Device and method for upgrading thermal field of single crystal furnace

Abstract

The present invention discloses a device for upgrading the thermal field of a single crystal furnace, which includes a coaxially arranged furnace cover (1), a large-diameter main furnace chamber (2), a large-diameter lower furnace body (3) and a furnace bottom plate (4). A transition flange (5) is connected between the furnace cover (1) and the large-diameter main furnace chamber (2), and a flange necking (6) is connected between the large-diameter lower furnace body (3) and the furnace bottom plate (4). The inner diameter of the transition flange (5) is the same as the inner cavity diameter of the furnace cover (1), and its outer diameter is the same as the outer diameter of the large-diameter main furnace chamber (2). The inner diameter of the large-diameter main furnace chamber (2) is larger than the inner cavity diameter of the furnace cover (1). The outer diameter of the flange necking (6) is the same as the outer diameter of the large-diameter lower furnace body (3), and its inner diameter is smaller than the outer diameter of the furnace bottom plate (4). The outer diameter of the furnace bottom plate (4) is smaller than the inner cavity diameter of the large-diameter lower furnace body (3). The advantages of the present invention are to meet the installation and production requirements of a thermal field of 36 inches or larger, improve the daily single output of the single crystal furnace and the quality of monocrystalline silicon, and reduce the equipment investment cost.

Description

Technical Field

[0001] The present invention relates to the technical field of single crystal furnace production, and in particular to a device and method for upgrading the thermal field of a single crystal furnace. Background Art

[0002] In recent years, with the vigorous development of the photovoltaic new energy industry, the market demand for monocrystalline silicon, a material used in solar cells, has continued to expand. A single crystal furnace is a device that uses graphite heaters to melt polycrystalline materials such as polysilicon in an inert gas environment, primarily nitrogen and helium, and grows dislocation-free single crystal silicon using the Czochralski method. The thermal system used to grow single crystal silicon within the furnace is called a thermal field.

[0003] The size of the heat field determines the single charge volume of the single crystal furnace. Constant diameter growth is the source of effective single crystal silicon output. A large heat field, corresponding to a large charge volume, effectively increases the proportion of constant diameter growth time in the single crystal silicon production process, thereby increasing the daily single crystal silicon output. Furthermore, when producing single crystal silicon, a large heat field can improve the uniformity of the single crystal silicon rod's resistance distribution and reduce the oxygen and carbon impurity content in the single crystal silicon.

[0004] Currently, the industry is primarily developing large heating chambers, with 36-inch furnaces being the mainstream of future development. Furnaces with 32-inch and smaller heating chambers currently hold approximately 80% of the market share. Based on current production technology, the daily output of a 36-inch furnace is 205 kg, while that of a 32-inch furnace is 165 kg. Large furnaces offer a clear production advantage. With the rapid development of the industry, low-capacity furnaces will be unable to meet the rapidly changing market demands. Without upgrading and renovation, they will be eliminated from the market.

[0005] At present, most furnaces with 32-inch and below hot fields have a service life of no more than 5 years, while the service life of single crystal furnaces is more than 10 years. The equipment investment is about 1.5 million yuan, and the depreciation is less than half. If the large hot field furnace is directly replaced, it will incur a large investment cost. The elimination of the old furnace will cause a waste of resources, and the equipment will not be used to its maximum value. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems of high cost and waste of resources in upgrading and replacing the thermal field of existing single crystal furnaces. A device for upgrading the thermal field of a single crystal furnace is provided. By upgrading and transforming the original equipment, it meets the installation and production requirements of 36-inch or larger thermal fields, improves the daily output of single crystal furnaces and the quality of single crystal silicon, reduces equipment investment costs, and maximizes the use value of the equipment.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A device for upgrading the thermal field of a single crystal furnace, comprising a furnace cover, a large-diameter main furnace chamber, a large-diameter lower furnace body, and a furnace chassis arranged in sequence from top to bottom. A transition flange is connected between the furnace cover and the large-diameter main furnace chamber, and a flange necking is connected between the large-diameter lower furnace body and the furnace chassis;

[0009] The inner diameter of the transition flange is the same as the inner cavity diameter of the furnace cover, its upper surface is connected to the lower end of the furnace cover, the outer diameter of the transition flange is the same as the outer diameter of the large-diameter main furnace chamber, and its lower surface is connected to the upper end of the large-diameter main furnace chamber. The inner diameter of the large-diameter main furnace chamber is greater than the inner cavity diameter of the furnace cover;

[0010] The outer diameter of the flange necking is the same as the outer diameter of the large-diameter lower furnace body, its upper surface is connected to the lower end of the large-diameter lower furnace body, the inner diameter of the flange necking is smaller than the outer diameter of the furnace chassis, and its lower surface is connected to the upper end of the furnace chassis. The outer diameter of the furnace chassis is smaller than the inner cavity diameter of the large-diameter lower furnace body;

[0011] The diameter of the large-diameter main furnace chamber is the same as the diameter of the large-diameter lower furnace body, and their axes coincide with each other.

[0012] Further, the large-diameter main furnace chamber is a cylindrical structure, and first flanges are provided at both the upper and lower ends of the cylinder body. A sealing strip is provided on the upper end surface of the cylinder body.

[0013] Further, the large-diameter lower furnace body is a cylindrical structure, and second flanges are provided at both the upper and lower ends of the cylinder body. The outer diameter of the second flange is the same as the outer diameter of the first flange of the large-diameter main furnace chamber. Sealing strips are provided on both the upper and lower end surfaces of the cylinder body.

[0014] Further, the transition flange is a plate-shaped annular structure, and its outer diameter is the same as the outer diameter of the first flange of the large-diameter main furnace chamber.

[0015] Further, the flange necking is a plate-shaped annular structure, and its outer diameter is the same as the outer diameter of the second flange of the large-diameter lower furnace body. A sealing ring is provided on the contact surface between the flange necking and the furnace chassis.

[0016] Further, the axis of the transition flange coincides with the inner cavity axes of both the furnace cover and the large-diameter main furnace chamber.

[0017] Further, the axis of the flange necking coincides with the axes of both the large-diameter lower furnace body and the furnace chassis.

[0018] To further achieve the purpose of the present invention, a method for upgrading the thermal field of a single crystal furnace is also provided. The specific steps are as follows, including:

[0019] (1) Replace the large-diameter lower furnace body, install the flange necking above the original furnace chassis, and install the large-diameter lower furnace body above the flange necking;

[0020] (2) Install a large-diameter main furnace chamber above the large-diameter lower furnace body. The diameter of the large-diameter main furnace chamber is the same as that of the large-diameter lower furnace body.

[0021] (3) Install a transition flange above the large-diameter main furnace chamber. One end of the transition flange is connected to the large-diameter main furnace chamber, and the other end is connected to the original furnace cover. (4) Modify the lifting device of the large-diameter main furnace chamber to match the replaced large-diameter main furnace chamber, and modify the length of the cantilever section, the position of the gripper, and the lifting stroke of the lifting device.

[0022] In the technical solution of the present invention, by upgrading and transforming the original equipment, there is no need to directly eliminate the original equipment. By increasing the large-diameter main furnace chamber and the large-diameter lower furnace body, without changing the structures of the furnace cover and the furnace bottom, the method of connecting through the transition flange and the flange necking is used to achieve the upgrade of the thermal field. The device of the present invention reduces the equipment investment cost, fully exerts the value of the existing equipment, meets the installation and production requirements of the 36-inch thermal field, improves the daily single output of the single crystal furnace, and also improves the quality of single crystal silicon. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic structural diagram of the original furnace body in the prior art;

[0024] Figure 2 is a schematic structural diagram of the device for upgrading the thermal field of a single crystal furnace according to the present invention;

[0025] Figure 3 is a schematic diagram of the original furnace body size in the prior art;

[0026] Figure 4 is a schematic diagram of the device size for upgrading the thermal field of a single crystal furnace in this embodiment. DETAILED DESCRIPTION OF THE INVENTION [[ID=!]]

[0027] Embodiment 1

[0028] To make the present invention clearer and more understandable, the following further describes a device and method for upgrading the thermal field of a single crystal furnace of the present invention with reference to the accompanying drawings. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] Refer to Figure 2 , a device and method for upgrading the thermal field of a single crystal furnace, including a furnace cover 1, a large-diameter main furnace chamber 2, a large-diameter lower furnace body 3, and a furnace chassis 4 arranged in sequence from top to bottom. It is characterized in that:

[0030] A transition flange 5 is connected between the furnace cover 1 and the large-diameter main furnace chamber 2, and a flange necking 6 is connected between the large-diameter lower furnace body 3 and the furnace chassis 4;

[0031] The inner diameter of the transition flange 5 is the same as the inner cavity diameter of the furnace lid 1, its upper surface is connected to the lower end of the furnace lid 1, and their axes coincide with each other;

[0032] The outer diameter of the transition flange 5 is the same as the outer diameter of the large-diameter main furnace chamber 2, its lower surface is connected to the upper end of the large-diameter main furnace chamber 2, and their axes also coincide with each other. The inner diameter of the large-diameter main furnace chamber 2 is larger than the inner cavity diameter of the furnace lid 1;

[0033] The outer diameter of the flange necking 6 is the same as the outer diameter of the large-diameter lower furnace body 3, its upper surface is connected to the lower end of the large-diameter lower furnace body 3, and their axes coincide with each other;

[0034] The inner diameter of the flange necking 6 is smaller than the outer diameter of the furnace bottom plate 4, its lower surface is connected to the upper end of the furnace bottom plate 4, and their axes also coincide with each other. The outer diameter of the furnace bottom plate 4 is smaller than the inner cavity diameter of the large-diameter lower furnace body 3;

[0035] The diameter of the large-diameter main furnace chamber 2 is the same as the diameter of the large-diameter lower furnace body 3, and their axes coincide with each other.

[0036] See Figure 1 、 Figure 3 and Figure 4 , which are the steps to transform the existing 130-furnace 32-inch thermal field into a 36-inch thermal field. The inner diameters of the large-diameter lower furnace body and the main furnace body of the 130-furnace are 1300 mm, and the maximum thermal field size that can be installed is 32 inches. Now, to upgrade to a 36-inch thermal field, the inner diameters of the large-diameter lower furnace body and the large-diameter main furnace chamber need to be increased to 1500 mm. Specifically, it includes:

[0037] (1) The furnace bottom plate 4 can be changed according to actual process conditions or remain unchanged in its original structure;

[0038] (2) Install the flange necking 6 above the original furnace bottom plate 4, install the large-diameter lower furnace body 3 above the flange necking 6, and then install the large-diameter main furnace chamber 2 above the large-diameter lower furnace body 3. The diameter of the large-diameter main furnace chamber 2 is the same as the diameter of the large-diameter lower furnace body 3. The flange necking 6 is a plate-shaped ring with an inner diameter of 1300 mm, which is the same as the inner diameter of the main chamber of the original furnace type, and an outer diameter of 1600 mm, and is installed above the original furnace bottom;

[0039] (3) The inner diameter of the large-diameter lower furnace body 3 is 1500 mm, the flange diameters at the upper and lower sides are 1600 mm, the diameter of the middle part is 1564 mm, and the height is 500 mm. It is installed above the flange necking 6;

[0040] (4) The inner diameter of the large-diameter main furnace chamber 2 is 1500 mm, the flange diameters at the upper and lower sides are 1600 mm, the diameter of the middle part is 1564 mm, and the height is 1200 mm. It is installed above the large-diameter lower furnace body 3;

[0041] (5) Install a transition flange 5 above the large-diameter main furnace chamber 2. One end of the transition flange 5 is connected to the large-diameter main furnace chamber 2 with an outer diameter of 1600 mm, and the other end is connected to the furnace cover 1 of the original furnace platform with an inner diameter of 1300 mm.

[0042] (6) After the transformation, the diameter of the large-diameter main furnace chamber 2 increases, and the lifting device of the original large-diameter main furnace chamber does not match the replaced large-diameter main furnace chamber. It is necessary to transform the cantilever length, gripper position, lifting stroke, etc. of the lifting device.

[0043] (7) After the transformation, the charging amount corresponding to the 36-inch thermal field increases, and the height of the crucible increases. Therefore, it is necessary to change the load-bearing structure and stroke of the crucible lifting device.

[0044] (8) The charging amount increases, and the produced single-crystal silicon rod is longer and heavier. It is necessary to increase the height of the auxiliary chamber cylinder, the load-bearing structure of the seed crystal lifting head, and the seed crystal stroke.

[0045] (9) After the transformation, the furnace chamber volume corresponding to the 36-inch thermal field is larger, and the pumping capacity of the original vacuum pump does not meet the use requirements. It is necessary to replace the vacuum pump and its accessories.

[0046] In the present invention, the large-diameter main furnace chamber 2 is of a cylindrical structure with an inner diameter of 1500 mm - 1600 mm, a wall thickness of the cylinder wall of 32 mm, a height of 1200 mm - 1400 mm. First flanges 2a are provided at both the upper and lower ends of the cylinder body, and the wall thickness at the first flanges 2a is 50 mm. A sealing strip is provided on the upper end face of the cylinder body. The large-diameter lower furnace body 3 is of a cylindrical structure with the same inner diameter and wall thickness as the large-diameter main furnace chamber, a height of 500 mm. Second flanges 3a are provided at both the upper and lower ends of the cylinder body, and the outer diameter of the second flanges 3a is the same as the outer diameter of the first flanges 2a of the large-diameter main furnace chamber 2. Sealing strips are provided on both the upper and lower end faces of the cylinder body.

[0047] Compared with the 36-inch thermal field of the 160 furnace type after the transformation of the present invention, it has the same large thermal field, but the structure is more compact, the furnace chamber volume is smaller, the production power consumption is lower, and the thermal field operation is more stable.

[0048] After the transformation, the furnace platform can realize the installation of the 36-inch thermal field and adopt the current 36-inch thermal field production process. The daily single output is 205 kg / day. The daily single output of the original furnace platform with the 32-inch thermal field installed is 165 kg / day, and the daily single output increases by 24%, and the efficiency improvement is obvious.

[0049] In addition, the maximum installation limit for the 130 furnace is a 32-inch heat field, with equipment procurement costs of approximately 1.5 million yuan. After five years of use, the equipment has a service life of 10 years, and equipment depreciation of 650,000 yuan. The 160 furnace corresponds to a 36-inch heat field, with equipment procurement costs of approximately 1.8 million yuan. There are two options for upgrading to a 36-inch heat field. Option 1: Replacing the old equipment with new equipment. The loss of the original equipment will include undepreciated equipment costs of approximately 650,000 yuan, and the cost of purchasing new equipment is approximately 1.8 million yuan, for a total of 2.45 million yuan. Option 2: Upgrading the original equipment requires an investment of approximately 450,000 yuan, which is 18% of the investment cost of Option 1.

[0050] The present invention can also improve the quality of single crystal silicon. The resistance distribution of single crystal silicon rods produced in a large thermal field is more uniform, and the content of oxygen, carbon and other impurities is lower.

[0051] In addition to the above embodiments, the present invention may also have other implementations. Any technical solution formed by equivalent replacement or equivalent transformation falls within the scope of protection required by the present invention.

Claims

1. A method for upgrading the thermal field of a single crystal furnace using a device for upgrading the thermal field of a single crystal furnace, characterized in that: The device includes a furnace cover (1), a large-diameter main furnace chamber (2), a large-diameter lower furnace body (3), and a furnace chassis (4) arranged in sequence from top to bottom. A transition flange (5) is connected between the furnace cover (1) and the large-diameter main furnace chamber (2), and a flange necking (6) is connected between the large-diameter lower furnace body (3) and the furnace chassis (4); the inner diameter of the transition flange (5) is the same as the inner cavity diameter of the furnace cover (1), its upper surface is connected to the lower end of the furnace cover (1), the outer diameter of the transition flange (5) is the same as the outer diameter of the large-diameter main furnace chamber (2), and its lower surface is connected to the upper end of the large-diameter main furnace chamber (2), and the inner diameter of the large-diameter main furnace chamber (2) is greater than the inner cavity diameter of the furnace cover (1); the outer diameter of the flange necking (6) is the same as the outer diameter of the large-diameter lower furnace body (3), its upper surface is connected to the lower end of the large-diameter lower furnace body (3), the inner diameter of the flange necking (6) is less than the outer diameter of the furnace chassis (4), and its lower surface is connected to the upper end of the furnace chassis (4), and the outer diameter of the furnace chassis (4) is less than the inner cavity diameter of the large-diameter lower furnace body (3); the diameter of the large-diameter main furnace chamber (2) is the same as the diameter of the large-diameter lower furnace body (3), and their axes coincide with each other; The specific steps of the method are as follows: Step 1: Replace with the large-diameter lower furnace body (3), install the flange necking (6) above the original furnace chassis (4), and install the large-diameter lower furnace body (3) above the flange necking (6); Step 2: Install the large-diameter main furnace chamber (2) above the large-diameter lower furnace body (3), and the diameter of the large-diameter main furnace chamber (2) is the same as the diameter of the large-diameter lower furnace body (3); Step 3: Install the transition flange (5) above the large-diameter main furnace chamber (2), one end of the transition flange (5) is connected to the large-diameter main furnace chamber (2), and the other end is connected to the original furnace cover (1); Step 4: Modify the lifting device of the large-diameter main furnace chamber (2) to make it match the replaced large-diameter main furnace chamber (2), and modify the length of the cantilever section, the position of the gripper, and the lifting stroke of the lifting device.

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