JP2000086383A - Quartz glass crucible for pulling silicon single crystal and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the yield of single crystal formation in pulling a silicon single crystal by making a quartz glass crucible include a specific amount of foams in a zone from the interior surface of a transparent quartz glass layer to a specific distance and specifying the content of a sulfur compound gas contained in the foams. SOLUTION: This quartz glass crucible for pulling up a silicon single crystal contains 1×10-7 to 3×10-3 mm3/mm3 foam amount in a zone from the surface of a transparent quartz glass layer to at least 1 mm. A sulfur compound gas is an SO2 gas or a H2S gas and the content is <=50 vol.% based on the total gas amount of foams. A production apparatus 2 is used. A revolving shaft 7 is rotated in the direction of the arrow to turn a crucible forming mold 3 at a high speed. High-purity quartz powder is supplied from above to the mold to form a quartz filled layer 12 of a crucible shape. The quartz packed layer is decompressed by a decompressing mechanism 10 and heated by sending an electric current to carbon electrodes 11. The quartz packed layer 12 is successively melted from the inside, only very small foams having 10-30 μm diameter are left in the inner layer, the quartz glass layer is made transparent in appearance and a great number of foams are collected on the exterior surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a quartz glass crucible for pulling a silicon single crystal and a method for producing the same.
In particular, the present invention relates to a quartz glass crucible for pulling a silicon single crystal, which improves the yield of single crystal crystallization when pulling a silicon single crystal, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A silicon single crystal used for a substrate of a semiconductor device is generally manufactured by a Czochralski method (CZ method). In the CZ method, a polycrystalline silicon raw material is loaded into a quartz glass crucible and loaded. The obtained silicon raw material is heated and melted from the surroundings, and the seed crystal suspended from above is brought into contact with the silicon melt and then pulled up.

At the time of this pulling, the quartz glass crucible is eroded from its surface by the silicon melt.
If there are many bubbles in the inner layer of the quartz glass crucible, the erosion causes the bubbles to be exposed at the interface with the silicon melt, so that the single crystallization becomes unstable and the single crystallization yield decreases as a result. There was a problem.

[0004] In recent years, various methods for producing a bubble-free inner layer of a quartz glass crucible have been studied. However, at present, it has not been completely bubble-free. Even if the air bubbles in the inner layer were significantly reduced as compared with the glass crucible, the yield of single crystal crystallization of silicon single crystal was not improved to a sufficiently satisfactory level.

[0005]

SUMMARY OF THE INVENTION The present inventors have conducted intensive studies, focusing on whether the yield in single crystallization may be affected by, for example, a component in bubbles existing in the inner layer even in a very small amount.

As a result, it has been found that bubbles existing in the inner layer of the conventional quartz glass crucible contain a large amount of SO ₂ gas components, and this greatly affects the yield of single crystallization.

[0007] Further studies have been carried out, and in addition to the SO ₂ gas, sulfide compound gas such as H ₂ S gas is present in the bubbles existing in the inner layer of the quartz glass crucible. It has been found that the single crystallization yield can be improved by reducing the amount to a certain amount or less.

Furthermore, it has been found that the cause of the sulfur compound gas being contained in the quartz glass crucible is the carbon electrode for arc discharge used in the process of manufacturing the quartz glass crucible by the arc melting method.

The present invention has been made based on these findings of the present inventors, and an object of the present invention is to provide a quartz glass crucible capable of improving the yield of single crystallization when pulling a silicon single crystal and a method of manufacturing the same. .

[0010]

Means for Solving the Problems The present invention, which has been made to achieve the above object, has an opaque quartz glass layer containing a large number of bubbles and a transparent quartz glass layer formed on the inner surface thereof. In the quartz glass crucible for pulling a silicon single crystal, 1 × 10 ^{−7 to} 3 × 10 ⁻³ mm is provided at least in a region having a thickness of 1 mm from the inner surface of the transparent quartz glass layer.
³ / mm ³ bubbles, wherein the content of the sulfur compound gas contained in the bubbles is 50% by volume or less based on the total gas amount contained in the bubbles, wherein the quartz is used for pulling a silicon single crystal. The gist is that it is a glass crucible.

In the invention of claim 2 of the present application, the gist is that the sulfur compound gas is SO _2, which is the quartz glass crucible for pulling a silicon single crystal according to claim 1.

In the invention of claim 3 of the present application, the gist is that the sulfur compound gas is H ₂ S, which is a quartz glass crucible for pulling a silicon single crystal according to claim 1.

According to a fourth aspect of the present invention, there is provided a method for producing a quartz glass crucible for pulling a silicon single crystal, which comprises preparing a crucible forming mold filled with quartz powder in a crucible shape and performing arc discharge for a predetermined time. The gist of the present invention is to provide a method for producing a quartz glass crucible for pulling a silicon single crystal, characterized in that the content of a sulfur component in a carbon electrode is reduced to 1 ppm or less.

According to the invention of claim 5 of the present application, the quartz glass crucible has an opaque quartz glass layer containing a large number of air bubbles and a transparent quartz glass layer formed on the inner surface thereof. Contains at least a region of 1 × 10 ^{−7 to} 3 × 10 ⁻³ mm ³ / mm ^{3 in} a thickness of 1 mm, and the content of the sulfur compound gas contained in the bubbles is the total amount of gas contained in the bubbles. The method is intended to be a method for producing a quartz glass crucible for pulling a silicon single crystal according to claim 4, wherein the content is 50% by volume or less.

In the invention of claim 6 of the present application, the method for producing a quartz glass crucible for pulling a silicon single crystal according to claim 4 or 5, wherein the method for producing a quartz glass crucible is performed in an air atmosphere. The main point is.

According to a seventh aspect of the present invention, there is provided the method for producing a silicon single crystal pulling quartz glass crucible according to claim 4 or 5, wherein the method for producing a quartz glass crucible is performed in a hydrogen atmosphere. The main point is.

According to the invention of claim 8 of the present application, the method for producing a quartz glass crucible for pulling a silicon single crystal according to claim 4 or 5, wherein the method for producing a quartz glass crucible is performed in a nitrogen or helium atmosphere. The gist is that there is.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a quartz glass crucible according to the present invention and a method for manufacturing the same will be described below with reference to the accompanying drawings.

FIG. 1 shows a quartz glass crucible 1 according to the present invention.
A quartz glass crucible 1 manufactured by the manufacturing apparatus 2 has a thickness of about 10 mm as shown in FIGS. 2 and 3, and is made of opaque quartz containing a large number of bubbles. The glass layer and the 3 layer formed on the inner surface
And a transparent quartz glass layer of about 5 μm.

At least 1 × 10 ^{−7 to} 3 × 10 ⁻³ mm ^{3 in} a region having a thickness of 1 mm from the inner surface of the transparent quartz glass layer.
/ Mm ³ of bubbles B, which are generated in the quartz glass crucible 1 when the quartz glass crucible 1 is manufactured. In addition to the N ₂ and O ₂ gases, the bubbles B contain SO ₂ gas. include. The content of the sulfur compound gas contained in the bubble B is 50% by volume or less based on the total gas amount contained in the bubble B.

Next, the manufacturing apparatus 2 will be described with reference to the drawings.

The crucible-forming mold 3 of the manufacturing apparatus 2 as shown in FIG. 1 is composed of a gas permeable member such as a mold having a plurality of through holes or a highly purified porous carbon mold. Inner member 4 and a ventilation portion 5
And a holding body 6 for holding the inner member 4.

A rotating shaft 7 connected to rotating means (not shown) is fixed to a lower portion of the holding body 6 and is supported so as to be rotatable together with the crucible-forming mold 3. The ventilation section 5 is connected to an exhaust port 9 provided at the center of the rotating shaft 7 through an opening 8 provided at a lower portion of the holding body 6. This ventilation path 7 is connected to a pressure reducing mechanism 10.

A carbon electrode 11 for arc discharge is provided on an upper portion facing the inner member 2, and the carbon electrode 11 contains carbon and a plurality of other elements. One of the other elements includes sulfur,
Its content is 1 ppm or less.

The manufacturing apparatus used in the method for manufacturing a quartz glass crucible according to the present invention has the above-described structure, and the method for manufacturing a quartz glass crucible according to the present invention will be described.

In order to manufacture a crucible using the above-described manufacturing apparatus 2, the crucible forming die 3 is rotated at a high speed by operating a rotary drive source (not shown) and rotating the rotating shaft 7 in the direction of the arrow. A supply pipe (not shown) supplies high-purity quartz powder into the crucible-forming mold 3 from above. The supplied quartz powder is pressed against the inner surface of the crucible molding die 3 by centrifugal force and is formed as a crucible-shaped quartz filling layer 12.

Further, in the atmosphere, the carbon electrode 11 is energized and heated from the inside of the quartz filling layer 12 almost simultaneously with the pressure reduction by the operation of the pressure reduction mechanism 10.

The heating of the quartz-filled layer 12 by the carbon electrode 11 causes the quartz-filled layer 12 to be sequentially melted from the inside, but the inner layer contains only a very small and few bubbles B having a diameter of about 10 to 30 μm. Thus, a double-layer quartz glass crucible 1 having a transparent appearance and a large number of bubbles B on the outer surface is produced.

In the manufacturing process of the quartz glass crucible 1, the sulfur contained in the arc discharge carbon electrode 11 for heating the quartz filling layer 12 formed on the inner member 4 is combined with oxygen in the atmosphere to form SO ₂ . Become.

This SO ₂ is taken into the melting quartz glass crucible 1 and is contained in the bubbles B in the quartz glass crucible 1 like N ₂ and O ₂ in the atmosphere.

At this time, since the sulfur content in the carbon electrode 11 is controlled to 1 ppm or less, the bubble B
Is 50% by volume or less based on the total gas amount.

As described above, by controlling the sulfur component content in the carbon electrode 11 which has not been conventionally controlled, the SO ₂ gas content in the quartz glass crucible 1 manufactured using the carbon electrode 11 is controlled. It became possible to control.

By controlling the content of SO ₂ gas contained in the bubbles contained in the quartz glass crucible 1, the quartz glass crucible 1 melts into the silicon melt in the single crystal pulling step and causes OSF. SO ₂ can be controlled, and the yield of single crystallization when pulling a silicon single crystal using the quartz glass crucible 1 can be improved.

Next, another embodiment of the quartz glass crucible and the method of manufacturing the same according to the present invention will be described. Since the overall structure of the quartz glass crucible in this embodiment is not different from that shown in FIG. 1, the same parts will be described with the same reference numerals with reference to FIG.

A quartz glass crucible 1 is manufactured by a manufacturing apparatus 2 in a hydrogen atmosphere.

As in the above-described embodiment, the carbon electrode 11
Is discharged and the quartz glass crucible 1 is manufactured by heating the quartz filling layer 12, and the sulfur component contained in the carbon electrode 11 is combined with hydrogen of the atmospheric gas by melting of the carbon electrode 11 to become H ₂ S.

The quartz glass crucible 1 in which this H ₂ S is being melted
And is contained in bubbles B existing in the quartz glass crucible 1. Also in this embodiment, since the sulfur component in the carbon electrode 11 is controlled to 1 ppm or less as described above, the H ₂ S gas contained in the bubbles B contained in the quartz glass crucible 1 is the total gas amount contained in the bubbles B. Is controlled to 50% by volume or less.

As described above, by manufacturing the quartz glass crucible 1 using the carbon electrode 11 whose sulfur content is controlled to a predetermined value or less, the content of H ₂ S gas contained in the quartz glass crucible 1 is reduced. It became possible to control. By controlling the content of H ₂ S gas contained in the quartz glass crucible 1, in the single crystal pulling step,
OS melts into silicon melt from quartz glass crucible 1
The control of H ₂ S, which causes the generation of F, becomes possible, and the yield of single crystallization when pulling a silicon single crystal using the quartz glass crucible 1 can be improved.

Incidentally, even when N ₂ or He gas is used as the atmospheric gas, by reducing the sulfur component content of the carbon electrode 11 to a predetermined value or less as described above, bubbles B contained in the quartz glass crucible 1 are removed. The contained sulfur compound gas can be reduced to 50% by volume or less based on the total amount of gas contained in the bubble B. In the single crystal pulling process, the sulfur compound gas is dissolved into the silicon melt from the quartz glass crucible 1 and causes OSF generation. Thus, the control of the sulfur compound gas becomes possible, and the single crystallization yield when pulling the silicon single crystal using the quartz glass crucible 1 can be improved.

[0040]

EXAMPLES (1) Purpose of measurement: Laser Raman spectroscopy using a laser Raman spectrometer is used to examine gas components contained in bubbles present in the transparent quartz glass layer inside the quartz glass crucible.

(2) Sample: A sample was prepared from a quartz glass crucible arc-melted in a hydrogen atmosphere using a carbon electrode containing a sulfur component of 0.5 ppm (Sample 1).

Using a conventional carbon electrode containing 5 ppm of sulfur, a sample was cut out from a quartz glass crucible arc-melted in a hydrogen atmosphere to prepare a sample (sample 2). (3) Measuring method: Each sample is measured by laser Raman spectroscopy using a laser Raman spectrometer as shown in FIG. (4) Measurement results: In sample 1, SO ₂ , O ₂ , and N ₂ were detected as gases as shown in FIG. Raman band assignments are shown in Table 1 and in the spectrum of FIG.

[0043]

[Table 1] The other broad Raman bands in FIGS. 5 and 6 are made of quartz (SiO ₂ ).

In Sample 2, as shown in FIG. 6, SO ₂ ,
N ₂ has been detected.

The relative intensity of the Raman band as shown in Table 2 can be obtained from each sample, and the intensity ratio of the Raman band is proportional to the partial pressure. Therefore, the band intensity ratio provides a measure of the composition ratio.

[0046]

[Table 2] As described above, the presence of SO ₂ was confirmed from Sample 1 and Sample 2.

It has been confirmed that reducing the proportion of SO _{2 in} the bubbles makes it possible to reduce the amount of SO ₂ dissolved in the silicon single crystal, thereby suppressing variations in the OSF of the silicon single crystal.

Also, it was confirmed that the reduction of the sulfur component contained in the arc electrode can reduce the ratio of the SO ₂ content in the bubbles to the total gas.

Using the quartz glass crucible obtained by the same manufacturing method as the quartz glass crucible obtained by cutting out the samples 1 and 2 above, the silicon single crystal was pulled up using the embodiment 1 and the comparative example 1. Example 1 had a single crystallization yield of 92%, whereas Example 1 had a single crystallization yield of 98%.
Significant improvement was observed.

[0050]

By controlling the sulfur component content in the carbon electrode, which has not been controlled conventionally, the content of the sulfur compound gas contained in the quartz glass crucible manufactured using the carbon electrode can be controlled, In the single crystal pulling process, it is possible to control the sulfur compound gas that dissolves into the silicon melt from the quartz glass crucible and causes OSF generation, and the single crystal crystallization yield when pulling the silicon single crystal using the quartz glass crucible Can be improved.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a manufacturing apparatus for a quartz glass crucible used in a method for manufacturing a quartz glass crucible according to the present invention.

FIG. 2 is a sectional view of a quartz glass crucible according to the present invention.

FIG. 3 is an enlarged cross-sectional view showing a portion X in FIG. 2;

FIG. 4 is a conceptual diagram of a Raman spectrometer used for analyzing components contained in bubbles contained in a quartz glass crucible.

FIG. 5 is a Raman spectrum of bubbles in a conventional quartz glass crucible.

FIG. 6 is a Raman spectrum of bubbles in another conventional quartz glass crucible.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quartz glass crucible 2 Manufacturing apparatus for quartz glass crucibles 3 Crucible mold 4 Inner member 5 Ventilation unit 6 Holder 7 Rotating shaft 8 Opening 9 Exhaust port 10 Decompression mechanism 11 Carbon electrode 12 Quartz filling layer B Bubbles

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Kauchi 30 Soya, Hadano-shi, Kanagawa F-term in Toshiba Ceramics Development Co., Ltd. F-term (reference) 3K084 AA12 BA08 CA07 CA09 4G014 AH02 4G077 AA02 BA04 CF00 EG02 EG05 PD01 PD08

Claims (8)

[Claims] 1. A quartz glass crucible for pulling a silicon single crystal comprising an opaque quartz glass layer containing a large number of air bubbles and a transparent quartz glass layer formed on the inner surface thereof.
A thickness of at least 1 m from the inner surface of the transparent quartz glass layer
In the region of m, bubbles of 1 × 10 ^{−7 to} 3 × 10 ⁻³ mm ³ / mm ³ are contained, and the content of the sulfur compound gas contained in the bubbles is 50 with respect to the total gas content contained in the bubbles. A quartz glass crucible for pulling a silicon single crystal, wherein the volume is not more than% by volume. 2. The quartz glass crucible for pulling a silicon single crystal according to claim 1, wherein the sulfur compound gas is SO ₂ . 3. The quartz glass crucible for pulling a silicon single crystal according to claim 1, wherein the sulfur compound gas is H ₂ S. 4. A method for producing a quartz glass crucible for pulling a silicon single crystal, in which a crucible mold filled with quartz powder in a crucible shape and performing arc discharge for a predetermined time is provided. A method for producing a quartz glass crucible for pulling a silicon single crystal, wherein the content of sulfur component is 1 ppm or less. 5. The quartz glass crucible has an opaque quartz glass layer containing a number of air bubbles and a transparent quartz glass layer formed on the inner surface thereof, and has a thickness of at least 1 mm from the inner surface of the transparent quartz glass layer. 1 × 10 ^{-7 to} 3 × 1 in the area of
The method according to claim 1, wherein bubbles of 0 ^-3 mm ³ / mm ³ are contained, and the content of the sulfur compound gas contained in the bubbles is 50% by volume or less based on the total gas amount contained in the bubbles. 5. The method for producing a quartz glass crucible for pulling a silicon single crystal according to 4. 6. The method for producing a quartz glass crucible for pulling a silicon single crystal according to claim 4, wherein the method for producing a quartz glass crucible is performed in an air atmosphere. 7. The method for producing a quartz glass crucible for pulling a silicon single crystal according to claim 4, wherein the method for producing a quartz glass crucible is performed in a hydrogen atmosphere. 8. The method for manufacturing a quartz glass crucible according to claim 4, wherein the method is performed in a nitrogen or helium atmosphere.
Or the method for producing a quartz glass crucible for pulling a silicon single crystal according to 5.