JP2005060152A - Manufacturing method for quartz crucible, quartz crucible, and manufacturing method for silicon single crystal using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a quartz crucible having increased<SP>28</SP>Si content and suitable for pulling up silicon single crystal, at a low cost, the quartz crucible, and a manufacturing method for the silicon single crystal using the same. <P>SOLUTION: In the manufacturing method for the quartz crucible for pulling up the silicon single crystal, the quartz crucible is manufactured by supplying crystalline natural quartz powder and/or silica powder into a rotating mold to form a crucible shaped powder layer, heating the powder layer internally to melt the powder layer, and during or after a process for forming a crucible base body having many bubbles, supplying synthetic silica power containing ≥92.3% silicon isotope<SP>28</SP>Si into the inside of the base body and at least partially melting the silica powder to be deposited on the inside surface of the base body to form a transparent synthetic silica glass layer containing ≥92.3%<SP>28</SP>Si on the inside surface of the base body. The quartz crucible and the manufacturing method for silicon single crystal using the same are provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a method for producing a quartz crucible for pulling a silicon single crystal, a quartz crucible, and a method for producing a silicon single crystal using the same. In particular, the present invention relates to a method for producing a quartz crucible suitable for pulling a silicon single crystal containing ²⁸ Si in a proportion higher than that in a natural Si raw material, a quartz crucible, and a method for producing a silicon single crystal using the same.

  Conventionally, in pulling a silicon single crystal by the Czochralski method (CZ method), a quartz crucible has been used as a container for storing a silicon melt as a raw material. This quartz crucible for pulling up a silicon single crystal is generally manufactured by an arc heating rotary molding method using a purified quartz powder obtained by pulverizing and purifying naturally produced quartz or quartz as a raw material.

  The quartz crucible manufactured by this method is a raw material powder layer formed in a crucible shape in a rotating mold and melt-formed by arc discharge heating from the inside, and thus has a smooth inner surface, It has a translucent appearance that contains fine bubbles in high density in the layer. This so-called multi-bubble layer has the function of making the heat conduction from the external heating source into the crucible uniform, but the quartz crucible for pulling up the silicon single crystal has the structure of this multi-bubble layer and the inner surface. It is extremely important to stabilize the pulling of the silicon single crystal.

  To realize the above structure, it has a two-layer structure in which a substantially bubble-free transparent layer having a smooth inner surface and a predetermined thickness (about 0.5 mm to 2 mm) is used as an inner layer and a multi-bubble layer is used as an outer layer. A quartz crucible has been confirmed to be extremely excellent, and a quartz crucible and a manufacturing method thereof have been disclosed (see, for example, Patent Documents 1 to 3).

  The quartz crucible according to the above disclosure has a smooth inner surface of the crucible and a bubble-free inner layer of a predetermined thickness, so that even if the inner surface of the crucible melts during the pulling of the silicon single crystal, the surface becomes rough. Since the liquid level of the silicon melt accompanying the pull-up is very low, the liquid level does not vibrate, and cristobalite due to surface roughness is rarely generated on the inner surface of the crucible. Does not leave the crucible surface and fall into the silicon melt. Accordingly, the pulling of the silicon single crystal can be stably performed, and the productivity of the silicon single crystal can be greatly improved.

  On the other hand, high-quality silicon wafers are required for recent VLSI manufacturing. Attempts to use synthetic quartz powder instead of conventional natural quartz or quartz powder as raw material powder for crucible production to produce high-purity quartz crucibles necessary for stable production of high-quality silicon wafers Has been made. For example, a quartz crucible is disclosed in which a multi-bubble layer is formed with natural quartz particles, the inner surface is lined with synthetic quartz particles, and a smooth thin amorphous layer is formed on the surface of the lining layer (for example, a patent) Reference 4). However, the crucible disclosed herein has a smooth thin amorphous film on its inner surface, but has a thickness of at most about 0.1 mm, and the entire layer has a multi-bubble structure. . In other words, it is not a crucible having a substantially bubble-free transparent layer with a thickness of 0.5 mm or more as described above, so that it can withstand long-time use such as single crystal pulling multiple times. Absent.

  Also disclosed is a method of obtaining a high-purity quartz glass crucible by melting a sintered product of a product made from high-purity silicon tetrachloride as a raw material (see, for example, Patent Document 5). . On the other hand, in order to contain a high concentration of oxygen in the silicon single crystal, the inner layer as a glass layer is formed by melting synthetic quartz powder having an OH group content of 200 ppm or more, and the outer layer is a natural crystal powder having an OH group content of 100 ppm or less. There is disclosed a quartz crucible for pulling a silicon single crystal formed by melting (see, for example, Patent Document 6). The main purpose of these disclosures is to obtain a high-purity quartz crucible and to ensure that oxygen impurities are contained in a silicon single crystal to a certain degree of high concentration. By simply melting synthetic quartz powder according to these teachings, a glass layer is obtained. By simply forming, the obtained glass layer does not become a sufficiently bubble-free transparent layer, and cannot be suitable for stable silicon single crystal pulling. Furthermore, since the crucibles disclosed in these are not crucibles having a substantially bubble-free transparent layer with a thickness of 0.5 mm or more, they can withstand long-time use such as pulling a single crystal multiple times. It is not a thing.

  As a raw material for forming the synthetic silica glass layer, crystalline synthetic silica may be used, but crystalline synthetic silica is an amorphous material obtained by hydrolysis of ester silane or sodium silicate or halogenated silane. Silica is expensive because it undergoes many steps of crystallizing by heat devitrification using alkali or the like as a seed for crystallization, purifying and pulverizing, and has not yet been economically put into practical use.

Synthetic silica powder is generally amorphous and has the advantage of being economical for forming a glass layer. However, since amorphous silica powder has a stable melting point, it is difficult to form a smooth surface, and this property is an obstacle to the use of synthetic silica powder.
Therefore, in a quartz crucible having a two-layer structure in which a substantially bubble-free transparent layer is an inner layer and a multi-bubble layer is an outer layer, the inner layer is a high-purity synthetic silica glass having a predetermined thickness (0.5 mm or more). And a crucible manufactured by the method (see, for example, Patent Document 7).

Meanwhile, there are three types of stable isotope ^{28 Si,} 29 ^Si, 30 Si is a silicon element, the natural silicon, these composition ratios ²⁸ Si is ^92.23%, 29 Si is 4.67% , ³⁰ Si is always constant at 3.10%. Silica present in nature contains silicon as SiOx, and the composition ratio of isotopes is the same as the composition ratio of silicon.

On the other hand, silicon wafers with good thermal conductivity are required for recent VLSI manufacturing in order to ensure stable operating characteristics. The good when the silicon wafer thermal conductivity in order to stably produce, polysilicon of ^{28 Si} in a quartz crucible of ^{28 Si} which is an isotope element containing more than 92.3% of the silicon containing more than 92.3% There is known a method of manufacturing a silicon wafer having good thermal conductivity by pulling up a silicon single crystal in which the content of ²⁸ Si is increased by charging the silicon (see, for example, Patent Document 8).
Si having an increased proportion of isotopes can be produced by a gas diffusion method, a centrifugal separation method, a laser separation method, or the like (see, for example, Patent Document 9).

JP-A-1-148718 Japanese Patent Laid-Open No. 1-148882 Japanese Patent Laid-Open No. 1-148883 U.S. Pat. No. 4,528,163 Japanese Examined Patent Publication No. 62-36974 JP 61-44793 A Japanese Patent No. 2933404 JP 2002-87900 A JP 2001-199792 A

However, the production of Si with one kind of isotope element as described above is expensive, and a production method for obtaining such a quartz crucible at low cost has been demanded.
The main object of the present invention is to solve the above-mentioned problems and to provide a method for producing a quartz crucible suitable for pulling up a silicon single crystal having an increased content of ²⁸ Si, and a quartz crucible.

In order to achieve the above object, the present invention provides a method for producing a quartz crucible for pulling a silicon single crystal, wherein a crystalline natural quartz powder and / or silica powder is supplied into a rotating mold to obtain a crucible-shaped powder. A layer is formed and heated from the inner surface of the powder layer to melt the powder layer, and during or after the step of forming a multi-bubble crucible substrate, silicon isotope ²⁸ Si is formed inside the substrate. Is supplied to the inner surface of the substrate while at least partially melting the synthetic silica powder, and ²⁸ Si is 92% on the inner surface of the substrate. Provided is a method for producing a quartz crucible for pulling a silicon single crystal, wherein a transparent synthetic silica glass layer containing 3% or more is formed (claim 1).

Thus, the crucible base body of the multi bubbles after formation with or formed as an outer layer, the inner surface ^{28 Si} of the substrate by forming a transparent synthetic silica glass layer which is contained more than 92.3%, the ^{28 Si} A quartz crucible suitable for pulling up a silicon single crystal having a high content can be manufactured at low cost.

At this time, it is preferable to use the synthetic silica powder having a specific surface area of 5 m ² / g or less.
Thus, by using a synthetic silica powder having a specific surface area of 5 m ² / g or less as a synthetic silica powder containing ²⁸ Si at a rate of 92.3% or more, a bubble-free transparent synthetic silica having a smooth inner surface is used. A glass layer can be formed, and a quartz crucible suitable for stably pulling a silicon single crystal with an increased content of ²⁸ Si can be manufactured at a low cost.

Further, it is preferable to use amorphous synthetic silica powder synthesized so that silicon isotope element ²⁸ Si is contained in a proportion of 92.3% or more as the synthetic silica powder.
Thus, if a transparent silica glass layer is formed using amorphous synthetic silica powder synthesized so that ²⁸ Si is contained at a rate of 92.3% or more, the content of ²⁸ Si can be ensured. A quartz crucible suitable for pulling up the raised silicon single crystal can be manufactured at low cost.

Moreover, it is preferable to use the synthetic silica powder having an OH group content of 170 ppm or less.
Thus, if a transparent silica glass layer is formed using a synthetic silica powder containing ²⁸ Si at a rate of 92.3% or more and having an OH group content of 170 ppm or less, the strength and resistance of the glass layer are improved. meltable is high, it is possible to inexpensively manufacture a more stable quartz crucible suitable for pulling up a silicon single crystal having an increased content of ^{28 Si.}

The transparent synthetic silica glass layer is preferably formed to have a thickness of 0.5 mm or more.
Thus, if a transparent synthetic silica glass layer containing 28.3% or more of ²⁸ Si is formed to have a thickness of 0.5 mm or more, a silicon single crystal with an increased ²⁸ Si content can be pulled up. A quartz crucible that is suitable and can withstand long-term use can be manufactured at low cost.

The crucible base is preferably formed so that the Al concentration is 5 ppm or more.
In this way, if the multi-bubble crucible base material as the outer layer is formed so that the Al concentration is 5 ppm or more, it is suitable for pulling up a silicon single crystal with an increased ²⁸ Si content, and has a higher heat resistance and a longer length. A quartz crucible that can withstand the use of time can be manufactured at low cost.

The crucible base is preferably formed to have a diameter of 350 mm or more.
In this way, when the multi-bubble crucible base material which is the outer layer is formed to have a diameter of 350 mm or more, a large diameter of 150 mm or more required recently, for example 200 mm (in this case, the diameter of the crucible is about 450 mm). Suitable for pulling up a silicon single crystal having a diameter such as (preferably) or 300 mm (in this case, the diameter of the crucible is preferably about 500 mm) and having an increased content of ²⁸ Si. become.

Further, the present invention is a quartz crucible containing a crystal raw material, which has a base made of multi-bubble quartz glass and an inner layer made of transparent synthetic silica glass, and the inner layer is made of silicon isotope element ²⁸ Si of 92.3. A quartz crucible characterized in that it is contained at a rate of not less than% is provided (claim 8).

Thus, if the quartz crucible consists of two layers of the base and the inner layer, and the inner layer contains silicon isotope element ²⁸ Si in a proportion of 92.3% or more, the content rate of ²⁸ Si was increased. It becomes an inexpensive quartz crucible suitable for pulling up a silicon single crystal.

The inner layer preferably has an OH group content of 200 ppm or less.
As described above, when the OH group content of the inner layer containing ²⁸ Si at a rate of 92.3% or more is 200 ppm or less, the strength of the inner layer and the melt resistance are high, and the silicon content of ²⁸ Si is increased. It becomes an inexpensive quartz crucible suitable for pulling a single crystal more stably.

The inner layer preferably has a thickness of 0.5 mm or more.
^Thus, if the 0.5mm or more thickness of the inner layer 28 Si is contained more than ^92.3%, suitable for pulling a silicon single crystal having an increased content of 28 Si, and for a long time more An inexpensive quartz crucible that can withstand use.

The substrate preferably has an Al concentration of 5 ppm or more.
Thus, if the Al concentration of the multi-bubble crucible base material as the outer layer is 5 ppm or more, it is suitable for pulling up a silicon single crystal with an increased ²⁸ Si content, and has a higher heat-resistant strength and can be used for a long time. An inexpensive quartz crucible that can withstand

The diameter is preferably 350 mm or more (claim 12).
Thus, in the case of a quartz crucible having a diameter of 350 mm or more, a large diameter of 150 mm or more required recently, for example, 200 mm (in this case, the diameter of the crucible is preferably about 450 mm) or 300 mm (in this case, the crucible of the crucible). diameter less expensive quartz crucible suitable for pulling about 500mm is has a diameter such as preferred), and silicon increase the content ratio of ^{28 Si} single crystal.

The present invention also provides a method for producing a silicon single crystal characterized by using the above-mentioned quartz crucible to pull up the silicon single crystal (claim 13).
If the silicon single crystal is pulled up by using a quartz crucible in which such an inner layer contains the silicon isotope element ²⁸ Si in a proportion of 92.3% or more, the silicon single crystal having an increased ²⁸ Si content is reduced. Can be manufactured at cost.

According to the present invention, a multi-bubble crucible base is formed using crystalline natural quartz powder and / or silica powder as a raw material, and silicon isotope element ²⁸ Si is contained in the base at a ratio of 92.3% or more. the synthetic silica powder was supplied, the synthetic silica powder at least partially while melting adhere to the inner surface of the substrate a transparent synthetic silica glass layer in which the inner surface ^{28 Si} of the substrate is contained more than 92.3% by forming the, from the content of the ^{28 Si} transparent synthetic silica glass layer is the inner surface is not less than 92.3%, Si to melt into the silicon melt is the content of ^{28 Si} than native Si high. And without the use of expensive SiOx material is high content of ^{28 Si} in the production of such a quartz crucible in large quantities, synthetic silica glass layer of the quartz crucible inner layer only since may be used as a high content of ^{28 Si, 28} Si A quartz crucible suitable for pulling up a silicon single crystal with a high content of can be produced at a low cost.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.
As described ^above, making the 28 Si from a silicon single crystal of ²⁸ Si in a quartz crucible containing by charging the polysilicon containing more than 92.3% increased the content of the manufactured ²⁸ Si least 92.3% The silicon wafer has a high thermal conductivity, and has high performance in recent years manufactured using the same, and enhances the heat dissipation effect of the VLSI that becomes high temperature during operation, and is suitable for stabilizing the operation characteristics.

However, a raw material with an increased content of ²⁸ Si is expensive because it is difficult to mass-produce. Therefore, while suppressing the use of raw material with an increased content of ^{28 Si,} is pulling the silicon single crystal having an increased content of ^{28 Si} suppress the production cost, it is important in producing an inexpensive product.

The inventors of the present invention have a two-layer structure of a quartz crucible used in the production of a silicon single crystal having an increased ²⁸ Si content, and an inner layer of a transparent synthetic silica glass layer containing at least 92.3% of ²⁸ Si. if the outer layer and multi-bubble of the crucible base body, with the advantages of the quartz crucible of a conventional two-layer structure, and so may be used raw materials with increased content of only ^{28 Si} in the inner layer, the entire quartz crucible ²⁸ It has been found that the cost of raw materials can be significantly reduced compared to the case of using a raw material with a high Si content, and that the manufacturing cost can be reduced, so that a silicon single crystal can be produced at a low cost, and the present invention has been completed. It was.

Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of a rotary molding apparatus for producing a quartz crucible used in the method of the present invention.

  A rotary mold 1 shown in FIG. 1 includes a rotary shaft 2, and a cavity 1 a is formed in the rotary mold 1. First, the rotary mold 1 is rotated around the rotary shaft 2 to supply crystalline natural quartz powder and / or silica powder into the cavity 1a, and the powder is preformed into a desired crucible shape, and this preformed powder is used as a heat source. The multi-bubble crucible base 3 that forms the outer layer of the quartz crucible is formed by heating from the inner surface 5 to melt and cool the powder.

  The diameter of the crucible base 3 formed at this time is not particularly limited, but if the diameter is 350 mm or more, a large diameter of 150 mm or more recently required, for example 200 mm (in this case, the diameter of the crucible is about 450 mm). And a quartz crucible suitable for pulling up a silicon single crystal having a diameter of 300 mm (in this case, the diameter of the crucible is preferably about 500 mm). In this case, the crucible base 3 can have a desired diameter by selecting the diameter of the rotary mold 1.

  Moreover, regarding the crystalline natural quartz powder and / or silica powder supplied at this time, it is preferable that the content of each of Na, K, and Li is 0.3 ppm or less and the Al content is 5 ppm or more. Each of the alkali metal Na, K, and Li ions has a relatively high diffusion rate at a high temperature in quartz glass, affects the deterioration of the inner layer surface, and deteriorates the quality of the silicon single crystal to be pulled. If the content of Na, K, Li is 0.3 ppm or less, the above problem does not occur. Moreover, although the heat resistance strength of a quartz crucible improves by containing Al, it is preferable to contain 5 ppm or more in order to ensure sufficient heat resistance strength. The upper limit of the Al content is not particularly limited, but the Al content of quartz usually used as a raw material for crystal natural quartz powder is about 60 ppm or less, and even if it is further increased, the heat resistance strength is not particularly improved. Therefore, the use of crystalline natural quartz powder having an Al content of 5 to 60 ppm is industrially advantageous.

  Since the crucible substrate 3 formed in this way is multi-bubble, when the silicon single crystal is pulled up, the heat conduction from the external heating source to the inside of the crucible is made uniform and the mechanical strength of the crucible is increased to pull up the silicon single crystal. It has the effect of reducing thermal deformation at time (about 1450 ° C.). If the crystalline quartz component is unevenly distributed in the vicinity of the outer surface of the substrate 3, thermal deformation can be further reduced.

Next, the inside of the substrate 3 is heated by the heat source 5 while rotating the mold 1. The base 3 has an open upper end, and a lid 7 is installed so as to leave a ring-shaped gap above the opening. The lid 7 is installed to adjust the temperature inside the substrate during melting and heating, but the fine powder (particle size of 30 μm or less) slightly contained in the silica and the sublimation component of the silica are scattered, leaving the gap. Next, the synthetic silica powder 6 containing ²⁸ Si in a proportion of 92.3% or more is supplied to the inside of the substrate 3. The synthetic silica powder 6 is supplied from the supply tank 9 to the inside of the substrate 3 through the nozzle 8 while adjusting the supply amount with a measuring feeder.

  The inside of the substrate 3 is heated, and when the supplied synthetic silica powder 6 reaches the inner surface of the substrate 3, at least a part is in a molten state. At this time, the inner surface of the substrate 3 is also in a molten state, and the synthetic silica powder 6 adheres to the inner surface of the substrate 3 to form a transparent synthetic silica glass layer 4 that is integral with the substrate 3 and substantially free of bubbles. .

The synthetic silica powder 6 supplied at this time is desirably non-porous in order to form a complete transparent silica glass layer 4 without bubbles, and has a specific surface area of 5 m ² as a measure of non-porosity. / G or less is desirable. If the synthetic silica powder 6 is porous, even if the synthetic silica powder 6 in the molten state as described above adheres to the inner surface of the substrate 3, only a layer containing a large amount of bubbles is formed. It is impossible to form a transparent synthetic silica glass layer 4 that is free of bubbles. The synthetic silica powder 6 having a particle size of 30 to 1000 μm can be used, but preferably has a particle size of 100 to 300 μm.

  Furthermore, it is preferable to use the synthetic silica powder 6 having an OH group content of 170 ppm or less. If the OH group content of the raw material synthetic silica powder 6 is 170 ppm or more, the OH group content of the formed transparent silica glass layer 4 tends to increase a little more than 200 ppm or more. Thus, when the OH group content of the transparent silica glass layer, which is the inner layer of the quartz crucible, is 200 ppm or more, the strength is lowered and the material is easily softened, and the dissolution rate in the silicon melt is increased. As a result, when pulling up a silicon single crystal using this quartz crucible, irregularities are generated at the interface with the silicon melt, the silicon melt surface is vibrated up and down, and the diameter of the pulled silicon single crystal fluctuates or is pulled up. Defects increase, which is undesirable. Further, when the OH group content is 500 ppm or more, the crystal is often broken during the pulling of the silicon single crystal. However, if a synthetic silica powder 6 having an OH group content of 170 ppm or less is used, such a problem can be suppressed and a stable silicon single crystal can be pulled up.

The synthetic silica powder 6 is preferably an amorphous synthetic silica powder synthesized so that the silicon isotope element ²⁸ Si is contained in a proportion of 92.3% or more. Thus, if a transparent silica glass layer is formed using amorphous synthetic silica powder synthesized so that ²⁸ Si is contained at a rate of 92.3% or more, the content of ²⁸ Si can be ensured. Can be high and inexpensive.

Such synthetic silica powder is produced by, for example, tetramethoxysilane, tetraalkoxysilane such as ethyl orthosilicate, or tetraalkoxysilane, which is produced by a centrifugal separation method or a gas diffusion method and contains ²⁸ Si in a proportion of 92.3% or more. Silica is synthesized by the so-called sol-gel method, flame hydrolysis method or other known methods in which raw materials such as halogenated silane are hydrolyzed and dried and sintered, and powder is obtained at this synthesis stage, or this synthetic silica is For example, a transparent glass body can be obtained by defoaming and melted, and the transparent glass body can be pulverized to obtain a non-porous material.

  Further, if the transparent silica glass layer 4 is formed with a thickness of 0.5 mm or more, even if the inner surface of the crucible melts during the pulling of the silicon single crystal, there is sufficient thickness, so that all the glass layers 4 are melted. Since the surface roughness is very small, the quartz crucible can stably carry out the pulling of the silicon single crystal and can withstand longer use. In this case, it is preferable that the thickness of the transparent silica glass layer 4 is thick. However, if the thickness is too large, the cost increases, so 20 mm is sufficient. In addition, the elution rate to the silicon melt of the transparent silica glass layer 4 of the quartz crucible is measured in advance, and the upper limit of the thickness of the transparent silica glass layer 4 can be obtained from the maximum value of the silicon single crystal growth time.

Moreover, in the said embodiment, the multi-bubble crucible base | substrate 3 is formed first and the transparent synthetic silica layer 4 is formed in the inner surface. However, the present invention is not limited to the above embodiment, and is a rotating type rotating a mixed powder of crystalline natural quartz powder and synthetic silica powder containing silicon isotope element ²⁸ Si in a proportion of 92.3% or more. 1 is supplied, distributed along the inner surface of the rotary die 1 to form a powder layer having a predetermined thickness, and the quartz powder layer is heated and melted from the inner surface while the rotary die 1 is rotated. You may perform the process of forming the transparent synthetic silica glass layer 4 simultaneously with the process of forming the base | substrate 3. FIG. Further, when forming the crucible base 3, the heating conditions are adjusted at the stage where the powder layer is heated and melted from the inner surface, so that the entire powder layer is not vitrified or the outside of the rotary mold 1 is cooled as necessary. In addition, the crystalline natural quartz powder is unevenly distributed in the vicinity of the outer surface of the crucible base 3, so that the thermal deformation of the crucible when the silicon single crystal is pulled can be reduced.

  As a means for heating and melting the powder layer and the synthetic silica powder, it is effective to perform arc discharge or the like using an electrode such as carbon as the heat source 5. At least two electrodes, an anode and a cathode, are required as electrodes, but arc discharge is also possible with three or more electrodes. Separate electrodes may be prepared for forming the crucible base 3 and for forming the transparent synthetic silica glass layer 4. By adjusting the distance between the electrode and the distance between the tip of the electrode and the crucible substrate, the melting of the powder can be controlled, and a transparent synthetic silica glass layer having a desired thickness can be formed in the crucible substrate.

FIG. 2 shows a partially cut perspective view of a quartz crucible for pulling a silicon single crystal manufactured according to an embodiment of the present invention. This quartz crucible has a base 3 ′ made of multi-bubble quartz glass and an inner layer 4 ′ made of transparent synthetic silica glass, and the inner layer contains silicon isotope element ²⁸ Si in a ratio of 92.3% or more. It is. The substrate 3 'has Na, K, and Li contents of 0.3 ppm or less and an Al content of 5 ppm or more. The inner layer 4 'has an OH group content of 200 ppm or less. Further, the diameter of the quartz crucible is 350 mm or more, which is suitable for pulling a large-diameter silicon single crystal having a diameter of 150 mm or more.
In the present invention, in principle, the ratio of the silicon isotope element ²⁸ Si in the substrate 3 ′ is not limited. Typically, in order to reduce costs, it is preferable that only the inner layer 4 ′ has a high content of ²⁸ Si, so that all the inner walls of the crucible in contact with the silicon melt have a high content of ²⁸ Si. it can. However, increasing the ²⁸ Si content of the substrate 3 ′ is not excluded.

Examples of the present invention will be described in more detail below, but the present invention is not limited thereto.
(Example 1)
As an embodiment of the present invention, crystalline natural quartz powder having a particle size distribution of 100 to 300 μm is supplied into a molding die of a rotary molding apparatus to form a powder layer having a thickness of 14 mm, and is placed inside the powder layer. Arc discharge is performed using the carbon electrode thus formed and heated and melted from the inside to form a crucible base, and at the same time, synthetic silica powder is supplied to the inside of the powder layer and adhered to the inner surface of the powder layer while melting the synthetic silica powder. Thus, a quartz glass crucible having a thickness of 7.9 mm and a diameter of 350 mm having a transparent synthetic silica glass layer having a thickness of 1 mm was produced. Synthetic silica powder used as a raw material for the transparent synthetic silica glass layer is obtained by pulverizing silica glass synthesized from tetrachlorosilane which has been subjected to isotope separation by gas diffusion method and has a high content of silicon isotope ²⁸ Si. Yes, as a result of measurement using a secondary ion mass spectrometer (SIMS), the content of ²⁸ Si was 99.9%.

Synthetic silica powder content of ^{28 Si} used in the manufacture of the quartz glass crucible of 99.9% of the example was 12% or less of the Zenkonatai necessary raw materials in the crucible manufacture. Therefore, according to the present invention, a quartz crucible suitable for pulling up a silicon single crystal having an increased ²⁸ Si content can be produced at low cost without using a large amount of expensive raw materials in producing the quartz crucible. Moreover, since a smooth transparent glass layer is provided on the inner side of the quartz crucible, it is extremely preferable for growing a silicon single crystal.

  The present invention is not limited to the above embodiment. The above embodiment is merely an example, and the present invention has the same configuration as that of the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

It is a section schematic diagram of the rotation molding device for quartz crucible manufacture in the embodiment of the present invention. 1 shows a partially cut perspective view of a quartz crucible for pulling a silicon single crystal manufactured according to an embodiment of the present invention.

Explanation of symbols

1 ... Rotation type,
1a ... cavity,
2 ... Rotation axis,
3, 3 '... crucible base,
4, 4 '... transparent synthetic silica glass layer,
5 ... heat source,
6 ... Synthetic silica powder,
7 ... lid,
8 ... Nozzle,
9: Supply tank.

Claims (13)

A method for producing a quartz crucible for pulling a silicon single crystal, comprising supplying a crystalline natural quartz powder and / or silica powder into a rotating mold to form a crucible-shaped powder layer, During or after the step of forming the multi-bubble crucible base by heating from the inner surface to melt the powder layer, the silicon isotope element ²⁸ Si is contained in the base at a ratio of 92.3% or more. The synthetic silica powder is supplied and adhered to the inner surface of the substrate while at least partially melting the synthetic silica powder, and transparent synthetic silica containing 92.3% or more of ²⁸ Si on the inner surface of the substrate A method for producing a quartz crucible for pulling a silicon single crystal, wherein a glass layer is formed. The method for producing a quartz crucible for pulling a silicon single crystal according to claim 1, wherein the synthetic silica powder has a specific surface area of 5 m ² / g or less. The amorphous synthetic silica powder synthesized so that the silicon isotope element ²⁸ Si is contained in a proportion of 92.3% or more is used as the synthetic silica powder. The manufacturing method of the quartz crucible for silicon single crystal pulling of description.   The method for producing a quartz crucible for pulling a silicon single crystal according to any one of claims 1 to 3, wherein the synthetic silica powder has an OH group content of 170 ppm or less.   The method for producing a quartz crucible for pulling a silicon single crystal according to any one of claims 1 to 4, wherein the transparent synthetic silica glass layer is formed to have a thickness of 0.5 mm or more.   The method for producing a quartz crucible for pulling a silicon single crystal according to any one of claims 1 to 5, wherein the crucible base is formed so that the Al concentration is 5 ppm or more.   The method for producing a quartz crucible for pulling a silicon single crystal according to any one of claims 1 to 6, wherein the crucible base is formed to have a diameter of 350 mm or more. A quartz crucible containing a crystal raw material, having a base made of multi-bubble quartz glass and an inner layer made of transparent synthetic silica glass, the inner layer containing silicon isotope element ²⁸ Si in a proportion of 92.3% or more A quartz crucible characterized by being made.   The quartz crucible according to claim 8, wherein the inner layer has an OH group content of 200 ppm or less.   The quartz crucible according to claim 8 or 9, wherein the inner layer has a thickness of 0.5 mm or more.   The quartz crucible according to any one of claims 8 to 10, wherein the substrate has an Al concentration of 5 ppm or more.   The quartz crucible according to any one of claims 8 to 11, wherein the diameter is 350 mm or more.   A method for producing a silicon single crystal, comprising pulling up the silicon single crystal using the quartz crucible according to any one of claims 8 to 12.

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