Manufacturing apparatus for polysilicon rod

Abstract

The manufacturing apparatus for a polysilicon rod according to the invention manufactures a polycrystalline rod by the Siemens method, and is characterized in that it includes: a holding body 100 which is movably arranged on a bottom plate 20 in a horizontal direction, electrically connects a core wire holder 1 to an electrode 4, and rotatably holds the core wire holder 1 relative to the bottom plate 20.

Description

Technical Field

[0001] The present invention relates to an apparatus for manufacturing a polysilicon rod by the Siemens method. Background Art

[0002] Polysilicon is a raw material for single-crystalline silicon used in semiconductor manufacturing and silicon used in solar cell manufacturing. A method for manufacturing polysilicon is known as the Siemens method. In this method, generally, a silane-based raw material gas is brought into contact with a heated silicon core wire, and polysilicon is deposited on the surface of the silicon core wire by the CVD (Chemical Vapor Deposition) method.

[0003] In the Siemens method, two silicon core wires are assembled in the vertical direction and one in the horizontal direction to form an inverted U-shaped structure, and after connecting both ends thereof to a core wire holder respectively, they are fixed to a pair of metal electrodes disposed on a bottom plate. Generally, a structure in which multiple sets of inverted U-shaped silicon core wires are arranged is adopted in the reaction furnace.

[0004] The inverted U-shaped silicon core wire is heated to the deposition temperature by energization. When a mixed gas of, for example, trichlorosilane and hydrogen as a raw material gas comes into contact with the silicon core wire, polysilicon grows in the gas phase on the silicon core wire, and a polysilicon rod having a desired diameter is formed in an inverted U shape.

[0005] The electrodes sandwich an insulator and pass through the bottom plate to be connected to other electrodes, or are connected to a power source disposed outside the reaction furnace. In the polysilicon deposition process, in order to prevent polysilicon from being deposited on the electrode portion or to prevent the polysilicon being deposited from being contaminated by metal due to the temperature rise of the electrode portion, the electrodes, the bottom plate, and the bell jar are cooled by a refrigerant such as water.

[0006] Figure 4 It is a conceptual diagram for showing the concept of mounting an electrode holder on an electrode and holding a core wire holder 11 in the prior art. In the example shown in this figure, a metal electrode 14 and a carbon core wire holder 11 are connected through an electrode adapter 13 for the purpose of suppressing the consumption of the electrode 14, etc., and the electrode adapter 13 is fixed to the electrode 14 by screwing.

[0007] Current is supplied from the electrode 14 via the core wire holder 11 to a silicon core wire (not shown) held at the top of the core wire holder 11, and the surface of the silicon core wire is heated to a temperature range of about 900°C to 1200°C in a hydrogen atmosphere by Joule heat. In this state, a mixed gas of, for example, trichlorosilane and hydrogen is supplied into the reaction furnace as a raw material gas, and high-purity silicon grows in the gas phase on the silicon core wire to cultivate a polysilicon rod.

[0008] In this process, as the diameter of the polysilicon rod increases, polysilicon precipitation also occurs on one side of the carbon core wire retainer 1 and gradually integrates with the core wire retainer 11. Additionally, since the resistance decreases as the polysilicon rod grows, in order to maintain the surface temperature of the polysilicon rod at a temperature suitable for the precipitation reaction, the supplied current will gradually increase.

[0009] In addition, the current supplied to the polysilicon rod is generally a large current of 2000 amperes to 4000 amperes at the end of the precipitation reaction. As the diameter of the polysilicon rod increases, the heat dissipation on the rod surface increases. Therefore, in order to maintain the temperature required for the precipitation reaction (900 - 1200 °C), it is necessary to increase the electrical energy supplied to the polysilicon rod to compensate for the heat loss due to its heat dissipation.

[0010] Moreover, since polysilicon has the property that its resistivity decreases as the temperature rises, the most current flows through the center of the body rod which is basically at a high temperature. Therefore, in the connecting bridge part of the rod body, the inside of the inverted U - shape is at a high temperature and has the largest current.

[0011] The reasons that can be thought of are as follows: Since the rod body is in an inverted U - shape, the circuit distance is shorter when passing through the inside at the corner, and the straight rod body and the connecting bridge at the corner are easily heated by their respective radiations, etc.

[0012]

Prior Art Documents

[0013]

Patent Document 1

[0014]

Patent Document 2

[0015] Therefore, there are the following problems: As the diameter of the silicon rod becomes thicker, the temperature difference between the inside and outside of the connecting bridge part becomes larger, and the elongation difference during the growth of the connecting bridge part and the shrinkage difference during cooling after growth end become more obvious, leading to cracks easily.

[0016] Cracks during growth generate a force that causes the inverted U - shape to expand outward due to the temperature difference between the high temperature inside and the low temperature outside at the corner of the inverted U - shaped part of the silicon rod. At this time, if the electrodes at the feet are fixed at both ends of the silicon rod, the rod body cannot deform and the stress exceeds a certain value, resulting in cracking. This cracking during growth will cause the energizing current to be disordered and the rod body temperature to be disordered, thus affecting the homogeneity of the crystal. Moreover, if the influence of the crack becomes larger, it may lead to the inability to conduct electricity and the reaction has to be interrupted halfway.

[0017] On the other hand, during cooling after growth, since the inner side of the corner at a higher temperature shrinks the most, a force is generated to close the inverted U shape. Moreover, if the rod body cannot deform and the stress exceeds a certain value, cracks will also occur. Past experience has shown that cracks during cooling are larger than those during growth, and the cracks will spread throughout the rod body, possibly leading to the collapse of the silicon rod.

[0018] As described above, in the Siemens method, the reason for the generation of cracks in the silicon rod is due to the temperature difference between the inner and outer sides of the inverted U shape. Therefore, in addition to the simple expansion and contraction caused by the overall temperature change of the silicon rod, a two-dimensional rotational force including rotation around the joint of the straight body part and the connecting bridge part of the rod body as a fulcrum is applied.

[0019] The occurrence of cracks causes relatively large economic damage to the manufacturing of silicon rods. In order to cope with the above two-dimensional rotational force, a mechanism for expansion, contraction, and rotation is required. Moreover, the materials that can be used in the Siemens method in terms of characteristics need to have high temperature resistance, high strength, and low pollution sources. In addition, in order to achieve continuous, efficient, and stable manufacturing in terms of quality, cleaning between batches and the convenience of rod body installation are also required. Therefore, it is very difficult to solve the above problems.

[0020] In addition, a new structure has also been proposed for the electrode adapter.

[0021] For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2006-240934), a device in which an electrode is electrically connected to a holder and can be folded is proposed, but it still cannot cope with the rotational force around the joint of the straight body part and the connecting bridge part of the rod body.

[0022] In Patent Document 2 (Patent No. 2805457), although the horizontal and tilting movements of the electrode holder can be achieved through spring elements, since spring elements are used, the shape becomes complicated, so it is very difficult to clean between batches, and it is almost impossible to keep all surfaces clean. In addition, the problem with relying on springs for holding is that the greater the movement amount, the greater the force required for movement. As the diameter further increases, the required movement amount becomes larger, and it is impossible to continuously ensure sufficient movement amount.

[0023] As described above, the existing electrode adapters do not have sufficient degrees of freedom of movement and / or batch cleaning measures. In view of this situation, the object of this patent is to provide a manufacturing device for polysilicon that can achieve horizontal movement and rotational movement of the electrode adapter and can be easily cleaned. Summary of the Invention

[0024] 【1】The manufacturing apparatus for a polysilicon rod according to the present invention manufactures a polysilicon rod by the Siemens method, and is characterized by including: a bottom plate; and a holder body that is movably provided on the bottom plate in a horizontal direction, for electrically connecting a core wire holder to an electrode and rotatably holding the core wire holder relative to the bottom plate.

[0025] 【2】In addition, for the manufacturing apparatus for a polysilicon rod according to the present invention, the holder body has: a base that is movably provided on the bottom plate in a horizontal direction; and an electrode adapter that is rotatably provided on the base and electrically connects the core wire holder to the electrode.

[0026] 【3】In addition, for the manufacturing apparatus for a polysilicon rod according to the present invention, the base has a curved surface portion, and the electrode adapter can rotate along the curved surface portion and can slide in a horizontal direction relative to the electrode.

[0027] 【4】In addition, for the manufacturing apparatus for a polysilicon rod according to the present invention, the electrode adapter has: an electrode adapter main body portion that is rotatably provided on the curved surface portion; and an electrode adapter sliding portion that extends in a horizontal direction from the electrode adapter main body portion and contacts the electrode. The manufacturing apparatus for the polysilicon rod further includes a pressing portion for clamping the electrode and the electrode adapter sliding portion together.

[0028] 【5】In addition, for the manufacturing apparatus for a polysilicon rod according to the present invention, the base, the electrode adapter, and the electrode are each composed of only a plane and a curved surface portion or a spherical surface with a radius of 5 mm or more.

[0029] 【6】In addition, for the manufacturing apparatus for a polysilicon rod according to the present invention, the base, the electrode adapter, and the electrode do not have inner corner portions with an angle less than 90 degrees.

[0030] 【7】In addition, for the manufacturing apparatus for a polysilicon rod according to the present invention, the base provided on the bottom plate is an insulator.

[0031] Advantages of the Invention

[0032] According to the present invention, it is possible to manufacture polysilicon that enables the horizontal movement and rotational movement of the electrode adapter and is easy to clean, and it is also possible to reduce cracks during the growth of polysilicon and during cooling after growth. Description of the Drawings

[0033] Figure 1 is a plan view of the electrode holder according to an embodiment of the present invention mounted on a metal electrode and holding the core wire holder;

[0034] Figure 2 is along Figure 1Side sectional view cut along the II-II section.

[0035] Figure 3 is a figure corresponding to Figure 1 and shows the plane of a modified example of an embodiment of the present invention.

[0036] Figure 4 is a side sectional view of an existing electrode holder mounted on a metal electrode and holding a core wire holder. Detailed Embodiment

[0037] This embodiment provides a manufacturing apparatus for a polysilicon rod, and this manufacturing apparatus manufactures polysilicon by the Siemens method. As Figure 1 and Figure 2 shown, the manufacturing apparatus for a polysilicon rod of this embodiment has a holding body 100, and this holding body 100 is arranged on a reactor bottom plate 20 so as to be movable in the horizontal direction and electrically connects a core wire holder 1 and a metal electrode 4. This holding body 100 holds the core wire support 1 rotatably (swingably) with respect to the reactor bottom plate 20. The holding body 100 can hold the core wire holder 1 so as to rotate in the up-and-down direction with respect to the reactor bottom plate 20, or can be rotatable in a horizontal plane. In Figure 2 , the arrows R1 and R2 are used to indicate that the holding body 100 holds the core wire holder 1 so as to be rotatable (swingable) in the up-and-down direction with respect to the reactor bottom plate 20. In addition, in Figure 2 , the arrows S1 and S2 for indicating that the holding body 100 can move in the horizontal direction with respect to the reactor bottom plate 20 are also shown.

[0038] The holding body 100 may have an adapter base 3 arranged on the reactor bottom plate 20 so as to be movable in the horizontal direction, and an electrode adapter 2 arranged rotatably (swingably) with respect to the adapter base 3 and electrically connecting the core wire holder 1 and the metal electrode 4.

[0039] The upper part of the adapter base 3 may have a curved surface portion 3a. The electrode adapter 2 can rotate along the curved surface portion 3a and can slide in the horizontal direction with respect to the metal electrode 4.

[0040] The electrode adapter 2 may further have: an electrode adapter main body portion 2a rotatably arranged on the curved surface portion 3a of the base 3, and an electrode adapter sliding portion 2b extending in the horizontal direction from the electrode adapter main body portion 2a and contacting the metal electrode 4. The electrode adapter main body portion 2a and the electrode adapter sliding portion 2b may be integrally formed.

[0041] As Figure 2As shown, the electrode adapter main body 2a is formed in a quadrilateral shape when viewed from above, and the electrode adapter sliding part 2b may also be formed in a quadrilateral shape when viewed from above. In addition, the adapter base 3 may also be formed in a quadrilateral shape when viewed from above. Further, the curved surface part 3a of the adapter base 3 may be circular when viewed from above.

[0042] As Figure 1 and Figure 2 shown, the metal electrode 4 is fixed to the reactor bottom plate 20 via the insulator 5 and is formed of a protruding part in a substantially rectangular parallelepiped shape. The pressing part composed of the electrode adapter sliding part 2b, the pressing plate 10, etc. contacts by clamping the metal electrode 4 and fastening with bolts 9a and nuts 9b. The metal electrode 4 can be clamped between the electrode adapter sliding part 2b and the pressing part such as the pressing plate 10 at a specified interval W of the electrode adapter sliding part 2b. By loosening the fastening of the bolts 9a and nuts 9b, the electrode adapter 2 can be slid horizontally relative to the metal electrode 4. The upper part of the electrode adapter main body 2a has a convex part 2a1 capable of connecting the core wire holder 1. The lower part of the electrode adapter main body 2a is connected to the adapter base 3 through the curved surface part 3a. By adopting this form, the core wire holder 1 can be slid and rotated.

[0043] The refrigerant 30 (refer to Figure 2 ) may also be disposed inside the metal electrode 4 to cool the metal electrode 4 from the inside.

[0044] In Figure 2 the manner shown, a gap G is provided in the vertical direction between the electrode adapter main body 2a and the adapter base 3, and the electrode adapter main body 2a can rotate (swing) in the vertical direction along Figure 2 (refer to the arrow R1 in Figure 2 ) and can move in the left - right direction along Figure 2 (refer to the arrow S1 in Figure 2 ). In addition, when the electrode adapter main body 2a rotates in the vertical direction, the electrode adapter sliding part 2b also rotates in the vertical direction (refer to the arrow R2 in Figure 2 ), and when the electrode adapter main body 2a moves in the left - right direction, the electrode adapter sliding part 2b also moves in the left - right direction (refer to the arrow S2 in Figure 2 ).

[0045] As an example, the metal electrode 4 may also be installed so as to be rotatable (swingable) in the horizontal direction. In this case, the electrode adapter main body 2a may also rotate in the horizontal direction relative to the adapter base 3.

[0046] The electrode adapter 2, adapter base 3, metal electrode 4, and pressing plate 10 that are continuously used among batches can all be composed of a simple spherical surface or curved surface part with a flat surface and an arc with a radius of more than 5 mm, and can also be a shape without an inner corner part less than 90 degrees. In this case, for example, cleaning tools such as BEMCOT cleanroom cleaning cloth (Asahi Kasei Corporation, Japan) can be easily used for cleaning by hand. In addition, since the bolts 9a and nuts 9b are small parts, even if new products are replaced for each batch, the economic burden is very light. In addition, even if two sets of bolts 9a and nuts 9b are prepared and one is cleaned during the use of the other, the time burden is very small. By adopting a form without an inner corner part less than 90 degrees, it is beneficial to not generate parts that are difficult to clean in the structure. In addition, the film accumulated at the acute-angle corner part (due to the increased stress of the accumulated film, the film becomes thicker, and / or in order not to maintain sufficient tightness with respect to the concave corner part and accumulate) may fall off during accumulation and scatter in the chamber, becoming a pollution source. By adopting a form without an inner corner part less than 90 degrees, the above situation can be prevented. When the form without an inner corner part less than 120 degrees is adopted, the convenience of cleaning can be further improved, thereby further reducing the possibility of becoming a pollution source, so it is more preferable. In addition, a form without an inner corner part less than 60 degrees can also be adopted. In this case, compared with the form without an inner corner part less than 90 degrees, the effect will be lower, but in terms of the convenience of cleaning and reducing the possibility of becoming a pollution source, certain effects can still be obtained. Figure 1 "c1" in Figure 2 is 90 degrees, and "c3" exceeds 90 degrees.

[0047] In addition, in order to prevent power supply to the reactor bottom plate 20, the adapter base 3 is preferably an insulator, but is not limited thereto. A conductive component can also be used as the adapter base 3. In this case, by using a material with high slidability, an insulator plate can be added between the adapter base 3 and the reactor bottom plate 20 to achieve the desired function.

[0048] In addition, a cover 40 can be provided at the vertex part of the metal electrode 4 as a stopper to prevent the electrode adapter sliding part 2b from accidentally falling off the metal electrode 4 (refer to Figure 3 ).

[0049] As Figure 3 shown, the adapter base 3 can also be provided on a guiding part 50 extending in the horizontal direction and can move in the horizontal direction along the guiding part 50. In Figure 3 the form shown, when viewed from the plane, the guiding part 50 extends in the same direction as the electrode adapter sliding part 2b.

[0050] A cover for protecting the movable part of the metal electrode 4 and the electrode adapter sliding part 2b can also be provided. Additionally, a carbon pad for assisting in energizing and bending the contact part can be clamped.

[0051]

Embodiment

[0052] By the Siemens method, reactions were carried out in 5 batches each to grow polysilicon rods with a diameter of approximately φ160 mm, and the crack incidence rate was confirmed. Among the Figure 4 most common existing types of fixed metal electrodes and electrode adapters, current disorders caused by cracks in the silicon rods were confirmed in 2 batches during growth, while cracks during cooling were confirmed in all 5 batches, and silicon rod collapse was confirmed in 1 batch. On the other hand, when using the Figure 1 and Figure 2 structures of the present embodiment shown, no current disorders caused by crack generation were confirmed during growth, and cracks generated during cooling were only confirmed in 3 batches, and silicon rod collapse did not occur in all 5 batches.

[0053]

Symbol Explanation

[0054] 1 Core wire holder

[0055] 2 Electrode adapter

[0056] 2a Electrode adapter main body part

[0057] 2b Electrode adapter sliding part

[0058] 3 Adapter base

[0059] 4 Metal electrode

[0060] 5 Insulator

[0061] 9a Bolt

[0062] 9b Nut

[0063] 10 Pressing plate

[0064] 20 Reactor bottom plate

[0065] 30 Refrigerant

[0066] 100 Holding body

[0067] S1, S2 Sliding direction

[0068] R1, R2 Rotation direction (swing direction).

Claims

1. A manufacturing apparatus for a polysilicon rod, which manufactures the polysilicon rod by the Siemens process, characterized in that, Comprising: A bottom plate; And A holding body, which is movably arranged on the bottom plate in the horizontal direction, is used to electrically connect the core wire holder with the electrode, and holds the core wire holder so as to be swingable in the up and down direction relative to the bottom plate.

2. The manufacturing device for a polysilicon rod according to claim 1, wherein: Among them, The holding body has: a base, which is movably arranged on the bottom plate in the horizontal direction; and an electrode adapter, which is swingably arranged on the base in the up and down direction and electrically connects the core wire holder with the electrode.

3. The manufacturing device for a polysilicon rod according to claim 2, wherein: Among them, The base has a curved surface portion, The electrode adapter can swing in the up and down direction along the curved surface portion and can slide in the horizontal direction relative to the electrode.

4. The manufacturing device for a polysilicon rod according to claim 3, wherein: Among them, The electrode adapter has: an electrode adapter main body portion, which is swingably arranged on the curved surface portion in the up and down direction; and an electrode adapter sliding portion, which extends in the horizontal direction from the electrode adapter main body portion and contacts the electrode, The manufacturing device for a polysilicon rod is further provided with a pressing portion for clamping the electrode and the electrode adapter sliding portion together.

5. The manufacturing device for a polysilicon rod according to claim 2 or 3, wherein: Among them, The base, the electrode adapter and the electrode are respectively composed only of a plane and a curved surface portion or a spherical surface with a radius of more than 5 mm.

6. The manufacturing device for a polysilicon rod according to claim 5, wherein: Among them, The base, the electrode adapter and the electrode do not have inner corner portions with an angle less than 90 degrees.

7. The manufacturing device for a polysilicon rod according to claim 2 or 3, wherein: Among them, The base arranged on the bottom plate is an insulator.

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