JP2010254561A - Polycrystalline silicon manufacturing apparatus and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the formation of a silicon film to the inside face of a viewing window, and to effectively maintain the function as that of a viewing window during manufacturing of polycrystal silicon. <P>SOLUTION: The outside face of the wall 3a of a reaction furnace wherein polycrystal silicon is precipitated by the reaction of gaseous starting materials is fixed with one edge of a sleeve 23 communicating with an opening part 21 formed at the wall 3a. The other edge of the sleeve 23 is provided with a window plate 25 which clogs the edge part and further can observe the inside of the reaction furnace via the opening part 21, and the sleeve 23 is connected with a gaseous hydrogen feeding system 34 feeding gaseous hydrogen to the inside of the sleeve 23. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a polycrystalline silicon manufacturing apparatus in which a raw material gas is reacted in a reaction furnace to deposit polycrystalline silicon, and the polycrystalline silicon manufacturing apparatus provided with a viewing window capable of observing the inside of the reaction furnace, The present invention relates to a method for producing crystalline silicon.

  As this type of polycrystalline silicon manufacturing apparatus, a manufacturing apparatus based on the Siemens method is known. In the production using this polycrystalline silicon production apparatus, a large number of silicon core rods serving as seed rods are placed in a reaction furnace and heated, and a raw material gas comprising a mixed gas containing chlorosilane gas and hydrogen gas in the reaction furnace. Is supplied, is brought into contact with a heated silicon core rod, and polycrystalline silicon generated by thermal decomposition of the source gas and hydrogen reduction is deposited on the surface thereof in a columnar shape.

In such a polycrystalline silicon manufacturing apparatus, a viewing window is provided on the wall of the reaction furnace in order to observe the state in the furnace during the reaction. For example, as described in Patent Document 1 or Patent Document 2, the viewing window has a cylindrical body fixed so as to pass through the wall of the reactor jacket structure, and a window plate is provided at the end of the cylindrical body. It is set as the structure. An optical pyrometer is installed on the side of the reaction furnace, and the surface temperature of the polycrystalline silicon in the reaction furnace can be measured through the viewing window.
Moreover, in the structure of the viewing window described in Patent Document 3, a double structure in which a window plate is attached to each of an opening portion of the inner furnace wall and an opening portion of the outer furnace wall that are double-structured by a jacket is provided. Cooling water can be circulated between the plates.

Special Table 2002-508294 JP 2003-40612 A Japanese Patent No. 3749471

  By the way, the reactor is filled with unreacted raw material gas and by-products such as silicon tetrachloride, hydrochloric acid gas, polymer compound, silicon powder generated during the reaction, etc. (these are called process gases). The polymer contained in these process gases is condensed by adhering to the inner surface of the viewing window, and is easily formed into a silicon film by reaction heat. Since this silicon film is opaque, there is a problem that when the growth proceeds, internal observation becomes impossible during the production of polycrystalline silicon.

  The present invention has been made in view of such circumstances, and can suppress the formation of a silicon film on the inner surface of the viewing window, and can effectively maintain the function as the viewing window during the production of polycrystalline silicon. An object is to provide a polycrystalline silicon manufacturing apparatus and a polycrystalline silicon manufacturing method.

  In the polycrystalline silicon production apparatus of the present invention, one end of a sleeve communicating with the opening formed in the wall is fixed to the outer surface of the reaction furnace wall where the polycrystalline silicon is deposited by the reaction of the raw material gas. The other end is provided with a window plate that closes the end and allows the inside of the reactor to be visually observed through the opening, and is connected to the sleeve with a hydrogen gas supply system that supplies hydrogen gas into the sleeve. It is characterized by being.

  In this polycrystalline silicon manufacturing apparatus, by supplying hydrogen gas into the sleeve, the sleeve is filled with hydrogen gas, and a flow of hydrogen gas from the sleeve toward the reactor is formed, so that process gas in the reactor is formed. It is possible to suppress the polymer inside from entering the sleeve and reaching the inner surface of the window plate. This hydrogen gas is used as a part of the raw material gas for the production of polycrystalline silicon, and is also contained in the process gas after the reaction. There is no problem in the treatment of exhaust gas. Moreover, since the inner surface of the window plate is cooled by the supply of the hydrogen gas, it is not necessary to provide a special cooling means for the window plate.

In the polycrystalline silicon manufacturing apparatus of the present invention, the sleeve may have an inner diameter set in a range of 10 to 20% of the length.
In this case, the length of the sleeve may be about 150 mm or more.
By setting the sleeve to such a dimension, a hydrogen gas supply system using a general compressor or the like can be used as means for supplying a hydrogen gas in an amount necessary for preventing the polymer from entering the process gas. . The supply amount of hydrogen gas is preferably 50 liters / minute or more, for example.

In the polycrystalline silicon manufacturing apparatus of the present invention, a valve that opens and closes the internal space may be provided at a midway position in the length direction of the sleeve.
When the inside is not monitored from the viewing window, the supply of hydrogen gas can be stopped by keeping the valve closed.

  Further, in the polycrystalline silicon manufacturing apparatus of the present invention, a ring-shaped jacket is provided so as to surround a fixed portion between the reactor wall and the sleeve, and a cooling water supply system for circulating cooling water is connected to the jacket. It is good also as the structure currently made.

  In this polycrystalline silicon manufacturing apparatus, since the one end side of the sleeve close to the wall of the reactor is cooled, the influence of heat on the window plate can be further reduced.

In the method for producing polycrystalline silicon according to the present invention, one end of a sleeve communicating with an opening formed in the wall is fixed to the outer surface of the reactor wall, and the end is closed at the other end of the sleeve. In addition, a window plate capable of observing the inside of the reaction furnace through the opening is provided, and the raw material gas is introduced into the reaction furnace while supplying hydrogen gas into the sleeve from a hydrogen gas supply system connected to the sleeve. Supplying and depositing polycrystalline silicon is characterized.
By supplying hydrogen gas into the sleeve, the visibility from the window plate can be maintained well, so the inside of the reactor is observed from the outside and the temperature of the required part is accurately measured, while the supply amount of raw material gas, etc. The desired polycrystalline silicon can be obtained by appropriately controlling the above.

  According to the present invention, by supplying hydrogen gas into the sleeve, the polymer in the process gas in the reaction furnace is prevented from entering the sleeve and sticking to the inner surface of the window plate to form a silicon film. Therefore, the inside of the reaction furnace can be accurately monitored while maintaining the transmittance of the window plate during the production of polycrystalline silicon. Moreover, since this hydrogen gas is used as a part of the raw material gas for the production of polycrystalline silicon and is also included in the process gas after the reaction, the production of polycrystalline silicon even if mixed in the reaction furnace. There is no problem in the treatment of exhaust gas after that. Further, since the inner surface of the window plate is cooled by the supply of the hydrogen gas, it is not necessary to provide a special cooling means, and the apparatus structure can be simplified and maintenance can be facilitated.

It is the whole perspective view which fractured | ruptured one part which shows one Embodiment of the polycrystalline-silicon manufacturing apparatus which concerns on this invention. It is the longitudinal cross-sectional view which expanded and showed the part of the observation window unit in FIG. It is a cross-sectional view showing an example in which the observation window unit is attached while being inclined in the horizontal direction with respect to the normal line of the outer surface of the reaction furnace.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing the entire polycrystalline silicon production apparatus of this embodiment. A reaction furnace 1 of the polycrystalline silicon production apparatus includes a bottom plate portion 2 constituting a furnace bottom, and desorption on the bottom plate portion 2. A bell-shaped bell jar 3 attached freely is provided.
Then, a plurality of pairs of electrodes 5 to which a silicon core rod 4 formed of polycrystalline silicon is attached to the bottom plate portion 2, an ejection nozzle 6 for ejecting a raw material gas into the furnace, and a gas after reaction outside the furnace A plurality of gas discharge ports 7 are provided for discharging the gas. These ejection nozzles 6 are connected to a source gas supply system 8 outside the reaction furnace 1. In addition, a plurality of gas discharge ports 7 are installed in the vicinity of the outer peripheral portion on the bottom plate portion 2 with appropriate intervals in the circumferential direction, and are connected to an external gas processing system 9. Each electrode 5 is connected to an external power supply unit 10.

Moreover, the silicon | silicone core stick | rod 4 is standingly extended and extended by fixing the state in which the lower end part was inserted in the electrode 5, Two of them are made into a pair, and one piece is set by the upper end part. By being connected by the short connecting member 12, the seed assembly 13 is constructed so as to have an inverted U-shape or hook shape as a whole. These seed assemblies 13 are arranged substantially concentrically as a whole by arranging the electrodes 5 substantially concentrically from the center of the reaction furnace 1.
Further, the bottom plate portion 2 and the wall of the bell jar 3 of the reaction furnace 1 have a jacket structure, and a flow path 14 for circulating a heat medium is formed therein, and a heat medium supply system for circulating cooling water or the like in the flow path 14. 15 is connected.

Then, an opening 21 communicating with the inside of the reactor is formed in a taper shape that gradually increases the inner diameter from the outside of the wall 3a of the bell jar 3 toward the inside of the radius. A viewing window unit 22 is attached to the opening 21. As shown in FIG. 2, the viewing window unit 22 includes a sleeve 23 that communicates with the opening 21 and protrudes from the wall 3 a of the bell jar 3, and a ring-shaped housing that surrounds the sleeve 23 and the wall 3 a of the bell jar 3. 24 and a window plate 25 provided at the tip of the sleeve 23 on the protruding side.
One end of the sleeve 23 is fixed to the wall 3a of the bell jar 3 and is erected vertically from the wall 3a. The inner diameter of the sleeve 23 is smaller than the inner diameter of the opening 21 of the wall 3a of the bell jar 3. A flange 26 is integrally formed at the end (the other end).
The ring-shaped housing 24 is formed in a ring shape around one end portion of the sleeve 23 by an outer cylindrical body 27 having a diameter larger than that of the sleeve 23 and a pair of ring-shaped side plates 28 fixed to both ends of the outer cylindrical body 27. A flow path 29 is formed, and a cooling water supply system 30 for circulating the cooling water is connected to the ring-shaped flow path 29.

The window plate 25 is formed in a circular plate shape using transparent glass or the like. Then, the window plate 25 is brought into contact with the flange 26 at the tip of the sleeve 23 via the seal ring 31, and the ring frame 32 is further brought into contact with the outer surface of the window plate 25 via the seal ring 31. 32 and the flange 26 are fixed by screws (not shown) or the like, so that the window plate 25 is sandwiched between them.
Further, a pipe 33 communicating with the internal space 23 a is fixed vertically at an intermediate position in the length direction of the sleeve 23, and a hydrogen gas supply system 34 is connected to the pipe 33. Further, a valve 35 such as a ball valve is provided between the connecting portion of the tube 33 and the window plate 25 to open and close the middle position of the internal space 23 a of the sleeve 23.
In addition, the code | symbol 36 has shown the optical pyrometer (pyroscope) which monitors the inside of the reaction furnace 1 through the observation window unit 22. FIG.

Next, a method for manufacturing polycrystalline silicon using the thus configured polycrystalline silicon manufacturing apparatus will be described.
These silicon core rods 4 are heated by energizing each silicon core rod 4 standing in the reaction furnace 1 from the power supply unit 10, and contain trichlorosilane and hydrogen gas from the raw material gas supply system 8. When the raw material gas is supplied and ejected from the ejection nozzle 6 into the furnace, the raw material gas deposits polycrystalline silicon on the surface of the silicon core rod 4, and its diameter is gradually increased to grow as a cylindrical silicon rod. To do. For example, in order to obtain a silicon rod having an outer diameter of 11.8 to 12.4 cm, the raw material gas to be supplied is 216 to 228 tons of trichlorosilane and 273,000 to 288000 m ^{3 of} hydrogen gas within a reaction time of 114 to 119 hours. Supplied.
During the production of the polycrystalline silicon, the valve 35 is opened, and the heat generation state of the silicon core rod 4 and the growth state of the polycrystalline silicon are monitored while being measured by the optical pyrometer 36 through the window plate 25 of the viewing window unit 22. To do.

  In the polycrystalline silicon manufacturing apparatus of this embodiment, before the valve 35 is opened or simultaneously with the opening of the valve 35, the hydrogen gas supply system is shown in the sleeve 23 of the viewing window unit 22 as indicated by the solid line arrow in FIG. A hydrogen gas at room temperature is supplied from 34. By supplying this hydrogen gas, the hydrogen gas is filled into the sleeve 23 and flows into the reactor 1 from the sleeve 23 through the opening 21 as indicated by the broken arrow A. On the other hand, the reaction furnace 1 is filled with silicon tetrachloride, hydrochloric acid gas, polymer compound, and silicon powder generated as by-products as process gas as well as unreacted raw material gas. Since the hydrogen gas flows out from the sleeve 23 of the observation window unit 22, the polymer in the process gas in the reaction furnace 1 is pushed back by the hydrogen gas when trying to enter the sleeve 23 from the opening 21. It does not reach the window plate 25 disposed in the back, and most of the inside of the sleeve 23 is maintained in a hydrogen gas atmosphere.

Therefore, it is possible to suppress the silicon film from being formed on the window plate 25 of the viewing window unit 22 and maintain the transparency of the window plate 25, and to accurately perform the measurement from the optical pyrometer 36. As a result, production control of polycrystalline silicon can be facilitated to produce high quality polycrystalline silicon.
The amount of normal-temperature hydrogen gas supplied to the sleeve 23 is about 40 to 100 liters / minute, preferably 50 to 50 for the sleeve 23 having a length L of 150 to 310 mm and an inner diameter in the range of 10 to 20%. 65 liters / minute.
With such a supply amount, it is considerably smaller than the amount of hydrogen gas supplied as a part of the source gas into the reaction furnace described above, and thus does not affect the precipitation of polycrystalline silicon.

  Further, in the viewing window described in Patent Document 3, the cooling water is brought into contact with the window plate. However, in the viewing window unit of the present embodiment, the window plate 25 is an end portion on the protruding side of the sleeve 23. Since the hydrogen gas supplied from the outside into the sleeve 23 comes into contact with the window plate 25 as shown by the broken line arrow B in FIG. The window plate 25 is also cooled by the hydrogen gas. Therefore, it is not necessary to provide special cooling means for the window plate 25. Moreover, since the cooling water circulates in the ring-shaped housing 24 provided around the opening 21, the influence of heat on the window plate 25 can be further reduced.

In the viewing window unit 22 as described above, if the length L of the sleeve 23 is short, the field of view when looking into the reaction furnace 1 from the window plate 25 is widened, but the distance from the reaction furnace 1 is short. Further, the cooling effect of the window plate 25 by hydrogen gas is low, and the polymer easily adheres to the window plate 25. On the other hand, if L is too long, the polymer is difficult to adhere to the window plate 25, but the field of view is narrowed as the distance from the inside of the reactor 1 increases.
Table 1 shows the result of visually observing whether or not the polymer adheres to the window plate 25 while changing the length L and the inner diameter D of the sleeve 23 and supplying a predetermined amount of hydrogen gas from the pipe 33. In this case, the valve 35 was continuously kept open during the observation. In Table 1, in Examples 1 to 5 and Comparative Example 1, the sleeve 23 was provided along the normal line of the outer surface of the reaction furnace 1, but in Example 6, as shown in FIG. The sleeve 23 is attached at an inclination angle θ of 20 ° in the horizontal direction with respect to the normal line. Each element in FIG. 3 is given the same reference numeral as that of the embodiment shown in FIGS.

  As can be seen from Table 1, no polymer adhesion to the window plate was observed in about 2 days after the start of observation, but in Comparative Example 1, the sleeve length L was shorter than the sleeve inner diameter D. Therefore, polymer adhesion was observed after 3 days. In addition, for each example, when the reaction was continuously observed for about 5 days thereafter, polymer adhesion to the window plate 25 was not confirmed for Examples 1, 2, 4, 5, and 6 in Table 1, The inside of the furnace could be observed well. In Example 3, where the hydrogen gas flow rate is lower than in the other examples, although slight polymer adhesion was observed after about 5 days, the view was not obstructed and the inside of the reactor could be observed. It was. In addition, if the sleeve is attached to the reactor in a tilted manner as in Example 6, the monitoring position inside the reactor 1 can be changed, and if used in combination with a sleeve provided along the normal line Since the monitoring range is further expanded, the amount of information obtained by monitoring increases.

From the above results, the length L of the sleeve 23 is preferably about 150 mm or more in order to effectively exhibit the function of the viewing window unit 22, and the inner diameter D in that case is 10% to 10% of the length. 20% is preferred. For example, the length is 150 to 300 mm, and the inner diameter is set to 15 to 60 mm. By setting the internal capacity of the sleeve 23 to this level, a hydrogen gas supply system 34 using a general pump or the like is used as means for supplying a hydrogen gas in an amount necessary for preventing the polymer from entering the process gas. be able to. In this case, the supply amount of hydrogen gas is 50 liters / minute or more.
When the monitoring operation is completed, the valve 35 is closed and the supply of hydrogen gas from the hydrogen gas supply system 34 is shut off.

  By providing the viewing window unit 22 as described above in the reaction furnace 1, by supplying hydrogen gas into the sleeve 23 of the viewing window unit 22 when producing polycrystalline silicon, Since the field of view can be maintained well, the inside of the reactor 1 can be observed from the outside, and the temperature of the necessary part can be accurately measured, thereby appropriately controlling the supply amount of the raw material gas and the like. The polycrystalline silicon can be obtained.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, the viewing window unit may be provided in a fixed state on the wall of the reaction furnace, or a stud bolt may be erected from the wall of the reaction furnace and detachably attached to the stud bolt. In that case, it is good also as a structure which can be attached and rotated via the hinge between the walls of a reaction furnace. Further, although the valve is provided between the tube and the window plate, it may be provided in any one of the length ranges of the sleeve.
In FIG. 3, the sleeve is attached so as to incline in the horizontal direction with respect to the normal direction of the outer surface of the reactor. However, the sleeve may be attached in an up and down direction depending on the area to be monitored in the reactor. It may be installed at the right angle and angle. In addition, it is possible to increase the amount of information collected by installing observation windows at a plurality of locations around the reactor and observing the inside of the reactor from different positions.

DESCRIPTION OF SYMBOLS 1 Reaction furnace 2 Bottom plate part 3 Belger 3a Wall 4 Silicon core stick 5 Electrode 6 Injection nozzle 7 Gas exhaust port 8 Raw material gas supply system 9 Gas processing system 10 Power supply part 12 Connecting member 13 Seed assembly 21 Opening part 22 Viewing window unit 23 Sleeve 24 Ring-shaped housing 25 Window plate 29 Flow path 30 Cooling water supply system 34 Hydrogen gas supply system 35 Valve

Claims (5)

  One end of a sleeve communicating with the opening formed in the wall is fixed to the outer surface of the reactor wall where polycrystalline silicon is deposited by the reaction of the raw material gas, and the end is closed at the other end of the sleeve. And a window plate capable of observing the inside of the reaction furnace through the opening, and a hydrogen gas supply system for supplying hydrogen gas to the inside of the sleeve is connected to the sleeve. Silicon manufacturing equipment.   The polycrystalline silicon manufacturing apparatus according to claim 1, wherein an inner diameter of the sleeve is set within a range of 10 to 20% of a length.   The polycrystalline silicon manufacturing apparatus according to claim 1, wherein a valve that opens and closes the internal space is provided at an intermediate position in the length direction of the sleeve.   The ring-shaped housing is provided so as to surround a fixed portion between the wall of the reaction furnace and the sleeve, and a cooling water supply system for circulating cooling water is connected to the ring-shaped housing. The polycrystalline silicon manufacturing apparatus according to any one of 1 to 3.   One end of a sleeve communicating with the opening formed in the wall is fixed to the outer surface of the reaction furnace wall, and the end is closed at the other end of the sleeve and the inside of the reaction furnace is observed through the opening. A possible window plate is provided, and while supplying hydrogen gas from the hydrogen gas supply system connected to the sleeve to the inside of the sleeve, a raw material gas is supplied into the reactor to deposit polycrystalline silicon. A method for producing polycrystalline silicon.

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