JP4081879B2 - Nozzle structure used in polycrystalline silicon rod manufacturing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of a nozzle made of graphite covering an end of a stainless steel supply pipe attached to a reaction furnace of an apparatus for producing a high purity polycrystalline silicon rod for semiconductor.
[0002]
[Prior art]
The Czochralski method and the float zone method are known as methods for growing silicon single crystals for semiconductors using polycrystalline silicon as a raw material. The polycrystalline silicon used as the raw material is formed by thermal decomposition of a halosilane compound such as trichlorosilane. A polycrystalline silicon rod having a large diameter is manufactured by depositing silicon on the rod. As an apparatus for manufacturing this polycrystalline silicon rod, there is known a device in which a supply pipe made of stainless steel for introducing a gas containing a silane compound is installed in a reaction furnace provided with a core rod. When stainless steel is exposed inside the furnace, the stainless steel contaminates the interior of the furnace during the manufacture of the polycrystalline silicon rod. For this reason, a nozzle made of graphite is screwed to an end portion of the supply pipe of the apparatus in the reaction furnace so as to cover the end portion.
[0003]
As shown in FIG. 3, a nozzle 1 used in a conventional polycrystalline silicon rod manufacturing apparatus has an annular portion 2 in which an internal thread 2a is formed on an inner peripheral surface, and a supply tube in a screwed state at an end portion of the supply tube 3. The nozzle 1 is made by cutting bulk graphite. A through hole 4 a communicating with the supply pipe 3 is formed concentrically with the annular portion 2 in the cover portion 4 of the nozzle 1. By screwing the nozzle 1 having such a structure to the end of the supply pipe 3, the contamination of the stainless steel protruding into the furnace is prevented and the silane compound supplied from the supply pipe 3 is prevented. It is possible to effectively produce a polycrystalline silicon rod by effectively diffusing a gas containing bismuth into a reaction furnace.
[0004]
[Problems to be solved by the invention]
The above-described conventional nozzle 1 is removed from the supply pipe 3 in order to avoid water from adhering when the reactor is washed with water after silicon is deposited. However, since the nozzle 1 is made of graphite, there is a problem that cementite (Fe ₃ C) is generated at the contact portion in a threaded state on the supply pipe 3 made of stainless steel. That is, Fe in stainless steel and C in the nozzle 1 react with heat at the time of manufacturing the polycrystalline silicon rod to generate cementite, and the nozzle 1 screwed due to the generation of the cementite is connected to the end of the supply pipe 3. There is a problem that it is difficult to remove the nozzle 1 due to adhesion to the part. Thus, when the nozzle 1 adheres to the end of the supply pipe 3, it is necessary to apply a great amount of torque to the nozzle 1 when removing the nozzle 1, and the damage rate of the nozzle 1 is relatively high due to this great torque. There is a problem.
[0005]
Further, since the conventional nozzle 1 has a large area of the contact portion, the heat of the substrate of the reaction furnace is directly transferred to the nozzle 1 through the supply pipe 3 and becomes high temperature. When the reaction furnace is rapidly cooled after the polycrystalline silicon rod is manufactured, the high temperature nozzle 1 is also rapidly cooled, and the nozzle 1 is subjected to thermal shock (thermal stress). On the other hand, the thermal conductivity of graphite composing the nozzle is extremely small at a temperature of 1000 K, 64 W / m · K in the vertical direction and 49 W / m · K in the horizontal direction. Generally, thermal shock is inversely proportional to the thermal conductivity of the material. The nozzle 1 made of graphite was subjected to a great amount of thermal stress, resulting in minute cracks on the surface.
An object of the present invention is to provide a nozzle structure used in an apparatus for manufacturing a polycrystalline silicon rod that can effectively reduce breakage caused by removal of a nozzle or thermal shock.
[0006]
[Means for Solving the Problems]
As shown in FIG. 2, the invention according to claim 1 is made of stainless steel that is attached through a reaction furnace 11 for producing rod-shaped polycrystalline silicon and introduces a gas containing a silane compound into the reaction furnace. 1 is a nozzle 16 made of graphite that is screwed onto an end portion of the supply pipe 12 in the reaction furnace so as to cover the end portion. As shown in FIG. 1, the nozzle 16 has an internal thread 17a formed on the inner peripheral surface. The formed annular portion 17 and a through hole 18a that is formed integrally with the annular portion 17 and communicates with the supply pipe 12 are formed concentrically with the annular portion 17 and abuts against the edge of the supply pipe 12 in a screwed state. This is an improvement of the nozzle structure used in the polycrystalline silicon rod manufacturing apparatus having the portion 18.
The characteristic configuration is such that an annular bulging portion 19 that faces the end edge 12a of the supply pipe 12 and that is screwed to the cover portion 18 surrounds the through hole 18a. There is.
[0007]
In the production of polycrystalline silicon, the nozzle 16 made of graphite is only in contact with the supply pipe 12 made of stainless steel, that is, only at the tip of the bulging portion 19 in contact with the edge 12a of the supply pipe 12. Cementite is generated, and the generation area of cementite is smaller than that of the conventional nozzle. The nozzle 16 adhering to the end of the supply pipe 12 can be easily removed with a torque smaller than that of the prior art by reducing the generation area of cementite.
Further, the formation of the bulging portion 19 forms a gas layer between the cover portion 18 and the edge 12a of the supply pipe 12, and thermal shock caused by direct contact as compared with a conventional nozzle having no gas layer. Can be reduced, and the occurrence of cracks due to the thermal shock of the nozzle 16 can be suppressed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 2, the polycrystalline silicon rod manufacturing apparatus 10 includes a reaction furnace 11 and a supply pipe 12 that is attached to the reaction furnace 11 so as to penetrate therethrough. The reaction furnace 11 includes a substrate 11a constituting a bottom portion and a bell jar 11b made of a cylindrical body whose upper side is closed in a dome shape. The substrate 11 a is provided with a pair of chucks 11 c that hold the lower end of the inverted U-shaped core rod 13. The core rod 13 is fixed inside the reaction furnace 11 by being held by the chuck 11 c. The pair of chucks 11 c is wired with an output terminal of the power feeding device 14, and the core bar 13 is configured to be heated by the power from the power feeding device 14. The supply pipe 12 is made of stainless steel and is attached through the substrate 11a. An external thread is formed on the outer peripheral surface of the end of the supply pipe 12 in the reaction furnace 11, and the supply pipe 12 introduces a gas containing a silane compound, for example, a mixed gas of silane trichloride and hydrogen into the reaction furnace 11. Composed. A nozzle 16 is screwed onto the male screw at the end of the supply pipe 12 in the reaction furnace 11 so as to cover this end.
[0009]
As shown in FIG. 1, the nozzle 16 is made by cutting bulk graphite, and a female screw 17 a is supplied to the annular portion 17 formed on the inner peripheral surface and to the end of the supply pipe 12 in a screwed state. And a cover portion 18 that comes into contact with the end edge 12 a of the tube 12. A through-hole 18a communicating with the supply pipe 12 is formed concentrically with the annular part 17 in the cover part 18 of the nozzle 16, and the nozzle 16 is screwed to the end of the supply pipe 12 to be supplied by the supply pipe 12. The mixed gas of silane trichloride and hydrogen to be diffused into the reaction furnace 11 effectively.
The characteristic configuration of the present invention is that an annular bulging portion 19 is formed in the cover portion 18. The bulging portion 19 is formed so as to face the end edge 12 a of the supply pipe 12, and the tip surface thereof is such that the tip contacts the end edge 12 a of the supply pipe 12 when the nozzle 16 is screwed to the end of the supply pipe 12. They are formed on substantially the same plane. The bulging portion 19 is integrally formed with the cover portion 18 during cutting in the manufacture of the nozzle 16, and the annular bulging portion 19 in this embodiment has the same inner diameter as the through hole 18a. It is formed concentrically with the through hole 18a so as to surround it.
[0010]
The operation of the nozzle structure used in the polycrystalline silicon rod manufacturing apparatus configured as described above will be described.
First, in order to produce a polycrystalline silicon rod, the core rod 13 is installed in the reaction furnace 11. The core rod 13 is installed by holding the lower end of the core rod 13 on a chuck 11c provided on the substrate 11a. Thereafter, the core rod 13 is heated by energizing the power supply device 14 via the chuck 11c. After heating the core rod 13, a mixed gas of silane trichloride and hydrogen is introduced into the reaction furnace 11 from the supply pipe 12. The gas supplied to the supply pipe 12 is introduced into the reaction furnace 11 through the through hole 18 a of the nozzle 16, and the gas rises inside the reaction furnace 11 heated by the heating of the core rod 13. While rising, the silane trichloride gas undergoes a reduction reaction with hydrogen, and the polycrystalline silicon 20 (FIG. 2) adheres to the surface of the core rod 13 and is generated.
[0011]
When the polycrystalline silicon 20 is produced, the nozzle 16 made of graphite produces cementite at the contact portion with the supply pipe 12 made of stainless steel. It is generated only at the tip portion of the bulging portion 19 and is limited to an area range smaller than the cementite generation area in the conventional nozzle 1 shown in FIG. The nozzle 16 screwed due to the generation of cementite adheres to the end portion of the supply pipe 12, but the torque applied to the nozzle 16 at the time of removal can be reduced due to the fact that the adhesion area is narrower than before. . In particular, since the bulging portion 19 is formed so as to surround the through hole 18a with the same inner diameter as the through hole 18a, the distance to the adhering portion with respect to the rotation center of the nozzle 16 can be reduced, and the torque applied to the nozzle 16 The nozzle 16 can be easily removed from the supply pipe 12 even if the nozzle is smaller than the conventional one.
[0012]
Further, the portion that contacts the end edge 12 a of the supply pipe 12 is the tip portion of the bulging portion 19, and a gas layer is formed between the other cover portion 18 and the end edge 12 a of the supply pipe 12. For this reason, the thermal shock value received by the nozzle 16 based on the cooling in the reaction furnace 11 after the polycrystalline silicon rod is manufactured is the conventional one in which there is no gas layer between the cover 18 and the edge 12 a of the supply pipe 12. And the occurrence of cracks due to the thermal shock of the nozzle 16 can be suppressed.
[0013]
【The invention's effect】
As described above, according to the present invention, the annular bulging portion that faces the end edge of the supply pipe and is screwed to the cover portion of the nozzle is surrounded by the through hole. Since it formed, the contact part with the supply pipe | tube consisting of stainless steel can be limited to the front-end | tip part of a bulging part, and the production | generation area of the cementite in a contact part can be made small. Based on the reduction of the cementite generation area, the nozzle attached to the end of the supply pipe can be easily removed with a torque smaller than the conventional one.
In addition, by forming a bulge, a gas layer is formed between the cover and the edge of the supply pipe, reducing thermal shock caused by direct contact compared to conventional nozzles without a gas layer can do. As a result, it is possible to effectively reduce breakage caused by nozzle cracks caused by thermal shock when the nozzle is removed from the supply pipe after use.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a nozzle structure of the present invention.
FIG. 2 is a conceptual diagram of a polycrystalline silicon rod manufacturing apparatus using the nozzle.
FIG. 3 is a longitudinal sectional view corresponding to FIG. 1 showing a conventional nozzle structure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Reaction furnace 12 Supply pipe 12a End edge 16 Nozzle 17 Annular part 17a Female thread 18 Cover part 18a Through-hole 19 Swelling part

Claims (1)

A feed pipe (12) made of stainless steel, which is attached through a reaction furnace (11) for producing rod-shaped polycrystalline silicon and introduced into the reaction furnace, is installed in the reaction furnace. A nozzle (16) made of graphite that is screwed onto the end so as to cover the end,
The nozzle (16) includes an annular part (17) in which an internal thread (17a) is formed on the inner peripheral surface, and a through hole (integrated with the annular part (17) and communicated with the supply pipe (12) ( 18a) is used in an apparatus for manufacturing a polycrystalline silicon rod having a cover part (18) formed concentrically with the annular part (17) and in contact with the edge of the supply pipe (12) in a screwed state In the nozzle structure,
An annular bulging portion (19) that faces the end edge (12a) of the supply pipe (12) to the cover portion (18) and has a tip abutting on the end edge (12a) in the threaded state is provided in the through hole ( A nozzle structure used for an apparatus for manufacturing a polycrystalline silicon rod, characterized by being formed so as to surround 18a).

Images