JPH10236816A - Method for regenerating residual body of polycrystalline silicon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regenerate the residual body of polycrystalline silicon to reusable polycrystalline silicon at a good yield by crushing and cogging the residual body of the polycrystalline silicon solidified in a quarts crucible for melting the polycrystalline silicon and injecting silicon grains to the surfaces of the cogged bodies for contact with the crucible, thereby removing the impurities adhered to the cogged bodies. SOLUTION: The residual body of the polycrystalline silicone solidified in the quartz crucible for melting the polycrystalline silicon is divided to a plural number of pieces of the cogged bodies. The silicon grains having a grain size of 0.1 to 2.0mm are injected under an injection pressure of 0.2 to 0.5MPa to the cogged bodies to remove the impurities sticking to the cogged bodies. Raw materials for production of single crystal silicon are used for the silicon grains. For example, the cogged bodies 4 with the surfaces 3 for contact with the inside wall of the quartz crucible faced upward are placed within a vessel 5 on a turn table 9 in a projection chamber 6. The silicon grains S in a hopper 23 are injected onto the contact surfaces 3 of the rotating cogged bodies 4 while an injection nozzle 16 is oscillated in a direction A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for regenerating a polycrystalline silicon residue which solidifies and adheres to a quartz crucible when single crystal silicon for semiconductors is manufactured by a pulling method.

[0002]

2. Description of the Related Art In a single crystal silicon manufacturing method by a pulling method, polycrystalline silicon is charged into a quartz crucible, melted by heating, a seed crystal is immersed in the melt, and the melt is pulled while rotating.
It is re-solidified to produce single crystal silicon. In this manufacturing method, after the operation is completed, as shown in FIG. 1, a polycrystalline silicon residue 2 is solidified and remains in a quartz crucible 1, and this polycrystalline silicon residue 2 is brought into contact with the inner wall of the quartz crucible 1. 3 is difficult to take out due to the welding phenomenon in FIG.
Is divided into irregularly shaped masses 4 as shown in FIG. However, impurities 5 such as glass shards from the quartz crucible 1 are deposited on the contact surface 3 portion of each agglomerate 4, and these are manually removed with a hammer, grinder, or the like to remove polycrystals. Silicon is recovered and reused.

However, since such a regeneration operation is a manual operation, it is inefficient and difficult to handle because it is an irregular mass. In addition to the impurities 5 to be removed, a considerable amount of polycrystalline silicon is removed. There are many problems, such as removal of the alloy, resulting in poor yield, and the possibility that iron and other impurities may be mixed during the regeneration operation.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to quickly and mechanically remove impurities attached to a polycrystalline silicon residue taken out of a quartz crucible. Another object of the present invention is to provide a method for regenerating a polycrystalline silicon residue that can regenerate a polycrystalline silicon residue with good yield into reusable polycrystalline silicon.

[0005]

SUMMARY OF THE INVENTION The present invention, which has been completed to solve the above-mentioned problems, comprises a method of converting polycrystalline silicon solidified in a quartz crucible for melting polycrystalline silicon into a plurality of agglomerates. It is characterized in that impurities adhering to the agglomerate are removed by injecting silicon particles having a particle size of 0.1 to 2.0 mm into the agglomerate at an injection pressure of 0.2 to 0.5 MPa. It is assumed that.

In this manner, a predetermined number of agglomerates are placed in a container on a turntable with the contact surface with the impurities attached thereon facing upward. When silicon particles having a diameter of 0.1 to 2.0 mm are jetted at an injection pressure of 0.2 to 0.5 MPa, all impurities on the contact surfaces of the agglomerates are removed by the impact of the silicon particles.

[0007]

Next, a preferred embodiment of the present invention will be described with reference to the apparatus shown in FIG. A bearing 8 is mounted on a frame 7 installed in a box-shaped projection chamber 6, and a vertical axis 10 of a turntable 9 is supported by the bearing 8.
A belt 14 is stretched between a pulley 11 attached to the lower end of the projection table 6 and a pulley 13 of a motor 12 attached to the outer surface of the projection chamber 6, and the turntable 9 can be horizontally rotated by the motor 12.

On the turntable 9, a basket-shaped container 15 having an open top is provided detachably, and a predetermined number of masses 4 can be placed with the contact surface 3 facing upward. Above the turntable 9, an injection nozzle 16 having an injection port downward is held by a rotating shaft 17 provided in the projection chamber 6, and a rubber hose 18 for supplying compressed air is provided above the injection nozzle 16. The base end of a rubber hose 19 for introducing silicon particles S as a projection material is connected to the base end, the other end of the rubber hose 18 is connected to a compressed air source (not shown), and the other end of the rubber hose 19 is connected to a lower hopper 2 described later.
Connected to 3.

A rubber hose 21 for returning the deposited silicon particles S is provided at the lower end of the bottom hopper 20 below the projection chamber 6.
Is connected to one end, and the other end is connected to a separation box 22 for separating silicon particles S provided on the ceiling of the projection chamber 6. A lower hopper 23 connected to the lower part of the separation box 22 faces upward in the projection chamber 6, and a lower end thereof is connected to a tip of the rubber hose 19. A duct 24 connected to the dust device is connected.

In each of the above device sections, the inner surfaces of the projection chamber 6, the bottom hopper 20, and the injection nozzle 16, the entire surface of the turntable 9, the container 15, the outer surfaces of the frame 7, the bearing 8, the rotating shaft 17, and Urethane coating is applied to the inner surface of the separation chamber 22 and the inner and outer surfaces of the lower hopper 23 so that impurities such as iron do not enter or adhere to the silicon granules S and the lumps 4.

The silicon particles S are granular polycrystalline silicon produced by a fluidized bed method using monosilane, trichloride silane, or the like as a raw material, and are used as a raw material for producing single-crystal silicon for semiconductors having a purity of about 99.99%. Things. In the above-described apparatus, a predetermined amount of silicon granules S are charged into the separation box 22, and a predetermined number of agglomerates 4 are arranged in the container 15 with the contact surface 3 thereof facing upward, and the motor 12 is The container 15 is horizontally rotated together with the turntable 9 via the pulley 13, the belt 14, the pulley 11, and the longitudinal axis 10 upon activation. Further, the rotating shaft 17 is operated by a driving device (not shown) to swing the injection nozzle 16 as shown by the arrow A.

Next, when the dust collector is operated and compressed air is supplied from the compressed air source to the injection nozzle 16 through the rubber hose 18, the silicon particles S in the separation box 22 flow into the injection nozzle 16 from the rubber hose 19. Then, it is jetted onto each mass 4 from the jet port at the tip. Each agglomerate 4
The contact surface 3 side is entirely polished by the rotation of the turntable 9 and the swinging of the injection nozzle 16, so that all the impurities 5 are removed.

The silicon particles S, which have been cleaned, fall into the bottom hopper 20, flow upward in the rubber hose 21 by suction airflow from the dust collecting device, and are returned to the separation box 22, where the impurities 5 are removed. The foreign matter such as the small particles is separated, only the regular silicon particles S flow down to the lower hopper 23 and are circulated, and the foreign matter is sent to the dust collector via the duct 24 and processed.

When the cleaning is completed in this manner, the driving of the driving units and the silicon granules S is stopped, and the agglomerates 4 are taken out. After removing the attached dust and the like, the contact surface 3 is washed with hydrofluoric acid. It should be processed.

Next, the results of treating the agglomerates 4 of approximately the same height with the dimensions of the contact surface 3 of about 5 cm × 5 cm using the apparatus described above are shown. Seven pieces of the masses 4 were placed in the container 15 with the contact surface 3 facing upward, and the turntable 9 was placed at 11 r.p.
m and the injection nozzle 16 is oscillated at 60 cpm.
When the contact surface 3 was cleaned for 3 minutes by injecting 6 mm silicon particles S at an ejection pressure of 0.3 MPa, the impurities 5 on all the contact surfaces 3 were removed. In this case, the projection distance of the silicon particles S to the contact surface 3 is 100 to 15
0mm, the removal of the contact surface 3 by polishing is 0.4 ~
It is about 1.0 mm.

The particle size of the silicon particles S used in the present invention is in the range of 0.1 to 2.0 mm. If the particle size is less than 0.1 mm, a sufficient polishing effect cannot be obtained and handling is troublesome. If the diameter exceeds 2.0 mm, the effect of embedding foreign matter on the surface becomes large, and the foreign matter removal efficiency is rather lowered, which is not preferable. Further, the injection pressure of the injection nozzle 16 is set to 0.1.
If the pressure is 2 to 0.5 MPa and the pressure is less than 0.2 MPa, the polishing force is weak and it takes a long time. If the pressure exceeds 0.5 MPa, there is a problem that silicon particles are liable to be crushed and the running cost is increased. Note that the injection amount of the silicon particles S is 100
~ 150kg / H, the injection distance to the mass 4 is 100 ~
About 200 mm is preferable.

[0017]

As described above, according to the present invention, when recovering polycrystalline silicon, impurities adhering to the contact surface with the quartz crucible are blasted and removed by spraying silicon particles to regenerate. It can be regenerated in a very short time without any labor, and the wear of the polycrystalline silicon residue by polishing is small, the yield is good, and silicon particles are used as the projectile, There is no risk of contamination with impurities, and a high-purity recycled product can be obtained. Therefore,
The present invention has a large effect on the industry as a method for regenerating a polycrystalline silicon residue which has solved the conventional problems of regenerating the polycrystalline silicon residue.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a polycrystalline silicon residue in a quartz crucible.

FIG. 2 is a perspective view of a lump obtained by dividing a polycrystalline silicon residual body.

FIG. 3 is a partially cutaway front view showing an example of a processing apparatus for carrying out the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quartz crucible 2 Residual body of polycrystalline silicon 4 Blob 5 Impurity 16 Injection nozzle

Claims (1)

[Claims] 1. A polycrystalline silicon residue solidified in a quartz crucible for melting polycrystalline silicon is divided into a plurality of agglomerates, and the agglomerates are made of silicon particles having a particle size of 0.1 to 2.0 mm. Of a polycrystalline silicon residue, characterized by removing impurities adhering to the agglomerates by injecting the particles at an injection pressure of 0.2 to 0.5 MPa.