JPH11171684A - Quartz glass crucible for producing silicon single crystal and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quartz crucible used for pulling up a silicon single crystal and suitable for improving the quality of the silicon single crystal in good productivity, and to provide a method for producing the quartz crucible. SOLUTION: This quartz glass crucible is obtained by charging silicon dioxide powder 6 into a rotated mold 1 to form a layered preform along the inner surface of the mold 1, heating the preform from its inner surface to partially melt the silicon dioxide powder of the preform, simultaneously or subsequently scattering a crystallization-accelerating agent on the inner wall surface of the formed base body outer layer 3 comprising the translucent quartz glass layer to form a crystallization-accelerating agent-containing layer 4a having a high crystallization-accelerating agent concentration, and subsequently scattering and fusing synthetic quartz powder 6 on the crystallization-accelerating agent layer 4a to form a synthetic quartz glass layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quartz glass crucible used for pulling a silicon single crystal and a method for manufacturing the same, and more particularly, to a silicon single crystal suitable for improving crucible productivity and silicon single crystal quality. The present invention relates to a quartz glass crucible for pulling and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a so-called Czochralski method has been widely adopted for producing a single crystal substance such as a single crystal semiconductor material. In this method, polycrystalline silicon is melted in a vessel, and the end of the seed crystal is immersed in the molten bath and pulled up while rotating. A single crystal having the same crystal orientation grows on the seed crystal. . For this single crystal pulling container, a quartz glass crucible is generally used.

Usually, a quartz glass crucible has been used for a long time while holding a silicon melt at 1400 ° C. or higher. At this time, brown cristobalite precipitated on the surface of the quartz glass in contact with the silicon melt, which was mixed into the melt and caused dislocation of the single crystal.

In recent years, as the size of a wafer has increased, the size of a quartz glass crucible used for manufacturing a single crystal has further increased. However, with the prolonged use time,
The generation of the brown cristobalite also increased, and these were mixed into the melt to increase crystal dislocation.

In consideration of this point, as disclosed in Japanese Patent Application Laid-Open No. 8-2932, a coating film containing a crystallization accelerator or a solid-melting layer is formed within a thickness of 1 mm on the inner surface of a quartz glass crucible for pulling a silicon single crystal. Accordingly, a crystal layer is formed on the inner surface of the crucible during the production of a single crystal to prevent the inner surface from being roughened, and the specification of EP 0 735 605 and EP 07488.
No. 85 proposes a cristobalite crucible by adding a crystallization accelerator to the inner and outer surfaces of the quartz glass crucible, but Ba on the inner surface is taken into the single crystal as an impurity and the quartz glass crucible is held. There is also contamination of graphite crucibles.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 9-52791, it has been proposed to make cristobalite by slow cooling after melting. If this proposal is used, the incorporation of impurities into the single crystal is eliminated, but productivity is poor and not satisfactory.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. In particular, only a low-viscosity inner synthetic silica glass layer is selectively crystallized to pull up a silicon single crystal. In addition to improving the single crystal crystallization rate by suppressing the inner surface roughness, the incorporation of impurities into the single crystal is small and defects can be kept extremely low, making it suitable for improving crucible productivity and silicon single crystal quality. An object of the present invention is to provide a quartz glass crucible for pulling a silicon single crystal and a method for manufacturing the same.

[0008]

In order to solve the above-mentioned problems, a method for manufacturing a quartz glass crucible for pulling a silicon single crystal according to the present invention comprises the steps of: A method of manufacturing, comprising: (a) charging silicon dioxide powder into the mold, and forming a layered shape along the inner surface of the mold to form a pre-molded body;
(B) heating the inner surface of the pre-molded body to partially melt the silicon dioxide powder to form a translucent quartz glass layer crucible substrate; (c) during or after forming the crucible substrate, (D) forming a crystallization accelerator-containing layer having a high crystallization accelerator concentration along the inner wall surface of the crucible substrate by scattering a crystallization accelerator on the inner wall surface of the crucible substrate; Forming a synthetic quartz glass layer by scattering and fusing the synthetic quartz powder on the crystallization accelerator-containing layer on the wall surface.

In the step (c), a high-temperature gas atmosphere is formed inside the crucible substrate, and a crystallization accelerator is contained in the synthetic quartz powder or supplied alone in the high-temperature gas atmosphere to form the high-temperature gas atmosphere. By melting in a gas atmosphere and scattering toward the inner wall surface of the crucible substrate, a step of forming a crystallization accelerator-containing layer having a high crystallization accelerator concentration along the inner wall surface of the crucible substrate is performed. preferable.

In the step (d), the synthetic quartz powder is supplied to the high-temperature gas atmosphere, melted in the high-temperature gas atmosphere, and scattered toward the crystallization accelerator-containing layer on the inner wall surface of the crucible substrate. Thus, it is preferable to form a step of forming a synthetic quartz layer.

A first embodiment of the quartz glass crucible for producing a silicon single crystal according to the present invention comprises a crucible base made of a translucent quartz glass layer, a crystallization accelerator-containing layer formed on the inner wall surface of the crucible base, It is characterized by comprising a synthetic quartz layer formed on the crystallization accelerator-containing layer.

A second aspect of the quartz glass crucible for producing a silicon single crystal according to the present invention is that a crystallized crystal layer is formed between an outer layer of a translucent quartz glass layer composed of a crucible substrate and a synthetic quartz layer formed inside the outer layer. It is characterized by having an accelerator-containing layer interposed and selectively crystallizing toward the inner surface of the synthetic quartz layer.

The above synthetic quartz layer has a thickness of 0.5 × 10 ⁻³ c.
m ³ / cm ³ or less, for example, 0.01 × 10 ^{−3 to} 0.20 ×
It is a transparent layer containing air bubbles of 10 ⁻³ cm ³ / cm ³ , and the thickness of the layer is 0.3 mm or more, for example, 1 to 5 mm. The total content of metal element impurities in the synthetic quartz powder and the synthetic quartz layer is less than 1 ppm.

[0014] The amount of the crystallization accelerator contained in the crystallization accelerator-containing layer is 1 × with respect to the inner surface of the crucible base.
It is preferable that the concentration be 10 ⁻⁸ to 1 × 10 ⁻⁵ M / cm ² .
If the amount of the crystallization accelerator is less than 1 × 10 ⁻⁸ M / cm ² , the effect is small, and if it exceeds 1 × 10 ⁻⁵ M / cm ² , crystallization occurs after the production is completed, and cristobalite is preferably separated. Absent.

As the crystallization accelerator, a Group 2a element or a Group 3b element may be used. Examples of the Group 2a element include magnesium, strontium, calcium and barium, and examples of the Group 3b element include aluminum. However, barium compounds such as barium hydroxide and barium oxide are particularly preferred.

These crystallization promoters can be used either in a simple form or in a mixture with synthetic quartz powder. The method of adding the crystallization accelerator is a method of spraying an aqueous solution on the inner surface of the outer layer during or after the formation of the outer layer, a method of depositing a synthetic quartz powder sufficiently impregnated with the aqueous solution, and a method of adding a crystallization accelerator. There is a method of using a powder obtained by mixing a synthetic quartz powder or a powder of a crystallization accelerator. The crystallization accelerator-containing layer exists as a coating film or a solid solution layer on the inner layer surface.

As the silicon dioxide powder, natural quartz powder can be used. When the outer layer is made of natural quartz, the inner synthetic quartz layer moves from the outer layer, for example, Li.
There is a disadvantage that it is contaminated by such factors.

There is a method in which the inner and outer layers are made of synthetic quartz glass using synthetic quartz powder as the silicon dioxide powder. However, in this case, there remains a problem that the viscosity is low and the material is susceptible to thermal deformation. However, since the crystallization accelerator-containing layer is interposed between the inner and outer layers, the crystallization accelerator-containing layer can be selectively crystallized in both the inner and outer directions with the crystallization accelerator-containing layer as a center. There is an advantage of being in a state of being left.

According to the principle of the present invention, the crystallization accelerator-containing layer containing a crystallization accelerator such as Ba between the inner layer of synthetic quartz glass and the outer layer of, for example, natural quartz glass is heated. The crystal nuclei are formed by the treatment, and the synthetic quartz layer on the inner surface is selectively transformed into cristobalite.

This synthetic quartz layer is in a heat-strengthened state due to its phase transition to cristobalite. The use of a quartz glass crucible having a synthetic quartz layer in which cristobalite undergoes a phase transition to cristobalite allows the elution of quartz glass into a silicon melt, which has been conventionally observed, during the production of silicon single crystals operating at about 1400 ° C. or higher. Spots formed by the reaction between the glass melt and the quartz glass and the silicon melt and polycrystallization due to the peeling thereof can be suppressed.

More specifically, the method for producing a quartz glass crucible for producing a silicon single crystal according to the present invention will be described. Natural quartz powder is put into a rotating upper opening mold and molded into a layer along the inner surface of the mold. After forming a pre-molded body and heating the inner surface of the pre-molded body to partially melt the natural quartz powder in a high-temperature gas atmosphere, it is cooled and solidified to form a crucible substrate of a translucent quartz glass layer. During or after the formation of the crucible substrate, a crystallization promoter, for example, a synthetic quartz powder containing a barium compound or a barium compound alone is continuously supplied and scattered toward the inner wall surface of the crucible substrate, whereby the crucible substrate is formed. A crystallization promoting containing layer having a high barium concentration is formed along the inner wall surface. Then, the synthetic quartz powder is supplied into the high-temperature gas atmosphere, and is scattered toward the inner wall surface of the crucible substrate, thereby forming a crystallization accelerator, for example, a synthetic quartz glass on a crystallization accelerator-containing layer having a high barium concentration. Form a layer.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory sectional view showing an apparatus used for carrying out the method of the present invention and a method for manufacturing a quartz crucible using the apparatus. FIG. 2 is a partial cross-sectional view of a quartz crucible for pulling a silicon single crystal obtained by the method of the present invention.

In FIG. 1, a rotary mold 1 has a rotating shaft 2. A cavity 1a is formed in the mold 1 and a base 3 of a quartz crucible constituting an outer layer, that is, a translucent quartz glass layer formed of silicon dioxide powder, for example, natural quartz powder, is disposed in the mold cavity 1a.

The substrate 3 is prepared by charging silicon dioxide powder into a rotating mold 1 and forming a layer along the inner wall of the mold 1 to obtain a preformed molded article having a crucible shape. It is manufactured by heating the inner surface to melt the quartz powder.

For heating from the inner surface, an arc discharge device 5 having carbon electrodes 51 and 52 connected to a power source 10 as shown in FIG. 1 can be used. A plasma discharge device may be used instead of the arc discharge device 5. The production of the base 3 is described in Japanese Patent Publication No. 4-2286.
No. 1 has a detailed description.

The apparatus shown in FIG. 1 includes a quartz powder supply tank containing synthetic quartz powder 6 above the mold 1 for forming the inner layer 4. The supply tank 9 is connected to a discharge pipe 93 provided with a measuring feeder 92. A stirring blade 91 is disposed in the supply tank 9. The upper part of the mold 1 is covered with the lid 71 except for the slit opening 75.

After or during the formation of the base 3, the carbon electrode 5 of the arc discharge device 5
A crystallization accelerator, for example, a barium compound, alone or in a state of being contained in synthetic quartz powder, is supplied to the inside of the substrate 3 while continuing the heating by the discharge from 1, 52. By the operation of the arc discharge device 5, a high-temperature gas atmosphere 8 is formed in the substrate 3. Therefore, the crystallization accelerator is supplied into the high-temperature gas atmosphere 8.

The crystallization accelerator supplied into the high-temperature gas atmosphere 8 is at least partially melted by the heat in the high-temperature gas atmosphere 8, and is simultaneously scattered toward the inner wall surface of the substrate 3. To form a crystallization-promoting agent-containing layer 4 a integrally with the substrate 3. The crystallization accelerator-containing layer 4a has a predetermined crystallization accelerator concentration.

Next, the measuring feeder 92 for supplying the synthetic quartz powder 6 is opened to the adjusted opening degree, and the discharge pipe 93 is opened.
To supply only the synthetic quartz powder 6 to form a substantially bubble-free quartz glass layer, that is, an inner layer 4 on the inner surface of the substrate 3. The method for forming the inner layer 4 is described in detail in the above-mentioned Japanese Patent Publication No. 4-22861.

FIG. 2 shows a cross section of a quartz crucible obtained by this method. The quartz crucible according to the present invention comprises an outer layer or base 3 formed by heating and melting silicon dioxide powder, for example, natural quartz powder from the inner surface, and a synthetic quartz powder discharged into a high-temperature gas atmosphere to be melted and scattered. And an inner layer 4 attached to the inner wall surface of the inner layer 4.
The crystallization accelerator-containing layer 4a is formed between them.

[0031]

Embodiments of the present invention will be described below.

Example 1 A 22-inch quartz glass crucible was manufactured using the apparatus shown in FIG. At the time of production, 20 kg of natural quartz powder was supplied and shaped into a rotating upper opening mold to prepare a pre-molded body to be an outer layer.

The pre-molded body is heated and melted from the inner surface, and after forming the outer layer, an aqueous solution of barium hydroxide containing 10 mM Ba ion is sprayed so that the volume becomes about 10 μg per square centimeter. The supplied synthetic quartz glass layer was formed as an inner layer which was a transparent layer.

20 × 50 × 1 cut out from this crucible
Table 1 shows the results of heating a 0 mm quartz glass piece at 1500 ° C. for 3 hours. As is clear from Table 1, the entire transparent layer was converted to cristobalite, and it was confirmed that a very good quartz glass crucible was obtained.

Comparative Example 1 Using the apparatus shown in FIG. 1, a quartz glass crucible was manufactured under the same conditions as in the example except that the aqueous barium hydroxide solution was not sprayed. 20 × cut out from this crucible
Table 1 shows the results of heating a 50 × 10 mm piece of quartz glass at 1500 ° C. for 3 hours. As shown in Table 1, cristobalite formation of the entire transparent layer did not occur.

[0036]

[Table 1]

[0037]

As described above, when the quartz glass crucible of the present invention is used for pulling a silicon single crystal, the transparent layer of the quartz glass crucible is selectively crystallized, so that impurities serving as a crystallization promoting agent become silicon. Since it is not in contact with the melt, no impurities are taken into the silicon single crystal, which is effective in suppressing crystal defects. Further, the quartz glass crucible of the present invention has an advantage that it can withstand long-time use because it is thermally strengthened. According to the method of the present invention, there is an effect that the quartz glass crucible according to the present invention can be effectively manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an apparatus used for carrying out the method of the present invention and a method for manufacturing a quartz crucible using the apparatus.

FIG. 2 is a cross-sectional view of a part of a silicon single crystal pulling quartz crucible obtained by the method of the present invention.

[Explanation of symbols]

1 mold, 1a cavity, 2 rotation axis, 3 outer layer, 4
Inner layer, 4a Crystallization accelerator containing layer, 5 Arc discharger, 6 Synthetic quartz powder, 9 Supply tank, 93 Discharge pipe

Claims (13)

[Claims] 1. A method of manufacturing a quartz glass crucible for pulling a silicon single crystal using a rotating upper opening mold, comprising the steps of: (a) charging silicon dioxide powder into the mold, and forming the powder along the inner surface of the mold; Forming a pre-molded body by molding into a layer,
(B) heating the inner surface of the pre-molded body to partially melt the silicon dioxide powder to form a translucent quartz glass layer crucible substrate; (c) during or after forming the crucible substrate, (D) forming a crystallization accelerator-containing layer having a high crystallization accelerator concentration along the inner wall surface of the crucible substrate by scattering a crystallization accelerator on the inner wall surface of the crucible substrate; Forming a synthetic quartz glass layer by scattering and fusing the synthetic quartz powder on the crystallization-promoting agent-containing layer on the wall surface, thereby producing a quartz glass crucible for producing a silicon single crystal. 2. In the step (c), a high-temperature gas atmosphere is formed inside the crucible base, and a crystallization accelerator is contained in the synthetic quartz powder in the high-temperature gas atmosphere or supplied alone, and A step of forming a crystallization accelerator-containing layer having a high crystallization accelerator concentration along the inner wall surface of the crucible substrate by melting in a high-temperature gas atmosphere and scattering toward the inner wall surface of the crucible substrate. Claim 1 characterized by the following:
A method for producing a quartz glass crucible for producing a silicon single crystal as described above. 3. In the step (d), the synthetic quartz powder is supplied to the high-temperature gas atmosphere, melted by the high-temperature gas atmosphere, and scattered toward the crystallization promoter-containing layer on the inner wall surface of the crucible base. 3. The method for producing a quartz glass crucible for producing a silicon single crystal according to claim 2, wherein the step is a step of forming a synthetic quartz layer. 4. The amount of the crystallization accelerator contained in the crystallization accelerator-containing layer is 1 × 10 5 with respect to the inner surface of the crucible base.
^-8 to 1 × 10 ^-5 any one method for manufacturing a silicon single crystal for producing a quartz glass crucible according to claim 1, characterized in that the M / cm ^2. 5. The method according to claim 1, wherein the crystallization promoter is a Group 2a element or 3b.
The method for producing a quartz glass crucible for producing a silicon single crystal according to claim 1, wherein the method is a group III element. 6. The method for producing a quartz glass crucible for producing a silicon single crystal according to claim 1, wherein the crystallization accelerator is a barium compound. 7. The method for producing a quartz glass crucible for producing a silicon single crystal according to claim 1, wherein the silicon dioxide powder is a natural quartz powder. 8. A crucible base made of a translucent quartz glass layer, a crystallization accelerator-containing layer formed on the inner wall surface of the crucible base, and a synthetic quartz layer formed on the crystallization accelerator-containing layer. A quartz glass crucible for producing a silicon single crystal. 9. A crystallization accelerator-containing layer is interposed between an outer layer of a translucent quartz glass layer comprising a crucible substrate and a synthetic quartz layer formed inside the outer layer, and an inner surface of the synthetic quartz layer is provided. A quartz glass crucible for producing a silicon single crystal, which is selectively crystallized toward the surface. 10. The crystallization accelerator contained in the crystallization accelerator-containing layer is 1 × 10 ^{−5 with} respect to the inner surface of the crucible base.
~1 × 10 ^-8 M / cm ² silicon single crystal for producing a quartz glass crucible according to claim 8 or 9 wherein, wherein the a. 11. The quartz glass crucible for producing a silicon single crystal according to claim 8, wherein the semi-transparent quartz glass layer is a translucent natural quartz glass layer. 12. The method according to claim 12, wherein the crystallization promoter is a Group 2a element or 3
The quartz glass crucible for producing a silicon single crystal according to any one of claims 8 to 11, wherein the crucible is a group b element. 13. The quartz glass crucible for producing a silicon single crystal according to claim 8, wherein the crystallization accelerator is a barium compound.