JPH11171682A - Carbon susceptor for single crystal pull-up device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject carbon susceptor intended for its longer service life through selective reaction of exchange members with SiO gas produced from a quartz crucible to effectively prevent the wall thickness decrease of the carbon susceptor. SOLUTION: This carbon susceptor 21 which holdingly supports a quartz crucible reserving a semiconductor melt therein and is divided in the circumferential direction, has such a scheme that the inner circumference thereof is detachably fitted with exchange members 22 of carbonaceous material along the division lines 24; the exchange members 22 are divided so as to superpose upon the division lines of this carbon susceptor and so designed that CO gas produced by silicification reaction between SiO gas and the exchange members is released via the division lines of this carbon susceptor into the outside; thereby CO gas concentration does not increase around the division lines of the exchange members, effecting that the above silicification reaction is carried out in a selective way.

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 pulling a semiconductor single crystal from a semiconductor melt stored using a crucible, and more particularly to a quartz crucible for storing a semiconductor melt. And a carbon susceptor to support.

[0002]

2. Description of the Related Art Conventionally, a Czochralski method (hereinafter referred to as a CZ method) is known as one of methods for producing a semiconductor single crystal such as silicon (Si) or gallium arsenide (GaAs). This CZ method is used in the production of various semiconductor single crystals because it has a feature that a large-diameter, high-purity single crystal can be easily obtained without dislocations or with extremely few lattice defects. Is the way.

FIG. 5 shows an example of a silicon single crystal pulling apparatus using the CZ method. In the single crystal pulling apparatus 1, a quartz crucible 3 and a heater 4 are arranged in a chamber 2, which is a hollow airtight container, and a magnet 5 is arranged outside the chamber 2.

The quartz crucible 3 is housed in a carbon susceptor 7 rotatably supported by a shaft 6 around its axis in order to prevent softening deformation due to thermal deformation. The carbon susceptor 7 is divided in the circumferential direction and mounted on the outer periphery of the quartz crucible 3 in order to prevent cracking during cooling or the like.

[0005] In the single crystal pulling apparatus 1, the seed crystal 9 rotatably suspended from above on the semiconductor melt 8.
Immersed in the semiconductor single crystal and pulled up
2 to grow.

[0006]

By the way, during the operation of pulling up the semiconductor single crystal, the SiO 2 generated from the quartz crucible 3 was removed.
Between the gas and the carbon susceptor 7, a silicification reaction of SiO + 2C → SiC + CO ↑ proceeds, and carbon (C) is transferred from the carbon susceptor 7.
Are released as CO gas, resulting in thinning.

[0007] The portion where this thinning is likely to occur can be explained as follows. That is, the heater 4
When the quartz crucible 3 reaches a temperature at which the quartz crucible 3 is deformed by the heating of the semiconductor crucible 3, the quartz crucible 3 comes into close contact with the carbon susceptor 7 by the weight of the semiconductor melt 8, and the passage of the CO gas concentrates on the divided portion of the carbon susceptor 7. .

In the vicinity of the division, the CO gas can move out of the carbon susceptor 7 through the division, so that the CO gas concentration does not increase and the silicidation reaction proceeds continuously. On the other hand, in a portion other than the divided portion, the generated C
Since the O gas is difficult to move and easily stays, the silicidation reaction does not easily proceed.

Therefore, in the divided portion of the carbon susceptor 7, since the CO gas concentration does not increase and the silicidation reaction tends to proceed to the right side, it is considered that the thinning proceeds more easily than other portions.

[0010] The thickness of the curved portion 7A other than the divided portion is also reduced, though not as much as the divided portion.
Since the temperature distribution in the temperature distribution in the direction of the single crystal growth axis is in a high temperature region, it is considered that temperature is also involved as a condition for promoting the silicidation reaction.

[0011] In recent years, the quartz crucible 3 has been increased in diameter with the demand for longer single crystal and larger diameter.
The temperature of the heater 4 during the melting of the raw material or during the crystal growth rises, which causes a problem that the silicidation reaction is accelerated and the life of the carbon susceptor 7 is shortened.

That is, as the silicidation reaction proceeds, as shown in FIGS. 6 (a) to 6 (c), the wall thickness of the curved portion 7A is accelerated, and the replacement frequency of replacing the carbon susceptor 7 with a new one is increased. Increases cost. For this reason, conventionally, in order to extend the life of the carbon susceptor 7,
Various improvements have been attempted.

For example, Japanese Patent No. 2578126 discloses FIG.
As shown in FIG. 5, the carbon ring 11 is fitted into the lower inner surface of the carbon susceptor 7, which receives a large amount of heat from the heater 4 and promotes the silicidation reaction, and only the carbon ring 11 having a reduced thickness is replaced. A technique for extending the life of the carbon susceptor 7 is disclosed.

As shown in FIG. 8, the carbon piece 12 is divided along the dividing line 8a of the carbon susceptor 7 (see FIG. 7).
In addition, a technique is conceivable in which the thickness of the carbon susceptor 7 is prolonged by suppressing the thickness reduction in the divided portion 13 by replacing the carbon piece 12 with the reduced thickness.

However, in any of these cases, the path of the CO gas generated by the silicidation reaction passes through the contact portion 14 between the carbon susceptor 7 and the carbon ring 11 (see FIG. 7) and the carbon susceptor 7 and the carbon piece 12. Therefore, the reduction in wall thickness cannot be suppressed effectively, and there is a limit to extending the life of the carbon susceptor 7.

The present invention has been made in view of the above circumstances, and it is possible to effectively prevent the carbon susceptor from thinning by selectively reacting SiO gas generated from a quartz crucible with an exchange member. An object is to provide a carbon susceptor for a single crystal pulling apparatus.

[0017]

In order to solve the above-mentioned problems and to achieve the above object, a carbon susceptor of a single crystal pulling apparatus according to the present invention comprises a quartz crucible for storing a semiconductor melt in a chamber. A single crystal pulling apparatus provided with a circumferentially divided carbon susceptor for accommodating and supporting the quartz crucible, wherein an inner periphery of the carbon susceptor is formed of a carbon material along the dividing line. A member is detachably fitted, and the replacement member is divided so as to overlap a dividing line of the carbon susceptor.

In such a configuration, since the replacement member is divided so as to overlap the dividing line of the carbon susceptor,
The CO gas generated by the silicidation reaction between the replacement member and the SiO gas from the quartz crucible is discharged outside from the divided portion of the carbon susceptor.

Therefore, the CO gas concentration does not increase around the divided portion of the replacement member, and the silicidation reaction with the SiO gas is promoted. As a result, the SiO gas is consumed while passing through the division of the replacement member, and does not flow through the division of the carbon susceptor.

Therefore, in the divided portion of the carbon susceptor,
Although the CO gas concentration does not increase and the temperature is higher than that of the replacement member facing the heater, the silicidation reaction with the SiO gas is easily promoted.

According to a second aspect of the present invention, there is provided a carbon susceptor for a single crystal pulling apparatus, wherein a notch is formed on an inner periphery of the replacement member along a dividing line thereof. It is characterized by being formed.

With such a structure, the SiO
The silicidation reaction with the exchange member by the gas will be accelerated in the notch formed in the exchange member. Thereby, the silicidation reaction between the SiO gas and the exchange member can be performed more selectively, and the silicidation reaction between the SiO gas and the carbon susceptor can be effectively suppressed.

The carbon susceptor of the single crystal pulling apparatus according to the third aspect is the carbon susceptor of the single crystal pulling apparatus according to any one of the first and second aspects, wherein: A shielding film made of a carbon material is provided to cover a contact line between the replacement member and the carbon susceptor.

With this configuration, the silicidation reaction due to the SiO gas at the contact portion between the carbon susceptor and the replacement member can be prevented, so that the silicidation reaction between the SiO gas and the carbon susceptor around the contact portion can be prevented. Can be effectively suppressed.

Further, the shielding film prevents the SiO gas from coming into direct contact with the contact portion between the carbon susceptor and the replacement member, so that the silicidation reaction at the divided portion of the replacement member is performed more selectively. The silicidation reaction between the SiO gas and the carbon susceptor can be more effectively suppressed.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a carbon susceptor according to a first embodiment of the present invention, and FIG.
2 is a cross-sectional view taken along line AA of FIG. 1, wherein reference numeral 21 denotes a carbon susceptor, and 22 denotes an exchange member.

As shown in FIG. 1, the carbon susceptor 21 has side portions 21a, 21b, 21 divided into three in the circumferential direction.
c, which are assembled to accommodate a quartz crucible (not shown).

On the inner periphery of the carbon susceptor 21, there is provided a groove 23 for accommodating the replacement member 22 along a dividing line formed by the assembled side portions 21a, 21b, 21c abutting on each other. .

The replacement member 22 is made of a carbon material, and includes a plate-shaped portion 22a and a curved portion 22b so as to be fitted into the grooves 23 corresponding to the straight portion 21A and the curved portion 21B in the side portions 21a, 21b, 21c. ing.

The replacement member 22 is connected to the side portion 21.
a, 21b, and 21c are divided in the longitudinal direction of themselves so as to overlap a dividing line formed by abutting each other, and the dividing line 24 of the replacement member 22 and the side surfaces 21a, 21b, and 21c are divided.
Are arranged in the same plane.

With this configuration, the SiO gas generated from the quartz crucible can be supplied to the carbon susceptor 21.
1 and 2, the CO gas generated by the silicidation reaction with the exchange member 22 divided by the dividing line 24 so as to overlap with the dividing line of FIG.
As shown by, it is released out of the carbon susceptor 21.

Therefore, the CO gas concentration does not increase around the divided portion of the exchange member 22, and the silicidation reaction between the SiO gas and the exchange member 22 is promoted. With this, SiO
The gas is consumed while passing through the division of the exchange member 22,
The divided portion of the carbon susceptor 21 does not flow.

Therefore, in the divided portion of the carbon susceptor 21, the CO gas concentration does not increase, and the temperature is higher than the exchange member 22 facing the heater, so that the silicidation reaction is easily promoted. In addition, the silicidation reaction with the SiO gas is suppressed, and a decrease in the thickness of the carbon susceptor 21 itself can be effectively prevented.

Therefore, in this embodiment, the life of the carbon susceptor 21 can be extended and the frequency of replacement can be reduced by replacing only the replacement member 22 whose thickness has been reduced by the silicidation reaction with the SiO gas. The overall cost of the carbon susceptor 21 can be kept low.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a perspective view showing a main part of the carbon susceptor according to the present embodiment.
Reference numeral 31 denotes a carbon susceptor, and 32 denotes an exchange member.

The carbon susceptor 31 according to the present embodiment
The carbon susceptor 21 according to the first embodiment is characterized in that an exchange member 32 divided so as to overlap a dividing line formed by assembling the side portions 31a and 31b is fitted along the dividing line. And the exchange member 32
A notch 33 having a wedge-shaped cross section along the dividing line
Is provided.

In such a configuration, the silicidation reaction with the exchange member 32 by the SiO gas is promoted in the notch 33 formed in the exchange member 32, and the silicidation reaction in the divided portion 34 of the exchange member 32 is promoted. It will be performed more selectively.

Therefore, also in the present embodiment, the life of the carbon susceptor 31 can be extended and the frequency of replacement can be reduced by replacing only the replacement member 32 whose wall thickness has been reduced by the silicidation reaction with the SiO gas. Thus, the overall cost of the carbon susceptor 31 can be kept low.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a perspective view showing a main part of the carbon susceptor according to the present embodiment.
Reference numeral 41 denotes a carbon susceptor, and reference numeral 42 denotes an exchange member.

The carbon susceptor 41 according to this embodiment
The carbon susceptor 21 according to the first embodiment is characterized in that a replacement member 42 divided so as to overlap a dividing line formed by assembling the side surface portions 41a and 41b is fitted along the dividing line. The replacement member 42 and the carbon susceptor 4
1 in that a shielding film 44 made of a carbon material is provided to cover the contact line 43 with No. 1.

In the case of such a configuration, the SiO 2 at the contact portion 45 between the carbon susceptor 41 and the replacement member 42 is
Since the silicidation reaction due to the gas can be prevented, the silicidation reaction between the SiO gas and the carbon susceptor 41 around the contact portion 45 can be effectively suppressed.

Since the shielding film 44 prevents the SiO gas from directly contacting the contact portion 45, the silicidation reaction with the replacement member 42 is more selectively performed, and the SiO gas and the carbon susceptor 41 Can be more effectively suppressed.

Therefore, according to the present embodiment as well, the life of the carbon susceptor 41 can be extended and the frequency of replacement can be reduced by replacing only the replacement member 42 whose thickness has been reduced by the silicidation reaction with the SiO gas. Thus, the overall cost of the carbon susceptor 41 can be kept low.

FIG. 4 shows a state in which the shielding film 44 does not cover the upper part of the contact line 43.
The shielding film 44 may be provided so as to cover all the contact lines 43.

[0045]

As is clear from the above description, according to the present invention, the following effects can be obtained. (A) According to the carbon susceptor of the single crystal pulling apparatus according to the first aspect, since the replacement member is divided so as to overlap the dividing line of the carbon susceptor, the silicidation reaction between the SiO gas and the carbon susceptor is suppressed. And a silicidation reaction by the SiO gas can be selectively performed with the exchange member.

Therefore, the replacement frequency of the carbon susceptor can be reduced by simply replacing only the replacement member having a reduced thickness due to the silicidation reaction with the SiO gas, and the overall cost can be reduced.

(B) According to the carbon susceptor of the single crystal pulling apparatus according to the second aspect, the silicidation reaction with the exchange member by the SiO gas is selectively performed in the notch. As a result, the life of the carbon susceptor can be further extended, and the overall cost can be reduced.

(C) According to the carbon susceptor of the single crystal pulling apparatus according to the third aspect, the silicidation reaction due to the SiO gas at the contact portion between the carbon susceptor and the exchange member can be prevented. , The silicidation reaction between the SiO gas and the carbon susceptor can be effectively prevented.

Further, since the shielding film prevents the contact portion between the carbon susceptor and the replacement member from coming into direct contact with the SiO gas, the silicidation reaction at the divided portion of the replacement member is more selectively performed. The silicidation reaction between the SiO gas and the carbon susceptor can be more effectively suppressed. Therefore, the life of the carbon susceptor can be significantly extended, and the overall cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a carbon susceptor according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a perspective view showing a main part of a carbon susceptor according to a second embodiment of the present invention.

FIG. 4 is a perspective view showing a main part of a carbon susceptor according to a third embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a main part of an example of a conventional single crystal pulling apparatus.

6A is a perspective view showing a state where the carbon susceptor is locally thinned, FIG. 6B is a cross-sectional view taken along the line AA in FIG. 6A, and FIG. 6C is a line BB in FIG. It is sectional drawing.

FIG. 7 is a perspective view showing a first improved example of a conventional carbon susceptor.

FIG. 8 is a perspective view showing a second improved example of the conventional carbon susceptor.

[Explanation of symbols]

 21, 31, 41 Carbon susceptor 24 Parting line 22, 32, 42 Replacement member 33 Notch 43 Contact line 44 Shielding film

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsuhito Taniguchi 1-5-1, Otemachi, Chiyoda-ku, Tokyo Within Mitsubishi Materials Silicon Co., Ltd. (72) Inventor Takashi Atami 1-5, Otemachi, Chiyoda-ku, Tokyo No. 1 Mitsubishi Materials Silicon Corporation

Claims (3)

[Claims] 1. A single crystal pulling apparatus in which a quartz crucible for storing a semiconductor melt and a carbon susceptor circumferentially divided for accommodating and supporting the quartz crucible are provided in a chamber. An exchange member made of a carbon material is detachably fitted into the inner periphery of the carbon susceptor along a division line thereof, and the exchange member is divided so as to overlap the division line of the carbon susceptor. The carbon susceptor of the single crystal pulling apparatus. 2. A carbon susceptor for a single crystal pulling apparatus according to claim 1, wherein a notch is formed on an inner periphery of said replacement member along a dividing line thereof. 3. The carbon film according to claim 1, wherein a shielding film made of a carbon material is provided on an inner periphery of the carbon susceptor to cover a contact line between the replacement member and the carbon susceptor. A carbon susceptor for the single crystal pulling apparatus according to any one of the above.