Chemical vapor deposition reactor in polycrystalline silicon production process

Abstract

The chemical vapor deposition reactor used in the polycrystalline silicon production process comprises at least one reaction chamber, the filament assemblies are arranged along the circumference with the center of the reaction chamber as the circle center; each filament assembly includes: a filament including a pair of vertical portions and a bridge horizontally connecting tops of the pair of vertical portions, bottoms of the pair of vertical portions being connected to a pair of electrodes, respectively, the filament being heated by an electric current; and a pair of heat transfer jackets surrounding the pair of vertical portions of the filament, each heat transfer jacket comprising a double wall comprising a space containing a heat transfer medium, each heat transfer jacket comprising at least one heat transfer medium inlet and at least one heat transfer medium outlet, each heat transfer jacket comprising: a body portion surrounding the pair of vertical portions, the upper part of the main body part is positioned below the bridge; and an extension portion connected to the main body portion, the extension portion being disposed to face one side of the bridge, an upper edge of the extension portion being higher than a bottom of the bridge, the heat transfer medium outlet being located in the extension portion.

Description

Technical Field

[0001] One or more embodiments of this invention relate to a chemical vapor deposition reactor for increasing polysilicon yield during polysilicon manufacturing. One or more embodiments of this invention also relate to a chemical vapor deposition reactor designed for the large-scale production of high-quality polysilicon. Furthermore, one or more embodiments of this invention relate to a chemical vapor deposition reactor for effectively controlling heat during polysilicon production. Background Technology

[0002] Polycrystalline silicon is a raw material for semiconductors or solar panels. There are generally many methods for producing polycrystalline silicon. The Siemens chemical vapor deposition (CVD) process is one of the most widely used methods for producing polycrystalline silicon. In the Siemens process, silicon grows onto an electrically heated silicon filament in a CVD reactor as a reactive gas containing silicon is supplied. The silicon is deposited on the filament under CVD action, thus growing a long, thin polycrystalline silicon body, commonly known as a polycrystalline silicon rod.

[0003] For various reasons, the surface temperature of polycrystalline silicon rods in a chemical vapor deposition reactor may be uneven. For example, some surfaces of the polycrystalline silicon rod may have lower temperatures at locations with greater radiative heat loss, while other surfaces may have higher temperatures at locations with less radiative heat loss.

[0004] During the cooling process of polycrystalline silicon rods, stress is generated within the rods due to temperature differences during growth. Complicating matters further, the center temperature of the polycrystalline silicon rod is higher than its surface temperature. Once polycrystalline silicon growth is complete and the rod begins to cool, it shrinks, and as stress increases, cracks form, potentially leading to rod breakage. Generally, since the rod or wire is a U-shaped needle, well-grown polycrystalline silicon rods have a uniform shape. Cracks are easily observed at bends or corners of the polycrystalline silicon rod. If the polycrystalline silicon rod breaks and contacts the reactor surface, the crack promotes the introduction of impurities to the polycrystalline silicon surface, thus reducing the efficiency of producing high-purity polycrystalline silicon. Furthermore, cracks can propagate downwards along the vertical sections of the polycrystalline silicon rod. Unbroken, long sections of polycrystalline silicon rods, due to their uniform length and diameter, are the most commercially valuable. Cracks reduce the yield of the vertical sections. Additionally, differences in surface temperature cause variations in surface morphology and rod diameter. These variations reduce reactor productivity.

[0005] Therefore, it is necessary to mitigate or control the stress caused by thermal differences in polycrystalline silicon, thereby mitigating and controlling cracks caused by these stresses.

[0006] The information disclosed in this background section was already known to the inventor before the invention was developed, or is technical information obtained during the development of the invention. Therefore, it may contain information that does not constitute prior art known to those skilled in the art in this country. Utility Model Content

[0007] In one or more embodiments of the present invention, a chemical vapor deposition reactor for polycrystalline silicon production is provided. The reactor may include at least one reaction chamber; a plurality of filaments, each filament including a pair of vertical portions and a bridge horizontally connecting the tops of the pair of vertical portions, wherein the bottoms of the pair of vertical portions are respectively connected to a pair of electrodes, and wherein the plurality of filaments are heated by an electric current applied through the pair of electrodes; a plurality of heat transfer jackets surrounding the pair of vertical portions of the plurality of filaments, each heat transfer jacket including a double wall, wherein the double wall includes a space therein for containing a heat transfer medium, and each heat transfer jacket including at least one heat transfer medium inlet for providing the heat transfer medium into the space of the double wall, and at least one heat transfer medium outlet for discharging the heat transfer medium, wherein each heat transfer jacket includes a body portion surrounding the pair of vertical portions, wherein the upper portion of the body portion is located below the bridge, and an extension portion connected to the body portion, wherein the extension portion is configured to face the bridge and the upper edge of the extension portion is higher than the bottom of the bridge, and wherein the heat transfer medium outlet is located in the extension portion to enhance radiative heat transfer.

[0008] According to one or more embodiments, the arcuate central angle of the extension portion exceeds 180 degrees relative to the main body portion.

[0009] According to one or more embodiments, the arcuate central angle of the extension is greater than 180 degrees and less than or equal to 270 degrees relative to the main body.

[0010] According to one or more embodiments, at least a portion of at least one heat transfer jacket has a circular cross-section.

[0011] According to one or more embodiments, the surface of the double-walled structure facing each filament includes a reflective surface that reflects radiant heat emitted from each filament back to that filament, and the reflective surface is located in an extension of the heat transfer jacket.

[0012] According to one or more embodiments, the thickness of the extension portion is greater than the thickness of the main body portion.

[0013] According to one or more embodiments, the heat transfer medium is water.

[0014] As described above, according to the embodiments of the present invention, the yield of polycrystalline silicon can be increased by controlling the temperature difference in the polycrystalline silicon rod, thereby controlling cracks in the polycrystalline silicon deposition.

[0015] Other aspects will be set forth in the following sections of the specification, some of which will be obvious from the specification or may be learned by practicing the presented embodiments. Attached Figure Description

[0016] These and / or other aspects will become apparent and more readily understood by reading the following description of embodiments in conjunction with the accompanying drawings, wherein:

[0017] Figure 1 This is a perspective view of a chemical vapor deposition reactor for producing polycrystalline silicon according to an embodiment of the present invention.

[0018] Figure 2 yes Figure 1 A transparent view.

[0019] Figure 3 yes Figure 1 Enlarged cross-sectional view of the filament assembly.

[0020] Figure 4 yes Figure 1 A plan view of the filament assembly.

[0021] Figure 5 Is with Figure 2 A magnified cross-sectional view of another filament assembly from a different embodiment.

[0022] Figure 6 yes Figure 1 A magnified 3D view of part VI.

[0023] Figure 7A It schematically shows the relationship with Figure 1 and Figure 2 Top view of chemical vapor deposition reactors of different embodiments shown.

[0024] Figure 7B schematically shown Figure 7A Side view.

[0025] Figure 8A , 8B And 8C is Figure 3 Enlarged cross-sectional views of different embodiments of part VIII.

[0026] Figure 9A and 9B This is a schematic diagram showing heat transfer jackets with and without extensions.

[0027] Figure 10 This is a perspective view of a chemical vapor deposition reactor according to a comparative example.

[0028] In each figure, the same elements are indicated by the same reference numerals. The dimensions of the elements in the figures may be enlarged for ease of interpretation. In other words, since the dimensions and thicknesses of the parts in the figures are arbitrarily shown for ease of interpretation, the following embodiments are not limited to these dimensions and thicknesses. Detailed Implementation

[0029] Reference will now be made in detail to embodiments, examples of which are shown in the accompanying drawings, wherein the same reference numerals refer to the same elements throughout the text. In this respect, embodiments may take different forms and should not be construed as limited to the description set forth herein. Therefore, the following embodiments are described only with reference to the accompanying drawings to explain aspects of this description. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one,” when placed before the list of elements, modify the entire list of elements, not any individual element in the list.

[0030] Figure 1 This is a perspective view of a chemical vapor deposition reactor 1 for producing polycrystalline silicon according to an embodiment of the present invention. Figure 2 yes Figure 1 A transparent view.

[0031] The chemical vapor deposition reactor 1 includes at least one reaction chamber 100. The reaction chamber 100 can be separated by a base plate 300 and a shell 200. The chemical vapor deposition reactor 1 also includes a filament assembly 400, which includes an electrode 401 and a heated filament 420.

[0032] The base plate 300 may be a circular plate, and the housing 200 is connected to the upper part of the base plate 300 to provide the reaction chamber 100.

[0033] The outer casing 200 may be bell-shaped and may be secured to the base plate 300 by means of a flange formed at the bottom. A seal (not shown) may be installed between the outer casing 200 and the base plate 300 to seal the reaction chamber 100 relative to the outside.

[0034] The base plate 300 includes a gas injection unit 201 for supplying a reaction gas from a silicon-containing gas source (not shown) into the reaction chamber 100. The reaction gas may include, for example, monosilane (SiH4) or disilane (Si2H6) as silicon-containing gases. The supplied reaction gas decomposes upon contact with a heated filament 420 and is then deposited as polycrystalline silicon on the surface of the filament 420 to form a polycrystalline silicon rod 423. The position and shape of the gas injection unit 201 can vary and are not limited to those shown in the figures.

[0035] The base plate 300 may have an outlet 202. Byproducts, unreacted gases, or fine powders in the reaction chamber 100 are discharged to the outside through the outlet 202. The location and shape of the outlet 202 may vary and are not limited to those shown in the accompanying drawings.

[0036] As described above, the chemical vapor deposition reactor 1 includes a filament assembly 400, which includes an electrode 401 and a filament 420.

[0037] The filament 420 is a high-purity silicon rod. The filament 420 includes a pair of vertical portions 422 and a bridge 421 connecting them. The portion connecting each vertical portion 422 to the bridge 421 is primarily curved. The filament 420 is secured to a chuck (not shown) and stands upright in an inverted U-shape. The filament 420 can have various diameters or lengths. The reactive gases, explained later, react and deposit on the filament 420 to produce a grown polycrystalline silicon rod 423.

[0038] Electrode 401 can be mounted through base plate 300. A filament 420 is connected to electrode 401 via a chuck (not shown). Electrode 401 can be connected to a separate power supply unit (not shown). The filament 420 can be heated to the polysilicon deposition temperature by applying current to the filament 420 through electrode 401. The filament 420 can be heated in the range of approximately 600°C to approximately 1200°C. The filament 420 provides an initial deposition surface for polysilicon deposition. Subsequently, the outer surface of the deposited polysilicon serves as the deposition surface. At this time, when using silane as the silicon gas source, the deposition surface can be maintained between approximately 800°C and approximately 900°C.

[0039] The filament assembly 400 also includes a heat transfer jacket 430. The heat transfer jacket 430 is mounted parallel to the filament 420 to surround its vertical portion 422. The heat transfer jacket 430 may have a circular cross-section. For example, the heat transfer jacket 430 may have a shape such as... Figure 1 The cylindrical shape is shown. However, the shape of the heat transfer jacket 430 is not limited to a cylindrical body, and can have various shapes including polygonal cylinders.

[0040] The heat transfer jacket 430 has a double-walled structure (such as...) Figure 2 (As shown) to contain a heat transfer medium. The heat transfer jacket 430 includes a heat transfer medium inlet 491 for supplying the heat transfer medium into the space of the double-walled structure and a heat transfer medium outlet 493 for discharging the heat transfer medium circulating in the heat transfer jacket 430. The heat transfer medium inlet 491 is located in the lower portion of the heat transfer jacket 430, where "lower portion" can refer to an area closer to the base plate 300. The heat transfer medium outlet 493 is located in the upper portion of the heat transfer jacket 430, where "upper portion" can refer to an area closer to the top of the housing 200. A detailed description of the placement of the heat transfer medium inlet 491 and the heat transfer medium outlet 493 is provided in [the relevant section]. Figure 6 Provided by China.

[0041] A heat transfer medium supply line 492 is connected to a heat transfer medium inlet 491 to supply the heat transfer medium into the double-walled space of the heat transfer jacket 430. The heat transfer medium supply line 492 may pass through the base plate 300 and be connected to a heat transfer medium supply source (not shown).

[0042] A heat transfer medium discharge line 494 is connected to a heat transfer medium outlet 493 to discharge the heat transfer medium from the space between the double walls of the heat transfer jacket. The heat transfer medium discharge line 494 can pass through the base plate 300 to discharge the heat transfer medium to the outside or return it to the heat transfer medium supply source (not shown).

[0043] Connector 495 connects the space of the double-walled structure of multiple adjacent heat transfer jackets. Connector 495 connects the heat transfer medium outlet 493 of one heat transfer jacket to the heat transfer medium inlet 491 of an adjacent heat transfer jacket. In a heat transfer jacket ( Figure 1 and Figure 2 The heat transfer medium circulating in the double-walled space of the left heat transfer jacket 430a can be moved to the next heat transfer jacket via connector 495. Figure 1 and Figure 2 The medium flows through the double-walled space of the right-side heat transfer jacket 430b. Figure 2 The arrow is shown in the middle.

[0044] A heat transfer medium is supplied to the heat transfer jacket 430 to cool it. The temperature of the heat transfer medium can be between about 20°C and about 60°C. The heat transfer medium can be a liquid. For example, the heat transfer medium can be cooling water to achieve economic and efficiency benefits. The heat transfer jacket 430 prevents the reaction chamber 100 from overheating to prevent the formation of unwanted byproducts due to excessively high temperatures in the reaction chamber 100.

[0045] For example, when monosilane gas decomposes at high temperatures, fine silicon powder is produced. This silicon powder not only hinders the growth of the polycrystalline silicon rod 423 but also causes surface inhomogeneity. Silicon powder deposits on the surface of the heat transfer jacket 430 or the housing 200, and the deposited silicon powder can then detach from the surface and fall off. Some of the fallen silicon powder can adhere to the surface of the polycrystalline silicon rod 423. Some of the silicon powder adhering to the polycrystalline silicon rod 423 may cause abnormal dendrite growth and lead to product defects. This phenomenon is more likely to occur in reaction gases containing silicon in the form of non-halogenated silane compounds, such as monosilane (SiH4), disilane (Si2H6), or compounds thereof. The heat transfer jacket 430 prevents the interior of the reaction chamber 100 from rising to excessively high temperatures, thereby suppressing the generation of excessive silicon powder.

[0046] Meanwhile, as the silicon powder circulates in the reaction chamber 100, most of the silicon powder deposits on the low-temperature surface. Therefore, the cooling heat transfer jacket 430 not only reduces the temperature inside the reaction chamber 100, but also allows the silicon powder to adhere to the surface of the heat transfer jacket.

[0047] Figure 3 yes Figure 1 Enlarged cross-sectional view of the filament assembly 400. Figure 4 yes Figure 1 A plan view of the filament assembly 400. Meanwhile, Figure 5 Is with Figure 2 A magnified cross-sectional view of another filament assembly 400a from a different embodiment. Meanwhile, in Figure 3 and Figure 5 For ease of description, the heat transfer medium inlet 491, heat transfer medium supply pipeline 492, heat transfer medium outlet 493, and heat transfer medium discharge pipeline 494 are excluded.

[0048] like Figure 3 As shown, the heat transfer jacket 430 includes a main body portion 435 and an extension portion 436. The names of the main body portion 435 and the extension portion 436 are used for ease of explanation. As we described earlier, the main body portion 435 and the extension portion 436 are joined to form a heat transfer jacket 430. Therefore, the extension portion 436 also includes double walls for circulating the heat transfer medium between them, and includes a reflective surface 434 on the outer surface of the double walls facing the filaments 420.

[0049] The main body portion 435 surrounds the vertical portion 422 of the filament or polycrystalline silicon rod, and the upper end of the main body portion 435 is as follows: Figure 3 The location shown is below the bridge.

[0050] The extension portion 436 connected to the main body portion 435 is configured as follows: Figure 4 The extension shown extends to the opposite side of the bridge. Since the polysilicon rod 423 is heated by the flow of current and is conductive, electrical problems may occur if the extension 436 is positioned too close to or in contact with the polysilicon rod 423. Simultaneously, the extension 436 should cover the polysilicon rod 423 as much as possible to prevent heat loss from the polysilicon rod 423. Therefore, as... Figure 4As shown, the two ends of the extension 436 extend beyond half the center of the cross-section of the main body 435 to prevent it from getting too close to or contacting the bridge, while also reducing heat loss from the polysilicon rod 423. According to an alternative embodiment, the angle “θ” between the two edges of the extension 436 and the center of the cross-section of the main body 435 can exceed 180 degrees but be less than or equal to 270 degrees. If the angle “θ” exceeds 270 degrees, the heat transfer jacket 430 and the polysilicon rod 423 may be too close to each other, potentially causing electrical problems, especially if the rod is tilted. If the angle “θ” is less than or equal to 180 degrees, the polysilicon rod 423 may experience more heat loss. According to another alternative embodiment, the distance d2 between the outer surface of the polysilicon rod 423 and the end of the extension 436 is preferably 30% to 70% of the distance d1 between the outer surface of the polysilicon rod 423 and the remainder of the extension 436 (0.3 x d1 ≤ d2 ≤ 0.7 x d1). For example, if the distance d2 between the outer surface of the polysilicon rod 423 and the end of the extension 436 is less than 30% of the distance d1 between the outer surface of the polysilicon rod 423 and the rest of the extension 436, the heat transfer jacket 430 and the polysilicon rod 423 may be too close to each other, which may cause electrical problems, especially if the rod is tilted. Meanwhile, if the distance d2 between the outer surface of the polysilicon rod 423 and the end of the extension 436 is greater than 70% of the distance d1 between the outer surface of the polysilicon rod 423 and the rest of the extension 436, the polysilicon rod 423 may experience more heat loss, and the quality of the polysilicon rod 423 formed between the bridge and vertical portions may decrease.

[0051] The upper end of the extension 436 can be positioned at least above the bottom of the bridge of the polysilicon rod 423 to reflect radiant heat to the filament or polysilicon rod. For example, the upper end of the extension 436 can be positioned at... Figure 3 The extension portion 436 is positioned at or above line a-a' in the filament bridge. According to one embodiment of the present invention, the upper end of the extension portion 436 is positioned at the same height as or above the top of the filament bridge 421. For example, the upper end of the extension portion 436 may be positioned at... Figure 3 Above or on line b-b' in the present invention. According to other embodiments of the present invention, the upper end of the extension 436 is positioned as follows: Figure 3 The bridge shown is at the same height as the top of the polysilicon rod 423, or as shown below. Figure 5 The height "h" of the top of the bridge above the polysilicon rod 423 is shown. The height "h" can be modified in various ways by those skilled in the art and is not limited to the case shown in the figures. For example, the upper end of the extension 436 can be positioned at... Figure 3 and Figure 5Above or on line c-c' in the polysilicon rod. According to an exemplary embodiment, the upper end of the extension 436 is higher than the top of the bridge of the polysilicon rod 423, i.e. Figure 5 The line c-c' in the polysilicon body 423 has a height "h" that can be equal to or less than twice the diameter of the polysilicon body 423. This is because the portion with a height "h" greater than twice the diameter of the polysilicon body 423 receives less radiant heat from the heated filament 420.

[0052] Figure 6 yes Figure 1 A magnified 3D view of part of VI. (Reference) Figure 6 The heat transfer medium outlet 493 is located in the extension 436 of the heat transfer jacket 430. For example... Figure 1 As explained, the heat transfer medium inlet 491 is located on the main body portion 435 near the base plate 300. Since the extension portion 436 is located in the opposite direction of gravity compared to the main body portion 435, additional force is required for the heat transfer medium to reach all areas of the extension portion 436. Heat generally tends to rise, so the relatively cooler heat transfer medium enters the lower part of the heat transfer jacket 430 and naturally rises when heated. By positioning the heat transfer medium outlet 493 in the extension portion 436 of the heat transfer jacket 430, more efficient heat transfer and heat transfer medium flow can be achieved through the use of natural convection. Furthermore, as the heat transfer medium flows from the bottom to the top of the heat transfer jacket 430, it gradually heats up, reaching a higher temperature upon reaching the extension portion 436. This allows the extension portion 436 to more effectively transfer heat to the polycrystalline silicon rod 423. Additionally, by positioning the heat transfer medium outlet 493 in the extension portion 436, air bubbles that may form during the flow of the heat transfer medium can be effectively removed, preventing a decrease in heat transfer efficiency. Air is lighter than water or other liquid heat transfer media, so it naturally rises. If bubbles form inside the heat transfer jacket 430, they tend to move upward regardless of the flow of the heat transfer medium. Therefore, when the heat transfer medium outlet 493 is positioned in the upper part of the heat transfer jacket 430, particularly in the extension 436, the bubbles naturally escape through the heat transfer medium outlet 493. The position of the heat transfer medium outlet 493 in each embodiment prevents air from accumulating in the extension 436, ensuring that heat exchange performance can be maintained. According to one embodiment of this disclosure, by positioning the heat transfer medium outlet 493 in the extension 436, heat exchange performance can be maintained, and the problem of uneven polysilicon deposition on the surface of the polysilicon rod 423 corresponding to the extension 436 can be solved. This will refer to Figure 9A and 9B To explain in more detail.

[0053] Figure 7A It schematically shows the relationship with Figure 1 and Figure 2Top view of chemical vapor deposition reactor 1b of different embodiments shown. Figure 7B The diagram schematically shows the view from the direction of the arrow. Figure 7A Side view. In Figure 7B In this configuration, the orientation of the heat transfer jacket has been arbitrarily adjusted to better display the inlet and outlet of the heat transfer medium. Figure 1 and Figure 2 compared to, Figure 7A and Figure 7B The chemical vapor deposition reactor 1b is shown to include more than two pairs of filament assemblies 400b.

[0054] refer to Figure 7A and Figure 7B According to another embodiment of the present disclosure, the chemical vapor deposition reactor 1b may include a reaction chamber 100b defined by a base plate (not shown) and a shell (not shown). A plurality of filament assemblies 400b are provided inside the reaction chamber 100b. Because the reaction chamber 100b and... Figure 1 and Figure 2 The descriptions are similar to those in the text, so repeated descriptions are omitted.

[0055] Each filament assembly may include a filament on which polycrystalline silicon is deposited and a pair of electrodes on which electricity is applied to the filament. The filament, the pair of electrodes, and the polycrystalline silicon rod formed by the reaction and deposition of reactive gases on the filament are already... Figure 1 and Figure 2 The description is as described in the text, therefore repeated descriptions are omitted.

[0056] Multiple filament assemblies 400b can be arranged along a circumference centered on the center of the reaction chamber 100b.

[0057] Each filament assembly may include a filament 420 and / or a polycrystalline silicon rod 423, and a pair of heat transfer jackets with double walls. Each heat transfer jacket includes a body portion 435 surrounding a vertical portion of the polycrystalline silicon rod 423 and an extension portion 436 located on top of the body portion 435. The heat transfer jacket 430 also includes a heat transfer medium inlet 491 for supplying heat transfer medium into the space between the double walls, and a heat transfer medium outlet 493 for discharging heat transfer medium circulating in the heat transfer jacket 430. The heat transfer medium outlet 493 is located in the extension portion 436 of the heat transfer jacket 430, while the heat transfer medium inlet 491 is placed in the body portion 435, preferably near the base plate. The heat transfer inlet and outlet are connected by connectors 495. Connectors 495 may be configured to have a single wall. The heat transfer medium inlet 491, the heat transfer medium outlet 493, and the connectors 495 are positioned toward the center of a plurality of filament assemblies 400b arranged in a circular pattern. This minimizes the travel distance of the heat transfer medium and allows for efficient use of the space in reaction chamber 100b.

[0058] Simultaneously, the heat transfer medium supplied to and discharged from the heat transfer jacket 430 circulates within the chemical vapor deposition reactor 1b via a cooling circuit 497. The cooling circuit 497 can be arranged to surround the outer periphery of multiple pairs of heat transfer jackets 430. The cooling circuit 497 is located on the side of the heat transfer jacket 430 opposite to the locations of the heat transfer medium inlet 491, heat transfer medium outlet 493, and connector 495. The cooling circuit 497 can be connected to the heat transfer medium supply line 492 and the heat transfer medium discharge line 494, allowing the heat transfer medium that has circulated in the multiple pairs of heat transfer jackets 430 to return to the jacket. Although not shown, the cooling circuit 497 can be equipped with a separate cooler and can also provide a separate inlet for introducing the heat transfer medium into the chemical vapor deposition reactor 1b and a separate outlet for discharging the heat transfer medium from the reactor 1b. The heat transfer medium supply line 492 and the heat transfer medium discharge line 494 can be located at the points furthest from each other on the cooling circuit 497. For example, the heat transfer medium supply line 492 and the heat transfer medium discharge line 494 can be positioned relative to each other on the cooling circuit 497.

[0059] exist Figure 7B In the diagram, the direction of movement of the heat transfer medium is indicated by arrows. (Reference) Figure 7B The first heat transfer medium inlet 491b can be located at the lower end of the main body of the first heat transfer jacket 430a. The first heat transfer medium inlet 491b can be connected to the heat transfer medium supply line 492. The heat transfer medium entering the first heat transfer jacket 430a through the heat transfer medium supply line 492 circulates within the first heat transfer jacket 430a. Next, the heat transfer medium is discharged through the first heat transfer medium outlet 493a and enters the second heat transfer jacket 430b through the second heat transfer medium inlet 491b. In the same manner, the heat transfer medium is discharged through the second heat transfer medium outlet 493b and enters the third heat transfer jacket 430c through the third heat transfer medium inlet 491c, then the heat transfer medium is discharged through the third heat transfer medium outlet 493c and enters the fourth heat transfer jacket 430d through the fourth heat transfer medium inlet 491d. Similarly, the heat transfer medium is discharged through the fourth heat transfer medium outlet 493d and enters the fifth heat transfer jacket 430e through the fifth heat transfer medium inlet 491e. Then, the heat transfer medium is discharged through the fifth heat transfer medium outlet 493e and enters the sixth heat transfer jacket 430f through the sixth heat transfer medium inlet 491f. The sixth heat transfer medium outlet 493f of the extension 436 of the sixth heat transfer jacket 430f is connected to the heat transfer medium discharge line 494. The heat transfer medium circulated through the heat transfer jacket 430 is transferred to the cooling circuit 497 via the heat transfer medium discharge line 494. The heat transfer medium circulates through the cooling circuit 497 and then returns to the heat transfer jacket 430 via the heat transfer medium supply line 492. The positioning of each heat transfer medium outlet in the extension of each heat transfer jacket improves heat transfer efficiency and contributes to the formation of a uniform, high-quality polycrystalline silicon rod.

[0060] at the same time, Figure 7A Only one half of the reaction chamber 100b is shown, containing multiple filament assemblies 400b; the other half is omitted. According to one embodiment, the other half may be arranged in conjunction with... Figure 7A The image shown is a half-mirror. According to another embodiment, additional filament components can be integrated with... Figure 7A The same arrangement is shown along a circle centered on the middle of the reaction chamber.

[0061] Figure 8A , 8B And 8C is Figure 3 Enlarged cross-sectional views of different embodiments of part VIII. Although Figure 8A , 8B And 8C is relative to Figure 3 The examples shown are, of course, applicable to all embodiments disclosed herein.

[0062] In the double-walled structure of the heat transfer jacket, the outer surface of the wall facing the filament 420 and / or polycrystalline silicon rod 423 is formed by a reflective surface 434, which reflects at least a portion of the radiant heat emitted from the filament 420 and / or polycrystalline silicon rod 423 back to the filament 420 and / or polycrystalline silicon rod 423. The reflective surface 434 is made of or coated with a material having good radiant heat reflection efficiency. For example, such as... Figure 8A As shown, the reflective surface 434a is plated with at least one material selected from stainless steel, nickel, nickel alloys, molybdenum, molybdenum alloys, tungsten, tungsten alloys, cobalt, cobalt alloys, titanium, titanium alloys, silver, silver alloys, gold, gold alloys, tantalum, tantalum alloys, platinum, and / or platinum alloys. For example, as... Figure 8B As shown, the reflective surface 434b can be formed only on the wall of the extension 436 of the heat transfer jacket 430 facing the filament 420 and / or the polycrystalline silicon rod 423. Therefore, the extension 436 can have a greater thickness than the main body 435. By forming the extension 436 with a thicker structure, it can more effectively reflect radiant heat and improve heat transfer efficiency. Meanwhile, as... Figure 8C As shown, the reflective surface 434c is made of at least one material selected from stainless steel, nickel, nickel alloys, molybdenum, molybdenum alloys, tungsten, tungsten alloys, cobalt, cobalt alloys, titanium, titanium alloys, silver, silver alloys, gold, gold alloys, tantalum, tantalum alloys, platinum, and / or platinum alloys. The reflective surface 434 can reflect at least a portion of the radiant heat generated from the heated filament 420 to help heat the filament 420 and / or polycrystalline silicon rod 423 and maintain a high deposition temperature. In this way, reactive gases can be deposited on the surfaces of the filament 420 and / or polycrystalline silicon rod 423.

[0063] On the other hand, in the double-walled heat transfer jacket, the outer surface of the wall 433 facing the outer shell 200 is not coated with a material with good radiative heat reflection efficiency.

[0064] Figure 9A and 9B The diagram schematically shows a heat transfer jacket 430 with and without the extension portion 436. Figure 9A This is a prior art diagram schematically illustrating a crack in a polysilicon rod 423 when the extension portion 436 is absent. On the other hand, Figure 9B This is a schematic diagram of an ideal polycrystalline silicon rod 423 when the extension portion 436 is present.

[0065] like Figure 9A As shown, without the extension section, section A cannot receive radiant heat through the reflective surface, and a significant amount of heat is lost into the reaction chamber. Therefore, section A has a relatively low temperature (Ta). Due to the relatively low temperature of section A, polycrystalline silicon may not be deposited correctly in section A. Conversely, section B has a high temperature (Tb) due to overheating at the corner where the heated vertical section and the bridge meet closely. Section B overheats and may exhibit popcorn-shaped defects. Due to the temperature difference between Ta and Tb (|Ta-Tb|), sections A and B have different coefficients of thermal expansion, and stress accumulates in both sections. After polycrystalline silicon growth is complete, as the rod begins to cool, the accumulated stress begins to manifest as cracks. Cracks may begin at the corners and propagate downwards along the vertical section. Since the vertical section, with a uniform diameter along its length, is the most commercially valuable section, cracks reduce the yield of the vertical section. Furthermore, cracks help introduce impurities into the polycrystalline silicon, thereby reducing the production efficiency of high-purity polycrystalline silicon.

[0066] However, as Figure 9B As shown, the extension 436, including the reflective surface 434, reflects radiant heat generated from the rod 423 back to the upper part of the rod 423, particularly to the vertical portion and the bridge connection portion. The extension 436 can maintain the high temperature (Ta') in portion A by reflecting radiant heat back to portion A. As described above, according to one or more embodiments of the present invention, there is no large temperature difference (|Ta'-Tb|<<|Ta-Tb|) between portion A and portion B. As a result, when the rod cools, there is only small stress due to these small temperature differences. Due to the low stress, fewer or no cracks appear in the polycrystalline silicon. The yield of the commercially valuable vertical portion is increased, and high-purity polycrystalline silicon can be obtained due to the reduction of contamination caused by cracks.

[0067] Figure 10This is a perspective view showing a chemical vapor deposition reactor according to a comparative example. Compared to the comparative example, the chemical vapor deposition reactor according to one embodiment of the present disclosure is arranged such that both ends of the extension 436 of the heat transfer jacket 430 extend beyond half the center of the cross-section of the main body portion 435, and experiments have shown that it can produce high-quality polycrystalline silicon rods. Furthermore, the chemical vapor deposition reactor according to one embodiment of the present disclosure has a heat transfer medium outlet 493 located in the extension 436 of the heat transfer jacket 430, which improves thermal efficiency and effectively reduces defects in the polycrystalline silicon rod 423. It should be understood that the exemplary embodiments described herein should be considered in a descriptive sense only and not for limiting purposes. The description of features or aspects in each embodiment should generally be considered applicable to other similar features or aspects in other embodiments.

[0068] Although one or more embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

Claims

1. A chemical vapor deposition reactor for polycrystalline silicon production, characterized in that, The reactor includes: At least one reaction chamber; and Multiple filament assemblies are arranged along a circumference centered on the center of the reaction chamber; Each filament assembly includes: A filament comprising a pair of vertical portions and a bridge horizontally connecting the tops of the pair of vertical portions, wherein the bottoms of the pair of vertical portions are respectively connected to a pair of electrodes, and wherein the filament is heated by an electric current applied through the pair of electrodes; and A pair of heat transfer jackets surrounding the pair of vertical portions of the filament, each heat transfer jacket including a double wall, wherein the double wall includes a space therein for receiving a heat transfer medium, and each heat transfer jacket including at least one heat transfer medium inlet for supplying the heat transfer medium into the space of the double wall and at least one heat transfer medium outlet for discharging the heat transfer medium. Each heat transfer jacket includes a main body portion surrounding the pair of vertical portions, wherein the upper portion of the main body portion is located below the bridge, and an extension portion connected to the main body portion, wherein the extension portion is configured to face the bridge and its upper edge is higher than the bottom of the bridge, and wherein the heat transfer medium outlet is located in the extension portion to enhance radiative heat transfer. The arc-shaped central angle of the extended portion exceeds 180 degrees relative to the main body portion.

2. The chemical vapor deposition reactor in the polycrystalline silicon production process according to claim 1, characterized in that, The arcuate central angle of the extended portion is greater than 180 degrees and less than or equal to 270 degrees relative to the main body portion.

3. The chemical vapor deposition reactor in the polycrystalline silicon production process according to claim 1, characterized in that, At least a portion of the at least one heat transfer jacket has a circular cross-section.

4. The chemical vapor deposition reactor in the polycrystalline silicon production process according to claim 1, characterized in that, The surface of the double-walled structure facing each filament includes a reflective surface that reflects radiant heat emitted from each filament back to that filament, and the reflective surface is located in the extension of the heat transfer jacket.

5. The chemical vapor deposition reactor in the polycrystalline silicon production process according to claim 4, characterized in that, The thickness of the extension portion is greater than the thickness of the main body portion.

6. The chemical vapor deposition reactor in the polycrystalline silicon production process according to claim 1, characterized in that, The heat transfer medium is water.

7. The chemical vapor deposition reactor in the polycrystalline silicon production process according to claim 1, characterized in that, It also includes a cooling circuit configured to surround the periphery of the plurality of filament assemblies, wherein the cooling circuit is located on the side of the heat transfer jacket opposite to the location of the heat transfer medium outlet.

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