JPH0769776A - Equipment for pulling up silicone single crystal - Google Patents

Abstract

PURPOSE:To lift up a high quality silicone single crystal, capable of preventing the contamination of impurities caused by the friction among the feeder parts, by setting a discharge route along the circumference of semicircle of a cylinder at the bottom of the slant rotating cylinder, connecting one end of it with a hole made at a bottom plate of the cylindrical feeder, and making another end a discharge port. CONSTITUTION:In a silicone single crystal pulling up equipment, a unit for feeding granular raw materials into a crucible consists of a slant rotating cylinder, inside of which granular raw materials for feeding are staying at a resting angle, having an eccentric hole in the bottom plate, a cylindrical feeder rotating along an axis, and a discharge route which receives the granular raw materials flowing out from the eccentric hole by rotation to feed them intermittently by a constant amount into the crucible, and a driving unit of the feeder which can change a rate of rotation of the cylindrical feeder at will. Figure shows the feeding mechanism of granular polysilicone during the rotation of the cylindrical feeder. It shows a state that the eccentric hole 24 is at the lowest position and the discharge port 22 is at the highest position, and the granular polysilicone 2 flows into the discharge route 23 through the eccentric hole 24 by the resting angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for supplying granular polysilicon or an impurity dopant in the step of pulling a silicon single crystal by the Czochralski single crystal pulling method.

[0002]

2. Description of the Related Art Conventionally, an apparatus for supplying granular polysilicon into a crucible in a silicon single crystal pulling process by the Czochralski single crystal pulling method squeezes the tip of a cylinder,
A conical valve or a shutter-type valve is attached there, and a supply device of the type that controls the supply of granular polysilicon by opening and closing it, or a supply device that supplies granular polysilicon using a belt conveyor or the like is used. ing.

[0003]

Normally, a valve or shutter type structure is used at the time of starting and stopping the supply of the granular material such as the granular polysilicon. However, such a structure always causes friction between members. Particulates and the like are mixed into the granular polysilicon, and there is a problem that the quality of the pulled single crystal deteriorates, or the yield decreases. In addition, while the method of pulling up a single crystal while continuously supplying granular polysilicon requires precise control of the amount of polysilicon to be supplied, the conventional belt conveyor method and the precise control of the opening of the hopper valve are required. Is difficult Further, it is difficult for the conventional supplying device to be made of a material that has a complicated structure and does not affect pulling of a silicon single crystal such as high-purity quartz or high-purity polysilicon.

It is an object of the present invention to provide a silicon single crystal pulling apparatus that solves the above problems.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a silicon single crystal pulling apparatus provided with a supply device for supplying a granular raw material into a crucible, which comprises an inclined cylinder for retaining the supplied granular raw material inside at a repose angle. The bottom end plate has an eccentric hole, and has a cylindrical feeder that rotates about an axis, and a discharge path that intermittently discharges the granular raw material that flows out from the eccentric hole with the rotation of the cylindrical feeder into the crucible. The apparatus for pulling a silicon single crystal is characterized in that the cylindrical feeder is provided with a drive device capable of changing a rotation speed.

The discharge path is a curved tube which is arranged along the periphery of the bottom end plate of the cylindrical feeder, and has one end coupled to the eccentric hole and the other end open, and the length of the curved tube is
It is preferable in terms of smooth material supply that the granular material discharged from the eccentric hole is discharged from the eccentric hole after each rotation of the cylindrical feeder and then discharged from the curved tube. The required length for this is the length of the bottom end plate. It is preferable that the length is equal to or longer than a quarter of the circumference.

Further, it is preferable to use high-purity silicon or high-purity quartz as the material of the cylindrical feeder, because there is no risk of impurities being mixed into the granular raw material.

[0008]

The starting and stopping of the supply of the granular polysilicon or the like according to the present invention is performed as follows. An eccentric hole is provided in the end plate of the inclined cylindrical feeder, and the hole is, for example,
It is connected to a discharge passage formed of a curved pipe provided along the periphery of the cylinder. By rotating the inclined cylindrical feeder once, a certain amount of granular polysilicon is discharged from the eccentric hole and is supplied to the crucible through the discharge passage. It is possible to start and stop the supply of the granular raw material by starting and stopping the rotation of the cylindrical feeder. The supply amount can be controlled by controlling the rotation speed.

The cylindrical feeder is connected to the lower part of the raw material hopper, and the granular raw material in the cylindrical feeder is held at an angle of repose. When the amount of the granular raw material in the cylindrical feeder is reduced to form a gap, the angle of repose allows the supply hopper to smoothly and smoothly supply the granular raw material into the cylindrical feeder. There is no portion where members slide and collide with each other in the passage of the granular polysilicon which is the granular raw material, and impurities are not mixed into the polysilicon. Further, if all the parts through which the granular polysilicon passes are made of silicon or quartz, it is possible to prevent the mixing of impurities.

[0010]

EXAMPLE FIG. 4 is a vertical sectional view of a silicon single crystal pulling apparatus of an example. In the Czochralski single crystal pulling apparatus, a quartz crucible 8 is supported by a graphite crucible 7, a molten silicon 9 is held in the quartz crucible 8 and heated by a heater 6 for heating. The raw material granular polysilicon 2 is housed in a hopper 3, a cylindrical feeder 1 formed of an inclined cylinder is provided at the lower end of the hopper 3, and a connecting portion 4 is inserted therein. The granular polysilicon 2 flows down through the connecting portion 4 into the cylindrical feeder 1 at an angle of repose and is supplied. The cylindrical feeder 1 is driven by a feeder rotation motor 12 to rotate.

The supply introduction pipe 5 guides the granular polysilicon discharged from the cylindrical feeder 1 into the crucible 8. The raw material hopper 3, the cylindrical feeder 1 and the like are housed in a closed container 10, and the portion where the shaft of the feeder rotation motor 12 penetrates the wall of the closed container is sealed by a vacuum seal 11. FIG. 1 shows a perspective view of a main part of the cylindrical feeder 1 of the embodiment. The axis of the cylindrical feeder 1 is inclined,
It is composed of a cylindrical wall 21, a bottom end plate 26, an eccentric hole 24, a discharge passage 23, a discharge port 22 and an opening 25 for connecting to a hopper, and is rotated about its axis by a rotation motor 12 whose rotation speed is variable as shown in FIG. .

2 and 3 show a supply mechanism of granular polysilicon when the cylindrical feeder 1 is rotated. Figure 2
Shows the state in which the eccentric hole 24 is located at the lowermost end and the discharge port 22 is located at the uppermost end.
4 and flows into the discharge passage 23 at an angle of repose.

In FIG. 3, the eccentric hole 24 is at the uppermost end, and the discharge port 2
2 shows the state of being located at the lowermost end, the granular polysilicon 2 is discharged from the discharge port 22, while the granular polysilicon 2 in the cylindrical feeder 1 does not enter the discharge path 23.
In this way, a certain amount of granular polysilicon is discharged as the cylindrical feeder 1 rotates. When introducing impurities that determine the conductivity type of semiconductor silicon single crystals, especially Sb and As must be introduced after the raw material polysilicon is melted. At this time, if all of the necessary amounts are added at one time, the impurities will not enter the required amount in the molten silicon and will be evaporated. Therefore, the introduction of a fixed amount at a fixed time interval is a key to ensuring quality and dislocation-free single crystal. Therefore, by controlling the number of rotations of the cylindrical feeder 1 in the apparatus of this embodiment, the automation of this charging process was achieved.

Also for the supply of granular polysilicon, FIG.
As described above, by controlling the rotation speed of the cylindrical feeder 1, a predetermined amount of granular polysilicon could be continuously charged. In addition, since all the surfaces in contact with impurities (dopants) and granular polysilicon are made of high-purity quartz, polysilicon, etc., the pulled silicon single crystal does not contain more impurities than are contained in ordinary pulling.

[0015]

EFFECTS OF THE INVENTION In the apparatus of the present invention, impurities are not mixed into the granular polysilicon due to the friction between the members of the supplying apparatus and the like, so that a high quality silicon single crystal can be pulled. Further, even in the continuous supply, the supply amount of the granular polysilicon can be controlled easily and precisely.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a supply device according to an embodiment.

FIG. 2 is a vertical sectional view of a supply device according to an embodiment.

FIG. 3 is a vertical cross-sectional view of a supply device according to an embodiment.

FIG. 4 is an overall view of a single crystal pulling apparatus of an example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cylindrical feeder 2 Granular polysilicon 3 Hopper 4 Connection part 5 Supply introduction pipe 6 Heating heater 7 Graphite crucible 8 Quartz crucible 9 Silicon melt 10 Sealed container 11 Vacuum seal 12 Feeder rotation motor 21 Cylindrical wall 22 Discharge port 23 Discharge path 24 Eccentric hole 25 Communication opening 26 Bottom plate

Claims (3)

[Claims] 1. A silicon single crystal pulling apparatus equipped with a supply device for supplying granular raw material into a crucible, comprising an inclined cylinder for retaining the supplied granular raw material inside at a repose angle, and having an eccentric hole in a bottom end plate. A cylindrical feeder that rotates about an axis, and a discharge passage that receives the granular raw material that flows out from the eccentric hole with the rotation of the cylindrical feeder and discharges it into the crucible in a fixed amount intermittently. An apparatus for pulling up a silicon single crystal, which is equipped with a drive device capable of changing a rotation speed. 2. The discharge passage is a curved pipe having a length of a quarter circle or more along the periphery of the bottom end plate, one end of which is connected to the eccentric hole, and the other end of which is open. The silicon single crystal pulling apparatus according to claim 1, which is characterized in that. 3. The silicon single crystal pulling apparatus according to claim 1, wherein the material of the cylindrical feeder is high-purity silicon or high-purity quartz.