JPH04321586A - Single crystal pulling device - Google Patents

Abstract

PURPOSE:To obtain single crystal having relatively large diameter in high probability in the title device equipped with a partition wall-like suspended crucible in an outer crucible by Czochralski method by installing a melt stirring tool standing from the bottom of the outer crucible. CONSTITUTION:For example, melt 2 is put in an outer crucible 1, polycrystalline silicon raw material powder is supplied through a raw material feed pipe 3 to the outer crucible. In order to prevent precipitation of the raw material fed on single crystal which is being pulled up, a partition wall-like inner crucible 4 is suspended. Tools 5 and 6 for preventing scattering of the raw material are attached to the partition wall. A heater 8 is set in a casing 7 and a straightening column 9 of Ar flow is laid. In the device, a cylindrical shell-like inner crucible standing from the bottom of the outer crucible 1 and having a through hole 11 is laid as a melt stirring tool 10. The inner crucible 10 is not previously fixed to the outer crucible 1, is settled in the melt 2 by empty weight, is rotated together with the outer crucible 1 and the melt in the outer and inner crucibles can flow through the hole 11. Conseqnently, nonuniformity of temperature in the peripheral direction caused in the device can be eliminated to attain the purpose.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal pulling apparatus using the Czochralski method.

0002

2. Description of the Related Art There is a continuous feeding device that continuously pulls a single crystal while supplying raw materials using a single crystal pulling device using the Czochralski method (CZ method). When pulling a single crystal by continuous feeding using small solid raw materials, it is necessary to use a normal crucible (outside the An inner crucible is used to divide the melt into a part for supplying and melting raw materials inside the crucible and a part for pulling the single crystal. There are mainly two types of inner crucibles used in continuous feeding devices that use small particulate raw materials. (a) As shown in FIG. 3, a suspended inner crucible 4 is suspended from above and is separated from the outer crucible 1 in the form of a partition. (b) As shown in FIG. 4, the wall body 14 is integrated with the outer crucible 1 at the bottom and rotates together with the outer crucible 1.

Here, (a) has the following advantages compared to (b). (1) The total cost of the outer crucible 1 and the suspended inner crucible 4 is low. (2) The hanging inner crucible 4 shaped like a partition wall can be reused. (3) Since the suspended inner crucible 4 is suspended from above,
Less buckling due to own weight and less deformation. (4) Since the partition wall-shaped hanging inner crucible 4 does not rotate, it is easy to design a structure that prevents raw material powder from precipitating on the raw material supply pipe 3 (quartz) and the single crystal 20, thereby preventing polycrystalization. , long-term continuous pulling is possible.

0004

Although the pulling device having the hanging inner crucible in the form of partition walls has excellent advantages, it has the following drawbacks. In other words, since the hanging inner crucible in the shape of a partition wall does not generally rotate, non-uniform temperature distribution tends to occur in the circumferential direction within the melt inside the hanging inner crucible, and the single crystal that is pulled while rotating is periodically subject to significant temperature fluctuations. Therefore, single crystals that can be pulled with high probability using a hanging crucible with partition walls are limited to single crystals with a diameter of about 1/3 or less of the inner diameter of the hanging crucible with a partition wall, and relatively large diameter single crystals. It is difficult to raise the value continuously. An object of the present invention is to provide a single-crystal pulling apparatus that takes advantage of the advantages of a pulling apparatus having a suspended internal crucible in the form of partitions and eliminates the above-mentioned drawbacks.

[0005]

[Means for Solving the Problems] The present invention provides a single crystal pulling apparatus having a hanging inner crucible in the shape of a partition inside an outer crucible, in which a vertical line is placed inside the hanging inner crucible from the bottom of the outer crucible. This is a single crystal pulling device characterized by being equipped with a stirring tool. As the melt stirring tool, a concentric cylindrical shell that protrudes to the upper surface of the melt and has many through holes in its wall, or a plurality of rods that protrude to the upper surface of the melt, etc. can be used.

[0006]

[Operation] A means for stirring the melt inside the hanging inner crucible in the shape of a partition is provided inside the hanging inner crucible, and the temperature in the circumferential direction of the melt inside the hanging inner crucible is By eliminating uneven distribution, it has become possible to continuously pull single crystals with a relatively large diameter compared to the inner diameter of the suspended inner crucible for a long time with high probability.

The melt stirring device may be one that moves relative to the stationary suspended inner crucible, and may be one that rotates together with the outer crucible and projects to the upper surface of the melt. Its shape is not limited, and a cylindrical shell shape or a rod shape is suitable, but it can be of any other shape.

[0008]

[Embodiment] An embodiment of the present invention is shown in FIG. The melt 2 is stored in the outer crucible 1, and the raw material powder of polycrystalline silicon is supplied to the raw material supply pipe 3.
It is supplied through. In order to prevent this feed material from precipitating on the single crystal being pulled, a partition-shaped inner crucible 4 is suspended. In addition, materials 5 and 6 for preventing scattering of raw materials are attached to this partition wall. Note that a heater 8 is provided within the casing 7, and an Ar flow rectifying tube 9 is provided.

In this embodiment, the melt stirring device of the present invention has a cylindrical shell-shaped inner crucible 10 that stands up from the bottom of an outer crucible 1.
This inner crucible 10 is provided with a hole 11 . diameter 18
Inside the outer crucible 1 with a diameter of 14 inches, a hanging inner crucible 4 in the form of a partition wall with a diameter of 14 inches is suspended from above (fixed and does not rotate).
An inch inner crucible 10 was provided. The inner crucible 10 having a diameter of 12 inches was designed to have a height of 135 mm so that it would sink into the silicon melt under its own weight and would protrude above the liquid surface in consideration of buoyancy and surface tension. Therefore, although this inner crucible 10 with a diameter of 12 inches is not fixed in advance to the outer crucible 1 with a diameter of 18 inches, it sinks into the silicon melt due to its own weight.
It rotates together with an outer crucible 1 having a diameter of 18 inches. The inner crucible 10 with a diameter of 12 inches has a through hole 11 with a diameter of 15 mm located 15 mm from the lower end, through which the melt inside and outside can flow.

FIG. 2 shows a longitudinal sectional view of another embodiment. In the example of FIG. 2, a rod 12 is provided inside the suspended inner crucible 4 to reach the upper surface of the melt from the outer crucible 1. Using the apparatus shown in Figure 1, 25 kg of high-purity silicon is used as a raw material, the specific resistance target value of the single crystal to be pulled is set to 3.5 Ωcm, and P is added as a dopant to match the amount of pulled single crystal. A single crystal with a diameter of 6 inches was pulled at a pulling speed of 50 mm/hour while supplying raw materials and dopants in an amount of 42 g/min. Each time the single crystal became polycrystallized, it was taken out and pulled again.

[0011] When a silicon single crystal was continuously pulled in accordance with this embodiment, the continuous operation time was approximately 180 hours, and the total length of the straight body for pulling was approximately 6200 mm.
mm (10 pieces), average straight body length per piece 620 m
A good result of m was obtained. On the other hand, it is difficult to stably pull a single crystal with a diameter of 6 inches using a conventional single crystal pulling apparatus equipped only with a suspended internal crucible in the form of partition walls. Furthermore, when using a conventional single crystal pulling device equipped with an inner crucible that rotates together with an outer crucible, the probability of scattering of raw materials is high and the average pulling length is 300 mm or less. The inner crucible deforms due to the weight of the part that protrudes above the liquid,
It cannot be pulled up for a long time.

0012

Effects of the Invention: Since the temperature non-uniformity in the circumferential direction that occurs in a single crystal pulling device equipped with a hanging inner crucible in the form of a partition has been eliminated, single crystals with a relatively large diameter compared to the diameter of the hanging inner crucible can be It has become possible to continuously raise with high probability.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a single crystal pulling apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a single crystal pulling apparatus according to another embodiment.

FIG. 3 is a longitudinal sectional view of a conventional single crystal pulling apparatus.

FIG. 4 is a longitudinal sectional view of a conventional single crystal pulling apparatus.

[Explanation of symbols]

1 Outer crucible
2 Melt 3 Raw material supply pipe
4 Hanging inner crucible 5, 6
Raw material scattering prevention device 7 Casing 8 Heater
9 Rectifier cylinder 10 Inner crucible
11 Through hole 12
rod body
14 Wall 20 Pulled single crystal

Claims (3)

[Claims] 1. A single crystal pulling apparatus comprising a hanging inner crucible in the form of a partition inside an outer crucible, wherein a melt stirring tool is provided inside the hanging inner crucible and stands upright from the bottom of the outer crucible. A single crystal pulling device characterized by comprising: 2. The single crystal pulling device according to claim 1, wherein the melt stirring device is a concentric cylindrical shell that protrudes to the upper surface of the melt, and a large number of through holes are provided in the wall of the cylindrical shell. Upper device. 3. The single crystal pulling apparatus according to claim 1, wherein the melt stirring device is a plurality of rods that protrude up to the upper surface of the melt.