JPH09221385A - Device for pulling up single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent steam explosion and the danger of operators without the arriving of a fused raw material at the lower mechanism of a crucible even if the fused raw material flows out by integrally forming a melt leakage receiving tray capable of housing the entire fused raw material on the bottom of a chamber. SOLUTION: The crucible 31 supported at a supporting shaft 39 rotating in an arrow direction is arranged in the chamber 13. This supporting shaft 39 passes through the inside of bellows 17 for vacuum holding mounted at the outside wall surface 13a in the bottom of the chamber. A heater 32 is arranged concentrically on the outer side of the crucible 31 and a heat insulating cylinder 42 on the outer side thereof. An electrode 14 for energizing the heater is mounted at the lower part of the heater 32 and the raw material 33 fused by the heater 32 is packed into the crucible 31. The bottom 16a and side parts 16b of the melt leakage receiving tray 16 are integrally formed in contact with the inside wall surface 13b of the bottom of the chamber 13. The height of the side parts 16b covering the supporting shaft 39 and the electrode 14 are at the same level at the respective points. The inside volume of the melt leakage receiving tray 16 is set larger than the volume of the entire fused raw material 33. The inside surface thereof is covered with boron nitride having poor reactivity with fused silicon.

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 for growing a silicon single crystal used as a semiconductor material, for example.

[0002]

2. Description of the Related Art There are various methods for growing a single crystal, one of which is the Czochralski method (hereinafter referred to as the CZ method). FIG. 4 is a cross-sectional view schematically showing a main part of a single crystal pulling apparatus used in a conventional CZ method, and 31 in the figure shows a crucible.

The crucible 31 comprises a bottomed cylindrical quartz inner layer holding container 31a and a bottomed cylindrical graphite outer layer holding container 31b fitted to the outside of the inner layer holding container 31a. The crucible 31 is supported by a support shaft 39 that rotates at a predetermined speed in the direction of the arrow in the figure. Outside the crucible 31, a resistance heating type heater 32,
A heat insulating cylinder 42 that promotes heat transfer to the crucible 31 is concentrically arranged outside the heater 32. Inside the crucible 31, a melt 33 of the single crystal raw material melted by the heater 32 is provided. It is supposed to be filled.

A pulling shaft 34 made of a pulling rod or a wire is hung on the central axis of the crucible 31, and a seed crystal 35 attached to the tip of the pulling shaft 34 via a seed chuck 34a is melted. 33 is brought into contact with the surface of 33, and the pulling shaft 34 is pulled while rotating the pulling shaft 34 in the same axis as the supporting shaft 39 in the same direction or in the opposite direction at a predetermined speed, thereby solidifying the melt 33 and growing the single crystal 36. It has become.

[0005]

The inner layer holding container 31a made of quartz and the outer layer holding container 31b made of graphite in the single crystal pulling apparatus 3 described above have high heat resistance, but are relatively fragile and shock resistant. Poor sex. Therefore, if a polycrystalline raw material is charged into the crucible 31 during charging, the impact may cause a crack in the crucible 31. In this case, the high-temperature molten raw material (melt liquid) 33 flows out of the crucible 31 from the cracked portion. There is a risk of It is also known that the molten raw material 33 in the crucible 31 is scattered around the crucible 31 when the polycrystalline raw material is charged. Further, if the single crystal 36 falls during the pulling of the single crystal 36, the crucible 31
May be destroyed and the entire amount of the molten raw material 33 may flow out.

As described above, the high temperature molten raw material 33 is the crucible 31.
When the molten raw material 33 flows out or scatters outside, the molten raw material 33 reaches the chamber lower portion (not shown) from the crucible outer peripheral wall 31c, the chamber bottom portion, heater energizing electrode (neither is shown),
The metal portion such as the support shaft 39 is eroded, and further, the drive device of the crucible 31 and the cooling water pipe (hereinafter collectively referred to as a lower mechanism) are eroded. In particular, high-temperature silicon has a strong erosion effect on metals, so if the metal part of the cooling water pipe is eroded, the cooling water evaporates and the chamber is filled with high-pressure steam, which may cause a steam explosion. .

On the other hand, Japanese Unexamined Patent Publication No. 2-225393 proposes a single crystal pulling apparatus having a structure for preventing molten metal leakage. However, in the structure for preventing molten metal leakage, there is a possibility that the molten raw material may still leak between members for preventing molten metal leakage, and since the internal volume of the molten raw material is smaller than the volume of the total molten raw material, the molten raw material may reach the floor surface. There was a problem that there was a risk of overflowing.

Further, Japanese Patent Laid-Open No. 5-270967 proposes a single crystal pulling apparatus provided with a permeation member capable of permeating all the molten raw material when the molten raw material flows out. However, in the single crystal pulling apparatus, although there is no risk of the molten raw material overflowing without being absorbed by the permeating member, the bottom plate and the cover plate for holding the permeating member absorbing the melted raw material that has flowed out There was still a risk that the molten raw material would leak from the gap.

The present invention has been made in view of the above-mentioned problems, and even when the molten raw material flows out of the crucible, the molten raw material that has flowed out is surely prevented from reaching the crucible lower mechanism, and cooling is performed. It is an object of the present invention to provide a single crystal pulling apparatus capable of reliably preventing a steam explosion due to water evaporation and a leaked molten raw material overflowing to the floor surface and causing a danger to workers.

[0010]

In order to achieve the above object, a single crystal pulling apparatus according to the present invention is provided with a molten metal leak receiving tray at the bottom of a chamber, and the molten metal leak receiving tray is formed by integral molding. In addition, it is characterized by having an internal volume capable of accommodating all the molten raw materials (1).

According to the above single crystal pulling apparatus (1),
Even when the molten raw material flows out of the crucible, the molten metal leak tray can contain the molten raw material that has flowed out. Moreover, since the molten metal leak receiving tray is formed by integral molding, there is no risk that the contained molten raw material will flow out to other parts. Further, since the molten metal leak receiving tray has an internal volume capable of accommodating all the molten raw materials, there is no risk that the stored molten raw material overflows from the molten metal leak receiving tray.
Therefore, it is possible to reliably prevent the molten raw material from reaching the crucible lower mechanism, and to prevent a steam explosion due to the evaporation of cooling water and the overflowed molten raw material from overflowing to the floor and causing a danger to workers. can do.

Further, the apparatus for pulling a single crystal according to the present invention is characterized in that the inner surface of the molten metal leak pan provided at the bottom of the chamber is coated with boron nitride (2).

According to the above single crystal pulling apparatus (2),
The inner surface of the molten metal leak receiving tray is coated with boron nitride, and since boron nitride has poor reactivity with molten silicon and poor wettability, stress generated when the molten silicon solidifies can be easily released. it can. Therefore, the durability of the hot water leak receiving tray can be improved.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a single crystal pulling apparatus according to the present invention will be described below with reference to the drawings.

<Embodiment 1> FIG. 1A is a schematic sectional view showing a single crystal pulling apparatus according to an embodiment of the present invention, and FIG. 1B is a schematic partial plan view of an essential part. is there. 2 (a) and 2 (b) are schematic perspective views showing the hot water leak receiving tray in the embodiment. Note that components having the same functions as those of the conventional example are denoted by the same reference numerals.

Reference numeral 13 in the drawing denotes a chamber, and a crucible 31 is arranged in the chamber 13, and the crucible 31 is supported by a support shaft 39 which rotates at a predetermined speed in the direction of the arrow in the drawing. The lower end of the support shaft 39 is connected to a drive mechanism (not shown) for the crucible 31, and the support shaft 39 is a bellows 17 for holding vacuum which is attached to the chamber bottom outer wall surface 13a.
Penetrates inside. A heater 32 is provided outside the crucible 31,
A heat retaining tube 42 is concentrically arranged outside the heater 32, and a metallic heater energizing electrode 14 is attached to the lower portion of the heater 32. Further, the crucible 31 is filled with the molten raw material 33 melted by the heater 32.

An exhaust gas pipe 15 is arranged below the chamber 13, and a cooling water pipe (not shown) is formed on the peripheral wall of the chamber 13. A hot water leak receiving tray 16 made of a carbon material such as graphite or stainless steel is provided in contact with the inner wall surface 13b of the bottom of the chamber 13. Hot water leak saucer 1
6 is formed by integrally molding a bottom portion 16a and a side portion 16b, and the bottom portion 16a closely adheres to and covers substantially the entire bottom inner wall surface 13b of the chamber 13, and the side portion 16a.
Reference numeral b closely covers a predetermined outer peripheral portion of the support shaft 39, a predetermined outer peripheral portion of the heater energizing electrode 14, and the like. Also, the bottom portion 16a
The airtightness due to the close contact between the bottom inner wall surface 13b, the side portion 16b and the predetermined outer peripheral portion can be ensured by improving the design accuracy and press-fitting accuracy of the hot water leak receiving tray 16, and also by using a shield member or the like. It may have been done. The height of the side portion 16b covering the support shaft 39, the heater energizing electrode 14 and the like is at the same level at each location, and the internal volume of the molten metal leak tray 16 obtained from the bottom portion 16a and the side portion 16b is equal to that of the total molten raw material 33. It is set to the volume or more.

It is preferable that the hot water leak receiving tray 16 is made of, for example, graphite. However, if the hot water leak receiving tray 16 is made of, for example, stainless steel, stainless steel is relatively easily eroded by molten silicon. It is desirable that the hot water leak receiving tray 16 has a predetermined thickness so as not to be damaged.

The bottom 16a of the hot water leak receiving tray 16 may be flat as shown in FIG.
As shown in (b), the bottom portion 16a may have a curved bowl shape. When the bottom portion 16a has a curved bowl shape, the strength against the stress generated when the molten silicon is solidified can be improved.

As an example other than the above, the hot water leak receiving tray 1
It is also desirable to coat the inner surface of 6 with boron nitride (not shown). In this case, coating is preferable as the coating means, but if technically difficult, the boron nitride tiles may be laminated to coat the inner surface. When the inner surface of the hot water leak receiving tray 16 is coated with boron nitride, the boron nitride has poor reactivity with molten silicon and poor wettability, so that the stress generated when the molten silicon solidifies can be easily released. You can Therefore, the durability of the hot water leak receiving tray 16 can be enhanced.

In the single crystal pulling apparatus 1 configured as described above, the polycrystalline raw material such as silicon charged in the crucible 31 is melted by the heater 32 to form the molten raw material 33. A seed crystal 35 (FIG. 3) hung from above is immersed in the molten raw material 33, and a predetermined single crystal 36 (FIG. 3) is obtained by rotating the pulling shaft 34 (FIG. 3) and the crucible 31 at a predetermined speed. ) Grow.

In the above-mentioned single crystal pulling apparatus 1, for example, when a polycrystalline raw material is charged into the crucible 31 and a crack is generated in the crucible 31 due to the impact of charging the raw material, the molten raw material 33 flows out of the crucible 31 from the crack. Then, the melted raw material 33 that has flowed out flows downward along the outer peripheral wall 31c of the crucible 31 and falls to the bottom of the chamber 13. Here, according to the single crystal pulling apparatus 1 according to the first embodiment, the molten metal leak receiving tray 16 is disposed so as to be in contact with the chamber bottom inner wall surface 13b. Can be accommodated. Moreover, hot water leak saucer 1
6 has a bottom portion 16a and a side portion 16b integrally formed, there is no gap between the bottom portion 16a and the side portion 16b, and there is no risk that the stored molten raw material 33 will flow out to other portions. Absent. Further, since the molten metal leak receiving tray 16 has an internal volume capable of accommodating the entire amount of the molten raw material 33, there is no risk that the stored molten raw material 33 overflows from the molten metal leak receiving tray 16. Therefore, it is possible to reliably prevent the molten raw material 33 from reaching the lower mechanism of the crucible 31, and to ensure that the steam explosion due to the evaporation of the cooling water and the leaked molten raw material overflow from the floor and pose a danger to the worker. Can be prevented.

Single crystal pulling apparatus 1 according to the first embodiment
In the above, the case where the hot water leak receiving tray 16 is disposed inside the chamber bottom inner wall surface 13b by press fitting has been described.
The present invention is not limited to this, and in another embodiment, the hot water leak receiving tray 16 may be fixed to the bottom side wall of the chamber 13 by a bolt or the like.

Further, in the single crystal pulling apparatus according to the first embodiment, the case where the molten metal leak receiving tray 16 is arranged in contact with the chamber bottom inner wall surface 13b has been described, but the invention is not limited to this. Instead, as shown in the second embodiment below, it may itself form the bottom of the chamber 13.

<Second Embodiment> FIG. 3 is a schematic sectional view showing a single crystal pulling apparatus 2 according to a second embodiment.
The components having the same functions as those of the single crystal pulling apparatus according to the first embodiment are designated by the same reference numerals.

Reference numeral 23 in the drawing denotes a chamber, which has a substantially cylindrical shape without a bottom. A hot water leak receiving tray 26 is disposed below the chamber 23.
6 thereby fulfills the function of the bottom of the chamber 23, and has a structure having the same diameter and sufficient strength as the chamber 23. Each connecting portion (not shown) between the chamber 23 and the hot water leak receiving tray 26 is reliably shielded by a shield member or the like. The hot water leak receiving tray 26 is the hot water leak receiving tray 1
Similar to the case of FIG. 6 (FIG. 1), the bottom portion 26a and the side portion 26b are integrally formed, and the total molten raw material 33
Has an internal volume capable of accommodating

[0027]

【Example】

<Example> In the example, the single crystal pulling apparatus shown in FIG. 1 was manufactured under the following conditions.

Material of hot water leak receiving tray 16: graphite Internal volume of hot water leak receiving tray 16: 35000 cm ³ Arrangement method of hot water leak receiving tray 16: Volume of molten raw material 33 by press-fitting: 32200 cm ³ Single crystal growth apparatus 1 according to the above embodiment Using single crystal 36
As a result of the 192 times of pulling up, the crucible 31 was damaged in four cases (including the occurrence of a crack) in 4 cases. However, the number of workers damaged by the four damage accidents was zero, the lower mechanism of the crucible 31 was never damaged, and no steam explosion occurred.

[Brief description of drawings]

1A is a schematic cross-sectional view showing a single crystal pulling apparatus according to an embodiment of the present invention, and FIG. 1B is a schematic partial plan view of a main part.

2 (a) and 2 (b) are schematic perspective views showing a molten metal leak tray in the embodiment.

FIG. 3 is a schematic cross-sectional view showing a single crystal pulling apparatus according to another embodiment.

FIG. 4 is a schematic cross-sectional view showing a single crystal pulling apparatus used in the CZ method.

[Explanation of symbols]

 1, 2, 3 Single crystal pulling device 16, 26 Hot water leak receiving tray 33 Molten raw material

Claims (2)

[Claims] 1. A hot water leak receiving tray is provided at the bottom of the chamber, and the hot water leak receiving tray is formed by integral molding.
A single crystal pulling apparatus having an internal volume capable of accommodating all molten raw materials. 2. A single crystal pulling apparatus, wherein the inner surface of the molten metal leak receiving tray according to claim 1 is coated with boron nitride.