JP2001039798A - Heat shielding member for silicon single crystal growing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent foreign matters such as dust and coagulated matter of silicon from onto a silicon molten liquid. SOLUTION: A heat shielding member 27 having a cylindrical part 27a is included. The cylindrical part 27a surrounds the outer peripheral surface of a silicon single crystal rod 24 being pulled up from a silicon molten liquid stored in a quartz crucible 13, and the lower end of the cylindrical part 27a is set above the surface of the silicon molten liquid so that a space is formed between the lower end of the cylindrical part 27a and the surface of the silicon molten liquid, and further the cylindrical part 27a shields the radiation heat from a heater 18 for heating the silicon molten liquid. The cylindrical part 27a is formed in the conical form in such a manner that the diameter of the cylindrical part becomes smaller toward the lower part, and an inner cylinder 27b, which is integrally connected to the peripheral part of the lower end of the cylindrical part 27a, is provided at the inside of the cylindrical part 27a. A flange 27c projecting toward the cylindrical part 27a is disposed at the peripheral part of the upper end of the inner cylinder 27b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat shielding member of an apparatus for pulling a silicon single crystal based on the Czochralski method (hereinafter referred to as CZ method).

[0002]

2. Description of the Related Art A CZ method is used as one of the methods for producing a silicon single crystal. In this CZ method, polycrystalline silicon is heated and melted in a quartz crucible, and a seed crystal is immersed in a silicon melt stored in the quartz crucible.
By pulling this seed crystal by pulling means, a cylindrical silicon single crystal rod is manufactured. In this method, after pulling up a silicon single crystal rod, the inside of the chamber of the pulling device is cleaned before the next pulling to remove dust and the like generated during the pulling. This is because when a silicon single crystal rod is pulled up from a silicon melt in which impurities such as dust have fallen, the crystal is likely to be dislocated, and this dislocation is prevented.

On the other hand, during pulling of a silicon single crystal rod,
Part of the SiO _{2 on} the inner wall of the quartz crucible dissolves in the silicon melt, and the SiO ₂ and Si react to evaporate from the silicon melt into SiO gas. This SiO gas adheres to the structure inside the chamber of the pulling device above the silicon melt and solidifies. When the solidified matter is deposited, it may fall into the silicon melt. For this purpose, an inert gas is supplied into the chamber from the upper part of the chamber as a carrier gas, and the gas in the chamber including the SiO gas generated from the melt surface is positively discharged from the lower part of the chamber to the outside of the chamber by the carrier gas. I have.

[0004] When the carrier gas is moving during the pulling or when the pulling means located above the quartz crucible is operating, the carbon powder or silicon oxide that cannot be completely removed by the cleaning or the carrier gas is used. Dust such as powder is generated in the chamber above the quartz crucible. Further, when most of the bulk polycrystalline silicon of the raw material filled in the quartz crucible is melted, the upper polycrystalline silicon may be in a bridge shape. In this case, the polycrystalline silicon in the upper layer rapidly falls into the silicon melt during melting and jumps up. The jumped-up silicon melt adheres to the surface of the cylindrical portion of the heat shielding member and solidifies.

[0005]

However, the amount of dust generated during the pulling of the silicon single crystal rod may fall into the silicon melt, exceeding the carrier gas carrying capacity,
Alternatively, when the silicon solidified substance attached to the surface of the cylindrical portion falls into the silicon melt due to the vibration of the pulling device, the dislocation of the crystal also occurs. SUMMARY OF THE INVENTION An object of the present invention is to provide a heat shielding member of a silicon single crystal pulling apparatus capable of manufacturing a high quality silicon single crystal rod by preventing foreign substances such as dust and solidified silicon from falling into a silicon melt. is there.

[0006]

The invention according to claim 1 is
As shown in FIG. 1, the silicon single crystal rod 24 which is pulled up from the silicon melt 12 stored in the quartz crucible 13 surrounds the outer peripheral surface of the silicon single crystal rod 24 and the lower end is located above the silicon melt 12 at an interval from the surface thereof. In the heat shielding member 27 having the cylindrical portion 27a for shielding the radiant heat from the heater 18 for heating the melt 12, the cylindrical portion 27a is formed in a conical shape in which the cylindrical diameter decreases toward the lower portion, and is formed inside the cylindrical portion 27a. Inner cylinder 27 integrally connected to lower peripheral edge of cylinder portion 27a
b is a heat shield member of the silicon single crystal pulling apparatus, wherein the heat shield member is provided. In the heat shielding member of the silicon single crystal pulling apparatus according to the first aspect, dust and silicon solidified on the inner surface of the conical cylindrical portion 27a fall along the inner surface, and the cylindrical portion 27a Collect between 27b. As a result, foreign matter such as dust and solidified silicon does not fall into the silicon melt 12, and dislocation of the silicon single crystal can be prevented.

According to a second aspect of the present invention, there is provided a heat shielding member for a silicon single crystal pulling apparatus in which a flange 27c is provided in a direction of a cylindrical portion 27a on a peripheral edge of an upper end of an inner cylinder 27b. is there. In the heat shielding member of the silicon single crystal pulling apparatus according to the second aspect, the flange 27 is provided.
By providing c on the upper end periphery of the inner cylinder 27b, dust once accumulated between the cylinder portion 27a and the inner cylinder 27b is more reliably captured.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. As shown in FIG. 1, a quartz crucible 13 for storing a silicon melt 12 is provided in a chamber 11 of a silicon single crystal pulling apparatus 10, and the outer surface of the quartz crucible 13 is covered with a graphite susceptor 14.
The lower surface of the quartz crucible 13 is fixed to the upper end of a support shaft 16 via the graphite susceptor 14, and the lower portion of the support shaft 16 is connected to a crucible driving unit 17. The outer peripheral surface of the quartz crucible 13 is surrounded by a heater 18 at a predetermined interval from the quartz crucible 13, and the heater 18 is surrounded by a heat retaining tube 19. The high-purity silicon polycrystalline mass put into the quartz crucible 13 is melted by the heater 18 and the silicon melt 12 is melted.
become.

At the upper end of the chamber 11, a cylindrical casing 21 is provided. The casing 21 is provided with a pulling means 22. The pulling means 22 has a pulling head (not shown) provided at the upper end of the casing 21 so as to be pivotable in a horizontal state, and a wire cable 23 suspended from the head toward the center of rotation of the quartz crucible 13. At the lower end of the wire cable 23, a seed crystal 2 for dipping in the silicon melt 12 and pulling up the silicon single crystal rod 24 is provided.
6 is mounted. Between the outer peripheral surface of the silicon single crystal rod 24 and the inner peripheral surface of the quartz crucible 13, there is provided a silicon single crystal rod 24.
Is provided.

A characteristic configuration of the present embodiment is that, as shown in detail in FIG. 2, the heat shielding member 27 is formed in a conical shape in which the diameter of the cylinder becomes smaller toward the lower part, and the cylindrical portion 27a for shielding radiant heat from the heater 18 is provided. An inner cylinder 27b integrally connected to a lower peripheral edge of the cylindrical portion 27a inside the cylindrical portion 27a, and a flange 27c in the direction of the cylindrical portion 27a provided on an upper peripheral edge of the inner cylinder 27b. is there. In addition, a flange portion 27d projecting substantially horizontally outward is formed integrally with the cylindrical portion 27a at an upper portion of the cylindrical portion 27a. The heat shield member 27 is fixed in the chamber 11 by placing the flange portion 27d on the heat retaining cylinder 19.

The chamber 11 is filled with an inert gas such as an argon gas or a nitrogen gas by a silicon single crystal rod 24 and a heat shielding member 2.
7, a gas supply / discharge means 28 for discharging the gas to the outside of the chamber 11 through the surface of the silicon melt 12 is connected. The gas supply / discharge means 28 includes a gas supply pipe 28a having one end connected to the upper peripheral wall of the casing 21 and the other end connected to an air tank (not shown), and a vacuum pump having one end connected to the lower wall of the chamber 11 and the other end. (Not shown) and a gas discharge pipe 28b. Gas supply pipe 2
8a and the gas discharge pipe 28b
First and second flow control valves 28c and 28d for controlling the flow rate of the inert gas flowing through the flow paths a and 28b are provided, respectively.

The operation of the heat shielding member of the silicon single crystal pulling apparatus thus constructed will be described. As shown in FIG. 1, when pulling up the silicon single crystal rod 24, the first and second flow control valves 28c and 28d are adjusted, and the carrier gas is supplied from the gas supply pipe 28a to the gas discharge pipe 28b through the chamber. The evaporant such as SiO gas evaporating from the surface of the silicon melt 12 is discharged to the outside of the chamber 11 together with the carrier gas.

On the other hand, when the carrier gas is moving inside the chamber 11 during the pulling, or when the pulling means 22 located above the quartz crucible 13 is operating, the silicon single crystal is pulled. If dust such as carbon powder and silicon oxide powder that could not be completely removed by cleaning the inside of the chamber 11 or carrier gas performed before is generated in the chamber 11, the dust is generated by the carrier along the surface of the upper member in the chamber 11. The gas flows down along with the flow of the gas, flows along the inner peripheral surface of the cylindrical portion 27a of the heat shielding member 27, and accumulates between the cylindrical portion 27a and the inner cylinder 27b as shown by the arrow in the figure.

Also, when most of the bulk polycrystalline silicon of the raw material filled in the quartz crucible 13 is melted, the upper polycrystalline silicon becomes bridge-like, and the upper polycrystalline silicon is rapidly melted. When the silicon melt falls into the silicon melt 12 and jumps up, the silicon melt that jumps up may adhere to the surface of the cylindrical portion 27a and solidify. Even if the silicon coagulated material accumulates and peels off from the surface of the cylindrical portion 27a of the heat shielding member 27, it slides down along the inner peripheral surface of the cylindrical portion 27a and accumulates between the cylindrical portion 27a and the inner cylinder 27b.

As a result, the frequency of contamination of the silicon single crystal rod with dust and silicon coagulates is reduced, so that dislocation of the crystal is prevented and a high quality silicon single crystal rod can be manufactured.

In the above embodiment, the inner cylinder 27b is formed in a cylindrical shape. However, as shown in FIGS. 3 (a) and 3 (c), the inner cylinder 27b may be formed in a conical shape whose diameter decreases upward.
By making the inner cylinder 27b conical in this manner, heat from the upper surface of the silicon melt 12 can be reflected to the side of the silicon single crystal rod 24 near the melt as shown by the arrow in the figure, and the single crystal rod 24 can be reflected. The temperature gradient between the central part and the side part can be reduced. Further, in the above-described embodiment, the flange 27c is formed in a ring shape. However, in order to facilitate the flow of the carrier gas, the flange 27c is formed in a conical shape whose diameter increases upward as shown in FIGS. 3 (c) and 3 (d). Good. Further, a structure having a bottom portion 27e between the cylindrical portion and the inner cylinder as shown in FIGS. 3B and 3D may be employed to facilitate the removal of accumulated dust and the like.

[0017]

As described above, according to the present invention, dust and silicon coagulate generated in the chamber fall along the inner surface of the cylindrical portion of the heat shielding member and accumulate between the cylindrical portion and the inner cylinder. With this configuration, contamination of the silicon melt with impurities is reduced, dislocation of the crystal is prevented, and a high-quality silicon single crystal rod can be manufactured. Further, by attaching the flange to the upper peripheral edge of the inner cylinder, it is possible to more reliably capture dust and silicon coagulated matter once accumulated between the cylindrical portion and the inner cylinder.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a silicon single crystal pulling apparatus of the present invention.

FIG. 2 is a cutaway perspective view of a main part of a heat shielding member of the pulling device of FIG. 1;

FIG. 3 is a configuration diagram showing an application example of the heat shielding member of FIG. 1;

[Description of Signs] 10 Silicon single crystal pulling device 12 Silicon melt 13 Quartz crucible 18 Heater 24 Silicon single crystal rod 27 Heat shielding member 27a Tube portion 27b Inner tube 27c Flange

Claims (2)

[Claims] 1. A silicon single crystal rod (24) pulled up from a silicon melt (12) stored in a quartz crucible (13), surrounding the outer peripheral surface thereof and having a lower end spaced from the surface of the silicon melt (12). In a heat shielding member (27) having a cylindrical portion (27a) that is located above and that blocks radiant heat from a heater (18) that heats the silicon melt (12), the cylindrical portion (27a) faces downward. An inner cylinder (27b) integrally formed with a lower peripheral edge of the cylinder (27a) is provided inside the cylinder (27a), the diameter of which is reduced in accordance with the following. A heat shielding member of a silicon single crystal pulling apparatus. 2. The heat shielding member for a silicon single crystal pulling apparatus according to claim 1, wherein a flange (27c) is provided on a peripheral edge of an upper end of the inner cylinder (27b) in a direction of the cylinder (27a).