JPH09183685A - Method for building double crucible into furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease lattice defects, such as dislocation, as far as possible and to improve the working rate of a single crystal pulling-up device by lessening the occurrence of contamination. SOLUTION: An initial raw material is previously put (preset) into an outside crucible 11 in a clean chamber 31 and a crucible assembly 23 for supporting an inside crucible 12 is previously assembled at the time of charging the initial raw material in a method for assembling the double crucible consisting of the outside crucible 11 and the inside crucible 12 into the furnace of the single crystal pulling-up device. The outside crucible 11 and a susceptor 15 are thereafter transported into the furnace and are mounted on a revolving shaft. The inside crucible assembly 23 is mounted into the furnace. The inside crucible assembly 23 is previously assembled and is transported into the furnace and is mounted in addition to the presetting of the outside crucible 11, by which the occurrence of the contamination in the furnace is lessened and the working efficiency is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for incorporating a double crucible into a furnace in a single crystal pulling apparatus for pulling a semiconductor single crystal from a semiconductor melt stored by using a double structure crucible. Is.

[0002]

2. Description of the Related Art Conventionally, the CZ method is known as one of the methods for growing a semiconductor single crystal such as silicon (Si) or gallium arsenide (GaAs). This CZ method has a large diameter,
It is a method used for the growth of various semiconductor crystals because it has characteristics such that a high-purity single crystal can be easily obtained without dislocations or with very few lattice defects.

In recent years, with the demand for a single crystal having a large diameter, high purity, and uniform oxygen concentration and impurity concentration, the CZ
The method has been variously improved and put to practical use. As one of the improved types of the CZ method, a continuous charge type magnetic field applying CZ method using a so-called double crucible (hereinafter abbreviated as CMCZ method) has been proposed. This method is to apply a magnetic field to the semiconductor melt in the crucible from the outside, to suppress convection in the semiconductor melt and to grow a single crystal with a very good controllability of oxygen concentration and a good single crystallization rate. And the raw material can be continuously supplied from the outer crucible to easily obtain a long semiconductor single crystal. Therefore, it is said to be one of the most excellent methods for obtaining a large-diameter and long semiconductor single crystal.

FIG. 2 is a cross-sectional view of an example of a silicon single crystal pulling apparatus using the above CMCZ method. In this single crystal pulling apparatus 1, a double crucible 3, a heater 4 and a raw material supply pipe 5 are arranged in a chamber 2 which is a hollow furnace,
A magnet 9 is arranged outside the chamber 2. The chamber 2 is composed of an upper portion 2a, a main body portion 2b, and a bottom portion 2c, and is configured to be vertically separable.

The double crucible 3 is made of substantially hemispherical quartz (SiO 2).
₂ ) An outer crucible 11 made of quartz and an inner crucible 12 made of quartz (SiO ₂ ) which is a cylindrical partition body provided in the outer crucible 11, and the side wall of the inner crucible 12 has an inner A plurality of communication holes (not shown) are formed to communicate between the crucible 12 and the outer crucible 11 (raw material melting region) and the inner side of the inner crucible 12 (crystal growth region).

The double crucible 3 is placed on an upper flange portion 10 of a rotary shaft 14 which is vertically provided upright in the lower center of the chamber 2, and is arranged on a horizontal plane centered on the axis of the rotary shaft 14. It is configured to rotate at a predetermined angular velocity. A semiconductor melt (raw material for a semiconductor single crystal that has been heated and melted) 21 is stored in the double crucible 3.

The heater 4 heats and melts the semiconductor raw material in the crucible and keeps the temperature of the generated semiconductor melt 21, and normally resistance heating is used. Raw material supply pipe 5
Penetrates through the upper part 2a of the chamber 2 and its lower end opening 5a
From this, a predetermined amount of semiconductor raw material is continuously charged onto the surface of the semiconductor melt 21 between the outer crucible 11 and the inner crucible 12.

The magnet 9 applies a magnetic field from the outside of the double crucible 3 to the semiconductor melt 21 in the double crucible 3, whereby the Lorentz force generated in the semiconductor melt 21 causes the semiconductor melt 21 to move. Control of convection, control of oxygen concentration, suppression of liquid level vibration, etc. are performed.

Examples of the above-mentioned raw material include those obtained by crushing an ingot of polycrystalline silicon with a crusher or the like to form flakes, or granules of polycrystalline silicon deposited in a granular form from a gas raw material by a thermal decomposition method. It is preferably used, and if necessary, an additional element called a dopant such as boron (B) (when making a p-type silicon single crystal) or phosphorus (P) (when making an n-type silicon single crystal) is further supplied. .
The same applies to the case of gallium arsenide (GaAs), in which case the additive element is zinc (Zn) or silicon (S).
i) and so on.

By the single crystal pulling apparatus 1 described above, the seed crystal 3 is attached to the pulling shaft 34 arranged above the inner crucible 12 and axially.
5, the semiconductor single crystal 33 is grown on the semiconductor melt 21 with the seed crystal 35 as a nucleus.

By the way, in the above-mentioned single crystal pulling apparatus, as described in Japanese Patent Application Laid-Open No. 63-303894, the outer crucible 11 is used in the previous step of growing the single crystal.
A polycrystalline raw material such as a polycrystalline silicon ingot is melted in advance to store the semiconductor melt 21, and the inner crucible 12 arranged above the outer crucible 11 is placed in the outer crucible 11 to form a double crucible. 3 is formed. In this way, the double crucible is formed after melting the polycrystalline raw material because the raw material in the outer crucible 11 is heated by the heater 4 to obtain the semiconductor melt 21 by completely melting the polycrystalline raw material. This is because it is necessary to heat at a high temperature to the above temperature, and at this time, if the inner crucible 12 is formed in the outer crucible 11 in advance, large thermal deformation will occur in the inner crucible 12.

Therefore, after the raw material is completely melted, the heating by the heater 4 is reduced to some extent before the inner crucible 12 is melted.
Is formed in the outer crucible 11, thereby avoiding high-temperature heating at the time of holding the initial raw material melt and suppressing the deformation of the inner crucible 12.

Further, the communication hole formed in the inner crucible 12 is set to have a certain opening area or less so that the semiconductor melt 21 flows only from the outer crucible 11 side into the inner crucible 12 when the raw material is supplied. . This is because if the semiconductor melt 21 returns from the crystal growth region to the raw material melt region by convection, it becomes difficult to control the impurity temperature and the melt temperature during single crystal growth.

Argon gas (Ar) is supplied into the chamber 2 from the gas inlet 6a of the chamber 2. The argon gas (Ar) blows off SiO generated from the semiconductor melt 21 and also the lower end portion of the chamber 2. Are sequentially discharged from the gas discharge port 8.

Here, an example of the structure of the inner crucible assembly 23 will be described. An upper ring member 24 is placed on the upper end of the heat insulating cylinder 16, and a plurality of locking members that can be locked to the upper end portion of the circular tube-shaped inner crucible support member 13 fixed to the upper end portion of the inner crucible 12 are mounted on the upper ring member 24. Members 7a and 7b (in this example, there are three, and one locking member is not shown) are suspended. The plurality of locking members 7a and 7b are the upper ring member 2
4 are arranged side by side in the circumferential direction. The raw material supply pipe 5
Is hung from the upper part of the chamber 2 and penetrates the upper ring member 24 at a position where it does not interfere with the locking members 7a and 7b.

Regarding the initial charging method of the raw material in the single crystal pulling apparatus having the above structure, first, the upper part 2a of the chamber 2 is
Raise to open. In parallel with this, the outer crucible 1 held by the susceptor 15 in a predetermined clean room.
Put the ingredients in 1. The outer crucible 11 supported by the susceptor 15 is mounted on the rotating shaft 14 by mounting.

After that, the inner crucible assembly 23 is assembled in the chamber 2. That is, first, the three locking members 7
The upper ring member 24 suspending and supporting a and 7b (one locking member is not shown) is placed on the heat insulating cylinder 16. Here, the inner crucible support member 13 integrated with the inner crucible 12 is locked to the locking members 7a and 7b. Finally, the upper part 2a of the chamber 2 is closed. At this time, the raw material supply pipe 5 penetrates the upper ring member 24.

[0018]

However, in the above-mentioned prior art, although the outer crucible is pre-set, the inner crucible assembly is assembled in the furnace, so that the contamination of each component of this assembly causes contamination. It is liable to occur, and the generated contamination mixes with the material inside the outer crucible, resulting in the occurrence of lattice defects such as dislocations in the single crystal growth step. In addition, there is a problem that the assembly order of the inner crucible assembly is apt to be mistaken, work efficiency is low, and as a result, the furnace opening time is long and the operation rate of the single crystal pulling apparatus is low. .
Further, when the outer crucible and the inner crucible assembly are assembled, the atmosphere of the entire large furnace must be kept in a clean state, which takes time and labor, and there is a problem that equipment cost for that increases.

The present invention has been made in view of the above problems of the prior art. It reduces the occurrence of contamination, minimizes lattice defects such as dislocations, and operates the single crystal pulling apparatus. It is an object of the present invention to provide a method for assembling a double crucible in a furnace, which also improves the rate.

[0020]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a furnace that can be divided into upper and lower parts, an outer crucible mounted on a rotary shaft in the furnace via a susceptor, and at least an inner crucible. In an apparatus for pulling a single crystal with an inner crucible assembly that suspends and supports, in a method of incorporating a double crucible consisting of the outer crucible and the inner crucible into the furnace, at the time of initial raw material charging, In a clean room, the initial raw material is put in the outer crucible supported by the susceptor, and the inner crucible assembly is assembled in the clean room.First, the outer crucible and the susceptor are put into the furnace. It is characterized in that it is transported and mounted on the rotary shaft, and thereafter, the inner crucible assembly is mounted in the furnace.

Further, in another aspect of the present invention, in the clean chamber, after putting the raw material into the outer crucible, the outer crucible is covered with a lid, and the inner crucible assembly is covered with a dustproof member to cover the outer crucible. It is characterized in that the lid is removed after mounting in the furnace, and the dustproof member is removed after the inner crucible assembly is transported to the vicinity of the furnace.

The operation of the present invention will be described below. According to the first aspect of the present invention, in addition to presetting the outer crucible in the clean room, the inner crucible assembly is constructed in advance, and these are transferred into the furnace and sequentially assembled, thereby making it possible to achieve the conventional structure. However, it is not necessary to assemble the inner crucible assembly in the furnace. Therefore, the occurrence of contamination in the furnace is reduced and the work efficiency is improved. Further, as in the second aspect of the present invention, it is preferable to cover the inner crucible assembly, which is preset, with a dustproof member so as not to be dusted when the inner crucible assembly is transported to the furnace. Also, by covering the outer crucible with a lid between the time when the raw material is put in the outer crucible and immediately before the inner crucible assembly is installed in the furnace, dust and dirt are prevented from entering the outer crucible. it can.

[0023]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a state in which an outer crucible and an inner crucible assembly, which are components of a silicon pulling apparatus, are preset in a clean room.

First, as shown in FIG. 1, in a clean room (clean booth) 31, a susceptor 15 for holding an outer crucible 11 is mounted on a carriage 28 via a carbon stand (susceptor receiving stand) 29. ing. A predetermined amount of polycrystalline raw material such as polycrystalline silicon ingot is put into the outer crucible 11 (presetting of the outer crucible 11). After this, the outer crucible 1
1 is covered with a dustproof lid 30. On the other hand, carbon pedestals 26a and 26b are placed on another trolley 27, and the pedestals 26a and 26b
The inner crucible assembly 23 is built on 6b as described above. Here, on the upper ring member 24 of the inner crucible assembly 23, a plurality of I bolts 25a and 25b (four in this example, two I bolts) as a suspending tool are arranged at equal intervals in the circumferential direction. (Not shown) is screwed in and attached. Further, the inner crucible assembly 23 is covered with a dustproof sheet (dustproof member) 32. The dustproof sheet 32 has an I
Four holes are formed to expose the bolts 25a and 25b. The reference numerals 27a and 28a respectively indicate
The handles of the carriages 27 and 28 are shown.

Outer crucible 11 preset as described above
The trolley 28 on which is mounted is taken out of the clean chamber 31 and conveyed to the vicinity of the chamber 2, and the dolly 27 is also taken out of the clean chamber 31 and conveyed to the vicinity of the chamber 2. Here, the susceptor 15 and the outer crucible 11 are assembled into the chamber 2 and the lid 30 is removed. Thereafter, the dustproof sheet 32 is removed from the inner crucible assembly 23, and the inner crucible assembly 23 is attached to the plurality of I bolts 25 by a crane or the like (not shown).
It is lifted via a and 25b and mounted in the chamber 2. Here, the I bolts 25a and 25b are removed from the upper ring member 24.

The inside of the chamber 2 is evacuated by a vacuum pump to create a vacuum state. Next, the argon gas (A
r) or the like is introduced, and the rotary shaft 14 is rotated on the horizontal plane at a predetermined angular velocity about the axis to rotate the outer crucible 11 at a predetermined angular velocity while energizing the heater 4. The polycrystalline raw material in the crucible 11 is heated to a temperature higher than the single crystal growth temperature to completely melt the raw material. This melted raw material is called a semiconductor melt 21.

After the raw material is completely melted, the heating by the heater 4 is slightly weakened, and the inner crucible 12 arranged with the same axis above the outer crucible 11 is used as the semiconductor melt 21.
Place it inside. At this time, the inner crucible support member 13 is released from the engagement with the engagement members 7a and 7b. Then, when the inner crucible 12 is placed in the outer crucible 11 to form the double crucible 3, the communication hole of the inner crucible 12 serves as a communication portion through which the semiconductor melt 21 flows.

After forming the double crucible 3, the magnet 9 is formed.
And a predetermined magnetic field is applied to adjust the electric power of the heater 4 to maintain the temperature near the central liquid surface of the semiconductor melt 21 at the single crystal growth temperature, and the seed crystal 35 suspended by the pulling shaft 34 is used to melt the semiconductor. After being soaked in the liquid 21, a semiconductor single crystal 33 is grown with the seed crystal 35 as a nucleus.

In the crystal growth process, a granular silicon raw material is continuously charged from the raw material supply pipe 5 in accordance with the growth amount (pulling amount) of the semiconductor single crystal 33, and the charged raw material is the outside. It melts in the crucible 11 and is continuously supplied into the inner crucible 12 through the communication hole of the inner crucible 12. As described above, the semiconductor single crystal 33 can be grown. The raw material supplied from the raw material supply pipe 5 is, for example, a polycrystalline silicon ingot crushed by a crusher or the like into flakes, or a granular material deposited by a thermal decomposition method from a gas raw material. Granules of crystalline silicon are preferably used, and if necessary, boron (B)
An additional element called a dopant such as (when making a p-type silicon single crystal) or phosphorus (P) (when making an n-type silicon single crystal) is further supplied.

After manufacturing the semiconductor single crystal, the inner crucible assembly 23
Then, the outer crucible 11 and the outer crucible 11 are taken out of the chamber 2 by the reverse operation to the above-mentioned mounting, and thereafter, the outer crucible and the inner crucible assembly preset during the production of the single crystal in the preceding stage are sequentially introduced into the chamber 2. Attach and use.

As described above, in the present embodiment, the outer crucible 11 preset in the clean chamber 31 is mounted in the chamber 2, and then the preset inner crucible assembly 23 is set in the chamber 2. By installing inside,
In the chamber 2, the constituent parts of the inner crucible assembly 23 are not rubbed with each other, and the occurrence of contamination is reduced. In addition, mistakes in the assembly sequence at the time of presetting the inner crucible assembly 23 are less likely to occur, and work efficiency is improved. As a result, the time for opening the chamber 2 is short and the operation rate of the single crystal pulling apparatus 1 is improved. Further, a plurality of sets of the outer crucible 11 and the inner crucible assembly 23 are prepared, and the outer crucible and the inner crucible assembly which are not used are preset while the single crystal pulling apparatus 1 is in operation, and the operation is performed. After completion of the above step, the preset outer crucible and inner crucible assembly can be immediately mounted in the chamber and the single crystal pulling apparatus can be operated, so that the operating rate can be further improved.
Further, when the preset inner crucible assembly 23 is transported to the chamber 2, it is preferable to cover the dustproof sheet 32 so as not to be dusty. Further, by covering the outer crucible 11 with the lid 30 between the time when the raw material is put in the outer crucible 11 and immediately before the inner crucible assembly 23 is mounted in the chamber 2, dust inside the outer crucible 11 is prevented. Prevents dust from entering.

In the above embodiment, the initial raw material was put into the outer crucible and the inner crucible assembly was preset in the same clean chamber, but the present invention is not limited to this, and each work is performed in different clean chambers. May be. Also,
The outer crucible and the inner crucible assembly may be placed on the same carriage and transported. Furthermore, the lid of the outer crucible and the dustproof sheet of the inner crucible assembly do not necessarily have to be used. Although the CMCZ method was adopted as the single crystal pulling apparatus, another single crystal manufacturing apparatus may be provided as long as it has a double crucible structure. For example, continuous charge type (CC
Z method) may be adopted.

[0033]

Since the present invention is configured as described above, it has the following effects. According to the first aspect of the present invention, the outer crucible preset by incorporating the raw material in the clean room is mounted in the furnace, and then the preset inner crucible assembly is mounted in the furnace. The components of the inner crucible assembly are not rubbed with each other in the furnace, the occurrence of contamination is reduced, and the assembly order of the inner crucible assembly during presetting is unlikely to occur. As a result, the occurrence of lattice defects such as dislocations can be reduced as much as possible, and work efficiency is improved.
Further, the time for opening the furnace is short, and the operation rate of the single crystal pulling apparatus is improved. Also, prepare a plurality of sets of outer crucible and inner crucible assembly, and preset the outer crucible and inner crucible assembly that are not in use while the single crystal pulling apparatus is in operation, and finish the operation. After that, the preset outer crucible and inner crucible assembly can be immediately mounted in the furnace to operate the single crystal pulling apparatus, so that the operating rate can be further improved. In the invention described in claim 2, in addition to the above effects, it is preferable to cover the inside of the preset inner crucible assembly with a dustproof member so as not to be dusty when it is transported to the furnace. Also, by covering the outer crucible with a lid between the time when the raw material is put in the outer crucible and immediately before the inner crucible assembly is installed in the furnace, dust and dirt are prevented from entering the outer crucible. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which an outer crucible and an inner crucible assembly are preset in a clean chamber.

FIG. 2 is a vertical sectional view showing an example of a single crystal pulling apparatus.

[Explanation of symbols]

 1 Single crystal pulling apparatus 2 Chamber (furnace) 2a Upper part 2b Main body part 2c Bottom part 3 Double crucible 4 Heater 5 Raw material supply pipe 5a Lower end opening 6a Gas introduction port 7a, 7b Locking member 8 Gas discharge port 10 Upper flange part 11 Outer crucible 12 Inner crucible 13 Inner crucible support member 14 Rotating shaft 15 Susceptor 16 Heat retaining cylinder (heat shield member) 21 Semiconductor melt 23 Inner crucible assembly 24 Upper ring member 25a, 25b I bolt (hanger) 26a, 26b stand 27 , 28 trucks 29 trucks 30 lids 31 clean room (clean booth) 32 dust-proof sheet (dust-proof member) 33 semiconductor single crystal 34 pull-up shaft 35 seed crystal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisashi Furuya 1-5-1, Otemachi, Chiyoda-ku, Tokyo Sanritsu Material Silicon Co., Ltd. (72) Inventor Michio Kita 1-297 Kitabukuro-cho, Omiya-shi, Saitama Address Mitsubishi Materials Corporation, Research Institute

Claims (2)

[Claims] 1. A furnace that is vertically separable, and an outer crucible that is mounted on a rotating shaft in the furnace via a susceptor,
In a single crystal pulling apparatus including an inner crucible assembly that suspends and supports at least an inner crucible, in a method of incorporating a double crucible consisting of the outer crucible and the inner crucible into the furnace, at the time of initial raw material charging In advance, in the clean room, while putting the initial raw material in the outer crucible supported by the susceptor in advance, and assembling the inner crucible assembly in the clean room, first, the outer crucible and the susceptor are A method for assembling a double crucible in a furnace, which comprises transporting the crucible into a furnace, mounting the crucible on the rotating shaft, and then mounting the inner crucible assembly in the furnace. 2. The assembling method according to claim 1, wherein in the clean chamber, after putting the raw material in the outer crucible, the outer crucible is covered with a lid, and the inner crucible assembly is covered with a dustproof member. After mounting the outer crucible in the furnace, remove the lid,
Further, the method for assembling the double crucible in the furnace is characterized in that the dustproof member is removed after the inner crucible assembly is transported to the vicinity of the furnace.