Novel polycrystalline silicon reduction furnace

Abstract

The utility model relates to the technical field of polycrystalline silicon, in particular to a novel polycrystalline silicon reduction furnace which comprises a furnace body, an upper seal head is mounted above the furnace body, a first gas guide pipe is inserted into the upper seal head, an observation window is embedded into the outer wall of the furnace body, a base plate is mounted in the furnace body through a positioning pin, and a first gas guide pipe is inserted into the base plate. A cover plate is mounted above the furnace body through bolts; a connecting pipe is embedded in the upper portion of the base plate, a first nozzle is in threaded connection with the upper portion of the connecting pipe, and an electrode is installed on the upper portion of the base plate; according to the improved polycrystalline silicon reduction furnace, the distance between electrodes and the distance between nozzles are adjusted through a base plate in the polycrystalline silicon reduction furnace, the distance between silicon rods is remarkably increased, and therefore distribution of a thermal field in the furnace is optimized, the risk that the thermal field is out of control and atomization is reduced, meanwhile, an upper air injection assembly and a lower air injection assembly are arranged in the furnace body, and therefore the thermal field distribution is improved. And internal air flow is mixed more uniformly, so that air can be uniformly fed into the whole reduction furnace.

Description

Technical Field

[0001] The utility model relates to the technical field of polysilicon, in particular to a novel polysilicon reduction furnace. Background Technique

[0002] Polysilicon is a form of elemental silicon. When molten elemental silicon solidifies under supercooled conditions, silicon atoms arrange in a diamond lattice form to form many crystal nuclei. If these crystal nuclei grow into grains with different crystal plane orientations, then these grains combine to crystallize into polysilicon. Polysilicon has a gray metallic luster, a density of 2.32 - 2.34 g / cm 3 , a melting point of 1410 °C, a boiling point of 2355 °C, soluble in a mixed acid of hydrofluoric acid and nitric acid, insoluble in water, nitric acid and hydrochloric acid, with a hardness between germanium and quartz, brittle at room temperature and easily fragmented during cutting, ductile when heated above 800 °C, showing obvious deformation at 1300 °C, inactive at room temperature, reacting with oxygen, nitrogen, sulfur, etc. at high temperatures, having great chemical reactivity in a high-temperature molten state, almost able to react with any material, having semiconductor properties, being an extremely important excellent semiconductor material, but trace impurities can greatly affect its conductivity, widely used in the electronics industry as the basic material for manufacturing semiconductor radios, tape recorders, refrigerators, color TVs, video recorders, electronic computers, etc., obtained by chlorinating dry silicon powder and dry hydrogen chloride gas under certain conditions, and then through condensation, rectification, and reduction.

[0003] In the process of implementing the present utility model, the inventor found that the prior art has the following problems: 1. The shape of the chassis of the polysilicon reduction furnace is mostly circular or polygonal, which cooperates with the furnace body of the reduction furnace to form a closed reaction space. The chassis is usually provided with electrode mounting holes, air inlets, and air outlets. The existing electrode spacing is 235 mm, and the existing furnace type chassis usually has 1 exhaust point, which may lead to uneven gas discharge in the furnace, affecting the stability of the thermal field and temperature field. The small spacing between the silicon rods in the polysilicon reduction furnace results in a serious uneven distribution of the thermal field in the furnace. During the growth process, the temperature field is prone to getting out of control and generating atomization phenomena, which not only affects the quality of polysilicon but may also cause damage to the equipment; 2. In the polysilicon reduction furnace, the electrodes are mainly components used to provide electrical energy for the reduction reaction, usually made of materials with good electrical conductivity, such as graphite, etc. The polysilicon reduction furnace adopts a chassis air intake scheme, and the gas enters the interior of the reduction furnace from the bottom of the polysilicon reduction furnace. However, as the volume of the polysilicon reduction furnace continues to increase, the gas entering the interior of the reduction furnace from the bottom of the reduction furnace mainly concentrates in the middle and lower parts of the reduction furnace after entering the reduction furnace. The gas distribution in the upper part of the reduction furnace is uneven, and the circulating flow effect is poor, with a gas distribution blind area, unable to meet the requirement of uniform air intake throughout the interior of the reduction furnace. Content of the Utility Model

[0004] The purpose of the present utility model is to provide a novel polysilicon reduction furnace to solve the problems proposed in the above background technology, namely, the electrode spacing is 235 mm, and the existing furnace type chassis usually has only 1 exhaust point, which may lead to uneven gas emission in the furnace and affect the stability of the thermal field and temperature field. The small spacing between the silicon rods in the polysilicon reduction furnace results in a seriously uneven distribution of the thermal field in the furnace. To achieve the above purpose, the present utility model provides the following technical solutions: A novel polysilicon reduction furnace, including a furnace body, an upper head is installed above the furnace body, a first air pipe is inserted into the upper head, an observation window is embedded in the outer wall of the furnace body, a chassis is installed inside the furnace body through a positioning pin, and a cover plate is installed above the furnace body through bolts;

[0005] A connecting pipe is embedded above the chassis, a first nozzle is threadedly connected above the connecting pipe, and an electrode is installed above the chassis;

[0006] A gas valve is inserted at one end of the first air pipe, a first air inlet pipe and a second air pipe are respectively inserted on one side of the first air pipe, the second air pipe is provided above the first air inlet pipe, a second nozzle is inserted into the first air pipe, a second air inlet pipe is inserted below the first air pipe, and a third nozzle is threadedly connected to the outer wall of the second air inlet pipe.

[0007] Further preferably, the electrodes are distributed in a ring around the axis of the chassis, arranged in a ring-shaped surrounding pattern successively from the axis to the outside, and the inner circle of the electrode spacing is 252 mm and the outer circle is 240 mm.

[0008] Further preferably, the first nozzles are distributed in a ring around the axis of the chassis, arranged in a ring-shaped surrounding pattern successively from the axis to the outside, and the first nozzles are connected by a connecting pipe.

[0009] Further preferably, the first air inlet pipes are horizontally arranged on both sides of the first air pipe, with a cross shape, and the second nozzles are horizontally distributed below the second nozzles.

[0010] Further preferably, the third nozzles are vertically distributed on both sides of the second air inlet pipe.

[0011] Further preferably, the external structural dimensions of the upper end face of the furnace body are consistent with the internal structural dimensions of the lower end face of the cover plate, and a curved surface observation window is embedded inside the furnace body.

[0012] Further preferably, the connection between the first air pipe and the second air pipe is a "Y"-shaped pipe, and the third nozzle and the first air inlet pipe are respectively connected at the intersection of the "Y"-shaped pipe.

[0013] Compared with the prior art, the beneficial effects of the present utility model:

[0014] In this utility model, the chassis transmits gas to the first nozzle. The first nozzles are distributed in a ring around the axis of the chassis and are interconnected through connecting pipes. This layout enables the raw material gas to be evenly ejected upward from the chassis and, in conjunction with other nozzles, further improves the uniformity of gas distribution. Compared with the existing situation where the electrode spacing is 235 mm, the new gas inlet layout can better cooperate with the optimized electrode spacing, provide a more stable gas environment for the polysilicon reduction reaction, reduce the problem of uneven thermal field caused by uneven gas distribution. At the same time, the electrodes are distributed in a ring around the axis of the chassis, with the inner ring spacing being 252 mm and the outer ring spacing being 240 mm. The precisely designed electrode spacing helps to optimize the electric field distribution and thermal field uniformity in the furnace, solve the problem that the small spacing between silicon rods in the polysilicon reduction furnace leads to serious uneven distribution of the thermal field in the furnace and the temperature field is prone to getting out of control and generating atomization. The new electrode spacing can better control the electric field and thermal field, reduce the influence of uneven thermal field on polysilicon growth, and reduce the occurrence probability of temperature field out-of-control and atomization phenomenon, thereby improving the quality of polysilicon and reducing damage to the equipment.

[0015] In this utility model, the first intake pipes horizontally arranged on both sides of the first gas guide pipe, with a cross-shaped outer shape, the second nozzle inside the first gas guide pipe, the second intake pipe inserted below and the third nozzles vertically distributed on both sides thereof, as well as the "Y"-shaped pipe design at the connection between the first gas guide pipe and the second gas guide pipe enable gas to enter the furnace from multiple directions. This multi-directional gas intake method helps to improve the problem that as the volume of the reduction furnace increases, gas accumulates in the middle and lower parts and the distribution in the upper part is uneven. The nozzles in all directions work together to distribute gas more widely to different positions in the furnace, including the upper region where gas distribution blind spots are prone to appear. The chassis transmits gas to the first nozzle. The first nozzles are distributed in a ring around the axis of the chassis and are interconnected through connecting pipes. This layout enables the gas entering from the chassis to be evenly ejected into the furnace in a ring-shaped surrounding manner, gradually improving gas distribution from the bottom upward. Description of the Drawings

[0016] Figure 1 is a schematic cross-sectional structure diagram of this utility model;

[0017] Figure 2 is a schematic front view structure diagram of this utility model;

[0018] Figure 3 is a schematic structure diagram above the chassis of this utility model;

[0019] Figure 4 is a schematic structure diagram below the first gas guide pipe of this utility model.

[0020] In the figure: 1. Furnace body; 2. Chassis; 201. Connecting pipe; 202. Electrode; 203. First nozzle; 3. First air intake pipe; 301. Air valve; 302. First inlet pipe; 303. Second air intake pipe; 304. Second inlet pipe; 305. Second nozzle; 306. Third nozzle; 4. Observation window; 5. Upper head; 6. Cover plate. Specific implementation mode

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0022] Please refer to Figures 1 to 4 , the present invention provides a technical solution: a new type of polysilicon reduction furnace, including a furnace body 1, an upper head 5 is installed above the furnace body 1, a first air intake pipe 3 is inserted into the upper head 5, an observation window 4 is embedded in the outer wall of the furnace body 1, a chassis 2 is installed inside the furnace body 1 through a positioning pin, and a cover plate 6 is installed above the furnace body 1 through bolts;

[0023] A connecting pipe 201 is embedded above the chassis 2, a first nozzle 203 is threadedly connected above the connecting pipe 201, and an electrode 202 is installed above the chassis 2;

[0024] One end of the first air intake pipe 3 is inserted with an air valve 301, a first inlet pipe 302 and a second air intake pipe 303 are respectively inserted on one side of the first air intake pipe 3, the second air intake pipe 303 is arranged above the first inlet pipe 302, a second nozzle 305 is inserted into the first air intake pipe 3, a second inlet pipe 304 is inserted below the first air intake pipe 3, and a third nozzle 306 is threadedly connected to the outer wall of the second inlet pipe 304.

[0025] In this embodiment, as Figure 1 , Figure 2 and Figure 3 shown, the electrodes 202 are distributed in a ring around the axis of the chassis 2, arranged in a ring-shaped surrounding pattern from the axis to the outside in sequence, and the inner circle of the distance between the electrodes 202 is 252 mm, and the outer circle is 240 mm; the electrodes 202 provide electrical energy for the reduction reaction, so that raw materials such as hydrogen and trichlorosilane undergo chemical reactions under high temperature and high pressure conditions to generate polysilicon deposited on the silicon core. The accurately designed distance between the electrodes 202 helps to optimize the electric field distribution and thermal field uniformity in the furnace, can increase the single-furnace output by two tons, and the current drops by 2 kwb / kg, realizing the improvement of the production efficiency and quality of polysilicon.

[0026] In this embodiment, asFigure 1 , Figure 2 and Figure 3 As shown in Figure 1 , Figure 2 , and Figure 3 , the first nozzle 203 is distributed in a ring around the axis of the chassis 2, arranged in a ring-shaped surrounding pattern successively from the axis to the outside, and the first nozzles 203 are connected by a connecting pipe 201; through this special ring-shaped distribution method of the first nozzles 203, raw material gases such as hydrogen and trichlorosilane can be sprayed into the furnace more evenly to participate in the reduction reaction. The connecting pipe 201 enables the first nozzles 203 to communicate with each other, which helps to ensure the stability and uniformity of gas supply. This design helps to optimize the reaction environment in the furnace and improve the production efficiency and quality of polysilicon.

[0027] In this embodiment, as Figure 1 , Figure 2 and Figure 4 shown, the first inlet pipes 302 are horizontally arranged on both sides of the first gas guiding pipe 3, with a cross-shaped outer shape, and the second nozzles 305 are horizontally distributed below; the first gas guiding pipe 3 is connected to a gas valve 301 to control the entry of gas. The two first inlet pipes 302 on both sides have a cross-shaped outer shape and can introduce reaction gases from different directions. Cooperating with the second nozzles 305 horizontally distributed below, raw material gases such as hydrogen and trichlorosilane can be transported into the furnace more evenly to participate in the reduction reaction. The first gas guiding pipe 3 is inserted into the upper head 5, ensuring the stability and sealing of gas entry, which helps to optimize the reaction environment in the furnace and improve the production efficiency and quality of polysilicon.

[0028] In this embodiment, as Figure 4 shown, the third nozzles 306 are vertically distributed on both sides of the second inlet pipe 304; through the third nozzles 306 vertically distributed on both sides of the second inlet pipe 304, raw material gases such as hydrogen and trichlorosilane can be sprayed into the furnace from different angles, making the distribution of the raw material gases more uniform. This design helps to optimize the reaction environment in the polysilicon reduction furnace, ensure the full progress of the reaction, and improve the production efficiency and quality of polysilicon.

[0029] In this embodiment, as Figure 1 and Figure 2 shown, the external structure dimensions of the upper end face of the furnace body 1 are consistent with the internal structure dimensions of the lower end face of the cover plate 6, and the curved surface observation window 4 is embedded inside the furnace body 1; the structural dimensions of the furnace body 1 and the cover plate 6 match, ensuring the sealing of the polysilicon reduction furnace and providing a stable environment for the reduction reaction. The curved surface observation window 4 embedded inside the furnace body 1 allows operators to observe the reaction situation inside the furnace in real time during production, such as the growth state of polysilicon. Through the observation window 4, operators can adjust the reaction parameters in a timely manner to ensure the production efficiency and quality of polysilicon, and at the same time, it is also convenient to monitor and maintain the operation status of the equipment.

[0030] In this embodiment, asFigure 1 and Figure 4 As shown in Figure 4 , the connection between the first gas inlet pipe 3 and the second gas inlet pipe 303 is a "Y"-shaped pipe, and a third nozzle 306 and a first air inlet pipe 302 are respectively connected to the intersection of the "Y"-shaped pipes; the first gas inlet pipe 3 and the second gas inlet pipe 303 are connected through a "Y"-shaped pipe. This structural design enables the gas to be more evenly distributed to different positions in the furnace. The third nozzle 306 and the first air inlet pipe 302 connected to the intersection of the "Y"-shaped pipes can inject raw material gases such as hydrogen and trichlorosilane into the furnace from different directions, ensuring a more reasonable distribution of the raw material gases, which helps to optimize the reaction environment in the polysilicon reduction furnace and improve the production efficiency and quality of polysilicon.

[0031] Usage method and advantages of the present utility model: When in use, the working process of this new type of polysilicon reduction furnace is as follows:

[0032] such as Figure 1 、 Figure 2 、 Figure 3 and Figure 4As shown in the figure, first open the gas valve 301, and control the gas to enter through the first gas pipe 3. On both sides of the first gas pipe 3, there are horizontally arranged first inlet pipes 302, which are in a cross shape, and can introduce reaction gases from different directions. At the same time, a second nozzle 305 is inserted inside the first gas pipe 3, and a second inlet pipe 304 is inserted below it. On both sides of the second inlet pipe 304, there are vertically distributed third nozzles 306. In addition, the connection between the first gas pipe 3 and the second gas pipe 303 is a "Y"-shaped pipe, and at the intersection of the "Y"-shaped pipe, there are respectively connected a third nozzle 306 and the second gas pipe 303, so that the gas in the second gas pipe 303 enters the chassis 2, and the chassis 2 transmits the gas to the first nozzle 203. The first nozzle 203 is distributed in a ring around the axis of the chassis 2, and is arranged in a ring-shaped surrounding pattern from the axis to the outside in sequence, and the first nozzles 203 are connected by connecting pipes 201. The first nozzles 203 also spray the raw material gas into the furnace more evenly to participate in the reduction reaction. The connecting pipes 201 make the first nozzles 203 communicate with each other, which helps to ensure the stability and uniformity of gas supply. These structural designs enable raw material gases such as hydrogen and trichlorosilane to be more evenly distributed to different positions in the furnace, and are sprayed into the furnace from above and below at the same time, ensuring a more reasonable distribution of the raw material gas. Start the heating system to raise the temperature in the furnace body 1 to the high-temperature and high-pressure conditions required for the reduction reaction. For example, make the temperature in the furnace reach a certain value and the pressure reach a suitable range, creating conditions for chemical reactions of raw materials such as hydrogen and trichlorosilane under high-temperature and high-pressure conditions. In the reduction reaction stage, the electrodes 202 are distributed in a ring around the axis of the chassis 2, and are arranged in a ring-shaped surrounding pattern from the axis to the outside in sequence. The inner circle of the distance between the electrodes 202 is 252 mm, and the outer circle is 240 mm. The electrodes 202 provide electrical energy for the reduction reaction, enabling chemical reactions of raw materials such as hydrogen and trichlorosilane under high-temperature and high-pressure conditions, and generating polysilicon deposited on the silicon core. The accurately designed distance between the electrodes 202 helps to optimize the electric field distribution and thermal field uniformity in the furnace, and improve the production efficiency and quality of polysilicon. Under the action of high temperature, high pressure and electric energy, raw materials such as hydrogen and trichlorosilane undergo a reduction reaction in the furnace, and polysilicon gradually deposits on the silicon core. The reasonable layout of each jet component and intake component in the furnace ensures the uniform distribution of the raw material gas, enabling the reaction to proceed fully. In the monitoring and adjustment stage, through the curved observation window 4 embedded in the outer wall of the furnace body 1, the operator can observe the reaction situation in the furnace in real time, such as the growth state of polysilicon, etc. According to the situation observed through the observation window 4, adjust the reaction parameters in a timely manner, such as temperature, pressure, gas flow rate, etc., to ensure the production efficiency and quality of polysilicon, and at the same time facilitate the monitoring and maintenance of the equipment operation status. When the growth of polysilicon reaches the predetermined target, close the gas valve 301, stop the intake of gas, gradually reduce the furnace temperature, stop the heating system. After the furnace temperature drops to a certain level, open the cover plate 6 and take out the polysilicon product for subsequent processing.

[0033] The above has shown and described the basic principles, main features and advantages of the present utility model. Those skilled in the art should understand that the present utility model is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present utility model and are not used to limit the present utility model. Without departing from the spirit and scope of the present utility model, the present utility model will have various changes and improvements, and these changes and improvements all fall within the scope of the present utility model claimed. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents.

Claims

1. A novel polysilicon reduction furnace, comprising a furnace body (1), characterized in that: An upper end cover (5) is installed above the furnace body (1), a first air duct (3) is inserted into the interior of the upper end cover (5), an observation window (4) is embedded in the outer wall of the furnace body (1), a bottom plate (2) is installed inside the furnace body (1) via positioning pins, and a cover plate (6) is installed above the furnace body (1) via bolts; A connecting pipe (201) is embedded above the base plate (2), a first nozzle (203) is threadedly connected above the connecting pipe (201), and an electrode (202) is installed above the base plate (2); An air valve (301) is inserted at one end of the first air duct (3), a first air intake pipe (302) and a second air duct (303) are respectively inserted at one side of the first air duct (3), a second air duct (303) is arranged above the first air intake pipe (302), a second nozzle (305) is inserted inside the first air duct (3), a second air intake pipe (304) is inserted below the first air duct (3), and a third nozzle (306) is threadedly connected to the outer wall of the second air intake pipe (304).

2. A novel polysilicon reduction furnace according to claim 1, characterized in that: The electrodes (202) are distributed in a ring shape around the axis of the chassis (2), and are arranged in a ring shape from the axis to the outside, and the spacing between the electrodes (202) is 252 mm in the inner circle and 240 mm in the outer circle.

3. A novel polysilicon reduction furnace according to claim 1, characterized in that: The first nozzles (203) are distributed in a ring shape around the axis of the chassis (2), and are arranged in a ring shape from the axis to the outside, and the first nozzles (203) are connected by connecting pipes (201).

4. The novel polysilicon reduction furnace according to claim 1 is characterized in that: First air inlet pipes (302) are horizontally arranged on both sides of the first air duct (3) in a cross shape, and second nozzles (305) are horizontally distributed below the second nozzles (305).

5. The novel polysilicon reduction furnace according to claim 1 is characterized in that: Third nozzles (306) are vertically distributed on both sides of the second air inlet pipe (304).

6. The novel polysilicon reduction furnace according to claim 1 is characterized in that: The external structural dimensions of the upper end surface of the furnace body (1) are consistent with the internal structural dimensions of the lower end surface of the cover plate (6), and a curved observation window (4) is embedded in the interior of the furnace body (1).

7. The novel polysilicon reduction furnace according to claim 1 is characterized in that: The connection between the first air duct (3) and the second air duct (303) is a "Y"-shaped pipe, and the intersection of the "Y"-shaped pipes is respectively connected to the third nozzle (306) and the first air intake pipe (302).

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