Combined heater for polycrystalline silicon ingot casting furnace and polycrystalline silicon ingot casting furnace
By designing a combined heater in a polycrystalline silicon ingot furnace, a natural transition temperature distribution is formed using the resistance gradient of the heating unit, which solves the problem of difficult to control the movement speed of the crystal-growing interface, and achieves efficient and uniform polycrystalline silicon crystal growth and crystal Improved purity.
Patent Information
- Application Number
- CN201710893716.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2017-09-26
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2037-09-26
AI Technical Summary
In existing polysilicon ingot furnaces, the upward movement speed of the crystal growth interface is difficult to accurately control, affecting crystal quality and production efficiency, and the lifting speed of the heat insulation cage is difficult to accurately cooperate with the optimal crystal growth process.
Design a combined heater of a polycrystalline silicon ingot furnace, including a top heater and a side heater. The side heater consists of multiple heating units, and the resistance value of the heating unit is distributed from bottom to top from small to large. A temperature gradient of natural transition is formed to ensure uniform cooling and crystallization from bottom to top.
A stable temperature gradient and high-quality polysilicon crystal growth are achieved, which improves crystal growth efficiency and crystal purity, avoids dependence on the speed of the heat insulation cage, and improves production efficiency.
Smart Images
Figure CN107523864B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a polycrystalline silicon ingot casting device, in particular to a combined heater for a polycrystalline silicon ingot casting furnace and a polycrystalline silicon ingot casting furnace comprising the heater. Background Art
[0002] At present, most solar cells (groups) are polycrystalline silicon solar cells, among which crystalline silicon material is the most important photovoltaic material, and crystalline silicon material will remain the mainstream material of solar cells for a long time in the future. Usually, the equipment for manufacturing polycrystalline silicon is an ingot furnace, and the existing polycrystalline silicon ingot furnace is mainly composed of a furnace body, an insulation cage, a crucible, a heater, and a heat exchange table.
[0003] The working principle of the existing polysilicon ingot furnace is: when the silicon material is heated to a molten state, the heat insulation cage is opened from bottom to top. Since the crucible is set on the heat exchange table, the bottom of the crucible is cooled first, and the silicon liquid forms a crystal nucleus at this position and begins to grow crystals. Since the heat insulation cage moves from bottom to top, a temperature distribution with low temperature at the bottom and high temperature at the top is formed in the vertical direction, so that the crystal growth interface (isotherm) gradually moves from bottom to top, allowing the crystal to grow from bottom to top. As we all know, the crystal growth direction is closely related to the quality of the crystal. If you want to produce high-purity polysilicon, the key is to ensure the vertical temperature gradient and the horizontality of the radial crystal growth interface, that is, to let the crystal grow vertically from bottom to top.
[0004] In the existing polysilicon ingot furnace, the heater usually includes a top heater and a side heater. In order to heat each part evenly, the heating amount of the heater within its heat radiation range is uniform. For example, the invention patent application with application publication number CN106757338A discloses "graphite heater for polysilicon ingot furnace and polysilicon ingot furnace", and the invention patent with authorization announcement number CN103541003B discloses "polysilicon ingot furnace". Before the silicon liquid in this polysilicon ingot furnace crystallizes, the lateral temperature is uniform. During the crystal growth process, the lifting speed of the insulation cage must be reasonably controlled to ensure that the temperature is uniform. An ideal vertical temperature gradient can be obtained, allowing the crystal growth interface to grow horizontally from bottom to top. However, it is difficult to accurately coordinate the opening process of the insulation cage with the optimal crystal growth process. In actual production, the following deficiencies exist: 1. The upward movement speed of the crystal growth interface is difficult to accurately control. If the lifting speed of the insulation cage is too slow, the upward movement of the crystal growth interface will be slow, the efficiency will be low, and the crystal quality will be affected. If the lifting speed of the insulation cage is too fast, the silicon liquid above will cool faster than the silicon liquid below, and the crystal growth interface cannot be guaranteed to grow from bottom to top, which seriously affects the crystal quality. 2. The lifting speed of the insulation cage is slow, which affects production efficiency. Summary of the invention
[0005] The object of the present invention is to overcome the shortcomings of the prior art and provide a combined heater for a polysilicon ingot furnace, which can form a stable temperature gradient in the vertical direction of the ingot furnace, utilize the natural vertical temperature distribution to promote crystal growth, and improve the growth efficiency of polysilicon crystals and the purity of the crystals.
[0006] The purpose of the present invention is achieved through the following technical solutions:
[0007] A combined heater for a polysilicon ingot furnace comprises a bracket, a top heater arranged at the top of the bracket, a side heater arranged on the side of the bracket and a graphite electrode assembly; the side heater comprises a plurality of side heating modules arranged on the side of the bracket, a side heating module is arranged on each side of the bracket, and each of the side heating modules is composed of a plurality of heating units; the heating units in each side heating module are divided into a plurality of groups of heating components from bottom to top; the total resistance value of the heating components at the same height of all the side heating modules is the same, and the total resistance value of each heating component in the same side heating module is distributed from small to large from bottom to top.
[0008] The working principle of the combined heater of the above-mentioned polysilicon ingot furnace is:
[0009] The resistance value, size and shape of the heating unit in the present invention can be made into different specifications to form a heating unit library for selection; since the total resistance value of each heating component in the same side heating module is distributed from small to large from bottom to top, and the total resistance value of the heating components at the same height of all side heating modules is the same, after the silicon raw material is heated and melted, the temperature of the outside of the silicon liquid is regularly distributed from small to large from bottom to top, and at the junction of two adjacent groups of heating components, the temperature will not change abruptly through heat exchange at local positions, but will form a natural transition, so that the temperature of the outside of the silicon liquid rises evenly from bottom to top; in this way, during crystallization, the insulation cage can be opened at one time to allow the outside of the silicon liquid to have the same heat dissipation conditions from bottom to top. Since the temperature at the bottom is low and the heat dissipation is fast, the silicon liquid starts to grow crystals from the bottom. As time goes by, the crystallization temperature line gradually moves up, so that the crystal growth interface gradually moves vertically upward. Since the temperature environment around the silicon liquid is consistent, the crystal growth interface will remain in a horizontal state, so that uniform high-quality polycrystalline silicon that grows vertically upward can be obtained.
[0010] A preferred embodiment of the present invention, wherein the graphite electrode assembly includes a first graphite electrode group connected to the top heater and a second graphite electrode group connected to the side heater; the first graphite electrode group and the second graphite electrode group are connected to the first three-phase power supply and the second three-phase power supply, respectively. The top heater and the side heater are powered by the three-phase power supply, so that the time used to deliver the same heating power is shorter than that of the DC power supply, which can improve the efficiency, and at the same time can provide a stable voltage to ensure that the heating unit can heat evenly; in addition, since the top heater and the side heater are connected to different three-phase power supplies, by controlling the voltage ratio of the two three-phase power supplies, the power ratio of the top heater to the side heater can be changed, which is more conducive to obtaining the required temperature gradient.
[0011] In a preferred embodiment of the present invention, when there are multiple heating units in the heating assembly, the heating units are arranged vertically or / and radially. In this way, the total resistance value of each group of heating assemblies can be used as a target, and heating units with suitable resistance values and sizes can be flexibly selected for combination according to the vertical height of the heating assembly and the installation space.
[0012] In a preferred embodiment of the present invention, the heating unit includes a serpentine heating unit and a plate-shaped heating unit. The heating unit with a serpentine structure is conducive to saving materials and is conducive to heat dissipation in the subsequent heat dissipation process. The serpentine heating unit can be deliberately arranged at different positions to accelerate the heat dissipation of the position in the subsequent heat dissipation process, thereby being more conducive to obtaining the required temperature distribution; and the plate-shaped heating unit can be well combined with the serpentine heating unit in both radial and vertical directions.
[0013] In a preferred embodiment of the present invention, the bracket includes four connecting plates, each connecting plate includes a middle portion and two connecting portions connected to both sides of the middle portion; the two connecting portions in each connecting plate are respectively connected to one end of the heating unit in the two adjacent side heating modules; the four connecting plates connect all the heating units together to form a rectangular frame structure. This rectangular bracket shape is not only convenient for the installation and fixation of the heating unit and simplifies the structure of the heating unit, but also helps to ensure that each side of the bracket has consistent heating conditions and temperature distribution, and there will be no difference in temperature distribution in the circumferential direction.
[0014] A preferred solution of the present invention is that each connection part is provided with a plurality of mounting holes arranged in a vertical direction for connecting with the heating unit; both ends of each heating unit are provided with fixing holes matching with the mounting holes; the heating unit is connected to the connection part of the connecting plate by bolts. The advantage of this preferred solution is that it is convenient to install and disassemble the heating unit, and because the mounting holes are arranged in a vertical direction, the fixing position of the heating unit in the vertical direction can be flexibly adjusted, and it can also adapt to the fixing of heating units of different sizes and specifications, with good versatility, and better realization of flexible combination of heating units.
[0015] In a preferred embodiment of the present invention, the top heater includes five top serpentine heating units and a fixed connection block for connecting and fixing each top serpentine heating unit together. By providing a serpentine-shaped top heater, materials can be saved, and processing and subsequent heat dissipation are facilitated; in addition, the top serpentine heating units are connected and fixed by the fixed connection block, which is conducive to the installation and removal of the top serpentine heating units.
[0016] In a preferred embodiment of the present invention, the first graphite electrode group includes three first graphite electrodes, which are evenly arranged on the top serpentine heating unit; the three first graphite electrodes divide the five top serpentine heating units into three top heating blocks with equal resistance values; the three first graphite electrodes are respectively connected to the U, V, and W phases of the first three-phase power supply. The advantage of this preferred embodiment is that the top serpentine heating units of the top heater can obtain the same voltage, thereby obtaining a uniform thermal field in the top heater.
[0017] A preferred solution of the present invention, wherein the second graphite electrode group has three, and the heating assembly on the side heater is equally divided into three parts with the same resistance value in the circumferential direction; a conductive connection assembly for connecting the second graphite electrode and the heating assembly is provided at a position corresponding to the second graphite electrode on the heating assembly, and the connecting plate is made of a conductive material; the conductive connection assembly includes a vertical plate fixedly mounted on the heating assembly and a horizontal plate arranged at the upper end of the vertical plate, and the second graphite electrode is arranged on the horizontal plate; the three second graphite electrodes are respectively connected to the U, V, and W phases of the second three-phase power supply. By providing three electrodes, not only does it match the three-phase power supply, but the three electrodes also equally divide the heating assembly into three parts with the same resistance value in the circumferential direction, so that the heat generation of each part in the circumferential direction is uniform, so that uniform heat is obtained in the heater, which is conducive to obtaining a stable upward moving isotherm during crystallization.
[0018] The present invention further provides a polycrystalline silicon ingot casting furnace, comprising a furnace body, a heater, a crucible and a heat insulation layer, wherein the heater is a combined heater of the above-mentioned polycrystalline silicon ingot casting furnace.
[0019] Compared with the prior art, the present invention has the following beneficial effects:
[0020] 1. By selecting heating units with different resistance values and arranging them from bottom to top, or selecting heating units with the same resistance value but different numbers and arranging them from bottom to top, heating components with different resistance values can be obtained, so that an ideal temperature gradient can be formed in the vertical direction after the silicon liquid is cooled and crystallized. This temperature gradient has a power compensation effect on the crystal, making temperature control more convenient and accurate, thereby avoiding over-reliance on controlling the moving speed of the insulation cage to achieve temperature control, with higher efficiency and better crystal quality.
[0021] 2. The selection of heating units is flexible and varied. Not only can the resistance value of the heating unit be set to different specifications, but the shape and size can also be set to different specifications for selection. The installation position of the heating unit in the vertical direction is also flexible and varied, which is more conducive to obtaining an ideal temperature distribution gradient, and thus obtaining higher quality polycrystalline.
[0022] 3. By adding or reducing heating units with a certain resistance value at a specific position, isotherms of a specific shape can be obtained to obtain crystals of a specific quality. For example, the most ideal crystal growth interface is horizontal, but there are inevitably some impurities in the silicon raw material. Some impurities can be removed by volatilization after being heated and melted at high temperature, but some impurities will not melt and will be mixed in the silicon liquid. During the crystal growth process, these impurities will solidify inside the crystal, thus affecting the purity of the crystal. In order to exclude these impurities, the middle of the crystal growth interface can be slightly convex upward and tilted downward on all sides (this crystal growth interface with a slightly upward convex middle will not have a substantial effect on the direction of crystal growth and the crystal growth speed of each part). In this way, during the crystal growth process, impurities will flow around on the crystal growth interface, and eventually these impurities will gather on the surface or edge of the silicon ingot, so that they can be easily removed in the subsequent processing. Impurity removal; In order to obtain such a crystal growth interface with a slightly upward protrusion in the middle, it is required that on the cross section of the silicon liquid, the middle temperature should be slightly lower than the surrounding temperature. In the present invention, on the basis of the heating unit combination scheme with a horizontal crystal growth section, by adding one more heating unit to the bottom heating component, or selecting a heating unit with a larger resistance value on the bottom heating component, the temperature around the bottom of the silicon liquid can be made slightly higher than normal in the initial stage of crystallization. In this way, in the initial stage of crystallization of the silicon liquid, the middle silicon liquid will crystallize before the surrounding silicon liquid, so that a crystal growth interface with a slightly upward protrusion in the middle can be formed in the initial stage, and the subsequent crystal growth process will maintain this state, which is more conducive to obtaining crystals with higher purity. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1The present invention is a schematic diagram of the three-dimensional structure of a combined heater of a polysilicon ingot casting furnace.
[0024] Figure 2 for Figure 1 Top view of the top heater and the first graphite electrode.
[0025] Figure 3 for Figure 1 Schematic diagram of the three-dimensional structure of the middle connecting plate.
[0026] Figure 4 for Figure 1 Schematic diagram of the three-dimensional structure of the conductive connection component.
[0027] Figure 5 It is a schematic diagram of the three-dimensional structure of a serpentine heating unit in an embodiment of the present invention.
[0028] Figure 6 It is a schematic diagram of the three-dimensional structure of a large heating unit in an embodiment of the present invention.
[0029] Figure 7 It is a schematic diagram of the three-dimensional structure of a small heating unit in an embodiment of the present invention.
[0030] Figure 8 A schematic diagram of the three-dimensional structure of a combined heater for a polysilicon ingot furnace of the first combination of heating units.
[0031] Fig. 9 A schematic diagram of the three-dimensional structure of a combined heater for a polysilicon ingot furnace of the second combination of heating units.
[0032] Fig.10 A schematic diagram of the three-dimensional structure of a combined heater of a polysilicon ingot furnace which is a third combination of heating units.
[0033] Fig.11 It is a schematic cross-sectional view of the horizontal crystal growth interface in a multicrystalline silicon ingot casting furnace.
[0034] Fig.12 It is a cross-sectional schematic diagram of the slightly upwardly convex crystal growth interface and impurity discharge in the middle of a polycrystalline silicon ingot casting furnace. DETAILED DESCRIPTION
[0035] The present invention is further described below in conjunction with examples and drawings, but the embodiments of the present invention are not limited thereto.
[0036] See also Figure 1-Figure 4A combined heater for a polysilicon ingot furnace of this embodiment includes a bracket, a top heater 5 arranged at the top of the bracket, a side heater 2 arranged on the side of the bracket, and a graphite electrode assembly; the side heater 2 includes a plurality of side heating modules arranged on the side of the bracket, and a side heating module is arranged on each side of the bracket, and each of the side heating modules is composed of a plurality of heating units; the heating units in each side heating module are divided into several groups of heating components from bottom to top; the total resistance value of the heating components at the same height of all side heating modules is the same, and the total resistance value of each heating component in the same side heating module is distributed from small to large from bottom to top.
[0037] See also Figure 1 The graphite electrode assembly includes a first graphite electrode group 4 connected to the top heater 5 and a second graphite electrode group 3 connected to the side heater 2; the first graphite electrode group 4 and the second graphite electrode group 3 are connected to the first three-phase power supply and the second three-phase power supply, respectively. The top heater 5 and the side heater 2 are powered by a three-phase power supply, so that the time used to deliver the same heating power is shorter than that of a DC power supply, which can improve efficiency and provide a stable voltage to ensure that the heating unit can heat evenly; in addition, since the top heater 5 and the side heater 2 are connected to different three-phase power supplies, the power ratio of the top heater 5 to the side heater 2 can be changed by controlling the voltage ratio of the two three-phase power supplies, which is more conducive to obtaining the required temperature gradient.
[0038] See also Figure 1 When there are multiple heating units in the heating assembly, these heating units are arranged vertically or / and radially. In this way, the total resistance value of each group of heating assemblies can be used as a target, and heating units with appropriate resistance values and sizes can be flexibly selected for combination according to the vertical height of the heating assembly and the installation space.
[0039] See also Figure 1 The heating unit includes a serpentine heating unit and a plate-shaped heating unit. The heating unit with a serpentine structure is conducive to saving materials and is conducive to heat dissipation in the subsequent heat dissipation process. By deliberately setting the serpentine heating unit at different positions, it is conducive to accelerating the heat dissipation of the part in the subsequent heat dissipation process, so as to be more conducive to obtaining the required temperature distribution; and the plate-shaped heating unit can be well combined with the serpentine heating unit in both radial and vertical directions.
[0040] See also Figure 1 and Figure 3The bracket includes four connecting plates 1, each connecting plate 1 includes a middle portion 1-1 and two connecting portions 1-2 connected to both sides of the middle portion 1-1; the two connecting portions 1-2 in each connecting plate 1 are respectively connected to one end of the heating units in the two adjacent side heating modules; the four connecting plates 1 connect all the heating units together to form a rectangular frame structure. This rectangular bracket shape is not only convenient for the installation and fixation of the heating unit and simplifies the structure of the heating unit, but also helps to ensure that each side of the bracket has consistent heating conditions and temperature distribution, and there will be no difference in temperature distribution in the circumferential direction.
[0041] See also Figure 3 Each connection part 1-2 is provided with a plurality of mounting holes 1-21 arranged vertically for connecting with the heating unit; both ends of each heating unit are provided with fixing holes matching with the mounting holes 1-21; the heating unit is connected to the connection part 1-2 of the connecting plate 1 by bolts. The advantage of such a setting is that it is convenient to install and remove the heating unit, and because the mounting holes 1-21 are arranged vertically, the fixing position of the heating unit in the vertical direction can be flexibly adjusted, and it can also adapt to the fixing of heating units of different sizes and specifications, with good versatility, and better realization of flexible combination of heating units.
[0042] See also Figure 2 The top heater 5 includes five top serpentine heating units 5-1 and a fixed connection block 5-2 for connecting and fixing each top serpentine heating unit 5-1 together. By setting the top heater 5 in a serpentine shape, materials can be saved, and processing and subsequent heat dissipation are facilitated; in addition, the top serpentine heating units 5-1 are connected and fixed by the fixed connection block 5-2, which is conducive to the installation and removal of the top serpentine heating units 5-1.
[0043] See also Figure 1 and Figure 2 The first graphite electrode 4 group includes three first graphite electrodes 4, and is evenly arranged on the top serpentine heating unit 5-1; the three first graphite electrodes 4 divide the five top serpentine heating units 5-1 into three top heating blocks with equal resistance values; the three first graphite electrodes 4 are respectively connected to the U, V, and W phases of the first three-phase power supply. The advantage of this preferred solution is that the top serpentine heating units 5-1 of the top heater 5 can obtain the same voltage, thereby obtaining a uniform thermal field in the top heater 5.
[0044] See also Figure 1 and Figure 4, the second graphite electrode 3 has three groups, and the heating assembly on the side heater 2 is equally divided into three parts with the same resistance value in the circumferential direction; a conductive connection assembly 6 for connecting the second graphite electrode 3 and the heating assembly is provided at the corresponding position of the second graphite electrode 3 on the heating assembly, and the connecting plate 1 is made of conductive material; the conductive connection assembly 6 includes a vertical plate 6-1 installed and fixed on the heating assembly and a horizontal plate 6-2 arranged at the upper end of the vertical plate 6-1, and the second graphite electrode 3 is arranged on the horizontal plate 6-2; the three second graphite electrodes 3 are respectively connected to the U, V, and W phases of the second three-phase power supply. By setting three electrodes, not only does it match the three-phase power supply, but the three electrodes also equally divide the heating assembly into three parts with the same resistance value in the circumferential direction, so that the heat generation of each part in the circumferential direction is uniform, so that the heater obtains uniform heat, which is conducive to obtaining a stable upward moving isotherm during crystallization.
[0045] The working principle of the combined heater of a polycrystalline silicon ingot furnace of this embodiment is:
[0046] The resistance value, size and shape of the heating unit can be made into different specifications to form a heating unit library for selection; since the total resistance values of the heating components in the same side heating module are distributed from small to large from bottom to top, and the total resistance values of the heating components at the same height of all side heating modules are the same, after the silicon raw material is heated and melted, the temperature of the outside of the silicon liquid 10 is regularly distributed from small to large from bottom to top, and at the junction of two adjacent groups of heating components, the temperature will not change in a jump-like manner through the heat exchange at the local position, but will form a natural transition, so that the temperature of the outside of the silicon liquid 10 rises evenly from bottom to top; in this way, during crystallization, the insulation cage can be opened at one time to allow the outside of the silicon liquid 10 to have the same heat dissipation conditions from bottom to top. Since the temperature at the bottom is low and the heat dissipation is fast, the silicon liquid 10 starts to grow crystals from the bottom. As time goes by, the crystallization temperature line gradually moves up, so that the crystal growth interface 11 gradually moves vertically upward. Since the temperature environment around the silicon liquid 10 is consistent, the crystal growth interface 11 will remain in a horizontal state, so that uniform high-quality polycrystalline silicon that grows vertically upward can be obtained.
[0047] See also Figure 8-Figure 10 The combined heater of the polycrystalline silicon ingot furnace in this embodiment has a variety of combinations to achieve a temperature gradient in the vertical direction. To specifically reflect this feature of the present invention, the following examples are listed:
[0048] The heating unit library includes a small plate-shaped heating unit, a large plate-shaped heating unit and a serpentine heating unit 7. In addition, the resistance values of the above three heating units increase in sequence.
[0049] (1) The lowest heating component in the side heating module is composed of a small plate-shaped heating unit 8, the middle heating component is composed of a large plate-shaped heating unit, and the highest heating component is composed of a serpentine heating unit 7; (e.g. Figure 8 (shown)
[0050] (2) The lowest heating component in the side heating module is composed of two small plate-shaped heating units 8, the middle heating component is composed of a large plate-shaped heating unit 9, and the highest heating component is composed of two snake-shaped heating units 7; (e.g. Fig. 9 (shown)
[0051] (3) The heating assembly in the middle of the side heating module is composed of two small plate-shaped heating units 8, the heating assembly at the highest position is composed of a large plate-shaped heating unit 9, a small plate-shaped heating unit 8 and a serpentine heating unit 7, and no heating unit is set at the lowest position. (As shown in Fig.10 described)
[0052] The combined heater of the polysilicon ingot furnace of the present invention can be combined in various ways in actual work, and the heating unit library has more than three heating units. Through the combination of different heating units, a stable temperature gradient is finally formed, and the temperature in the vertical direction always rises from bottom to top, thereby improving the crystallization rate and the purity of the precipitated crystals.
[0053] See also Figure 11-Figure 12 In addition, the combination of the heating units can be adjusted according to the actual situation of crystallization. For example, the most ideal crystal growth interface 11 is horizontal (such as Fig.11 As shown), however, in order to facilitate the cleaning of impurities 14 after the crystals are precipitated, the middle of the crystal growth interface 11 can be slightly raised upwards and tilted downwards on all sides (this crystal growth interface 11 with a slightly raised middle portion will not have a substantial effect on the direction of crystal growth and the crystal growth speed of each part), so that the impurities 14 flow around on the crystal growth interface 11 and gather on the surface of the crystal; at this time, the worker can add an additional heating unit 13 (or select a heating unit with a slightly larger resistance value) to the lowest layer of the side heating module, so that in the initial stage of crystallization, the temperature around the bottom of the silicon liquid 10 can be slightly higher than normal, which will make the middle silicon liquid 10 crystallize before the surrounding ones, so that in the initial stage, a crystal growth interface 11 with a slightly raised middle portion can be formed in the polysilicon ingot furnace 12, and the subsequent crystal growth process will maintain this state, which is more conducive to obtaining crystals with higher purity.
[0054] The above is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited to the above content. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.
Claims
1. A combined heater for a polycrystalline silicon ingot furnace, comprising a support, a top heater arranged at the top of the support, a side heater arranged at the side of the support, and a graphite electrode assembly; It is characterized in that The side heater comprises a plurality of side heating modules arranged on the side of the bracket, one side heating module is arranged on each side of the bracket, and each side heating module is composed of a plurality of heating units; the heating units in each side heating module are divided into a plurality of groups of heating components from bottom to top; the total resistance value of the heating components at the same height of all the side heating modules is the same, and the total resistance value of each heating component in the same side heating module is distributed from small to large from bottom to top; The heating unit includes a serpentine heating unit and a plate-shaped heating unit; The graphite electrode assembly comprises a first graphite electrode group connected to the top heater and a second graphite electrode group connected to the side heater; the first graphite electrode group and the second graphite electrode group are connected to a first three-phase power supply and a second three-phase power supply, respectively; The bracket includes four connecting plates, each connecting plate includes a middle portion and two connecting portions connected to both sides of the middle portion; the two connecting portions in each connecting plate are respectively connected to one end of the heating units in two adjacent side heating modules; the four connecting plates connect all the heating units together to form a rectangular frame structure; Each connecting portion is provided with a plurality of mounting holes arranged vertically for connecting with the heating unit; both ends of each heating unit are provided with fixing holes matching with the mounting holes; the heating unit is connected to the connecting portion of the connecting plate by bolts; The resistance value, size and shape of the heating unit are made into different specifications to form a heating unit library; the heating unit library includes small plate-shaped heating units, large plate-shaped heating units and snake-shaped heating units; In the side heating module, the insulation cage is opened once during crystallization, and on the basis of the heating unit combination scheme with a horizontal crystal growth interface, an additional heating unit is added to the bottom heating component, or a heating unit with a larger resistance value is selected on the bottom heating component, so that a crystal growth interface with a slightly upward protrusion in the middle is formed in the polysilicon ingot furnace in the initial stage of crystallization.
2. The combined heater of a polycrystalline silicon ingot furnace according to claim 1, It is characterized in that When there are multiple heating units in the heating assembly, these heating units are arranged vertically and / or radially.
3. The combined heater of a polycrystalline silicon ingot furnace according to claim 1, It is characterized in that The heating unit includes a serpentine heating unit and a plate-shaped heating unit.
4. The combined heater of a polycrystalline silicon ingot casting furnace according to claim 1, It is characterized in that The top heater comprises five top serpentine heating units and a fixed connection block for connecting and fixing each top serpentine heating unit together.
5. The combined heater of a polycrystalline silicon ingot furnace according to claim 4, It is characterized in that The first graphite electrode group includes three first graphite electrodes, and is evenly arranged on the top serpentine heating unit; the three first graphite electrodes divide the five top serpentine heating units into three top heating blocks with equal resistance values; the three first graphite electrodes are respectively connected to the U, V, and W phases of the first three-phase power supply.
6. The combined heater of a polycrystalline silicon ingot furnace according to claim 1, It is characterized in that There are three second graphite electrode groups, and the heating component on the side heater is equally divided into three parts with the same resistance value in the circumferential direction; a conductive connection component for connecting the second graphite electrode and the heating component is provided at a position corresponding to the second graphite electrode on the heating component, and the connecting plate is made of conductive material; the conductive connection component includes a vertical plate installed and fixed on the heating component and a horizontal plate arranged at the upper end of the vertical plate, and the second graphite electrode is arranged on the horizontal plate; the three second graphite electrodes are respectively connected to the U, V, and W phases of the second three-phase power supply.
7. A polycrystalline silicon ingot casting furnace, comprising a furnace body, a heater, a crucible and a heat insulation layer, It is characterized in that The heater is a combined heater of a polycrystalline silicon ingot furnace as described in any one of claims 1 to 6.