A method and apparatus for reducing polycrystalline silicon

Abstract

This invention relates to a method and apparatus for polycrystalline silicon reduction. The method incorporates steps such as real-time monitoring of the silicon rod's tilting force during reduction and controlling the longitudinal flow velocity of the mixed gas within the furnace based on the magnitude of the tilting force. By detecting the tilting force of the silicon rod in real time, the method can detect uneven weight distribution on the rod in advance. The upward velocity of the mixed gas is then controlled according to the tilting force, increasing the aggregation rate of elemental silicon at the bottom of the rod and thus enhancing its stability and reducing the likelihood of tipping. The apparatus provided by this invention, combined with the method, ensures the smooth operation of the entire reduction process.

Description

Technical Field

[0001] This invention relates to the reduction of polycrystalline silicon, specifically to a method and apparatus for polycrystalline silicon reduction. Background Technology

[0002] Currently, the modified Siemens process is widely used in the production of polysilicon. The reduction furnace is the core equipment for polysilicon production. Trichlorosilane and hydrogen from the tank area are mixed and preheated and metered before being fed into the polysilicon reduction furnace for vapor deposition reaction to produce polysilicon.

[0003] In the above process, multiple pairs of silicon rods are used on the reduction furnace chassis. The reduced elemental silicon will continuously concentrate on the silicon rods, thereby increasing their thickness. The mixed gas enters the reduction furnace from the chassis. However, due to various reasons such as uneven silicon rod temperature, uneven density of the mixed gas, and excessively fast airflow, the weight increase of the upper and lower parts of the silicon rod may be inconsistent. When the top is too heavy, the silicon rod will usually collapse, thus affecting the reduction process. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] Given the following technical problems in the existing technology: the existing technology cannot effectively reduce or prevent the collapse of the silicon rod during the reduction process. To solve this technical problem, the present invention provides the following technical solution:

[0006] A method for reducing polycrystalline silicon includes at least the following steps:

[0007] The tilting force of the silicon rod is monitored in real time during the reduction process;

[0008] The longitudinal flow velocity of the mixed gas in the furnace is controlled according to the magnitude of the tilting force.

[0009] As a preferred technical solution for polycrystalline silicon reduction, the process of controlling the longitudinal flow rate is as follows: maintaining a constant air intake flow rate and controlling the airflow to change through the cross-section.

[0010] A polysilicon reduction apparatus, comprising a chassis and:

[0011] The electrodes are configured to rotate relative to the chassis.

[0012] A force detection element is supported between the electrode side and the chassis;

[0013] A matching intake channel gate valve assembly, wherein any silicon rod corresponds to multiple intake channels, and the gate valve assembly performs corresponding actions according to the force detection element.

[0014] As a preferred technical solution for a polysilicon reduction device, it further includes an upper support and a lower support. The electrode is fixedly connected to the upper support and rotatably connected to the lower support. The lower support is fixedly connected to the chassis. The force detection element abuts between the upper support and the lower support.

[0015] As a preferred technical solution for a polysilicon reduction device, the lower support includes a support block and a terminal fixed on the support block, the force detection element abuts between the support block and the upper support, and the electrode is rotatably connected to the terminal.

[0016] As a preferred technical solution for a polysilicon reduction device, the electrode includes an integrally connected electrode rod, an upper abutment block, and a lower abutment block. The electrode rod passes through the upper support portion, and the upper abutment block and the lower abutment block are respectively pressed against both sides of the upper support portion.

[0017] As a preferred technical solution for polycrystalline silicon reduction equipment, the upper abutment block is constructed with a bearing surface, which is distributed around the electrode rod.

[0018] As a preferred technical solution for polysilicon reduction equipment, the electrode rod is provided with an upper guide groove, and the terminal is provided with a lower guide groove, and the terminal is rotatably connected to the port of the upper guide groove.

[0019] As a preferred technical solution for a polysilicon reduction device, the air intake channel is constructed on the upper support and extends through the support block.

[0020] As a preferred technical solution for a polysilicon reduction device, it also includes a gas supply pipeline and multiple branches connected to the gas supply pipeline, the multiple branches being connected to multiple air inlet channels respectively, and the gate valve assembly including on / off valves respectively disposed on the multiple branches.

[0021] The present invention has the following beneficial effects:

[0022] 1. In the method provided by the present invention, the tilting force of the silicon rod is detected in real time, so that it can be detected in advance when there is uneven load on the upper and lower parts of the silicon rod. The upward speed of the mixed gas is controlled according to the tilting force, thereby increasing the attachment speed of silicon elemental at the lower part of the silicon rod, thereby increasing the stability of the silicon rod, reducing the phenomenon of silicon rod tipping, and ensuring the smooth progress of the entire reduction process.

[0023] 2. The device provided by the present invention can be used in conjunction with the method provided by the present invention through the mutual linkage between the force detection element and the gate valve assembly, so as to maintain the stability of the silicon rod throughout the reduction process and ensure the smooth progress of the reduction process. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0025] Figure 1 This is a perspective view of the second embodiment of the present invention.

[0026] Figure 2 For about Figure 1 Another perspective view.

[0027] Figure 3 for Figure 1 A separate diagram showing the middle section of the structure.

[0028] Figure 4 For about Figure 3 Another perspective view.

[0029] Figure 5 This is a schematic diagram illustrating the arrangement of the electrodes and corresponding components described in the embodiments of the present invention through a three-dimensional cutting method.

[0030] Figure 6 For about Figure 5 The formal floor plan.

[0031] Figure 7 This is a schematic diagram of the air intake channel in an embodiment of the present invention.

[0032] Figure 8 This is a schematic diagram showing the connection between the upper guide channel and the lower guide channel in an embodiment of the present invention.

[0033] Figure 9 This is a schematic diagram of the gas path connection between some structures in an embodiment of the present invention.

[0034] Figure label:

[0035] 1. Chassis; 2. Silicon rod; 3. Support block; 4. Terminal; 5. Electrode; 501. Electrode rod; 502. Upper abutment block; 503. Lower abutment block; 6. Force detection element; 7. Upper support part; 8. Air intake channel; 9. Upper guide groove; 10. Lower guide groove; 11. Air supply pipeline; 12. Branch line; 13. On / off valve. Detailed Implementation

[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0037] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0038] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0039] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0040] Example 1

[0041] The first embodiment of the present invention provides a polycrystalline silicon reduction method, which, compared with the prior art, adds a step of real-time tilting force detection of silicon rods in the existing reduction process, and adds a step of controlling the rising speed of trichlorosilane and hydrogen mixture in the furnace according to the magnitude of the tilting force.

[0042] Based on the above, specifically, each silicon rod has a corresponding inlet for mixed gas at its bottom position on the chassis of the reduction furnace. During the reduction process, the lateral tilting force of the silicon rod is monitored in real time. Under normal circumstances, there is generally no tilting force or the tilting force is within a certain range. When the silicon element accumulates rapidly at the top of the silicon rod, the rod becomes top-heavy and bottom-light, resulting in instability and a tendency to tip over. This increases the tilting force, exceeding the normal range. At this point, the speed of the mixed gas entering at the inlet is controlled to slow down the upward speed of the mixed gas in the furnace, increasing the concentration of the mixed gas near the chassis. This increases the accumulation speed of silicon element at the bottom of the silicon rod, thereby increasing the amount of silicon element accumulated at the root of the silicon rod, i.e., increasing the diameter of the silicon rod root, and thus increasing the stability of the silicon rod root supported on the chassis. Once the support force at the bottom of the silicon rod reaches a certain level, the mixed gas is kept flowing upward at a normal speed, thus keeping the silicon element accumulation speed at the top and bottom of the silicon rod uniform, allowing the reduction process to continue.

[0043] In the above implementation process, regarding the control of the gas mixture entry speed, specifically, keeping the flow rate of the gas mixture entering the furnace from the inlet constant and directly increasing the inlet diameter can slow down the upward flow speed of the gas mixture; when the inlet diameter is reduced, the compression effect on the gas mixture can be increased, thereby increasing the upward flow speed of the gas mixture.

[0044] Example 2

[0045] The second embodiment of the present invention provides a polysilicon reduction apparatus that utilizes the method described in Embodiment 1, specifically, as follows: Figure 1-7 As shown, the equipment includes a furnace body, which consists of a chassis 1 and a bell jar (not shown in the figure). Multiple support blocks 3 are fixedly installed on the chassis 1, each corresponding to a multiple silicon rod 2. The equipment also includes an upper support part 7 corresponding to the support block 3, a force detection element 6, and two electrodes 5. The two electrodes 5 are used to connect the silicon rod 2 and are fixed on the upper support part 7. They are used to connect to positive and negative power supplies. The bottom of the electrodes 5 is rotatably connected to the upper fixed position of the support block 3. The force detection element 6 can be a pressure strain gauge or a pressure detector. Specifically, the force detection element 6 abuts between the support block 3 and the upper support part 7, and there are two of them. They are distributed on both sides of the distance direction between the two electrodes 5. The upper support part 7 is also constructed with multiple air intake channels 8, which pass through the support block 3 and lead to the outside of the chassis 1. The multiple air intake channels 8 are used to connect to the same gas supply pipeline 11.

[0046] Based on the above:

[0047] The gas supply line 11 provides the mixed gas at a constant flow rate and enters the furnace through a single gas inlet channel 8. When multiple gas inlet channels 8 are kept open, the mixed gas enters the furnace in a dispersed manner through multiple gas inlet channels 8, that is, the opening of the mixed gas is kept wide enough when it enters the furnace, thereby slowing down the flow rate of the mixed gas when it enters the furnace. The opening and closing control process of multiple gas inlet channels 8 is provided by the gate valve assembly.

[0048] Regarding the detection of tilting force, since silicon rod 2 is fixedly connected to electrode 5, when silicon rod 2 has a large tilting tendency, the upper support part 7 will also tilt to both sides, so that the tilting force will be applied to the force detection element 6, and the magnitude of the tilting force will be detected by the force detection element 6. An electrical signal connection is established between the force detection element 6 and the gate valve assembly. When the force detection element 6 detects that the tilting force exceeds a certain range, the gate valve assembly controls multiple air intake channels 8 to open simultaneously, so as to slow down the upward flow speed of the mixed gas after entering the furnace, thereby increasing the attachment speed of silicon elemental at the root of silicon rod 2, and increasing the support stability of silicon rod 2. When the tilting force is reduced to the normal range, the gate valve assembly closes the remaining air intake channels 8 again, so as to keep the airflow rising at a normal speed, thereby keeping the diameter of silicon rod 2 growing uniformly at the top and bottom.

[0049] Furthermore, refer to Figure 5 and Figure 6 Regarding the structure of electrode 5, it includes an integrally constructed electrode rod 501, an upper abutment block 502, and a lower abutment block 503. The electrode rod 501 passes through the upper support portion 7, and the upper abutment block 502 and the lower abutment block 503 abut against both sides of the upper support portion 7, thereby ensuring the overall firmness of the fixed connection between the entire electrode 5 and the upper support portion 7. The top of the upper abutment block 502 has a planar structure and is distributed around the electrode rod 501, which facilitates the support of the continuously growing silicon rod 2, thereby ensuring the contact area between the entire electrode 5 and the growing silicon rod 2 to ensure good current conduction effect.

[0050] Furthermore, refer to 4-6 and Figure 8 Regarding the power supply method between electrode 5 and the outside, a terminal 4 is fixedly connected to the support block 3. The bottom of electrode 5 is rotatably engaged with the terminal 4, thereby achieving the effect of rotating and setting it at a fixed position on the top of the support block 3. The terminal 4 extends through to the bottom of the support block 3, that is, it is located outside the chassis 1. It is used to connect the power supply line. An upper guide groove 9 and a lower guide groove 10 are also constructed on the pole rod 501 and the terminal 4, respectively. The lower guide groove 10 extends through the entire terminal 4. The groove opening of the upper guide groove 9 is rotatably engaged with the terminal 4 to keep the upper guide groove 9 and the lower guide groove 10 connected. The lower guide groove 10 is used to connect to the external coolant pipeline, thereby cooling the electrode 5.

[0051] Furthermore, refer to Figure 9 Regarding the configuration of the gate valve assembly, the airflow goes from the air supply line 11 to the branch line 12, and then to the air intake channel 8. There are multiple branches 12, all of which are connected to the air supply line 11. Multiple air intake channels 8 are connected to multiple branches 12 respectively. The gate valve assembly includes an electrically operated on / off valve 13 configured on multiple branches 12. It is electrically linked to the force detection element 6. Under normal conditions, one on / off valve 13 is kept in the open state. When the tilting force reaches a predetermined level, multiple on / off valves 13 will all open to achieve air intake through multiple air intake channels 8.

[0052] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0053] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for reducing polycrystalline silicon, characterized by: At least involving the following steps: Monitoring the silicon rod tilting force in real time during reduction; Controlling the longitudinal flow rate of the mixed gas in the furnace according to the tilting force; Wherein, the process of controlling the longitudinal flow rate is: keeping the air inlet flow rate constant, and controlling the air flow through the cross-section diameter to produce changes.

2. A polycrystalline silicon reduction apparatus, characterized by: Applied to the polycrystalline silicon reduction method in claim 1, and comprising a base plate and: An electrode arranged in relative rotation with the base plate; A force detection element supported between the side of the electrode and the base plate; An air inlet channel and a gate valve assembly corresponding to any silicon rod, the gate valve assembly corresponding to the force detection element.

3. The polycrystalline silicon reduction apparatus of claim 2, wherein: Further comprising an upper support part and a lower support part, the electrode is fixedly connected with the upper support part and rotatably connected with the lower support part, the lower support part is fixedly connected with the base plate, and the force detection element is abutted between the upper support part and the lower support part.

4. The polycrystalline silicon reduction apparatus of claim 3, wherein: The lower support part comprises a supporting block and a wiring terminal fixed on the supporting block, the force detection element is abutted between the supporting block and the upper support part, and the electrode is rotatably connected with the wiring terminal.

5. The polycrystalline silicon reduction apparatus of claim 4, wherein: The electrode comprises an integrated pole, an upper abutting block and a lower abutting block, the pole penetrates through the upper support part, and the upper abutting block and the lower abutting block are respectively abutted on both sides of the upper support part.

6. The polycrystalline silicon reduction apparatus of claim 5, wherein: A bearing surface is formed on the upper abutting block and distributed around the pole.

7. The polycrystalline silicon reduction apparatus of claim 5, wherein: An upper flow guide groove is formed on the pole, a lower flow guide groove is formed on the wiring terminal, and the wiring terminal is rotatably connected with the upper flow guide groove port.

8. The polycrystalline silicon reduction apparatus of claim 4, wherein: The air inlet channel is formed on the upper support part and penetrates through the supporting block.

9. The polycrystalline silicon reduction apparatus of claim 2, wherein: Further comprising a gas supply pipeline and multiple branches in communication with the gas supply pipeline, multiple air inlet channels are respectively in communication with multiple branches, and the gate valve assembly comprises on-off valves arranged on multiple branches.

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