JP5793034B2 - Laminated crucible for casting silicon ingot and manufacturing method thereof - Google Patents

Description

  The present invention relates to a laminated crucible for casting a silicon ingot and an improvement of the manufacturing method thereof.

  Patent Document 1 discloses a mold for producing a silicon ingot for producing a silicon substrate for a photovoltaic power generation battery having excellent photoelectric conversion efficiency.

  As shown in the cross-sectional view of FIG. 2, the crucible for manufacturing a silicon ingot disclosed in Patent Document 1 is a fine fused silica sand 141 having a size of 50 to 300 μm made of silica inside a mold 102 made of quartz glass or graphite. It has a structure covered with a bonded inner layer 104. More specifically, the inner layer 104 is covered with an inner layer 104 formed by bonding fine fused silica sand 141 with silica 105, as shown in a partially enlarged view B of FIG. Since the inner layer 104 containing the fine fused silica sand 141 is easily peeled off from the inner wall of the mold 102, the outer periphery of the silicon ingot is pulled to the inner wall surface of the mold when the molten silicon is poured into the silicon ingot crucible 101 and solidified. As a result, peeling occurs and internal stress does not remain in the silicon ingot, and internal stress cracking does not occur during the manufacture of the silicon ingot. As a result, the yield is improved, and the light conversion efficiency of a photovoltaic power generation battery incorporating a silicon substrate produced using a silicon ingot with little residual internal stress is said to be greatly improved.

Japanese Patent Application Laid-Open No. 11-244988

  However, in the conventional crucible 101 for producing a silicon ingot in which the inner layer 104 mainly composed of the silica 105 and the fused silica sand 141 is formed inside the mold 102 made of quartz glass or graphite, when a silicon ingot is produced using the crucible 101, There was a problem that silica and fused silica sand, which are the main components of the inner layer, reacted with dissolved silicon, and oxygen easily dissolved in the silicon ingot. And in the silicon substrate produced using the silicon ingot which oxygen melt | dissolved, there existed a subject that it was difficult to improve the performance of the battery for photovoltaic power generation beyond this.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the laminated crucible for silicon ingot casting which can suppress the melt | dissolution of the oxygen in a silicon ingot, and its manufacturing method.

  In order to achieve the above object, the present inventors have conducted intensive research, and as a result, barium (Ba) is included in colloidal silica used as a binder when forming a stucco layer, thereby allowing crystallization at a lower temperature. I found out that I could do it. Further, since barium diffuses into the silica layer, the inventors have found that the effect of crystallization can be obtained by adding barium only to the stucco layer on the surface of the silica layer, and the present application has been completed.

That is, the present invention has the following configuration.
[1] A laminated crucible for casting a silicon ingot for producing a silicon ingot by melting and casting a silicon raw material,
Provided inside the cast mold, and the outer silica layer containing at least one layer of outer stucco layer coarse fused silica sand 500~1500μm bound with silica,
An inner silica layer including at least one inner stucco layer obtained by bonding fine fused silica sand of 50 to 300 μm with silica provided inside the outer silica layer,
The laminated crucible for casting a silicon ingot, wherein the inner stucco layer on the outermost surface of the inner silica layer contains barium hydroxide or barium carbonate having an average particle size of 0.1 to 0.01 µm.
[2] Any one or two or more stucco layers of the inner layer stucco layer other than the inner layer stucco layer on the outermost surface of the inner layer silica layer and the outer layer stucco layer of the outer layer silica layer are the barium hydroxide or barium carbonate. 2. A laminated crucible for casting a silicon ingot according to item 1 above.
[3] A slurry layer is formed by applying or spraying a slurry of fused silica powder and colloidal silica on the inside of the mold to form a slurry layer. Forming, and
Applying or spraying the slurry on the outer stucco layer to form a slurry layer, spraying 50-300 μm fine fused silica sand on the surface of the slurry layer, and forming an inner stucco layer;
Drying and firing,
Performing the step of forming the outer stucco layer one or more times, repeating the step of forming the inner stucco layer one or more times,
A silicon ingot characterized by using a barium-containing slurry obtained by adding barium hydroxide powder or barium carbonate powder having an average particle size of 0.1 to 0.01 μm to the slurry when forming the innermost stucco layer on the outermost surface. A method for producing a laminated crucible for casting.
[4] Using the barium-containing slurry in place of the slurry in any one or more of the step of forming the outer layer stucco layer and the step of forming the inner layer stucco layer other than the outermost inner layer stucco layer. 4. A method for producing a laminated crucible for casting a silicon ingot according to item 3 above.

  According to the laminated crucible for casting a silicon ingot of the present invention, the outer crucible layer is composed of one or more outer stucco layers provided inside the mold, and the one or more inner stucco layers are provided inside the outer silica layer. And an inner stucco layer on the outermost surface of the inner silica layer is configured to contain barium hydroxide or barium carbonate having an average particle size of 0.1 to 0.01 μm. Barium in the innermost stucco layer on the outermost surface diffuses into the inner and outer silica layers and lowers the temperature at which the silica layer changes, so that crystallization (cristobaliteization) of these inner and outer silica layers can be promoted. . Thereby, when a silicon ingot is cast from a silicon raw material that has been melted using a laminated crucible for casting a silicon ingot, it is possible to suppress the dissolution of silica into the silicon raw material, thereby reducing the oxygen concentration in the silicon ingot. be able to. Therefore, in the solar cell using the silicon ingot manufactured by the laminated crucible for casting the silicon ingot of the present invention, the photoelectric conversion efficiency can be improved.

  According to the method for manufacturing a laminated crucible for casting a silicon ingot according to the present invention, one or more outer stucco layers are formed inside a mold, one or more inner stucco layers are formed on the outer stucco layer, dried and fired. Thus, the outer silica layer and the inner silica layer are formed. When forming the outermost inner stucco layer, a barium-containing slurry obtained by adding barium hydroxide powder or barium carbonate powder having an average particle diameter of 0.1 to 0.01 μm to a slurry made of fused silica powder and colloidal silica is used. By using it, the laminated crucible for casting a silicon ingot of the present invention can be easily produced.

It is a figure for demonstrating the laminated crucible for silicon ingot casting which is one Embodiment to which this invention is applied, (a) is a cross-sectional schematic diagram, (b) is an expanded sectional view of A area | region shown in (a). is there. It is a cross-sectional schematic diagram which shows the conventional crucible for silicon ingot casting.

  Hereinafter, a laminated crucible for casting a silicon ingot which is an embodiment to which the present invention is applied will be described in detail. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.

As shown in FIG. 1 (a), a silicon crucible for crucible for silicon ingot casting (hereinafter simply referred to as “crucible”) 1 according to this embodiment is used for producing a silicon ingot by melting and casting a silicon raw material. The outer layer silica layer 3 provided inside the mold 2 and the inner layer silica layer 4 provided inside the outer layer silica layer 3 are schematically configured.
Since the crucible 1 has a laminated structure composed of the outer silica layer 3 and the inner silica layer 4, when the silicon ingot is produced by injecting and solidifying molten silicon into the cavity of the crucible 1, the outer periphery of the silicon ingot is Pulled on the inner wall surface of the crucible 1, the inner silica layer 4 adheres to the silicon ingot and peels from the outer silica layer 3. Thereby, internal stress does not generate | occur | produce in the solidified silicon ingot, but generation | occurrence | production of the crack and dislocation | rearrangement which are seen in the silicon ingot obtained by the conventional quartz crucible can be suppressed.

  The mold 2 is made of quartz glass or graphite. In addition, a space having an arbitrary size and shape (for example, a columnar space, a hexagonal columnar space, a cubical space, a rectangular parallelepiped space, or the like) is provided inside the mold 2, but is not particularly limited. Absent.

  For example, when a silicon ingot is manufactured using the crucible 1 formed of the mold 2 having a cubic or rectangular parallelepiped shape as the inner space, a silicon ingot having a square or rectangular cross section is obtained. And, when the silicon ingot having a square or rectangular cross section is used for manufacturing a silicon substrate having a square or a rectangle, such as a silicon substrate of a photovoltaic power generation battery, an expensive silicon ingot is most effectively utilized. Can do.

As shown in FIGS. 1A and 1B, the outer silica layer 3 includes one or more outer stucco layers 30 in which 500 to 1500 μm coarse fused silica sand 31 is bonded with a silica substrate (silica) 5. It consists of
Here, the reason why the particle size of the coarse fused silica sand 31 is limited to 500 to 1500 μm is as follows. That is, if the particle diameter of the coarse fused silica sand 31 is a fused silica sand coarser than 1500 μm, the specific gravity of the crucible 1 is lowered and the strength is lowered, which is not preferable. On the other hand, when the particle diameter of the coarse fused silica sand 31 is smaller than 500 μm, the strength of the outer silica layer 3 is reduced and the peelability from the inner silica layer 6 is deteriorated, which is not preferable.

The silica substrate 5 is composed of silica containing 10 to 6000 ppm of sodium.
Here, the sodium content of the silica constituting the silica substrate 5 is preferably in the range of 10 to 6000 ppm for the following reason. That is, if the sodium content is less than 10 ppm, it is not preferable because sufficient adhesion of the silica to the coarse fused silica sand 31 or the fine fused silica sand 41 cannot be obtained. On the other hand, if the sodium content of silica exceeds 6000 ppm, sodium will be contained in the silicon ingot as an impurity exceeding the allowable range, which is not preferable. A more preferable range of the sodium content contained in the silica is 500 to 6000 ppm.

  The layer thickness of the outer silica layer 3 needs to be at least about 3 mm because the strength of the crucible 1 at the time of manufacturing the silicon ingot must be maintained. On the other hand, if the layer thickness of the outer silica layer 3 is too thick, it is not preferable because it costs much. Therefore, specifically, the thickness of the outer silica layer 3 is preferably in the range of 3 to 20 mm.

As shown in FIGS. 1 (a) and 1 (b), the inner silica layer 4 includes at least one inner stucco layer 40 in which fine fused silica sand 41 of 50 to 300 μm is bonded with a silica substrate 5. ing.
Here, the reason why the particle diameter of the fine fused silica sand 41 is limited to 50 to 300 μm is as follows. That is, it is not preferable that the particle diameter of the fine fused silica sand 41 is coarser than 300 μm because it is difficult to peel from the outer silica layer 3. On the other hand, when the particle diameter of the fine fused silica sand 41 is finer than 50 μm, the inner silica layer 4 is easily peeled off, but the inner silica layer 4 is peeled off when the crucible 1 is manufactured (manufactured). It is not preferable.

In the crucible 1 of the present embodiment, as shown in FIG. 1B, a barium-containing inner layer stucco in which 50 to 300 μm fine fused silica sand 41 is bonded to at least the outermost surface of the inner silica layer 4 with a barium-containing silica substrate 6. It is characterized in that a layer 40 'is provided.
Thus, by providing the barium-containing inner layer stucco layer 40 ′ on the outermost surface of the inner layer silica layer 4, barium is diffused inside the inner layer silica layer 4 and the outer layer silica layer 3 to crystallize these silica layers. Can be promoted. In the present specification, a stucco layer formed using the barium-containing silica substrate 6 instead of the silica substrate 5 is referred to as a “barium-containing stucco layer”.

  The barium-containing silica substrate 6 includes 1 to 20% by volume of barium hydroxide or barium carbonate (hereinafter referred to as “barium-containing compound”) 61 having an average particle diameter of 0.1 to 0.01 μm in the silica substrate 5. It is contained so as to be in the concentration range.

  Here, the reason why the average particle size of the barium-containing compound 61 is limited to 0.1 to 0.01 μm is as follows. That is, it is not preferable that the average particle diameter of the barium-containing compound 61 is less than 0.01 μm because aggregation tends to occur. On the other hand, when the average particle size of the barium-containing compound 61 exceeds 0.1 μm, it is difficult to uniformly disperse, which is not preferable.

  The reason why the concentration of the barium-containing compound 61 is limited to 1 to 20% by volume is as follows. That is, it is not preferable that the concentration of the barium-containing compound 61 is less than 1% by volume because the degree of crystallinity is small. On the other hand, it is not preferable that the concentration of the barium-containing compound 61 exceeds 20% by volume because it does not dissolve.

  The thickness of the inner silica layer 4 is not particularly limited as long as it can be peeled off from the outer silica layer 3 by solidification shrinkage of the silicon ingot when the silicon ingot is manufactured using the crucible 1. is not. Specifically, the layer thickness is preferably in the range of 0.1 to 5 mm.

Next, the manufacturing method of the crucible 1 of this embodiment is demonstrated.
The method of manufacturing the crucible 1 of the present embodiment includes a step of forming the outer silica layer 3 inside the mold 2, a step of forming the inner silica layer 4 on the outer silica layer 3, a step of drying and firing, Is generally configured. Below, each process is demonstrated in detail.

(Preparation of slurry)
First, with respect to 100 parts of colloidal silica containing 10 to 6000 ppm of sodium and having an average particle size of 1 to 10 nm and containing 30% by volume, fused silica powder 200 having an average particle size of 30 to 100 μm. A slurry is prepared by mixing at a ratio of ˜400 parts.

(Adjustment of barium-containing slurry)
Next, a barium-containing slurry obtained by adding barium hydroxide powder or barium carbonate powder having an average particle diameter of 0.1 to 0.01 μm to the slurry is prepared.
Specifically, the slurry is mixed with barium hydroxide or barium carbonate having an average particle diameter of 0.1 to 0.01 μm so as to be in a concentration range of 1 to 20% by volume.

(Formation process of outer silica layer)
The outer silica layer 3 is formed by first applying or spraying the prepared slurry to the inside of the mold 2 to form a slurry layer. Next, 500 to 1500 μm of coarse fused silica sand 31 is sprayed on the surface of the slurry layer to form the outer stucco layer 30. The operation of forming the outer stucco layer 30 is repeated once or a plurality of times to form the outer silica layer 3.

(Formation process of inner silica layer)
In the step of forming the inner silica layer 4, first, the slurry is applied or sprayed on the outer silica layer 3 (outer stucco layer 30) to form a slurry layer. Next, the inner layer stucco layer 40 is formed by spraying 50 to 300 μm of fine fused silica sand 41 on the surface of the slurry layer.

  When the innermost stucco layer on the outermost silica layer 4 is formed, the adjusted barium-containing slurry is applied or sprayed on the inner stucco layer 40 (or the outer stucco layer 30) to form a barium-containing slurry layer. To do. Next, 50-300 μm fine fused silica sand 41 is sprayed on the surface of the barium-containing slurry layer, and the barium-containing slurry is applied or sprayed again to form a barium-containing inner layer stucco layer 40 ′.

Thus, the inner silica layer 4 is formed by repeating the operation of forming the inner stucco layer 40 once or a plurality of times.
When the operation of forming the inner stucco layer is performed once, the barium-containing inner stucco layer 40 ′ is formed on the outer stucco layer 30.

(Drying and firing process)
In the drying and firing step, first, the mold 2 having the outer layer silica layer 3 and the inner layer silica layer 4 laminated on the inside is dried in an environment of a temperature of 20 ° C. and a humidity of 50% over 24 hours. Next, baking is performed at about 1000 ° C. for 2 hours in the atmosphere. As a result, the outer silica layer 3 (outer stucco layer 30) and the inner silica layer 4 (inner stucco layer 40 and barium-containing inner stucco layer 40 ′) are formed inside the mold 2.

  Next, a method for manufacturing a silicon ingot using the crucible 1 of the present embodiment will be described.

First, raw silicon is charged into the crucible 1 and melted at 1500 ° C., or molten silicon at 1500 ° C. is injected.
Next, the lower part is cooled and solidified in one direction from the lower part to the upper part to produce a silicon ingot.

  Here, according to the crucible 1 of the present embodiment, since the outer layer silica layer 3 and the inner layer silica layer 4 have a laminated structure on the inner side, the outer periphery of the silicon ingot is pulled to the inner wall surface of the crucible 1, and the inner layer silica layer 4 Adheres to the silicon ingot and peels from the outer silica layer 3. Thereby, an internal stress does not generate | occur | produce in the solidified silicon ingot, but the silicon ingot by which generation | occurrence | production of the crack and dislocation | rearrangement seen by the silicon ingot obtained by the conventional quartz crucible was suppressed can be manufactured.

  By the way, with a conventional crucible, even when a silicon ingot is manufactured using a casting condition of 1500 ° C., the degree of crystallinity of the silica layer provided inside the mold is about 60%, and sufficient crystallization is achieved. Was not done. For this reason, there is a problem in that the silica, which is the main component of the silica layer, and the fused silica sand react with dissolved silicon, and oxygen dissolves into the molten silicon. Specifically, the oxygen concentration in the produced silicon ingot was about 20 ppm.

  On the other hand, according to the crucible 1 of the present embodiment, the barium-containing inner layer stucco layer 40 ′ is provided on the outermost surface of the inner silica layer 4 provided inside the mold 2, and this barium-containing inner layer stucco layer 40 is provided. Since barium diffuses from 'to the inner silica layer 4 or the outer silica layer 3, crystallization of these silica layers is promoted.

That is, when a silicon ingot is manufactured using a casting condition of 1500 ° C., the crystallization degree of the inner silica layer 4 and the outer silica layer 3 provided inside the mold 2 is about 90%, and sufficient crystallization is performed. The And reaction with the silica which is a main component of a silica layer, and fused silica sand, and molten silicon is suppressed. Specifically, the oxygen concentration in the silicon ingot produced by the crucible 1 of the present embodiment is reduced to about 10 ppm.
The crystallinity of the silica layer can be measured by, for example, XRD (X-ray diffractometer). The oxygen concentration in the silicon ingot can be measured by, for example, the FT-IR method.

  As described above, according to the crucible (laminated crucible for silicon ingot casting) 1 of the present embodiment, the outer silica layer 3 composed of one or more outer stucco layers 30 provided inside the mold 2, and the outer silica layer 3 and an inner layer silica layer 4 composed of one or more inner layer stucco layers 40, 40 'provided on the inner side of the inner layer 3, and the innermost layer stucco layer 40' of the inner layer silica layer 4 has an average particle size of 0.1 to 0. .01 μm of barium hydroxide or barium carbonate. The barium in the innermost stucco layer 40 'on the outermost surface diffuses into the inner and outer silica layers and lowers the transformation point temperature of the silica layer, so that the crystallization (cristobaliteization) of these inner and outer silica layers is promoted. Can do. Thereby, when casting a silicon ingot from the silicon raw material melted using the crucible 1, it is possible to suppress the dissolution of silica into the silicon raw material, so that the oxygen concentration in the silicon ingot can be reduced. Therefore, in the solar battery cell using the silicon ingot manufactured by the crucible 1 of the present embodiment, the photoelectric conversion efficiency can be improved.

  According to the method of manufacturing the crucible 1 of the present embodiment, one or more outer stucco layers 30 are formed inside the mold 2, and one or more inner stucco layers 40 are formed on the outer stucco layer 30, followed by drying and firing. Thus, the outer silica layer 3 and the inner silica layer 4 are formed. Then, when forming the outermost inner surface stucco layer 40 ', a barium-containing material is prepared by adding barium hydroxide powder or barium carbonate powder having an average particle size of 0.1 to 0.01 μm to a slurry made of fused silica powder and colloidal silica. By using the slurry, the crucible 1 of the present embodiment can be easily manufactured.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the crucible 1 of the above-described embodiment, an example in which only the outermost inner stucco layer 40 ′ constituting the inner silica layer 5 is a barium-containing stucco layer is shown, but the present invention is not limited to this.
Specifically, barium-containing slurry is used in place of the slurry in any one or more of the step of forming the outer layer stucco layer 30 and the step of forming the inner layer stucco layer 30 other than the innermost layer stucco layer 40 ′. Accordingly, any one or two or more stucco layers of the inner layer stucco layer 40 other than the innermost layer stucco layer 40 ′ other than the innermost layer stucco layer 40 ′ of the inner layer silica layer 4 and the outer layer stucco layer 3 are replaced with a barium-containing stucco layer It is good.
Thereby, the entire inner silica layer and the entire outer silica layer can be efficiently crystallized (cristobalite).

  Hereinafter, the effects of the present invention will be described in more detail by way of examples. In addition, this invention is not limited at all by the Example.

Example 1
A quartz glass mold having an inner diameter of 170 mm, an outer diameter of 190 mm, and a depth of 150 mm was prepared.
Further, ultrafine fused silica powder having an average particle diameter of 10 nm or less containing 0.5% of sodium: 100 parts of colloidal silica containing 30% by volume, with a ratio of 200 parts of fused silica powder having an average particle diameter of 40 μm. A slurry was prepared by mixing.
Further, the slurry was mixed at a ratio of barium carbonate having an average particle size of 0.1 μm or less: 10% by volume to prepare a barium-containing slurry.

  The slurry is applied to the inside of the quartz glass mold to form a slurry layer, and an outer stucco layer is formed by spraying coarse fused silica sand having an average particle diameter of 250 μm on the surface of the slurry layer. Repeatedly, an outer silica layer was formed.

  Next, the slurry is applied to the inside of the outer silica layer to form a slurry layer, and finely fused silica sand having an average particle size of 100 μm is sprayed on the surface of the slurry layer to form an inner stucco layer. Was repeated twice.

  Next, the barium-containing slurry is applied to the inside of the inner stucco layer to form a barium-containing slurry layer, and finely fused silica sand having an average particle size of 250 μm is sprayed on the surface of the slurry layer, and then the barium-containing slurry is again applied. It was applied to form a barium-containing inner layer stucco layer to form an inner silica layer.

  Next, a silica layer having a total thickness of 3 mm is formed on the inner side of the quartz glass mold by heating and holding at 1000 ° C. for 2 hours in the air atmosphere, followed by drying and firing. A laminated crucible for casting silicon ingot 1 (hereinafter simply referred to as a crucible) was produced.

  The crucible of Example 1 was charged with scraps (for example, bottom, tail, etc.) produced when pulling a single crystal as raw materials, and then kept at a temperature of 1500 ° C. to dissolve the raw materials. The molten silicon thus obtained was added at 0.3 ° C./min. The unidirectionally solidified silicon ingot was manufactured by cooling from below the mold at a cooling rate of 5 ° C.

When the surface of the obtained unidirectionally solidified silicon ingot was inspected for the presence of internal stress cracks, no internal stress cracks were confirmed.
Moreover, when the amount of interstitial oxygen contained in the obtained unidirectionally solidified silicon ingot was measured, it was 1.0 × 10 ⁻¹⁸ (atm / cc).
Furthermore, the obtained unidirectionally solidified silicon ingot was sliced to produce a photovoltaic power generation silicon substrate, and the photoelectric conversion efficiency was measured. As a result, the photoelectric conversion efficiency was about 15%.

(Comparative Example 1)
As in Example 1, the slurry was applied to the inside of the quartz glass mold to form a slurry layer, and an outer stucco layer was formed by spraying coarse fused silica sand having an average particle size of 250 μm on the surface of the slurry layer. And this operation was repeated three times to form an outer silica layer.

  Next, the slurry is applied to the inside of the outer silica layer to form a slurry layer, and finely fused silica sand having an average particle size of 100 μm is sprayed on the surface of the slurry layer to form an inner stucco layer. Was repeated three times to form an inner silica layer.

  Next, a silica layer having a total thickness of 3 mm is formed inside the quartz glass mold by heating and holding at 1000 ° C. for 2 hours in an air atmosphere, followed by drying and firing, and the crucible of Comparative Example 1 is formed. Manufactured.

  In this crucible of Comparative Example 1, the scrap produced at the time of pulling the single crystal was melted at 1500 ° C. in the same manner as in Example 1, and 0.3 ° C./min. The unidirectionally solidified silicon ingot was manufactured by cooling at a cooling rate of 1 mm.

When the surface of the obtained unidirectionally solidified silicon ingot was inspected for the presence of internal stress cracks, no internal stress cracks were confirmed.
Moreover, when the amount of interstitial oxygen contained in the obtained unidirectionally solidified silicon ingot was measured, it was 2.0 × 10 ⁻¹⁸ (atm / cc).
Furthermore, the obtained unidirectionally solidified silicon ingot was sliced to produce a photovoltaic power generation silicon substrate, and the photoelectric conversion efficiency was measured. As a result, the photoelectric conversion efficiency was about 14%.

1 ... Laminated crucible for casting silicon ingot (crucible)
2 ... Mold 3 ... Outer silica layer 4 ... Inner silica layer 5 ... Silica substrate 6 ... Barium-containing silica substrate 30 ... Outer stucco layer 31 ... Coarse fused silica sand 40 ..Inner stucco layer 40 '... barium-containing inner stucco layer 41 ... fine fused silica sand 61 ... barium-containing compound

Claims (4)

A laminated crucible for casting a silicon ingot for melting and casting a silicon raw material to produce a silicon ingot,
Provided inside the cast mold, and the outer silica layer containing at least one layer of outer stucco layer coarse fused silica sand 500~1500μm bound with silica,
An inner silica layer including at least one inner stucco layer obtained by bonding fine fused silica sand of 50 to 300 μm with silica provided inside the outer silica layer,
The laminated crucible for casting a silicon ingot, wherein the inner stucco layer on the outermost surface of the inner silica layer contains barium hydroxide or barium carbonate having an average particle size of 0.1 to 0.01 µm.   One or more stucco layers of the inner layer stucco layer other than the inner layer stucco layer on the outermost surface of the inner layer silica layer and the outer layer stucco layer of the outer layer silica layer contain the barium hydroxide or barium carbonate. The laminated crucible for casting a silicon ingot according to claim 1. Applying or spraying a slurry made of fused silica powder and colloidal silica to the inside of the mold to form a slurry layer, and spraying 500 to 1500 μm of coarse fused silica sand on the surface of the slurry layer to form an outer stucco layer When,
Applying or spraying the slurry on the outer stucco layer to form a slurry layer, spraying 50-300 μm fine fused silica sand on the surface of the slurry layer, and forming an inner stucco layer;
Drying and firing,
Performing the step of forming the outer stucco layer one or more times, repeating the step of forming the inner stucco layer one or more times,
A silicon ingot characterized by using a barium-containing slurry obtained by adding barium hydroxide powder or barium carbonate powder having an average particle size of 0.1 to 0.01 μm to the slurry when forming the innermost stucco layer on the outermost surface. A method for producing a laminated crucible for casting.   The barium-containing slurry is used instead of the slurry in any one or more of the step of forming the outer layer stucco layer and the step of forming the inner layer stucco layer other than the outermost inner layer stucco layer. A method for producing a laminated crucible for casting a silicon ingot according to claim 3.

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