JP2004298897A - Member for polycrystalline silicon casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a member for polycrystalline silicon casting which is excellent in durability, which can be repeatedly used, and which can be easily manufactured. <P>SOLUTION: The member for the polycrystalline silicon casting is composed of a carbon base material and a silicon nitride layer which is formed on the surface of the carbon base material. The arithmetic average roughness Ra on the surface of the carbon base material in contact with the silicon nitride layer based on JIS B 0601 is 1-15 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polycrystalline silicon casting member used when casting polycrystalline silicon as a material for a solar cell or the like.
[0002]
[Prior art]
2. Description of the Related Art In recent years, photovoltaic power generation has been spotlighted as a power generation method capable of generating power safely and at a low price, and research and development of solar cells have been actively carried out for its widespread use. Polycrystalline silicon has been used as a material for a semiconductor substrate constituting this solar cell. Polycrystalline silicon is produced by a method in which silicon melted at a high temperature is poured into a mold and cooled and solidified to form an ingot, or a method in which silicon is melted in a mold and cooled and solidified to form an ingot.
[0003]
As a mold used for casting polycrystalline silicon, an inexpensive graphite mold is usually used.In order to make it easy to take out a silicon ingot, the mold has a dividable structure, and a release material layer is provided on the inner surface thereof. Provided.
Examples of such release materials include silicon dioxide (SiO ₂ : see Patent Document 1), silicon carbide (SiC), silicon nitride (Si ₃ N ₄ : see Patent Document 2), and the like. Above all, if silicon nitride is used, high-quality polycrystalline silicon with few impurities can be obtained.
[0004]
Conventionally, a silicon nitride layer is prepared by mixing a powder of silicon nitride or the like in a solution composed of an appropriate binder and a solvent, stirring to form a slurry, and coating the slurry on the inner surface of the mold by means such as coating or spraying. It was formed by the thing.
However, since the silicon nitride layer is fragile and easily peeled, when polycrystalline silicon is cast using a graphite mold having a silicon nitride layer formed on the inner surface, it is necessary to dissolve the silicon raw material put in the mold. When pouring the silicon melt, solidifying the silicon melt, etc., the silicon nitride layer is damaged, the silicon ingot and the mold are bonded, and the silicon ingot and the mold are damaged when the mold is released. There was a problem of doing it.
[0005]
Therefore, as a technique for obtaining a mold capable of producing a silicon ingot that can be reused and has no crack, for example, a technique of applying a release material using both silicon nitride and silicon dioxide (see Patent Document 3) is proposed. However, although the layer containing silicon dioxide has good adhesion to graphite as a base material, it does not have sufficient releasability from a silicon ingot, and graphite is oxidized during use at high temperatures. As a result, there is a problem that the damage to the base material is accelerated.
In addition, a technique of providing a silicon nitride layer as a first layer and a silicon dioxide layer as a second layer to form a multilayer structure (see Patent Document 4), a silicon dioxide layer as a first layer, and silicon nitride and silicon dioxide as a second layer A technique of providing a silicon nitride layer as a third layer to form a multilayer structure (see Patent Document 5), a silicon nitride layer as a first layer, and silicon nitride and silicon dioxide mixed at a predetermined ratio as a second layer Although a technique of providing a mixed layer to form a multilayer structure (see Patent Document 6) and the like have also been proposed, a multilayer structure has a problem that it takes time and cost.
[0006]
[Patent Document 1]
JP-A-11-244988 [Patent Document 2]
JP-A-10-316489 [Patent Document 3]
JP 9-175809 A [Patent Document 4]
JP-A-6-144824 [Patent Document 5]
JP-A-7-206419 [Patent Document 6]
JP-A-2002-292449
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and has an object to provide a polycrystalline silicon casting member which has excellent durability, can be repeatedly used, and can be easily manufactured. is there.
[0008]
[Means for Solving the Problems]
To achieve the above object, a polycrystalline silicon casting member of the present invention is a polycrystalline silicon casting member comprising a carbon substrate and a silicon nitride layer formed on the surface of the carbon substrate, The arithmetic mean roughness Ra based on JISB0601 on the surface of the substrate in contact with the silicon nitride layer is 1 to 15 μm.
[0009]
Note that the polycrystalline silicon casting member of the present invention includes, among members used for polycrystalline silicon casting, all members to which silicon melt or vaporized silicon may adhere, for example, polycrystalline silicon. Examples include a silicon casting mold, a main body of a polycrystalline silicon casting apparatus, a top cover of a polycrystalline silicon casting apparatus, and a protection member for a heater for polycrystalline silicon casting.
Hereinafter, the polycrystalline silicon casting member of the present invention will be described in detail.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The polycrystalline silicon casting member of the present invention comprises a carbon substrate and a silicon nitride layer formed on the surface of the carbon substrate.
The carbon base material constituting the polycrystalline silicon casting member of the present invention has an arithmetic average roughness Ra based on JIS B 0601 of 1 to 15 μm on the surface in contact with the silicon nitride layer.
[0011]
When a silicon nitride layer is formed on a rough surface of a carbon substrate having an arithmetic average roughness Ra based on JIS B 0601 of 1 to 15 μm, an anchor effect is easily obtained between the carbon substrate and the silicon nitride layer. As a result, the bonding strength between them becomes strong, so that it is possible to prevent the occurrence of peeling or the like between the carbon base material and the silicon nitride layer.
[0012]
When the arithmetic average roughness Ra based on JIS B 0601 is less than 1 μm, the silicon nitride layer formed on the surface of the carbon base material has difficulty in obtaining an anchor effect between the carbon base material and the adhesive strength between the two. Insufficient. On the other hand, when the arithmetic average roughness Ra based on JIS B 0601 exceeds 15 μm, when forming the silicon nitride layer on the surface of the carbon base material, the silicon nitride crystal is formed at various heights on the surface of the carbon base material. Since the growth starts, the stacking of silicon nitride crystals does not proceed well, and the formed silicon nitride layer contains many pores, and it is presumed that the strength becomes weak due to the increase of the pores.
[0013]
The method for adjusting the arithmetic average roughness Ra based on JIS B 0601 on the surface of the carbon substrate in contact with the silicon nitride layer to 1 to 15 μm is not particularly limited, and includes, for example, sand blasting, cutting, sand paper or a grindstone. A surface processing method such as a polishing treatment may be used. Above all, cutting is preferably used. This is because it is relatively easy to adjust the surface roughness by adjusting the processing speed of the cutting process.
[0014]
A preferable lower limit of the arithmetic average roughness Ra based on JIS B 0601 on the surface of the carbon substrate in contact with the silicon nitride layer is 3.2 μm, and a preferable upper limit is 12.5 μm. Within this range, a sufficient anchor effect is obtained between the carbon base material and the silicon nitride layer, and the bonding strength between the two becomes particularly strong. The occurrence of peeling or the like can be particularly effectively prevented.
[0015]
The material of the carbon substrate is not particularly limited as long as it is excellent in heat resistance.For example, graphite is preferable, and among them, high-purity isotropic graphite excellent in affinity with the silicon nitride layer is particularly preferable. .
[0016]
The coefficient of thermal expansion of the carbon substrate is preferably ± 2.0 × 10 ⁻⁶ / K with respect to the coefficient of thermal expansion of the silicon nitride layer formed on the surface thereof. This is because thermal stress generated in the silicon nitride layer due to a difference in thermal expansion coefficient between the carbon base material and the silicon nitride layer is reduced.
[0017]
The average pore radius of the carbon substrate is preferably 0.2 to 5 μm. Here, the “average pore radius” is defined as a pore volume that is half the cumulative pore volume when the pore volume is determined by a mercury porosimeter under the conditions of a maximum pressure of 98 MPa and a contact angle between the sample and mercury of 141.3 °. The corresponding value of the pore radius.
When the average pore radius is less than 0.2 μm, the anchor effect cannot be sufficiently obtained, and the silicon nitride layer is easily peeled. On the other hand, if it exceeds 5 μm, the amount of gas released from the carbon substrate at a high temperature increases.
[0018]
The gas release pressure of the carbon substrate on a 1000 ° C. basis is preferably 10 ⁻⁴ Pa / g or less. Examples of the released gas include H ₂ , CH ₄ , CО, CО ₂ , and H ₂ О.
[0019]
The content of impurities in the carbon base material is preferably Al <0.3 ppm, Fe <1.0 ppm, Mg <0.1 ppm, Si <0.1 ppm, and the ash content is preferably 10 ppm or less. When the content of the impurity exceeds this range, the impurity and silicon nitride may cause a chemical reaction at a high temperature, and the interface between the carbon substrate and the silicon nitride layer may be separated.
[0020]
The shape of the carbon substrate is not particularly limited, and may take various shapes according to the type of the polycrystalline silicon casting member of the present invention, and examples include a flat plate shape.
[0021]
The silicon nitride layer constituting the polycrystalline silicon casting member of the present invention is formed on the surface of the carbon substrate. The silicon nitride layer may be formed on the entire surface of the carbon substrate, or may be formed on a part of the surface of the carbon substrate, but the carbon substrate is directly in contact with the silicon melt. It is preferable that it is formed so as not to be present.
[0022]
The silicon nitride layer is preferably a layer in which fine silicon nitride crystal grains are uniformly and densely stacked. When it is uniform and dense, a silicon nitride layer in which cracks are unlikely to be formed can be obtained. In addition, when the layers are stacked, even if cracks occur, the cracks are likely to progress in the direction of the lamination surface, so that the cracks are stopped at a shallow layer near the surface and hardly progress to the inside. Further, when the layers are stacked, even if the impurities (Fe, Al, etc.) in the carbon base material diffuse and reach the lower layer of the silicon nitride layer, the diffusion rate of the impurities in the silicon nitride layer can be reduced. Therefore, contamination of the silicon ingot due to the polycrystalline silicon casting member of the present invention can be prevented.
[0023]
A desirable lower limit of the thickness of the silicon nitride layer is 10 μm, and a desirable upper limit is 100 μm. If it is less than 10 μm, the strength of the silicon nitride layer may not be sufficient, and if it is more than 100 μm, the silicon nitride layer and the carbon substrate are likely to peel off due to a difference in thermal expansion coefficient and the like, Therefore, the cost of the polycrystalline silicon casting member of the present invention is increased.
[0024]
Next, an example of a method for manufacturing a polycrystalline silicon casting member of the present invention will be described. When manufacturing the polycrystalline silicon casting member of the present invention, first, a carbon base material is manufactured.
When manufacturing a carbon base material, first, the raw material coke and the like are pulverized and sized, and after dividing the pulverized particles into various particle sizes, a raw material powder is prepared by combining powders of a plurality of particle sizes. .
Next, a pitch or the like as a binder is added to the raw material powder, kneaded and, if necessary, crushed again, and then a molded body having a predetermined shape is produced by using a molding method such as CIP molding, embedding molding, or extrusion molding. I do.
Thereafter, the compact is buried in a packing material such as coke powder to prevent deformation and oxidation during the heat treatment. The compact is heated and fired at about 1000 ° C. in a reducing atmosphere. By performing the conversion treatment, a carbon base material made of graphite is manufactured.
In addition, the manufacturing method of the carbon base material is not limited to the above method, and another method may be used.
[0025]
Further, if necessary, the shape of the carbon base material is processed, the surface is roughened, or the carbon substrate is subjected to a high-purity treatment with a halogen gas or the like.
As a method of processing the shape of the carbon base material, dry cutting or grinding is preferable in order to prevent contamination by a cutting fluid.
[0026]
As described above, as the carbon constituting the carbon base material, isotropic graphite or the like is preferable. For example, isotropic graphite can be produced by molding by the CIP method or the like.
[0027]
Next, a silicon nitride layer is formed on the carbon substrate.
The method for forming the silicon nitride layer is not particularly limited. For example, a chemical vapor deposition (CVD) method, a thermal spraying method, a coating method, a physical vapor deposition (PVD) method, an electron beam (EB) vapor deposition method, an arc ion plating reaction And the like. Among them, a chemical vapor deposition (CVD) method and a thermal spraying method are preferably used.
[0028]
As the chemical vapor deposition (CVD) method, for example, an ammonia gas or a nitrogen gas as a source gas of nitrogen atoms and a silane gas as a source gas of silicon atoms are subjected to a thermal decomposition reaction in a vacuum heating furnace at 900 to 1600 ° C. And a method of depositing silicon nitride on a carbon base material.
[0029]
When the silicon nitride layer is formed by the chemical vapor deposition (CVD) method, the crystallinity of the silicon nitride layer is controlled by controlling reaction conditions such as a reaction temperature, a molar ratio of each source gas, and a degree of vacuum. Is relatively easy, and it is relatively easy to control the thickness of the silicon nitride layer by changing the reaction time or the like, which is suitable for manufacturing the polycrystalline silicon casting member of the present invention.
[0030]
In the thermal spraying method, silicon nitride is heated and melted, silicon nitride melt is made into fine particles, and the particles are made to collide with the surface of the carbon substrate, thereby depositing silicon nitride on the carbon substrate.
Examples of the spraying method include plasma spraying (heat source: electricity), arc spraying (heat source: electricity), flame spraying (heat source: combustion gas), and laser spraying (heat source: laser beam).
[0031]
When the silicon nitride layer is formed by the above thermal spraying method, the crystallinity of the silicon nitride layer can be controlled by controlling the size and the like of a silicon nitride melt droplet that collides with the surface of the carbon base material. It is relatively easy, and it is relatively easy to control the thickness of the silicon nitride layer by adjusting the amount of the silicon nitride melt that collides with the surface of the carbon substrate. It is suitable for the production of members for use.
[0032]
In the above coating method, a slurry-like silicon nitride solution is prepared and applied to a carbon substrate, and the silicon nitride solution is dried and hardened.
Examples of the silicon nitride solution include a mixture of silicon nitride, a solvent, a binder for coating and molding, an additive for improving fluidity, and the like.
The solvent is not particularly limited, and includes, for example, water and alcohol.
The binder for coating and molding is not particularly limited, but for example, polyvinyl alcohol is preferably used because of its excellent coatability and adhesiveness.
[0033]
When the silicon nitride solution is dried and cured, a degreasing treatment is generally performed at a temperature of about 600 ° C. in an oxidizing atmosphere. By performing the above degreasing treatment, when the silicon nitride layer is heated or comes into contact with the silicon melt and becomes high temperature, a thermal decomposition product is generated and mixed into the silicon melt. Can be prevented.
In the above-mentioned coating method, the binder for coating and molding may become a carbon residue such as soot and may be mixed into the inside of the silicon nitride layer or adhere to the surface of the silicon nitride layer. It needs to be managed sufficiently. If the carbon residue is mixed into the silicon nitride layer or adheres to the surface of the silicon nitride layer, the silicon melt contacts the silicon nitride layer, and carbon dissolves into the silicon ingot or carbon deposits on the silicon ingot surface. Or the like adheres to the silicon ingot, resulting in poor processing when slicing the silicon ingot or deteriorating the characteristics of the obtained solar cell.
[0034]
The method comprises the carbon substrate and the silicon nitride layer formed on the surface of the carbon substrate according to the method, wherein the surface of the carbon substrate in contact with the silicon nitride layer has an arithmetic average roughness based on JIS B0601. A polycrystalline silicon casting member having a thickness Ra of 1 to 15 μm can be manufactured.
[0035]
The shape of the polycrystalline silicon casting member of the present invention is not particularly limited, and may take various shapes according to the type of the polycrystalline silicon casting member of the present invention.
[0036]
FIG. 1 is a cross-sectional view schematically showing a polycrystalline silicon casting apparatus using the polycrystalline silicon casting member of the present invention.
FIG. 1 shows a polycrystalline silicon casting mold 10, a polycrystalline silicon casting apparatus main body 20, and a polycrystalline silicon casting apparatus upper lid 30 as the polycrystalline silicon casting member of the present invention.
[0037]
As shown in FIG. 1, the polycrystalline silicon casting mold 10 is composed of a carbon substrate 11 and a silicon nitride layer 12 formed on the surface of the carbon substrate 11, and has a container shape without an upper lid. . The polycrystalline silicon casting mold 10 is preferably formed by assembling a plurality of flat plates with bolts or a frame-like member for fastening (not shown) so as to be dividable.
When casting polycrystalline silicon, the polycrystalline silicon casting mold 10 is first heated and melted in the mold to produce a silicon melt 40, or the silicon melt 40 is poured into the mold. Is done. Next, the polycrystalline silicon casting mold 10 is cooled, the silicon melt 40 is solidified in the mold, and a silicon ingot is produced. Finally, the silicon ingot is taken out of the polycrystalline silicon casting mold 10. At this time, since the polycrystalline silicon casting mold 10 has the silicon nitride layer 12, it is easy to take out the silicon ingot, and it is possible to prevent the silicon ingot and the polycrystalline silicon casting mold 10 from being damaged. .
[0038]
The main body 20 of the polycrystalline silicon casting apparatus includes a carbon substrate 21, a silicon nitride layer 22 formed on the inner surface of the carbon substrate 21, and a polycrystalline silicon casting heater 23 provided inside the carbon substrate 21. And has a container shape without an upper lid. In addition, the main body 20 of the polycrystalline silicon casting apparatus of the present invention has a temperature measuring means (not shown) such as a thermocouple, and, if necessary, based on the temperature measured by the temperature measuring means. Output control means for controlling the output of the heater 23, cooling means for circulating a cooling medium such as water, and the like (not shown) are attached. In addition, the main body 20 of the polycrystalline silicon casting apparatus of the present invention does not need to include a built-in heater for polycrystalline silicon casting. In this case, the container of the polycrystalline silicon casting apparatus 20 of the present invention has A polycrystalline silicon casting heater covered with a protective member of the polycrystalline silicon casting heater, which is a polycrystalline silicon casting member of the present invention, is installed, or the polycrystalline silicon casting heater 20 is provided around the outer periphery of the polycrystalline silicon casting apparatus 20 of the present invention. It is preferable to provide a heater.
When casting polycrystalline silicon, the main body 20 of the polycrystalline silicon casting apparatus is provided with a polycrystalline silicon casting heater 23 provided therein and a polycrystalline silicon casting mold 10 placed in a container and the inside of the mold. Heat the silicon. In addition, the inside of the container is closed together with the upper lid 30 of the polycrystalline silicon casting apparatus to form an atmosphere optimal for the casting of polycrystalline silicon. At this time, since the body 20 of the polycrystalline silicon casting apparatus has the silicon nitride layer 22 on the inner surface, even if the scattered silicon adheres to the inner surface, it can be easily peeled off, and the inner surface can be easily cleaned. Yes, it is possible to reuse attached silicon.
[0039]
The upper lid 30 of the polycrystalline silicon casting apparatus is composed of a carbon substrate 31 and a silicon nitride layer 32 formed on the surface of the lower surface of the carbon substrate 31, and has a flat plate shape.
When casting polycrystalline silicon, the upper lid 30 of the polycrystalline silicon casting apparatus, together with the main body 20 of the polycrystalline silicon casting apparatus, closes the inside of the container to form an atmosphere optimal for casting of polycrystalline silicon. At this time, since the upper lid 30 of the polycrystalline silicon casting apparatus has the silicon nitride layer 32 on the lower surface, even if the scattered silicon adheres to the lower surface, it can be easily peeled off, and the silicon grows in an icicle shape on the lower surface. It is easy to clean the lower surface without waste, and the attached silicon can be reused.
[0040]
As described above, in the polycrystalline silicon casting member of the present invention, the arithmetic mean roughness Ra based on JIS B 0601 of the surface in contact with the silicon nitride layer of the carbon base material is adjusted to 1 to 15 μm.
Thereby, the silicon nitride layer formed on the surface of the carbon base material exhibits a strong anchoring effect with the carbon base material, and has a strong adhesive strength. Separation hardly occurs between them. Therefore, the polycrystalline silicon casting member of the present invention is excellent in durability, can be used repeatedly, and does not need to have a multilayer structure, and can be easily manufactured. Further, when the polycrystalline silicon casting member of the present invention is a polycrystalline silicon casting mold, peeling between the carbon base material and the silicon nitride layer hardly occurs, so that the silicon melt and the carbon base material Can be prevented from coming into contact, and the silicon ingot can be taken out without damaging the silicon ingot and the polycrystalline silicon casting mold of the present invention.
[0041]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to only these Examples.
[0042]
(Example 1)
For the bottom surface of the casting mold for polycrystalline silicon, isotropic graphite material (trade name: ET-10, manufactured by IBIDEN Co., Ltd.) is cut to produce a carbon plate made of graphite having a length of 350 mm, a width of 350 mm, and a thickness of 20 mm. did.
In addition, a carbon plate made of graphite having a length of 250 mm, a width of 350 mm, and a thickness of 10 mm is formed by cutting an isotropic graphite material (trade name: ET-10, manufactured by Ibiden Co., Ltd.) for the side surface of the polycrystalline silicon casting mold. Were produced.
The entire surface of these carbon plates was cut at a feed rate of 0.1 mm / sec to reduce the surface roughness Ra of the carbon plates to 1 μm.
Next, these carbon plates were subjected to high-purification treatment in a vacuum at 2000 ° C. using a halogen gas.
[0043]
Next, after setting the carbon plate after the above-mentioned purification treatment in a vacuum heating furnace, the inside of the vacuum heating furnace is set to 2000 Pa and 1500 ° C., and a silane gas and an ammonia gas are supplied and mixed, and a reaction is performed for 3 hours. Silicon nitride was deposited to a thickness of 30 μm on the entire surface of the carbon plate. That is, a silicon nitride layer was formed by a CVD method.
[0044]
Finally, the bottom carbon plate on which the silicon nitride layer was formed and the four carbon plates on the side surface on which the silicon nitride layer was formed were combined with bolts to produce a polycrystalline silicon casting mold.
[0045]
(Example 2)
Except that the feed rate at the time of cutting the entire surface of the bottom and side carbon plates was 0.3 mm / sec and the surface roughness Ra of the carbon plates was 5 μm, the polycrystal was produced in the same manner as in Example 1. A silicon casting mold was prepared.
[0046]
(Example 3)
Except that the feed rate at the time of cutting the entire surface of the bottom and side carbon plates was 0.8 mm / sec, and the surface roughness Ra of the carbon plates was 15 μm, polycrystal was prepared in the same manner as in Example 1. A silicon casting mold was prepared.
[0047]
(Comparative Example 1)
Except that the feed speed when cutting the entire surface of the bottom and side carbon plates was 0.1 mm / sec and the surface roughness Ra of the carbon plates was 0.3 μm, the same as in Example 1 was performed. A polycrystalline silicon casting mold was prepared.
[0048]
(Comparative Example 2)
Polycrystalline silicon casting was performed in the same manner as in Example 1 except that the feed rate when cutting the entire surface of the bottom and side carbon plates was set to 1 mm / sec, and the surface roughness Ra of the carbon plate was set to 18 μm. A casting mold was prepared.
[0049]
(Polycrystalline silicon casting)
The polycrystalline silicon casting molds according to Examples 1 to 3 and Comparative Examples 1 and 2 were placed in a polycrystalline silicon casting apparatus as shown in FIG. 1, and the inside of the apparatus was set to an argon atmosphere in which the pressure was reduced to 1000 Pa. With the polycrystalline silicon casting molds according to Examples 1 to 3 and Comparative Examples 1 and 2 kept at 1000 ° C., a silicon melt was poured. The silicon melt was gradually cooled and solidified over 7 hours to produce a silicon ingot. After cooling to room temperature, the silicon ingot was taken out of the polycrystalline silicon casting mold according to Examples 1 to 3 and Comparative Examples 1 and 2.
[0050]
From the polycrystalline silicon casting mold according to Examples 1 to 3, the silicon ingot can be easily taken out, and the polycrystalline silicon casting mold after taking out, and both the silicon ingot and the damage such as cracks are not seen. Was.
On the other hand, since the silicon ingot could not be easily removed from the polycrystalline silicon casting molds according to Comparative Examples 1 and 2, cracks were observed in both the removed polycrystalline silicon casting mold and the silicon ingot. Was done.
[0051]
【The invention's effect】
As described above, in the polycrystalline silicon casting member of the present invention, since the arithmetic average roughness Ra based on JIS B 0601 on the surface of the carbon substrate in contact with the silicon nitride layer is adjusted to 1 to 15 μm, The silicon nitride layer formed on the surface of the base material exhibits a strong anchoring effect with the carbon base material, has a strong adhesive strength, and causes peeling between the carbon base material and the silicon nitride layer. Hateful. Therefore, the polycrystalline silicon casting member of the present invention is excellent in durability, can be used repeatedly, and does not need to have a multilayer structure, and can be easily manufactured. Further, when the polycrystalline silicon casting member of the present invention is a polycrystalline silicon casting mold, peeling between the carbon base material and the silicon nitride layer hardly occurs, so that the silicon melt and the carbon base material Can be prevented from coming into contact, and the silicon ingot can be taken out without damaging the silicon ingot and the polycrystalline silicon casting mold of the present invention.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a polycrystalline silicon casting apparatus using a polycrystalline silicon casting member of the present invention.
[Explanation of symbols]
Reference Signs List 10 Polycrystalline silicon casting mold 11, 21, 31 Carbon base material 12, 22, 32 Silicon nitride layer 20 Polycrystalline silicon casting apparatus main body 23 Polycrystalline silicon casting heater 30 Polycrystalline silicon casting apparatus top lid 40 Silicon melt

Claims (3)

A polycrystalline silicon casting member comprising a carbon substrate and a silicon nitride layer formed on the surface of the carbon substrate,
A member for polycrystalline silicon casting, wherein an arithmetic mean roughness Ra based on JIS B0601 on a surface of the carbon substrate in contact with the silicon nitride layer is 1 to 15 μm. The polycrystalline silicon casting member according to claim 1, wherein the silicon nitride layer is formed by a chemical vapor deposition (CVD) method. The polycrystalline silicon casting member according to claim 1, wherein the silicon nitride layer is formed by a thermal spraying method.

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