating belt 15, the tail end of the first heating belt 13 is connected to the head end of the second heating belt 14, and the tail end of the second heating belt 14 is connected to the head end of the third heating belt 15. Figure 1As shown, the first heating belt 13 is formed by an arc-shaped bending section 111, a U-shaped bending section 111, a circular arc-shaped bending section 111, a U-shaped bending section 111, a U-shaped bending section 111 and a U-shaped bending section 111 from the head end to the tail end; the second heating belt 14 is formed by a U-shaped bending section 111, a U-shaped bending section 111, a U-shaped bending section 111, a U-shaped bending section 111 and a U-shaped bending section 111 from the head end to the tail end; the third heating belt 15 is formed by a U-shaped bending section 111, a U-shaped bending section 111, a U-shaped bending section 111, a circular arc-shaped bending section 111, a U-shaped bending section 111 and a circular arc-shaped bending section 111 from the head end to the tail end.

[0028] It can be understood that the arc-shaped bending section 111 is a heating belt including an arc segment, and the U-shaped bending section 111 is a heating belt including at least two straight line segments, one end of the two straight line segments are connected, and there is an angle between the two straight line segments; there may also be an arc segment or a straight line segment between the two straight line segments.

[0029] The staggered distribution of the bending segments 111 in the circular area means that the position of each bending segment 111 in the circular area is not completely aligned. It is understandable that in a given circular area, the number of bending segments 111 can be increased so that multiple bending segments 111 completely occupy the entire circular area, and at the same time, by controlling the distance between two adjacent bending segments 111, the structural density of the top heater 1 can be controlled. It should be noted that the two adjacent bending segments 111 here can be two bending segments 111 in the same heating belt 11, or two bending segments 111 in different heating belts 11.

[0030] In the embodiment of the present application, in the first direction X, the distance between two adjacent bending segments 111 is greater than or equal to 30 mm and less than or equal to 50 mm; exemplarily, the distance between two adjacent bending segments 111 in the first direction X may be 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, etc.; in the second direction Y, the distance between two adjacent bending segments 111 is greater than or equal to 8 mm and less than or equal to 12 mm, exemplarily, the distance between two adjacent bending segments 111 in the second direction Y may be 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, etc.; those skilled in the art may set the distance between the bending segments 111 according to actual needs.

[0031] It should be noted that the first direction X and the second direction Y are perpendicular to each other.

[0032] In addition, the distance between two straight line segments in the bending segment 111 can also be set according to the above range.

[0033] In this way, by utilizing the setting of multiple bending segments 111, the current trend in the top heater 1 is no longer limited to the horizontal direction, and the multiple staggered bending segments 111 can increase the structural density of the top heater 1, thereby increasing the radiation intensity per unit area of ​​the top heater 1. At the same time, by controlling the distance between the heating belts 11, the structural density of the top heater 1 can be better controlled, thereby making the heat distribution on the top heater 1 more uniform.

[0034] In addition, after the heater trend and the horizontal and vertical staggered density are improved, the original overall downward shift trend of the center temperature center of gravity is significantly improved (lateral temperature zone optimization), which can greatly reduce the proliferation rate of head dislocations, thereby reducing dislocations at the crystal head.

[0035] In addition, refer to Figure 3 and Figure 4 As shown, Figure 3 The middle left figure is a temperature distribution diagram of the axial cross section of the heater in the related art. Figure 3 The right figure is a temperature distribution diagram of the axial section of the heater provided in the embodiment of the present application, Figure 3 It can be seen that from the comparison between the isothermal curve of the silicon melt in the crucible inside the hot field and the temperature curve of the top heater 1, under the simulation under the same conditions, the temperature of the circular top heater 1 will be about 100 degrees higher (it can be understood that the darker the color of the relevant area in the figure, the higher the temperature of the area). Therefore, the effective heating value of the heater body is increased, the heating efficiency is improved, and it diffuses into the bottom melt, the temperature rises by about 50 degrees. At the same time, the isothermal curve inside the melt is more uniform, which reduces the energy consumption of the overall hot field, optimizes the melt temperature field distribution, and improves the convection intensity.

[0036] In an optional embodiment, referring to Figure 1 As shown, the embodiment of the present application further provides a heater, which also includes a plurality of side electrodes 3.

[0037] Specifically, the side electrode 3 is connected to the side heater 2 , and the side electrode 3 is used for connection with the copper electrode circuit and for hanging the side heater.

[0038] In one embodiment, the plurality of side electrodes 3 are all located in a circular region, and the side electrodes 3 and the heating belt 11 are at the same position in the third direction Z. The third direction Z is perpendicular to both the first direction X and the second direction Y. It is understandable that the third direction Z is also a direction perpendicular to the plane where the top heater 1 is located.

[0039] Of course, the side electrode 3 may also be arranged at the position where the side heater 2 is located, or the side electrode 3 and the heating belt 11 are not at the same position in the third direction.

[0040] In one embodiment, a graphite electrode 12 is disposed at the end of each heating belt 11, and the graphite electrode 12 is threadedly fastened to the heating belt 11 using a carbon-carbon screw and a carbon-carbon nut. The graphite electrode 12 is connected to a top power supply to provide current to the heating belt 11.

[0041] Reference Figure 2 As shown, in one embodiment, the top heater 1 includes three heating belts 11, and the distribution area of ​​each heating belt 11 in the circular region is the same.

[0042] Specifically, the three heating belts 11 present a distribution structure with an angle of 120 degrees in the circular area, that is, each heating belt 11 occupies 1 / 3 of the circular area, so that the heating of three equally divided independent areas can be uniformly achieved. Of course, the three heating belts 11 are not completely confined to the corresponding area, and the end of the heating belt 11 may be partially located in the area where the other heating belts 11 are located.

[0043] Reference Figure 2 As shown, in the embodiment of the present application, the three heating belts 11 are respectively a first heating belt 13, a second heating belt 14 and a third heating belt 15, wherein the first heating belt 13 and the third heating belt 15 are symmetrically distributed about a first straight line, the first straight line is a diameter line of a circular area parallel to the first direction, and the second heating belt 14 itself is symmetrically distributed about the first straight line, that is, the entire top heater 1 is a symmetrical structure, and this symmetrical structure can increase the uniformity of the temperature field in the top temperature zone.

[0044] Of course, in other embodiments, the top heater 1 may also be an asymmetric structure.

[0045] In one embodiment, the lengths of each heating belt 11 are the same.

[0046] Specifically, the length of the heating belt 11 refers to the linear distance from the starting end to the ending end. By making the length of each heating belt 11 the same, the heat generated between each heating belt 11 can be further uniformed.

[0047] In one embodiment, the connecting electrode between the top heater and the side heater (that is, the side electrode 3) often needs to be heated to achieve uniform overall temperature distribution due to its low heat generation. For this reason, in the embodiment of the present application, a groove is formed on the side electrode 3, and the groove can be used to increase the resistance without affecting the strength of the side electrode 3. It is understandable that the shape and size of the groove can be set according to actual needs.

[0048] Based on the same inventive concept, an embodiment of the present application discloses a single crystal casting furnace, comprising a furnace body and any one of the heaters described above in the embodiment of the present application, which is arranged in the furnace body.

[0049] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0050] It should also be noted that, in this article, the orientation or position relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations, nor can they be understood as indicating or implying relative importance. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. Without more restrictions, an element defined by the phrase "comprising a ..." does not exclude the existence of other identical elements in the process, method, article or terminal device comprising the element.

[0051] The technical solution provided by the present application is described in detail above. The principle and implementation method of the present application are described in this article using specific examples. The description of the above embodiments is only used to help understand the present application, and the content of this specification should not be understood as limiting the present application. At the same time, for those of ordinary skill in the art, according to the present application, there will be different forms of changes in the specific implementation methods and application scopes. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the scope of protection of the present application.

Claims

1. A heater, characterized in that: include: a top heater and side heaters disposed around the top heater; The top heater comprises a plurality of mutually connected heating belts, and the plurality of heating belts enclose a circular area; The heating belt comprises a plurality of mutually connected bending sections, and the plurality of bending sections are staggeredly distributed in the circular area; Wherein, in the first direction, the distance between two adjacent bending segments is greater than or equal to 30 mm and less than or equal to 50 mm; In the second direction, the distance between two adjacent bending segments is greater than or equal to 8 mm and less than or equal to 12 mm; The first direction and the second direction are perpendicular to each other.

2. The heater according to claim 1, characterized in that The heater further comprises: A plurality of side electrodes are connected to the side heaters, and the side electrodes are used to be connected to the copper electrode circuit.

3. The heater according to claim 2, characterized in that: The plurality of side electrodes are all located in the circular area, and the side electrodes and the heating belt are at the same position in the third direction; The third direction is perpendicular to both the first direction and the second direction.

4. The heater according to claim 1, characterized in that: A graphite electrode is arranged on the end of the heating belt, and the graphite electrode is threadedly connected to the heating belt.

5. The heater according to claim 1, characterized in that: The top heater includes three heating belts, and each of the heating belts has the same distribution area within the circular region.

6. The heater according to claim 5, characterized in that: The length of each heating belt is the same.

7. The heater according to claim 1, characterized in that: The top heater is arranged in a symmetrical structure.

8. The heater according to claim 1, characterized in that: The shape of the bending section is set to be U-shaped or arc-shaped.

9. A single crystal casting furnace, characterized in that: The invention comprises a furnace body and a heater as claimed in any one of claims 1 to 8 arranged in the furnace body.

Images