JPH09255477A - Composite quartz crucible for silicon melting and production of single crystal using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a quartz crucible for melting silicon, capable of preventing breakage of a single crystal growth. SOLUTION: The complex quartz crucible for melting silicon is a quartz crucible 1 for melting silicon inserted in the interior of carbon crucible 4 as crucible having double structure and the cylindrical part 1a and the bottom 1c are made of translucent quartz glass and a part containing a bending part 1b in the lower part is made of transparent quartz glass. This method for producing silicon single crystal compresses melting a silicon raw material on an inert atmosphere under reduced pressure and coagulating the melt while upwardly pulling by using seed crystal. In this case, the crystal is pulled up by using the composite quartz crucible as quartz crucible inserted in the interior of the carbon crucible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quartz crucible for melting silicon capable of preventing single crystal growth breakage that occurs during pulling of a silicon single crystal, and a method for producing a large-diameter silicon single crystal using the crucible. It is a thing.

[0002]

2. Description of the Related Art In order to manufacture a silicon single crystal, a method of melting a high-purity silicon raw material in an argon atmosphere under reduced pressure and solidifying it while pulling it upward with a seed crystal is widely used.

FIG. 2 is a longitudinal sectional view showing an apparatus for producing a silicon single crystal which is solidified while being pulled up. Symbols in the figure
Reference numeral 8 is a chamber for depressurizing the pulling atmosphere of the silicon single crystal 11, and inside the chamber is a double-structured melting crucible.
5, a heating heater 6 composed of an induction heating coil and the like is provided around the outer side of the crucible, and a heat insulating cylinder 7 formed of a heat insulating material in a cylindrical shape is further disposed outside thereof. . In the melting crucible, a raw material for crystal growth that is melted by a heater, that is, a molten silicon raw material 9 is stored. The lower end of the seed crystal 10 attached to the tip of the pulling wire 12 is brought into contact with the surface of the melt, and the seed crystal is pulled upward to grow a silicon single crystal 11 in which the melt is solidified at the lower end. .

At this time, the melting crucible is rotated by the rotating shaft 15, and the silicon single crystal is rotated by the rotating mechanism (not shown) provided above the pulling wire in opposite directions. The melting crucible has a double structure and the inside is made of quartz glass.
(Hereinafter, this is referred to as "quartz crucible"), and the outside is made up of a carbon container 4 (hereinafter referred to as "carbon crucible").

The inside of the chamber is depressurized to about 10 torr, argon gas is supplied from the gas supply port 13, and SiO gas generated from the surface of the silicon melt and CO gas generated from the carbon crucible and the heater are mixed with the argon gas. Exhaust from the gas exhaust port 14. When condensed impurities such as SiO gas and CO gas are taken into the single crystal growth interface, the growth of the single crystal is interrupted halfway, and a phenomenon of polycrystallization (hereinafter referred to as “DF break”) occurs.

In recent years, there has been an increasing demand for silicon single crystals having a large diameter (8 to 12 inches), the silicon single crystals to be pulled have a large diameter, and the yield of single crystals due to DF breakage decreases. Usually, during the pulling of the silicon single crystal, the boundary between the silicon melt and the crystal is monitored by a camera provided on the side wall of the chamber, and the pulling is stopped when a DF break occurs. Therefore, there is a problem that the yield of the single crystal is reduced due to the treatment of the residual hot water or the breakage of DF, and preventing this is an important issue especially in pulling the single crystal having a large diameter.

In order to prevent the occurrence of DF breakage, it is necessary to prevent impurities from being introduced into the single crystal growth interface, and various countermeasures have been proposed and implemented. Regarding the quartz crucible, the following proposals have been made because oxygen and bubbles contained in a small amount in the quartz glass can be dissolved in the silicon melt and cause DF breakage.

(1) In Japanese Utility Model Publication No. 62-175077, a bottomed cylinder made of semitransparent quartz glass is fitted with a bottomed or non-bottomed cylinder made of transparent quartz glass, and both There has been proposed a quartz crucible capable of pulling a single crystal having a uniform oxygen concentration distribution with less generation of dislocations and mixing of impurities by heating and integrating.

(2) JP-A-6-329493 discloses that the inner wall of the crucible is composed of a transparent glass layer in which substantially no bubbles are contained and an outer portion is a semitransparent glass layer in which bubbles are contained, and the bottom part is substantially formed. There has been proposed a quartz crucible that has good thermal conductivity and can improve the yield of single crystallization by using a crucible made of a transparent glass layer having no bubbles therein.

(3) In Japanese Patent Laid-Open No. 7-53295, at least the bottom of the quartz glass crucible is semitransparent, and the center line average roughness Ra of the entire outer surface of the quartz glass crucible is 0.1 μm to 50 μm.
There has been proposed a quartz crucible capable of improving contact with a carbon crucible and improving yield (single crystallization rate) of pulling a silicon single crystal by setting m.

(4) Kagami and Hayashi's supervision "Applied technology of high-purity silica" 1991.3.1 CMC published p.187 shows that as the transparentized part becomes thicker, the heat radiation from the upper edge of the crucible increases and the heating power The temperature distribution in the crucible increases and the temperature distribution inside the crucible increases. Therefore, it has been attempted to make the upper half of the crucible half transparent.

FIG. 3 is a longitudinal sectional view showing the structure of the quartz crucible proposed in the above-mentioned publicly known document. (A) and (b) are the crucible, (c) and () shown in document (2). d) is a crucible shown in Document (1), (e) is a crucible shown in Document (3), and (f) is a longitudinal sectional view showing the structure of the crucible shown in Document (4).

[0013]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a quartz crucible capable of reducing elution of bubbles from the quartz crucible and pulling a single crystal which does not have dislocations, and a manufacturing method using the same. Especially.

[0014]

As a result of various studies on the cause of DF breakage of a silicon single crystal, the present inventor has found that the higher the transparency of silica glass, that is, the lower the abundance of air bubbles, the more the air bubbles in silicon are formed. The inventors have found that the occurrence of DF breakage is reduced by using quartz glass with a low penetration and high transparency in the bent portion of the bottom, and thus the present invention has been completed. The gist of the present invention resides in the following silicon melting quartz crucible shown in FIG. 1 and a method for producing a silicon single crystal shown below.

A quartz crucible 1 for melting silicon, which is inserted into a carbon crucible 4 as a double-structured crucible, in which a straight body portion 1a and a bottom portion 1c are semitransparent quartz glass, and a lower bent portion.
A compound quartz crucible for melting silicon, in which the portion including 1b is transparent quartz glass.

In a method for producing a silicon single crystal in which a silicon raw material is melted in a depressurized inert atmosphere and is solidified while being pulled upward by using a seed crystal, a quartz crucible to be inserted into a carbon crucible is used as a straight cylinder. A method for producing a silicon single crystal in which a crystal is pulled using a compound quartz crucible in which the bottom and the bottom are semitransparent quartz glass and the portion including the lower bent portion is transparent quartz glass.

Here, transparent quartz glass means that the abundance of bubbles is 0.01% (hereinafter referred to as “vol.%”) Or less in volume ratio, and semitransparent quartz is 0.1 vol.% Or more. To do.

[0018]

1 is a longitudinal sectional view showing a silicon melting crucible having a quartz crucible of the present invention inserted therein. As shown in the figure, the melting crucible 5 of the present invention is a double-structured crucible in which the quartz crucible 1 is inserted inside the outer carbon crucible 4.

In the quartz crucible, the straight body portion 1a and the bottom portion 1c are made of semitransparent quartz glass, and the portion including the lower bent portion 1b is made of transparent quartz glass having a bubble existence rate of 0.01 vol.% Or less. Therefore, the elution of impurities such as alkali metals present in the bubbles is small.

From the results of various tests conducted by the inventors, it was found that the amount of bubbles eluted from the bent portion was particularly large in the quartz crucible, because the transparent quartz glass was used for the portion including the bent portion in the lower portion of the crucible. It is due to the fact. The reason is considered to be influenced by the flow of the silicon melt. Also,
Since the bottom is less affected by the above, it was considered that it is not necessary to use transparent glass.

As will be described in detail in Examples below, a quartz crucible was manufactured by combining quartz glass of various materials, and a pulling test of a silicon single crystal was conducted. It was found that when a composite quartz crucible for melting silicon, which is composed of transparent quartz glass and the lower bent portion is transparent quartz glass, the occurrence of DF breakage due to elution of bubbles is small.

The quartz crucible of the present invention is manufactured by melting and molding quartz powder by a usual arc melting method, and the following conventional methods can be used.

Quartz powder as a raw material is deposited on the inner peripheral surface of the mold. At this time, by making the grain size of the quartz powder forming the portion including the lower bent portion of the crucible sufficiently smaller than the grain diameter of the quartz powder forming the straight body portion and the bottom portion, the portion including the lower bent portion is made transparent. Can be encouraged. Next, the quartz powder deposited on the bottom surface of the mold with a certain thickness is melted by, for example, arc heating, the surface of the deposited quartz layer is melted and vitrified, and the pressure is reduced from the mold side. Air inside the quartz layer is sucked through the pores to form a transparent glass layer on the surface of the quartz layer. After that, the position of the heating source is adjusted, the heating source is brought close to the portion including the bending portion, and the portion including the bending portion is remelted under reduced pressure to make the portion including the bending portion transparent.

In the quartz crucible manufactured by this method, no clear boundary appears at the joint between the transparent portion and the semi-transparent portion, and it is confirmed that the abundance ratio of the bubbles changes.

[0025]

EXAMPLE A silicon single crystal manufacturing apparatus shown in FIG. 2 in which the melting quartz crucible shown in FIGS.
A 0 mm single crystal was produced.

A quartz crucible having an inner diameter of 560 mm, a height of 360 mm and a thickness of 12 mm, and the crucible shown in Table 1 were manufactured by the above method. Synthetic quartz is used for the transparent quartz glass part,
The range was 0.01 vol.% Or less. In addition, natural quartz is used for the semi-transparent quartz glass part, and the existence rate of bubbles is 0.1 vo.
The range is l.% or more.

[0027]

[Table 1]

Using a double-structured melting crucible in which the above quartz crucible was inserted into a carbon crucible, 100 kg of polycrystalline silicon was melted to produce a single crystal having a length of 1000 mm. Further, as a comparative example, a similar silicon single crystal was manufactured using the quartz crucible described in the report as shown in FIG. The oxygen concentration results and the DF cutting rate (value obtained by dividing the length of the polycrystallized portion by the total length) of the upper T, the central portion M and the bottom B of the obtained silicon single crystal were examined for each of three bodies. , Table 1
It was shown to.

The test piece in which the crucible of the present invention (crucible number 1) is arranged has little variation in oxygen concentration in TMB in the growth direction of the single crystal, and the DF cut rate is as small as 5%.

The test piece in which the crucible and the transparent glass of the present invention having the reverse configuration of the crucible (crucible number 2) are arranged has a large fluctuation in oxygen concentration in the single crystal TMB and a large DF cut rate of 20%. .

As shown in FIG. 3 (a), the test body in which the crucible (crucible number 3) made of transparent glass was placed in the inner layer was the case where the fluctuation of the oxygen concentration in the single crystal TMB was the case where the crucible of the present invention was used. It is slightly larger than the above, and the DF cut rate is 10%.

As shown in FIG. 3 (b), a test body in which a crucible (crucible number 4) made of transparent glass is arranged in a part of the inner layer is
The fluctuation of oxygen concentration in single crystal TMB is large and DF
The cutting rate is as high as 20%.

As shown in FIG. 3 (d), a test body having a crucible (crucible number 5) made of transparent glass on the inner layer and the bottom was used in the crucible of the present invention in which fluctuation of oxygen concentration in TMB of a single crystal was observed. It is slightly larger than when it is done and the DF cut rate is 10
%, Which is a little large.

Transparent glass on the straight body as shown in FIG. 3 (e),
The test piece in which a crucible (crucible number 6) using semitransparent glass is arranged at the bottom has a large fluctuation in oxygen concentration in TMB of a single crystal and a large DF cut rate of 15%.

As shown in FIG. 3 (f), a crucible having a semi-transparent glass for the straight body of the inner layer and a transparent glass for the bottom (crucible number 7)
In the test body in which the sample was arranged, the fluctuation of the oxygen concentration in the single crystal TMB was large, and the DF cut rate was as large as 15%.

The crucible conventionally used, that is, the test body in which the crucible (crucible number 8) using the translucent glass is arranged, has a large fluctuation of the oxygen concentration in the TMB of the single crystal,
The DF cut rate is as high as 20%.

[0037]

According to the apparatus for producing a silicon single crystal having the quartz crucible for melting silicon of the present invention, it is possible to reduce the DF cut rate due to the generation of dislocations.

[Brief description of drawings]

FIG. 1 is a longitudinal section showing a double crucible for melting silicon, in which a quartz crucible of the present invention is inserted.

FIG. 2 is a vertical sectional view showing a silicon single crystal manufacturing apparatus for solidifying while pulling.

FIG. 3 is a view showing a cross section of a known silicon melting crucible, (a) and (b) are references for improving thermal conductivity, (c) and (d) are references for reducing elution of impurities, and (e) is a crucible described in the literature that defines the surface roughness of the outer surface of the quartz crucible, and (f) is a longitudinal sectional view showing the structure of the crucible described in the literature whose bottom is made of transparent quartz glass. .

[Explanation of symbols]

 1. Quartz crucible 1a. Straight body part 1b. Bend 1c. Bottom 2. Semi-transparent part 3. Transparent part 4. Carbon crucible 5. Double structure melting crucible 6. Heater for heating 7. 7. Heat insulation tube Chamber 9. Silicon melt 10. Seed crystal 11. Silicon single crystal 12. Pull bar 13. Gas supply port 14. Gas outlet 15. Axis of rotation

Claims (2)

[Claims] 1. A quartz crucible for melting silicon, which is inserted into a carbon crucible as a double-structured crucible, wherein a straight body and a bottom are made of semitransparent quartz glass, and a portion including a lower bent portion is made of transparent quartz glass. A composite quartz crucible for melting silicon, which is characterized in that 2. In a method for producing a silicon single crystal in which a silicon raw material is melted in a depressurized inert atmosphere and solidified while being pulled up by using a seed crystal, a quartz crucible to be inserted into a carbon crucible, A method for producing a silicon single crystal, which comprises pulling a crystal using a compound quartz crucible having a straight body portion and a bottom portion of semitransparent quartz glass, and a portion including a lower bent portion is transparent quartz glass.