Ingot casting apparatus for casting annular multicrystalline silicon

Abstract

The utility model discloses a kind of ingot casting devices for casting annular polycrystalline silicon, it is related to ingot casting device technical field.The device includes: annular ingot cavity, including inner circumferential wall body and outer circumferential wall body;And the inner support of the inner side wall surface of the inner circumferential wall body and the outer support of the outer side wall surface of the outer circumferential wall body;When ingot casting, the inner support provides the support force towards outside to the inner side wall surface of the inner circumferential wall body, the outer support provides the support force towards inside to the outer side wall surface of the outer circumferential wall body.The ingot casting device provided in the utility model allows to select annular ingot cavity body of quartz material, both low in price and can guarantee polycrystalline silicon ring purity.

Description

Technical Field

[0001] This utility model relates to a polycrystalline silicon ingot casting device, specifically to an ingot casting device for casting ring-shaped polycrystalline silicon. Background Technology

[0002] Polycrystalline silicon rings are important auxiliary materials in the semiconductor chip manufacturing and processing field. Traditional preparation methods generally use large-sized polycrystalline silicon ingots to obtain them through mechanical processing methods such as cutting and drilling. These processing methods result in a large waste of raw materials and high production and processing costs.

[0003] In existing technologies, polycrystalline silicon ingots are cast using inner and outer crucibles or sandwiched crucibles. The product is directly cast into a ring shape, eliminating the need for drilling and machining. This effectively avoids the waste of the core pillar in the middle of the polycrystalline silicon ring, saves a significant amount of raw materials, and reduces subsequent machining processes and equipment investment. However, existing double-layer crucibles are mostly made of refractory metals, but metal crucibles in high-temperature environments can affect the purity of the material near the polycrystalline silicon ring, impacting the quality of the final product. Alternatively, zirconium oxide or silicon nitride ceramic crucibles are used, but these materials are expensive, hindering large-scale use and limiting production efficiency.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this utility model and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Utility Model Content

[0005] Purpose of this utility model: The technical problem to be solved by this utility model is to provide a casting device for casting ring-shaped polycrystalline silicon, which is inexpensive and can ensure the purity of the polycrystalline silicon ring, in order to address the shortcomings of the existing technology.

[0006] To solve the above-mentioned technical problems, this utility model discloses a casting device for casting toroidal polycrystalline silicon ingots, comprising:

[0007] The annular ingot cavity includes an inner peripheral wall and an outer peripheral wall;

[0008] And an inner support body that abuts against the inner side wall of the inner peripheral wall and an outer support body that surrounds the outer side wall of the outer peripheral wall;

[0009] During casting, the inner support provides outward support to the inner wall of the inner peripheral wall, and the outer support provides inward support to the outer wall of the outer peripheral wall.

[0010] In one embodiment of the annular ingot mold cavity, the ingot casting device includes an inner crucible and an outer crucible, the outer crucible having an inner cavity, the inner crucible being fitted inside the inner cavity of the outer crucible, the bottom surface of the inner crucible being in contact with the bottom surface of the inner cavity of the outer peripheral wall; the peripheral wall of the outer crucible is the outer peripheral wall, and the peripheral wall of the inner crucible is the inner peripheral wall.

[0011] This embodiment uses nested double-layer crucibles to form an annular ingot cavity. By changing quartz crucibles of different specifications, it is possible to produce polycrystalline silicon rings of different sizes and shapes, making the operation simple and flexible.

[0012] Preferably, the inner crucible and the outer crucible are both quartz crucibles.

[0013] In this embodiment, based on the combination of nested double-layer crucibles and inner and outer supports, the crucible material is selected as quartz, which not only improves the purity of the polycrystalline silicon ring, but also reduces equipment costs.

[0014] Optionally, the inner support and the outer support are both made of isostatic graphite.

[0015] In one embodiment of the inner support, in order for the inner support to provide outward support to the inner wall of the inner peripheral wall during ingot casting, the inner support is a hollow columnar structure with a hollow hole, and its outer wall surface matches the inner wall surface of the inner peripheral wall.

[0016] Specifically, for ease of installation, the inner support body includes two or more inner protective plates. All the inner protective plates are circumferentially spaced around the central axis of the inner crucible. The outer sidewall of each inner protective plate is attached to the inner sidewall of the inner circumferential wall, and a gap is formed between adjacent inner protective plates. The inner sidewalls of adjacent inner protective plates are detachably fixedly connected by a first connecting component, so that the inner support body constitutes a hollow columnar structure with a hollow hole.

[0017] Preferably, the hollow hole of the inner support is polygonal in shape, and the gap between adjacent inner protective plates is located at the corner of the polygon.

[0018] Specifically, the first connecting assembly includes a connector and a bolt. A seat hole is provided on the inner side of the inner guard plate near the gap. Two adjacent inner guard plates are fixedly connected by bolts passing through the connector and tightening them into the seat hole.

[0019] In one embodiment, to prevent the inner support from embedding into the bottom of the quartz crucible softened by high temperature, the casting device further includes a bottom guard plate disposed on the bottom surface of the inner cavity of the inner crucible, and the inner support is supported on the bottom guard plate.

[0020] Furthermore, to prevent the inner crucible from moving due to the buoyancy of the molten silicon, the ingot casting device also includes a counterweight, which is placed above the bottom guard plate and inside the inner support.

[0021] In one embodiment, in order to enable the ingot casting device to support pre-assembly outside the ingot casting furnace and then move into and out of the ingot casting furnace as a whole, the ingot casting device further includes a carrier plate, and the outer support body and the outer peripheral wall body are respectively located above the carrier plate and supported by the carrier plate.

[0022] In one embodiment of the outer support, the outer support includes two or more outer protective plates, which are circumferentially spaced around the central axis of the outer peripheral wall. The inner sidewall of each outer protective plate is attached to the outer sidewall of the outer peripheral wall, and adjacent outer protective plates are fixedly connected by a second connecting component.

[0023] Beneficial effects:

[0024] 1. The casting device for casting ring-shaped polycrystalline silicon provided by this utility model allows the inner and outer peripheral walls of the ring-shaped ingot cavity to be made of low-cost quartz material by setting supports on the inner side of the inner peripheral wall and the outer side of the outer peripheral wall, without worrying about the quartz ring-shaped ingot cavity softening and deforming at high temperatures. This device is also suitable for solving the problem of deformation of ring-shaped ingot cavities made of other materials due to excessively thin walls.

[0025] 2. By using nested double-layer crucibles to form an annular ingot cavity, and by changing quartz crucibles of different specifications, the production of polycrystalline silicon rings of different sizes and shapes can be achieved, making the operation simple and flexible; moreover, by using a combination of quartz crucibles and inner and outer supports, the purity of polycrystalline silicon rings is improved while reducing equipment costs.

[0026] 3. By adopting a modular inner and outer support structure, it is easy to load and unload and can better fit the corresponding crucible.

[0027] 4. By adding corresponding counterweights, the bottom of the inner crucible is ensured to be tightly attached to the bottom of the inner cavity of the outer crucible, preventing the inner crucible from moving due to the buoyancy of the silicon melt, thus further ensuring the product quality of the polycrystalline silicon ring. Attached Figure Description

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0029] Figure 1 This is a schematic diagram of the internal structure of an ingot casting device for casting ring-shaped polycrystalline silicon, provided in one embodiment of the present invention.

[0030] Figure 2This is a top view of the inner support body provided in one embodiment of the present invention;

[0031] Figure 3 This is a three-dimensional structural diagram of the inner protective plate provided in one embodiment of the present utility model;

[0032] Figure 4 This is a three-dimensional structural schematic diagram of a connector provided in one embodiment of the present utility model;

[0033] Figure 5 This is a structural diagram of the internal base plate provided in one embodiment of the present invention;

[0034] Figure 6 This is a schematic diagram of the assembled three-dimensional structure of the inner peripheral wall and the inner support body provided in one embodiment of the present invention.

[0035] The reference numerals in the attached drawings are as follows: 1. Inner crucible; 2. Outer crucible; 3. Annular ingot cavity; 31. Inner peripheral wall; 32. Outer peripheral wall; 4. Inner support; 41. Inner protective plate; 411. Seat hole; 42. Hole; 43. Gap; 5. Outer support; 51. Outer protective plate; 52. Vent hole; 6. Connector; 61. First connecting part; 62. Second connecting part; 63. Strip hole; 64. Bolt; 7. Bottom protective plate; 71. Pull screw hole; 72. Pull bolt; 8. Carrier plate; 9. Counterweight; 10. Cover plate; 101. Through hole; 102. Ventilation space. Detailed Implementation

[0036] Existing double-layer inner crucible 1 and outer crucible 2 are mostly made of refractory metals. However, metal crucibles can affect the purity of the polycrystalline silicon ring near the ring in high-temperature environments, thus affecting the quality of the final product. Alternatively, zirconium oxide or silicon nitride ceramic crucibles can be used, but these materials are expensive and not suitable for mass production, thus limiting production efficiency.

[0037] During polycrystalline silicon ingot casting, the temperature needs to reach above 1500℃, which exceeds the operating temperature of quartz products. At this temperature, the sidewalls of the quartz crucible soften and cannot support the molten silicon inside. If the sidewalls of the crucible collapse and the molten silicon flows out, the ingot casting equipment may be scrapped, or an explosion may occur, resulting in a serious safety accident.

[0038] Therefore, this invention provides a casting device for casting toroidal polycrystalline silicon. By providing supports on the inner side of the inner circumferential wall and the outer side of the outer circumferential wall of the toroidal ingot cavity, the inner and outer circumferential walls of the toroidal ingot cavity can be made of low-cost quartz material without worrying about the quartz to soften and deform at high temperatures. This device is also suitable for solving the problem of deformation of toroidal ingot cavities made of other materials due to excessively thin cavity walls.

[0039] See Figure 1An embodiment of this utility model provides an ingot casting apparatus for casting toroidal polycrystalline silicon, comprising:

[0040] The annular ingot cavity 3 includes an inner peripheral wall 31 and an outer peripheral wall 32;

[0041] The inner support 4, which abuts against the inner wall of the inner peripheral wall 31, and the outer support 5, which surrounds the outer wall of the outer peripheral wall 32, provide outward support to the inner wall of the inner peripheral wall 31 and inward support to the outer wall of the outer peripheral wall 32 during casting. The inner peripheral wall 31 and the outer peripheral wall 32 can be concentric or non-concentric.

[0042] In one embodiment, see Figure 1 The inner peripheral wall 31 and the outer peripheral wall 32 are arranged concentrically.

[0043] In one embodiment, the casting device includes an integrally formed annular crucible with a jacket, the outer peripheral wall of the annular crucible being the outer peripheral wall 32 of the annular casting cavity 3, and the inner peripheral wall of the annular crucible being the inner peripheral wall 31 of the annular casting cavity 3.

[0044] In another embodiment, see Figure 1 The ingot casting apparatus includes an inner crucible 1 and an outer crucible 2. The outer crucible 2 has an inner cavity, and the inner crucible 1 is fitted inside the inner cavity of the outer crucible 2. The bottom surface of the inner crucible 1 is in contact with the bottom surface of the inner cavity of the outer crucible 2. The peripheral wall of the outer crucible 2 is an outer peripheral wall 32, and the peripheral wall of the inner crucible 1 is an inner peripheral wall 31.

[0045] This embodiment uses a double-layered crucible to construct the annular ingot cavity. By combining crucibles with different outer diameters and heights, a series of polycrystalline silicon rings of different sizes can be flexibly obtained. By combining crucibles of different shapes, circular rings, square rings, and polycrystalline silicon products such as outer circle and inner square, outer square and inner circle, and irregular shapes can be obtained. There is no need to make many crucible molds, which can save a lot of crucible mold manufacturing costs. In addition, compared with annular crucibles, the manufacturing process of double-layered crucibles is simpler, the yield rate is higher, and the equipment cost of ingot casting is reduced.

[0046] In one embodiment, the inner crucible 1 and the outer crucible 2 are quartz crucibles, and the inner support 4 and the outer support 5 are isostatically pressed graphite.

[0047] In this embodiment, with the ingot casting apparatus equipped with inner and outer supports, both the inner crucible 1 and the outer crucible 2 can be made of quartz without concern about high-temperature softening. Alternatively, other crucibles that do not introduce other substances to contaminate the polycrystalline silicon ring during the ingot casting process can be used, such as high-temperature metal crucibles, zirconium oxide crucibles, silicon nitride crucibles, and silicon carbide crucibles. However, compared to these crucibles, quartz crucibles have the advantage of lower cost.

[0048] The inner support 4 and the outer support 5 are made of isostatic graphite. Isostatic graphite plates have the advantages of high temperature resistance, high stability and not easy to deform.

[0049] In one embodiment, see Figure 1 The inner support 4 is composed of two or more inner protective plates 41 arranged circumferentially around the central axis of the inner crucible 1. The outer side wall of each inner protective plate 41 is attached to the inner side wall of the inner peripheral wall 31, and a gap 43 is formed between adjacent inner protective plates 41. The inner side walls of adjacent inner protective plates 41 are fixedly connected by a first connecting assembly, so that the inner support 4 constitutes a hollow columnar structure with a hollow hole 42.

[0050] Preferably, the width of the gap 43 is controlled to be 3-5 mm.

[0051] Preferably, the hollow hole 42 of the inner support 4 is polygonal in shape. For ease of operation and fabrication of the protective plates, the gap 43 between each pair of inner protective plates 41 is located on the diagonal of the polygon. In a particular embodiment, see... Figure 2 The inner support 4 is composed of four inner protective plates 41 spliced ​​together in the circumferential direction. The inner edges of the four inner protective plates 41 are spliced ​​together to form a square. The radial side of the inner protective plate 41 forms an angle of 135° with its inner side, and the outer edge of the inner protective plate is an arc with a central angle of 90°.

[0052] Specifically, see Figure 2 and Figure 3 The first connecting component includes a connector 6 and bolts 64. A seat hole 411 is provided on the inner side of the inner protective plate 41 near the gap 43. Adjacent inner protective plates 41 are fixedly connected by bolts 64 passing through the connector 6 and tightened into the seat hole 411. The connector 6 is preferably made of isostatic graphite. After fixing, the shape and size of the outer side of the inner support 4 are adapted to the shape and size of the inner circumference of the inner peripheral wall 31. For the installation of the inner protective plate 41, it is assembled on-site inside the inner crucible 1. This is because the inner protective plate 41 needs to fit tightly against the inner circumference of the inner crucible 1; if it is installed on the outside first, it will be difficult to place it in smoothly. Furthermore, due to the crucible manufacturing process, the inner diameter and shape of the crucible will have a certain range of error, so it can only be fitted inside the inner crucible 1 and then fixed by the connector 6.

[0053] In this embodiment, such as Figure 4As shown, the connector 6 has an L-shaped structure, including a first connecting part 61 and a second connecting part 62 that are interconnected at an angle. The first connecting part 61 and the second connecting part 62 are respectively provided with strip-shaped holes 63 at positions corresponding to the seat holes 411. The connector 6 is fixed by bolts 64 through the strip-shaped holes 63 and the seat holes 411. The first connecting part 61 and the second connecting part 62 are integrally formed into the connector 6. The included angle between the connectors 6 is set according to the number of inner protective plates 41, ensuring that the first connecting part 61 and the second connecting part 62 respectively fit against the corresponding inner protective plates 41. The strip-shaped holes 63 can be rectangular, square, oval, waist-shaped, gourd-shaped, etc., and should preferably be through holes wider than the diameter of the bolts 64 to provide displacement space for thermal expansion of the object during the high-temperature casting process.

[0054] In one particular embodiment, to enhance the strength of the connection, three or more sets of seat holes 411 corresponding to each connector 6 are provided along the height direction. Figure 3 For example, three sets of seat holes 411 corresponding to each connector 6 are provided along the height direction.

[0055] In one embodiment, see Figure 1 The ingot casting device may also include a bottom guard plate 7, which is disposed on the bottom surface of the inner cavity of the inner crucible 1, and the inner support 4 is supported on the bottom guard plate 7.

[0056] In this embodiment, the bottom protective plate 7 is made of isostatically pressed graphite plate, and its diameter is the same as the inner diameter of the inner crucible 1. The bottom protective plate 7 is placed at the bottom of the inner cavity of the inner crucible 1, which provides support and protection for the bottom of the inner crucible 1. This prevents the inner support 4 from sinking into the bottom of the inner crucible 1 due to the softening of the quartz material at high temperatures, thus avoiding damage to the crucible structure. The bottom protective plate 7 serves to protect the crucible.

[0057] In this embodiment, such as Figure 5 As shown, the bottom protective plate 7 is provided with a lifting screw hole 71, which is used in conjunction with a lifting bolt 72. The lifting screw hole 71 is not a through hole but a blind hole, ensuring that the bottom of the bottom protective plate 7 is a complete flat surface, thus ensuring uniform force distribution on the bottom of the quartz inner crucible 1. To facilitate the placement of the bottom protective plate 7 onto the bottom surface of the inner cavity of the quartz inner crucible 1, a lifting bolt 72 of a certain length is installed in the lifting screw hole 71. The bottom protective plate 7 is lowered to the bottom surface of the inner cavity of the inner crucible 1 using the lifting bolt 72, and then the lifting bolt 72 is removed and the plate is taken out.

[0058] In this embodiment, the polycrystalline silicon ring typically adopts a circular design, which is a standard commercial specification. The inner diameter of the inner crucible 1 in this device is generally 250–300 mm. After the inner protective plate 41 is attached to the inner side of the peripheral wall of the inner crucible 1, there is still enough space on the inner side of the inner protective plate 41 to allow the operator to reach in and install the fixing connector 6. For smaller inner crucibles 1, such as when the hollow hole 42 of the inner support 4 is very small and a person cannot reach in to operate, a longer lifting bolt 72 can be used. It is not necessary to reach to the bottom to tighten the lifting bolt 72, and a wrench can be used to replace manual operation to complete the installation of the inner protective plate 41 and the fixing connector 6.

[0059] In one embodiment, see Figure 1 The ingot casting device may also include a carrier plate 8, an outer support body 5 and an outer peripheral wall 32 located above the carrier plate 8 and supported on the carrier plate 8.

[0060] In one embodiment, the outer support 5 is composed of two or more outer protective plates 51 spaced circumferentially around the central axis of the outer peripheral wall 32. The inner sidewall of each outer protective plate 51 is attached to the outer sidewall of the outer peripheral wall 32, and adjacent outer protective plates 51 are fixedly connected by a second connecting assembly. Since the specific structure of the outer support 5 is prior art, it will not be described in detail in this application.

[0061] In one embodiment, see Figure 1 The ingot casting apparatus may also include a cover plate 10, with the top of the outer support body 5 higher than the top of the outer peripheral wall 32, and the cover plate 10 covering the top of the outer support body 5. The cover plate 10 has a through hole 101, which allows argon gas from outside the ingot casting apparatus to enter the interior of the ingot casting apparatus during the ingot casting process; at the same time, the use of the cover plate 10 creates a separate space inside the ingot casting apparatus, avoiding contamination by impurities in the ingot casting furnace and ensuring the purity of the polycrystalline silicon ring.

[0062] In one embodiment, see Figure 1 The outer support 5 is higher than the outer peripheral wall 32 and also higher than the inner support 4, leaving a certain ventilation space 102 between the inner support 4 and the cover plate 1. The portion of the outer support 5 that extends above the outer peripheral wall 32 has an outlet hole 52. The outlet hole 52, the through hole 101, and the ventilation space 102 are interconnected to form an airflow channel for argon gas to flow in and out, facilitating the smooth entry of external argon gas into the ingot casting device within the ingot casting furnace and promoting the circulation of internal gases.

[0063] Preferably, the top of the inner support 4 is higher than or flush with the top of the inner peripheral wall 31. This design facilitates the placement of the inner protective plate 41 inside the inner crucible 1 during the assembly of the inner support 4; facilitates the lifting of the inner protective plate 41 during removal; and provides sufficient height for the quartz crucible to undergo thermal expansion deformation after high-temperature deformation due to the pressure between the inner and outer supports and the polycrystalline silicon melt during the ingot casting process, thus providing a multi-directional fixing function.

[0064] In one embodiment, see Figure 1 The ingot casting device may also include a counterweight 9, which is placed above the bottom guard plate 7 and inside the inner support 4.

[0065] This embodiment uses a counterweight 9 to prevent the inner crucible 1 from moving due to the buoyancy of the molten silicon. The weight of the counterweight 9 is calculated based on the ingot volume. The specific calculation process is: weight of counterweight 9 ≥ 1.82 × volume of inner crucible 1 - weight of inner crucible 1 + weight of inner support 4; where weight is in g and volume is in cm³. The counterweight 9 ensures that the bottom of the inner crucible 1 is tightly fitted to the bottom surface of the inner cavity of the outer crucible 2, preventing the inner crucible 1 from moving due to the buoyancy of the molten silicon.

[0066] In the above embodiment, a release layer is provided on the inner wall of the annular ingot cavity 3. The release layer can utilize a silicon nitride layer for demolding, which makes it easier to separate the solidified silicon ingot from the crucible. At the same time, the release layer also serves to isolate the crucible from the silicon material, preventing direct contact between the crucible and the silicon material during heating, thereby avoiding an increase in impurities in the silicon ingot due to the crucible.

[0067] The assembly process of the ingot casting device provided by this utility model is described below. The specific assembly process is as follows:

[0068] Based on the size and shape of the polycrystalline silicon ring, inner crucible 1 and outer crucible 2 with a diameter difference equal to that of the polycrystalline silicon ring are selected and nested together to form a double-layer crucible; the gap space between the peripheral wall of inner crucible 1 and the peripheral wall of outer crucible 2 forms an annular ingot cavity 3.

[0069] Based on the size of the outer crucible 2, select an appropriate size and number of outer protective plates 51 and carrier plates 8; based on the size of the inner crucible 1, select an appropriate size and number of inner protective plates 41 and a bottom protective plate 7 that matches the inner diameter of the inner peripheral wall 31.

[0070] Place the double-layered crucible in the middle of carrier plate 8;

[0071] The bottom protective plate 7 is lowered into the bottom surface of the inner cavity of the inner crucible 1 using the lifting bolt 72;

[0072] The inner protective plate 41 is spliced ​​and installed on the inner side wall of the inner peripheral wall 31, that is, on the inner side wall of the inner crucible 1, by means of the connector 6; the inner protective plate 41 is assembled to form the inner support body 4;

[0073] The counterweight 9 is lowered along the inner side of the inner guard plate 41 to the bottom guard plate 7 using a lifting method;

[0074] The outer protective plate 51 is spliced ​​and installed to surround the outer wall of the outer peripheral wall 32, that is, the outer wall surface of the outer crucible 2; the outer protective plate 51 is spliced ​​to obtain the outer support body 5;

[0075] The polycrystalline silicon raw material is placed into the annular ingot cavity 3;

[0076] Place the cover plate 10 on the upper end of the outer support body 5 to complete the assembly of the ingot casting device.

[0077] The process of preparing polycrystalline silicon rings using the ingot casting apparatus provided by this utility model is described below. The process includes the following steps:

[0078] The ingot casting device is sent into the ingot casting furnace, and the air inside the ingot casting furnace is evacuated into a vacuum; the furnace temperature is raised to 1500℃ and held for a certain time to complete the melting of polycrystalline silicon raw material into silicon melt;

[0079] Subsequently, the furnace temperature was lowered to allow the silicon melt to gradually cool and crystallize into polycrystalline silicon rings;

[0080] Wait for the furnace temperature to drop, open the lower furnace chamber, and remove the ingot casting device.

[0081] The cover plate 10, inner support 4, outer support 5, counterweight 9, bottom guard plate 7, carrier plate 8, inner crucible 1 and outer crucible 2 are removed in sequence to obtain a polycrystalline silicon ring blank, which is then polished to obtain the finished polycrystalline silicon ring.

[0082] Example 1

[0083] In this embodiment, the outer crucible 2 is a circular quartz crucible with an inner diameter of 550mm and a height of 460mm, and the inner crucible 1 is a circular quartz crucible with an outer diameter of 300mm and a height of 440mm. The two are combined to produce a polycrystalline silicon ring with an outer diameter of 550mm, an inner diameter of 300mm and a height of 250mm.

[0084] Spray a silicon nitride release layer onto the inside of the outer crucible 2 and the outside of the inner crucible 1. Place the outer crucible 2 in the middle of the carrier plate 8, and place the inner crucible 1 into the outer crucible 2, adjusting their concentricity. Place 100 kg of polycrystalline silicon raw material into the annular ingot cavity 3 between the inner and outer crucibles 2; install the outer support 5, the bottom protective plate 7, and the inner support 4 in sequence; place two 10 kg tungsten metal blocks as counterweights 9 on the bottom protective plate 7, and cover with a graphite cover plate 10. Send the ingot casting device into the ingot furnace. Close the upper cover of the ingot furnace insulation cage and the lower furnace chamber. Evacuate the air in the ingot furnace until the furnace pressure is <0.02 mbar; turn on the ingot furnace heating switch, and when the furnace temperature rises to 1175℃, continuously introduce argon gas into the furnace until the furnace pressure is stabilized at 600 mbar, continue heating to 1530℃ and hold for 4 hours to ensure that all the polycrystalline silicon raw material in the annular ingot cavity 3 is melted. The furnace temperature was lowered to 1430℃, and the insulation cage was slowly opened while continuously raising its top cover. The ingot casting device began directional cooling from bottom to top, and the silicon melt in the annular ingot cavity 3 cooled slowly from bottom to top until it solidified completely into a solid polycrystalline silicon ring. The furnace temperature was further lowered to 1350℃ and held for 2.5 hours to eliminate thermal stress inside the polycrystalline silicon ring. The ingot furnace heating system was turned off, and when the furnace temperature dropped below 450℃, the lower furnace chamber was opened, the ingot casting device was removed, and allowed to cool to room temperature on its own. The cover plate 10, inner support 4, outer support 5, counterweight 9, bottom guard plate 7, carrier plate 8, inner crucible 1, and outer crucible 2 were removed in sequence to obtain a polycrystalline silicon ring blank with an outer diameter of 550mm × an inner diameter of 300mm × a height of 250mm. The surface of the blank was polished using a polishing machine to obtain the finished polycrystalline silicon ring.

[0085] Example 2

[0086] In this embodiment, the outer crucible 2 is a circular quartz crucible with an inner diameter of 400mm and a height of 400mm, and the inner crucible 1 is a circular quartz crucible with an outer diameter of 250mm and a height of 400mm. The two are combined to produce a polycrystalline silicon ring with an outer diameter of 400mm, an inner diameter of 250mm and a height of 260mm.

[0087] Spray a silicon nitride release layer onto the inside of the outer crucible 2 and the outside of the inner crucible 1. Place the outer crucible 2 in the middle of the carrier plate 8, and place the inner crucible 1 into the outer crucible 2, adjusting their concentricity. Place 70 kg of polycrystalline silicon raw material into the annular ingot cavity 3 between the inner and outer crucibles; install the outer support 5, bottom protective plate 7, and inner support 4 in sequence; place a 5 kg tungsten metal block as a counterweight 9 on the bottom protective plate 7, and cover it with a graphite cover plate 10. Send the ingot casting device into the ingot furnace. Close the upper cover of the ingot furnace insulation cage and the lower furnace chamber. Evacuate the air in the ingot furnace until the furnace pressure is <0.02 mbar; turn on the ingot furnace heating switch, and when the furnace temperature rises to 1175℃, continuously introduce argon gas into the furnace until the furnace pressure is stabilized at 600 mbar, continue heating to 1500℃ and hold for 2 hours to ensure that all the polycrystalline silicon raw material in the annular ingot cavity 3 is melted. Lower the furnace temperature to 1430℃, and slowly raise the top cover of the insulation cage to open it. Starting from the bottom of the ingot casting device, directional cooling proceeds from the top, allowing the molten silicon in the annular ingot cavity 3 to cool slowly from bottom to top until it completely solidifies into a solid polycrystalline silicon ring. Continue lowering the furnace temperature to 1320℃ and hold for 2 hours to eliminate thermal stress inside the polycrystalline silicon ring. Turn off the ingot furnace heating system and wait for the furnace temperature to drop below 450℃. Open the lower furnace chamber, remove the ingot casting device, and allow it to cool to room temperature. Sequentially remove the cover plate 10, inner support 4, outer support 5, counterweight 9, bottom guard plate 7, carrier plate 8, inner crucible 1, and outer crucible 2 to obtain a polycrystalline silicon ring blank with an outer diameter of 400mm × an inner diameter of 250mm × a height of 260mm. Grind the surface of the blank using a grinder to obtain the finished polycrystalline silicon ring.

[0088] Example 3

[0089] In this embodiment, the outer crucible 2 is a square quartz crucible with a side length of 800×800mm×height of 325mm; the inner crucible 1 is a round quartz crucible with an outer diameter of 500mm×height of 300mm, producing a polycrystalline silicon irregular ring with an outer side of 800×800mm×inner diameter of 500mm×height of 225mm.

[0090] Spray a silicon nitride release coating on the inside of the outer crucible 2 and the outside of the inner crucible 1. Place the outer crucible 2 in the middle of the carrier plate 8, and place the inner crucible 1 inside the outer crucible 2, adjusting their concentricity. Place 230 kg of polycrystalline silicon raw material into the annular ingot cavity 3 between the inner and outer crucibles; install the outer support 5, bottom guard plate 7, and inner support 4 in sequence; place four 10 kg / piece tungsten rods as counterweights 9 on the bottom guard plate 7, and cover with a graphite cover plate 10. Send the ingot casting device into the ingot furnace. Close the upper cover of the ingot furnace insulation cage and the lower furnace chamber. Evacuate the air in the ingot furnace until the furnace pressure is <0.02 mbar; turn on the ingot furnace heating switch, and when the furnace temperature rises to 1175℃, continuously introduce argon gas into the furnace until the furnace pressure is stabilized at 600 mbar, continue heating to 1500℃ and hold for 2 hours to ensure that all the polycrystalline silicon raw material in the annular ingot cavity 3 is melted. Lower the furnace temperature to 1390℃, and slowly raise the top cover of the insulation cage to open it. Starting from the bottom of the ingot casting device, directional cooling is initiated from the top. The molten silicon in the annular ingot cavity 3 cools slowly from bottom to top until it completely solidifies into a solid polycrystalline silicon ring. Continue to lower the furnace temperature to 1300℃ and hold for 2 hours to eliminate thermal stress inside the polycrystalline silicon ring. Turn off the ingot furnace heating system and wait for the furnace temperature to drop below 350℃. Open the lower furnace chamber, remove the ingot casting device, and allow it to cool to room temperature. Sequentially remove the cover plate 10, inner support 4, outer support 5, counterweight 9, bottom guard plate 7, carrier plate 8, inner crucible 1, and outer crucible 2 to obtain a polycrystalline silicon shaped ring blank with an outer diameter of 800×800mm, an inner diameter of 500mm, and a height of 225mm. Grind the surface of the blank using a grinder to obtain the finished polycrystalline silicon shaped ring.

[0091] This invention provides a concept and method for casting ingots for casting ring-shaped polycrystalline silicon. Many methods and approaches exist for implementing this technical solution; the above is merely a preferred embodiment. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technology.

Claims

1. An ingot casting apparatus for casting a ring-shaped multicrystalline silicon, characterized by comprising: include: The annular ingot cavity (3) includes an inner peripheral wall (31) and an outer peripheral wall (32). And an inner support (4) that abuts against the inner side wall of the inner peripheral wall (31) and an outer support (5) that surrounds the outer side wall of the outer peripheral wall (32). During casting, the inner support (4) provides outward support to the inner wall of the inner peripheral wall (31), and the outer support (5) provides inward support to the outer wall of the outer peripheral wall (32).

2. The ingot casting apparatus for casting an annular polysilicon ingot according to claim 1, wherein It includes an inner crucible (1) and an outer crucible (2). The outer crucible (2) has an inner cavity. The inner crucible (1) is fitted inside the inner cavity of the outer crucible (2). The bottom surface of the inner crucible (1) is in contact with the bottom surface of the inner cavity of the outer peripheral wall (32). The peripheral wall of the outer crucible (2) is the outer peripheral wall (32), and the peripheral wall of the inner crucible (1) is the inner peripheral wall (31).

3. The ingot casting apparatus for casting ring-shaped polycrystalline silicon according to claim 2, characterized in that, The inner crucible (1) and the outer crucible (2) are quartz crucibles, and the inner support (4) and the outer support (5) are isostatic graphite materials.

4. The ingot casting apparatus for casting an annular polysilicon ingot according to claim 3, wherein The inner support (4) includes two or more inner protective plates (41). All the inner protective plates (41) are circumferentially spaced around the central axis of the inner crucible (1). The outer side wall of each inner protective plate (41) is attached to the inner side wall of the inner peripheral wall (31). A gap (43) is formed between adjacent inner protective plates (41). The inner side walls of adjacent inner protective plates (41) are fixedly connected by a first connecting component, so that the inner support (4) constitutes a hollow columnar structure with a hollow hole (42).

5. The ingot casting apparatus for casting an annular polysilicon ingot according to claim 4, wherein The hollow hole (42) of the inner support (4) is polygonal in shape, and the gap (43) between adjacent inner protective plates (41) is located at the corner of the polygon.

6. The ingot casting apparatus for casting an annular polysilicon ingot according to claim 5, wherein The first connecting assembly includes a connector (6) and a bolt (64). A seat hole (411) is provided on the inner side of the inner guard plate (41) near the gap (43). Two adjacent inner guard plates (41) are fixedly connected by bolts (64) passing through the connector (6) and tightening them into the seat hole (411).

7. The ingot casting apparatus for casting an annular polysilicon ingot according to claim 2, wherein It also includes a bottom guard plate (7), which is disposed on the bottom surface of the inner cavity of the inner crucible (1), and the inner support (4) is supported on the bottom guard plate (7).

8. The ingot casting apparatus for casting an annular polysilicon ingot according to claim 7, wherein It also includes a counterweight (9) which is placed above the bottom guard plate (7) and inside the inner support (4).

9. The ingot casting apparatus for casting an annular polysilicon ingot according to claim 1, wherein It also includes a carrier plate (8), the outer support (5) and the outer peripheral wall (32) are located above the carrier plate (8) and supported by the carrier plate (8).

10. The ingot casting apparatus for casting ring-shaped polycrystalline silicon according to claim 1, characterized in that, The outer support (5) includes two or more outer protective plates (51), which are circumferentially spaced around the central axis of the outer peripheral wall (32). The inner sidewall of each outer protective plate (51) is attached to the outer sidewall of the outer peripheral wall (32), and adjacent outer protective plates (51) are fixedly connected by a second connecting component.

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