Polysilicon manufacturing apparatus

Abstract

The polysilicon manufacturing apparatus of the present invention includes an electrode adapter that electrically connects a core clamp to a metal electrode, wherein the electrode adapter and the threaded portion disposed on the metal electrode are configured to be non-conductive. Furthermore, the polysilicon manufacturing apparatus of the present invention includes an electrode adapter that electrically connects a core clamp to a metal electrode, wherein the electrode adapter is fixed to the metal electrode by a fixing mechanism, and the electrode adapter and the fixing mechanism are configured to be non-conductive.

Description

TECHNICAL FIELD

[0001] The present application relates to an apparatus for producing polycrystalline silicon by a Siemens method, and more particularly to a structure of an electrode adapter for electrically connecting a core holder to a metal electrode. BACKGROUND

[0002] Polycrystalline silicon is a single-crystal silicon used for manufacturing semiconductors and a silicon raw material used for manufacturing solar cells. As a method for producing polycrystalline silicon, the Siemens method is known. The Siemens method is a method in which polycrystalline silicon is deposited on the surface of a silicon core by a CVD (Chemical Vapor Deposition) method by bringing a raw material gas based on silane into contact with a silicon core heated.

[0003] The Siemens method is a method in which, after two silicon cores in a vertical direction and one silicon core in a horizontal direction are assembled in a torii shape (inverted U shape), both ends thereof are connected to a core holder, and the core holder is fixed to a pair of electrodes made of metal provided on a substrate. Generally, a structure in which a plurality of inverted U-shaped silicon cores are arranged is formed in a reaction furnace. Such a structure is disclosed in, for example, Japanese Patent Application Publication No. 2010-235438.

[0004] After the inverted U-shaped silicon core is heated to a deposition temperature by electric current and a mixed gas of, for example, trichlorosilane and hydrogen as a raw material gas is brought into contact with the silicon core, polycrystalline silicon is vapor-deposited on the silicon core, and a polycrystalline silicon rod having a desired diameter is finally formed in an inverted U shape.

[0005] The electrodes sandwich an insulator through the substrate and are connected to the other electrodes or to a power source arranged outside the reaction furnace. In a deposition process of polycrystalline silicon, in order to achieve the purpose of preventing deposition of polycrystalline silicon at the electrode portion, preventing metal contamination of the polycrystalline silicon being deposited due to temperature rise of the electrode portion, and the like, the electrodes, the substrate, and the bell jar are cooled by a cooling medium such as water.

[0006] Figure 1 is a conceptual view illustrating a state in which the electrode holder is mounted to the electrode in the related art. In the drawing shown in the figure, the metal electrode 20 and the carbon core holder 24 are connected via the electrode adapter 23, and the electrode adapter 23 is fixed to the electrode 20 by screwing, thereby achieving the purpose of suppressing consumption of the electrode 20 and the like.

[0007] Current is supplied from the electrode 20 to the silicon core (not shown) held at the top of the core holder 24 via the core holder 24, and the surface of the silicon core is heated to a temperature range of about 900°C to 1200°C in a hydrogen atmosphere by Joule heat. In this state, a high-purity silicon is vapor-deposited on the silicon core by supplying a mixed gas of, for example, trichlorosilane and hydrogen as a raw material gas into the reaction furnace, and a polycrystalline silicon rod is grown.

[0008] In this process, as the diameter of the polysilicon rod increases, deposition of polysilicon also occurs on the side of the carbon-made core wire clamp 24, and gradually becomes integrated with the core wire clamp 24. In addition, 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 deposition reaction, the supplied current needs to be gradually increased.

[0009] In addition, generally, the current supplied to the polysilicon rod becomes a large current of 2000 amperes to 4000 amperes at the end of the deposition reaction. As the diameter of the polysilicon rod increases, the amount of heat dissipation from the surface of the rod also increases, and therefore, in order to maintain the temperature (900 to 1200°C) required for the deposition reaction, the electric power supplied to the polysilicon rod must be increased to compensate for the heat lost due to the heat dissipation.

[0010] Due to the above, the connection structure of the metal electrode, the electrode adapter, and the core wire clamp is required to withstand the above-mentioned large current supply and the weight of the polysilicon rod, which is heavy due to the large diameter.

[0011] Therefore, since the electrode adapter is made of carbon having high self-lubricity, it must be firmly fixed. In particular, in the case where the metal electrode and the adapter are connected by screwing, if the screw becomes loose, discharge occurs at the gap generated by the loosening, which causes damage to both the metal electrode and the adapter, and with the discharge, the metal and carbon diffused into the reaction furnace sometimes become a cause of contamination in the polysilicon.

[0012] With regard to the connection of the metal electrode, the electrode adapter, and the core wire clamp, new structures have been proposed so far.

[0013] For example, in Japanese Patent Application Publication No. 2010-235438, a configuration in which a clamp portion in which an internally threaded hole into which a core rod holding portion is screwed is formed is used to fix is disclosed, in which a holding hole into which a silicon core wire is inserted is formed at the upper end portion of the core rod holding portion, and a thread is formed on the peripheral surface. In this configuration, the core rod holding portion and the clamp portion are both composed of an electrically conductive material, and the current also flows through the screwing portion. However, the present inventors have found that, in recent years, as the large diameter development has been progressing, since the screwing portion has a concave-convex formed on the surface thereof, if a large current is caused to flow therethrough, even if the core rod holding portion and the clamp portion are firmly engaged, discharge occurs at a slight gap of the screwing portion due to, for example, the difference in thermal expansion rate between the metal electrode and the carbon-made electrode adapter.

[0014] Further, although a configuration is disclosed in Japanese Patent Application Publication No. 2010-235438 in which a nut member that is screwed to a clamp main body is used to support a core rod holding portion to a base plate portion, in which a lower portion of the core rod holding portion is inserted into a holding hole of the clamp main body, and an outer thread is formed on an outer peripheral surface of the clamp main body, since this configuration also makes these members conductive, as in the above-described configuration, the problem of easy occurrence of discharge if a large current flows through the screwing portion also occurs in this configuration.

[0015] Further, although a configuration is disclosed in Japanese Patent Application Publication No. 2002-338226 in which a support that supports a lower end portion of a seed (SEED) is supported by a first support base that is composed of an externally threaded member, and the first support base is supported in a manner that is liftable by a fixed second support base that is composed of an internally threaded member, since the first and second support bases are both used as a current passage, as in the configuration disclosed in Japanese Patent Application Publication No. 2010-235438, discharge occurs due to a large current flowing through the screwing portion.

[0016] As described above, the connection structure of the electrode adapter and the metal electrode in the related art is not sufficient as a countermeasure against discharge. Therefore, once damage occurs in the internal member of the furnace due to discharge, the aftertreatment is extremely troublesome. Specifically, in addition to the fact that the electrode must be replaced with a new one, the polysilicon rod is also contaminated. Further, the fact that the bell jar and the substrate are also contaminated results in the fact that the reaction exhaust gas in the recycling cycle contains a hydrocarbon as a dopant, which has an adverse effect on the subsequent batch of polysilicon production.

[0017] The present application is made in view of the above-described circumstances, and an object thereof is to provide a new structure of an electrode adapter that is simple in structure but can stably pass a current between a metal electrode and a core rod clamp. SUMMARY

[0018] CONCEPT 1

[0019] The polysilicon production apparatus according to the present application is a polysilicon production apparatus that produces polysilicon by a Siemens method, and includes an electrode adapter that electrically connects a core rod clamp and a metal electrode, and the electrode adapter and a screwing portion provided in the metal electrode can be made non-conductive.

[0020] CONCEPT 2

[0021] The polysilicon production apparatus according to the present application is a polysilicon production apparatus that produces polysilicon by a Siemens method, and includes an electrode adapter that electrically connects a core rod clamp and a metal electrode, and the electrode adapter and a screwing portion provided in the metal electrode can be made non-conductive.

[0022] CONCEPT 3

[0023] In the polycrystalline silicon manufacturing apparatus of Concept One and Concept Two, the adapter and the core holder can be made of the same material.

[0024] [Concept Four]

[0025] In any of the polycrystalline silicon manufacturing apparatuses of Concept One through Concept Three, at least one of the electrode adapter and the core holder is made of a carbon material.

[0026] [Concept Five]

[0027] In any of the polycrystalline silicon manufacturing apparatuses of Concept One through Concept Four, an electrically conductive member is inserted in the conductive portion of the electrode adapter and the metal electrode.

[0028] [Concept Six]

[0029] In any of the polycrystalline silicon manufacturing apparatuses of Concept One through Concept Five, the electrode adapter is fixed to the metal electrode by an insulating jig.

[0030] [Concept Seven]

[0031] In any of the polycrystalline silicon manufacturing apparatuses of Concept Two through Concept Six, at least the surface of the fixing mechanism portion is subjected to insulation treatment.

[0032] Inventive Effects

[0033] The present application provides an electrode adapter that enables stable conduction between a metal electrode and a core holder. Moreover, because of its simple structure, the core holder can be easily detached. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a conceptual diagram illustrating a configuration in which an electrode holder is installed on an electrode and holds a core holder.

[0035] Figure 2 is a schematic diagram illustrating a configuration example of a polycrystalline silicon manufacturing apparatus to which the present application is applied.

[0036] Figure 3 is a conceptual diagram illustrating a configuration in which an electrode holder is installed on an electrode and holds a core holder.

[0037] Figure 4 is a conceptual diagram illustrating another configuration in which an electrode holder is installed on an electrode and holds a core holder.

[0038] Figure 5 is a conceptual diagram illustrating another configuration in which an electrode holder is installed on an electrode and holds a core holder.

[0039] Figure 6is another conceptual view showing the state where the electrode holder is installed to the electrode after the core wire holder is installed to the electrode.

[0040] Figure 7 is a conceptual view showing the state after the conductive member is inserted into the conductive portion of the electrode adapter and the metal electrode. DETAILED DESCRIPTION

[0041] Figure 2 is a schematic view showing a configuration example of a reaction furnace of a polycrystal silicon manufacturing apparatus to which the present application is applied. The reaction furnace 100 has an electrode 10 insulated from a base plate 5 provided at a lower portion of a bell jar 1, the electrode 10 is connected to an electrode holder 13 by a fixing mechanism portion 17 made of an insulating material, and a carbon core wire holder 14 holding a silicon core wire 15 is fixed to the electrode holder 13. Electric current supplied from the electrode 10 is connected to pass through the electrode holder 13 and the core wire holder 14, and polycrystal silicon 16 is deposited on the silicon core wire 15 by a reaction of a raw material gas.

[0042] In Figure 1 the figure, the electrode 10 is provided with a screwing portion at a top portion thereof, the electrode adapter 13 is fixed by a fixing mechanism portion 17 screwed to the screwing portion, and a convex portion provided at a top portion of the electrode adapter 13 is fitted into a concave portion formed at a lower end portion of the core wire holder 14. Since the fixing mechanism portion 17 is made of an insulating material, the screwing portion is non-conductive, and electric power supply from the electrode 10 to the core wire holder 14 is performed via a portion other than the screwing portion of the electrode adapter 13. Thus, electric conduction at the screwing portion (a portion where surface irregularities are sharp) where discharge is likely to occur is completely suppressed, and damage due to discharge can be prevented.

[0043] Figures 3 to 6 is a conceptual view showing the state where the electrode holder is installed to the electrode after the core wire holder is installed to the electrode.

[0044] In Figure 3 the figure, the electrode 10 is provided with a screwing portion at a top portion thereof, the electrode adapter 13 is fixed by a fixing mechanism portion 17 screwed to the screwing portion, and a convex portion provided at a top portion of the electrode adapter 13 is fitted into a concave portion formed at a lower end portion of the core wire holder 14. Since the fixing mechanism portion 17 is made of an insulating material, the screwing portion is non-conductive, and electric power supply from the electrode 10 to the core wire holder 14 is performed via a portion other than the screwing portion of the electrode adapter 13. Thus, electric conduction at the screwing portion (a portion where surface irregularities are sharp) where discharge is likely to occur is completely suppressed, and damage due to discharge can be prevented.

[0045] In Figure 4In the illustrated state, a hole portion having a screwing portion (internal thread portion) is formed on the top of the electrode 10, and a fixing mechanism portion 17 having a screwing portion (external thread portion) is screwed into the hole portion. The electrode adapter 13 is fixed by the fixing mechanism portion 17, and a convex portion formed on the lower end portion of the core wire clamp 14 is fitted into a concave portion provided on the top of the electrode adapter 13. Since the fixing mechanism portion 17 is also made of an insulating material, the above-mentioned screwing portion is non-conductive, and the power supply from the electrode 10 to the core wire clamp 14 is performed via a portion other than the screwing portion of the electrode adapter 13. In this way, the electric conduction at the screwing portion (portion where the surface irregularity is severe) where discharge is likely to occur is completely suppressed, and thus damage due to discharge can be prevented.

[0046] In Figure 5 In the illustrated state, a screwing portion (external thread portion) is formed on the top of the electrode 10, and the electrode adapter 13 is placed on the top of the screwing portion (external thread portion). The electrode adapter 13 is fixed by a fixing mechanism portion 17 having a screwing portion formed on the inner face, and a concave portion formed on the lower end portion of the core wire clamp 14 is fitted into a convex portion provided on the top of the electrode adapter 13. Since the fixing mechanism portion 17 is also made of an insulating material, the above-mentioned screwing portion is non-conductive, and the power supply from the electrode 10 to the core wire clamp 14 is performed via a portion other than the screwing portion of the electrode adapter 13. In this way, the electric conduction at the screwing portion (portion where the surface irregularity is severe) where discharge is likely to occur is completely suppressed, and thus damage due to discharge can be prevented.

[0047] In Figure 6 In the illustrated state, a screwing portion (external thread portion) is formed on the top of the electrode 10, and a screwing portion formed on the inner face of the electrode adapter 13 is screwed into the screwing portion by an insulating fixing mechanism portion 17. At this time, by performing an insulating treatment on the screwing portion formed on the inner face of the electrode adapter 13, the inner face region of the electrode adapter 13 can also function as the fixing mechanism portion 17. A convex portion is provided on the top of the electrode adapter 13, and a concave portion formed on the lower end portion of the core wire clamp 14 is fitted into the convex portion. In this case, since the fixing mechanism portion 17 is also made of an insulating material, the above-mentioned screwing portion is non-conductive, and the power supply from the electrode 10 to the core wire clamp 14 is performed via a portion other than the screwing portion of the electrode adapter 13. In this way, the electric conduction at the screwing portion (portion where the surface irregularity is severe) where discharge is likely to occur is completely suppressed, and thus damage due to discharge can be prevented.

[0048] As described above, the present application is a device for manufacturing polycrystalline silicon by the Siemens method, which has an electrode adapter that electrically connects a core wire clamp and a metal electrode, and the electrode adapter is made non-conductive between a screwing portion provided on the metal electrode.

[0049] Further, the present application is an apparatus for producing polycrystalline silicon by the Siemens method, which has an electrode adapter that electrically connects a core holder to a metal electrode, the electrode adapter being fixed to the metal electrode by a fixing mechanism portion, and the electrode adapter and the fixing mechanism portion being configured to be non-conductive.

[0050] In this case, the electrode adapter and the core holder can be formed of the same material.

[0051] Further, at least one of the electrode adapter and the core holder can be formed of a carbon material. When the connecting portions of the core holder and the electrode adapter are both carbon, the contact surfaces can be adapted by sliding them when they are disposed. Therefore, even if the connecting portions of the core holder and the electrode adapter are only tapered, they can be sufficiently fixed, and discharge can also be effectively suppressed.

[0052] In order to effectively supply power to the core holder, a conductive member 30 such as a carbon sheet can be inserted into the conductive portions of the electrode adapter and the metal electrode.

[0053] The electrode adapter can be fixed to the metal electrode by an insulating jig as shown in the Figure 5 embodiment.

[0054] Further, although the fixing mechanism portion can be formed of an insulating material as a whole, it is sufficient if at least the surface thereof is insulated.

[0055] The insulating material described above is a material having a resistivity that is much higher than the resistivity of carbon (about 10 μΩm). As such a material, for example, silicon nitride (about 1 x 10 15 μΩm) or quartz glass (about 1 x 10 18 μΩm) can be exemplified. Further, a material having a resistivity of germanium (about 5 x 10 5 μΩm) or the like can also be used as the insulating material.

[0056]

EXAMPLE

[0057] After 20 batches of reactions for growing the weight of a pair of polycrystalline silicon rods to 80 to 200 kg were performed by the Siemens method, and it was confirmed whether there were any defects in the metal electrodes that were considered to be caused by discharge, the results were that no defects in the metal electrodes were found after the structure shown in Figure 3 was used (the fixing mechanism portion was composed of silicon nitride), whereas defect sites were found in 2 batches corresponding to 10% after the structure shown in Figure 1 was used, and in the batches in which these defects occurred, it was confirmed that it was possible that the defects were caused by thread discharge of the metal electrode.

[0058] The present application provides an electrode adapter capable of stable current conduction between a metal electrode and a core holder.

[0059] Explanation of symbols

[0060] 1 bell jar

[0061] 2 observation window

[0062] 3 cooling medium inlet (bell jar)

[0063] 4 cooling medium outlet (bell jar)

[0064] 5 substrate

[0065] 6 cooling medium inlet (bell jar)

[0066] 7 cooling medium outlet (bell jar)

[0067] 8 reaction exhaust gas outlet

[0068] 9 raw material gas supply nozzle

[0069] 10, 20 metal electrode

[0070] 11 cooling medium inlet (electrode)

[0071] 12 cooling medium outlet (electrode)

[0072] 13, 23 electrode adapter

[0073] 14, 24 core holder

[0074] 15 silicon core

[0075] 16 polysilicon

[0076] 17 fixing mechanism portion

[0077] 30 electrically conductive member

[0078] 100 reaction furnace

Claims

1. A polycrystalline silicon manufacturing apparatus for manufacturing polycrystalline silicon using the Siemens process, characterized in that, include: An electrode adapter that electrically connects the core wire clamp to the metal electrode. A fixing mechanism made of insulating material is provided between the electrode adapter and the threaded portion disposed on the metal electrode, thereby fixing the electrode adapter relative to the threaded portion. The electrode adapter and the screw portion disposed between the metal electrode are configured to be non-conductive.

2. A polycrystalline silicon manufacturing apparatus for manufacturing polycrystalline silicon using the Siemens process, characterized in that, include: An electrode adapter that electrically connects the core wire clamp to the metal electrode. The electrode adapter is fixed to the metal electrode by a screw engagement portion of a fixing mechanism made of insulating material, and the electrode adapter and the fixing mechanism are configured to be non-conductive.

3. The polycrystalline silicon manufacturing apparatus according to claim 1 or 2, characterized in that: in, The electrode adapter and the core clamp are made of the same material.

4. The polycrystalline silicon manufacturing apparatus according to claim 1 or 2, characterized in that: in, At least one of the electrode adapter and the core clamp is made of carbon material.

5. The polycrystalline silicon manufacturing apparatus according to claim 1 or 2, characterized in that: in, A conductive component is inserted into the conductive portion between the electrode adapter and the metal electrode.

6. The polycrystalline silicon manufacturing apparatus according to claim 1 or 2, characterized in that: in, The electrode adapter is fixed to the metal electrode by an insulating clamp.

7. The polycrystalline silicon manufacturing apparatus according to claim 2, characterized in that: in, The fixing mechanism is at least insulated on its surface.

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