JP6928262B2 - Surface cleaning method for crushed silicon - Google Patents

Description

The present invention relates to a method for cleaning the surface of crushed or lumpy pieces of high-purity polycrystalline silicon (hereinafter, simply referred to as crushed silicon).

When high-purity polycrystalline silicon is used as a raw material for single-crystal silicon produced by the Czochralski method (hereinafter referred to as the CZ method), it is usually 100 mm or less in order to facilitate the filling operation in the crucible. It is processed into silicon shards. When single crystal silicon is produced from this polycrystalline silicon by the CZ method or the like, extremely high purity is required for the polycrystalline silicon from the viewpoint of suppressing the uptake of impurities as low as possible.

For this reason, usually, in order to remove contamination of metals and the like adhering to the surface of polycrystalline silicon during and after processing, the polycrystalline silicon is washed with an acid solution, and surface impurities containing the adhered metal are polycrystalline. Removed from silicon. Specifically, a certain amount of processed polycrystalline silicon such as crushed or cut is placed in a special container, etc., etched with an acid solution (cleaning), rinsed with pure water, and then in the same container. After being dried as it is, the polycrystalline silicon is taken out from the container, inspected, and then packaged.

In recent years, as the performance of semiconductor products has improved and the demand for high purity in polycrystalline silicon has increased, contamination due to organic substances adhering to the surface of silicon products has become a problem, and methods for removing the contamination by heat treatment or the like have been disclosed. (See Patent Document 1). Patent Document 1 cites the contact of silicon with parts made of organic polymers and plastics during mechanical work as one of the causes of organic contamination of polycrystalline silicon, and carbon contamination in heat treatment in an inert gas stream. Is disclosed to be reduced.

Further, in the treatment of polycrystalline silicon, etching, pure water rinsing, drying and the like are performed as described above in order to ensure the surface quality. In such treatment, silicon is contained. It is known that the heat load on the container also causes deterioration of the container (see Patent Document 2). In Patent Document 2, in the state where the polycrystalline silicon lump is contained in the resin container, the treatment is performed in the order of the etching step with a chemical solution, the pure water rinsing step, and the gas blow drying step, and the drying performed in the treatment step is insufficient. It is described that the quality is deteriorated due to the occurrence of stains on the surface of the polycrystalline silicon mass. On the other hand, in order to suppress quality deterioration due to stains, it is necessary to lengthen the time in the drying process, but on the other hand, if the time in the drying process is lengthened, the container deteriorates due to the heat load in the drying stage. Is mentioned.

Japanese Unexamined Patent Publication No. 2013-170122 Japanese Unexamined Patent Publication No. 2016-5993

Generation of Organic Pollutants / Outgas, Mechanism and Trouble Countermeasures Examples (Published by Technical Information Association, Inc.) Pages 28-29

Such deterioration of the container also increases the contact surface with the silicon surface from the viewpoint of contamination by organic substances in Patent Document 1. Therefore, deterioration of the container containing silicon is one of the causes of contamination due to organic substances. Can also be. In addition, deterioration of the container leads to peeling of a part of the surface of the container, and a part of the deterioration also adheres to the silicon surface inside the container. Further, since a polycrystalline silicon lump as disclosed in Patent Document 2 involves processing such as crushing, when silicon which is a brittle material is crushed, the crushed pieces and crushed lumps have edges and corners of the crushed surface. It often has a blade surface or a sharp shape. As a result, silicon is crushed by the movement of silicon in the storage container, such as when the silicon lump is put into the storage container, vibration or movement due to etching treatment, pure water treatment, etc., or vibration due to movement between treatment operations. Damage occurs in which pieces pierce, damage, or scrape the surface of the container. Further, contact with silicon crushed pieces produces wear debris in the container. As a result, the scraped container pieces (resin pieces) and wear debris adhere to the silicon surface, which causes new contamination.

On the other hand, it is known that outgas is generated in resin-based materials depending on the environment (temperature) in which the resin is used (Non-Patent Document 1). When the above-mentioned treatment method in which polycrystalline silicon is contained in a container is applied to this outgas, the surface of silicon crushed pieces is caused by the generation of outgas due to the influence of the temperature at the time of drying after cleaning the polycrystalline silicon. It is possible that organic matter contamination will occur. From this point of view, the step of etching with a chemical solution, the step of rinsing pure water, and the step of gas blow drying in a state where the polycrystalline silicon lump is contained in a resin container, as disclosed in Patent Document 2, proceed in this order. Although this method has the effect of reducing the impact on quality due to deterioration of the container, measures are required to further reduce quality contamination.

An object of the present invention is to prevent quality contamination of silicon shards due to deterioration of a resin container caused by accommodating silicon shards and performing the treatment from cleaning to drying using the same container, particularly contamination due to organic substances. It is an object of the present invention to provide a method for cleaning the surface of silicon debris to be reduced. Another object of the present invention is to provide a method for cleaning the surface of crushed silicon pieces, which can shorten the drying time by using a second container that easily drains water. Yet another object of the present invention is to provide a method for cleaning the surface of silicon crushed pieces by using a second container that suppresses the generation of organic gas in a container for containing the crushed silicon pieces.

The first aspect of the present invention is to put the silicon crushed pieces in pure water or ultrapure water before drying the silicon crushed pieces after being housed in a resin first container and washed. This is a method for cleaning the surface of crushed silicon, which comprises transferring from a second container made of resin to a second container.

The second aspect of the present invention is the invention according to the first aspect, wherein the first container and the second container each have an opening at the upper part, and the transfer is pure water tank. After arranging the upper part of the second container upward in water or ultrapure water, the silicon crushed pieces after being housed in the first container and washed in the pure water or ultrapure water are placed. It is characterized in that the opening of the first container is tilted so that the opening of the first container is dropped into the inside of the second container.

A third aspect of the present invention is the invention according to the first or second aspect, wherein the opening area of the second container is larger than that of the first container, or the volume thereof is larger than that of the first container. It is characterized by being larger than the volume.

The fourth aspect of the present invention is the invention according to any one of the first to third aspects, wherein the first container and the second container have the peripheral wall portion and the bottom plate portion of the silicon crushed pieces. It is characterized in that a plurality of through holes having a diameter smaller than the size are formed.

The fifth aspect of the present invention is the invention according to any one of the first to fourth aspects, characterized in that the pure water or ultrapure water is flowing water.

A sixth aspect of the present invention is an invention according to any one of the first to fifth aspects, characterized in that the pure water or ultrapure water is set to a temperature of 10 to 70 ° C. ..

The seventh aspect of the present invention is the invention according to the fourth aspect, and the through hole formed in the peripheral wall portion of the second container has a hole peripheral surface of the lower half of the hole in the front view of the peripheral wall portion. It is characterized by having an inclined surface that gradually slopes downward linearly or curvedly.

The eighth aspect of the present invention is the invention according to the fourth aspect, from the installation surface of the second container to the outside of the outer bottom surface portion where the through hole of the bottom plate portion of the second container is not formed. It is characterized in that one or more protrusions that separate the bottom surfaces are formed, and the protrusions have an inclined surface that is gradually inclined downward linearly or curvedly in a vertical cross-sectional view.

The ninth aspect of the present invention is the invention according to the fourth or eighth aspect, and the through hole formed in the bottom plate portion of the first container or the second container is formed from the hole edge portion inside the container to the container. It is characterized in that it has a tapered shape or a curvature by reducing the diameter toward the outer edge portion.

The tenth aspect of the present invention is an invention according to any one of the first to fourth viewpoints or the seventh to ninth viewpoints, wherein the second container is polypropylene, polycarbonate, silicone synthetic resin, ethylene. Ethylene tetrafluoride copolymer (hereinafter, sometimes abbreviated as ETFE), polyetheretherketone (hereinafter, abbreviated as PEEK), polytetrafluoroethylene (hereinafter, abbreviated as PTFE), tetrafluoro Ethylene / perfluoro (alkyl vinyl ether) copolymer (hereinafter abbreviated as PFA), tetrafluoroethylene / hexafluoropropylene copolymer (hereinafter abbreviated as FEP) and polyvinylidene fluoride (hereinafter abbreviated as PVDF). It is characterized by being composed of one kind or two or more kinds of synthetic resins selected from the group consisting of.

In the method of the first aspect of the present invention, since the transfer is made with pure water or ultrapure water, the surface of the silicon crushed piece is not contaminated from the air. Further, when the silicon crushed pieces in the first resin container are transferred in water, the container pieces (resin pieces) are separated from the silicon crushed pieces and dispersed in water, so that the container pieces in the first container become the second. It is possible to reduce the amount taken into the container. As a result, the influence of organic matter contamination by the container piece is suppressed.

In the method of the second aspect of the present invention, by inclining the opening of the first container in water, the silicon crushed pieces of the first container are squeezed through the opening of the second container below. 2 Since the silicon crushed pieces are transferred by dropping them into the container, the silicon crushed pieces can be transferred more smoothly. In addition, since the silicon crushed pieces move slowly in water at the time of transfer, the damage caused by the collision of the silicon crushed pieces to the second container is reduced, and the silicon crushed due to the generation of the container pieces of the first container. It is possible to suppress contamination of the pieces and prevent damage to the inner surface of the second container due to the crushed silicon pieces. In addition, by reducing the damage caused by contact and collision between the silicon crushed pieces due to the transfer, the generation of silicon fine powder can be suppressed, and the influence of contamination via the silicon fine powder can be reduced. Further, when the weight of the crushed silicon pieces in the first container is large, the work load at the time of transfer in water can be reduced.

In the method of the third aspect of the present invention, the opening area or volume of the second container is made larger than the opening area or volume of the first container, respectively, thereby facilitating the transfer of the crushed silicon pieces in water and at the same time. At the time of transfer, the falling silicon crushed pieces can be reliably transferred into the second container, the mistake of transferring the silicon crushed pieces to the outside of the second container is eliminated, and the work efficiency is improved.

In the method of the fourth aspect of the present invention, by providing a plurality of through holes in the peripheral wall portion and the bottom plate portion of the first container, the container piece is discharged from the through holes to the outside of the container together with water. It is possible to reduce the amount of the container piece taken into the second container together with the silicon crushed piece. Further, when the second container after transferring the silicon crushed pieces is taken out from the water, the water in the container is discharged from the through hole of the second container, so that even if the container piece is taken into the second container, the through hole The container pieces are easily discharged as the water is discharged from the container. As a result, the residue of the container piece in the second container can be reduced, so that the contamination caused by organic substances can be suppressed, and the transport load of the second container containing the silicon crushed piece can be reduced to be used in the drying process. As well as being able to move, the drying time of silicon debris can be shortened. As a result, by shortening the drying time, contamination of the silicon crushed pieces from the second container due to organic substances can be suppressed, and the drying work efficiency can be improved.

In the method of the fifth aspect of the present invention, since pure water or ultrapure water is flowing water, it is possible to efficiently remove the container piece (resin piece) adhering to the surface of the silicon crushed piece to be transferred. Also, the container pieces adhering to the first container or the container pieces falling into the second container together with the silicon crushed pieces can be dispersed in water, so that the silicon crushed pieces are contaminated due to organic substances. Can be suppressed.

In the method of the sixth aspect of the present invention, the temperature of pure water or ultrapure water is set to 10 to 70 ° C., so that the temperature of the silicon debris and the second container is changed to the temperature of water during transfer in water. If the temperature of the water is set to 30 to 70 ° C., the silicon crushed pieces and the second container are heated, the drying time of the silicon crushed pieces in the next drying step is further shortened, and the second container is used. It is possible to suppress the contamination of silicon debris caused by organic substances from the water.

In the method of the seventh aspect of the present invention, the through hole formed in the peripheral wall portion of the second container is gradually inclined downward linearly or curvedly in the peripheral surface of the lower half of the hole in the front view of the peripheral wall portion. By having the inclined surface, the drainage after taking out the second container from the water tank is efficiently performed, and the amount of water adhering to the second container can be reduced. As a result, the drying time of the silicon shards in the next drying step is further shortened, so that the contamination of the silicon shards due to the organic matter from the second container can be suppressed.

In the method of the eighth aspect of the present invention, the protrusion formed on the outer bottom surface of the second container separates the container from the installation surface of the second container, so that a certain space is secured under the through hole of the bottom plate portion. It is possible to easily discharge the container pieces and silicon fine powder brought into the second container to the outside of the container through the through holes of the bottom plate of the second container, and the water outside the bottom plate of the second container. By making it difficult for container pieces and silicon fine powder to enter directly from the bottom surface of the tank, contamination of the silicon crushed pieces can be reduced. Further, since the protrusion has an inclined surface that gradually inclines downward in a linear or curved manner in the vertical cross-sectional view, it is possible to take a large space between the protrusions on the outer bottom surface of the second container. It is also possible to keep the silicon fine powder or a relatively large container piece taken into the second container at the time of transfer in the space between the protrusions on the outer bottom surface. As a result, contamination of silicon debris caused by organic substances can be suppressed.

In the method of the ninth aspect of the present invention, the through hole formed in the bottom plate portion of the second container has a tapered shape or curvature by reducing the diameter from the hole edge portion inside the container to the hole edge portion outside the container. By eliminating the corners and making it difficult for the hole edge inside the container to be scraped by the silicon piece, the generation of the container piece can be reduced, and the water adhering to the inner bottom surface and the container piece and silicon fine powder taken into the inside of the container can be reduced. Can also be facilitated to flow out through the through hole. Further, draining after taking out the second container from the water tank is performed more efficiently, and the amount of water adhering to the second container can be reduced. As a result, the drying time of the silicon debris in the next drying step can be further shortened, and the contamination of the silicon debris caused by the organic matter from the second container can be suppressed.

In the method of the tenth aspect of the present invention, the second container has low gasogenicity such as polypropylene, polycarbonate, silicone synthetic resin, ethylene / tetrafluoroethylene copolymer, PEEK, PTFE, PFA, FEP, PVDF, etc. In the case of a synthetic resin holding member, even if the temperature is 50 ° C. or higher during drying, the amount of organic gas such as a resin additive containing carbon generated from the holding member is small, so it depends on the organic material of the container piece. Contamination can be reduced. Further, although the amount of gas generated by the silicone resin is not smaller than that of the above resins, the generated gas is less likely to adhere to the silicon surface, and the carbon contamination of the crushed fragments can be reduced.

It is a figure which shows the situation which transfers the silicon crushed piece of the embodiment of this invention from a 1st container to a 2nd container in water. It is an external perspective view of the 2nd container. It is an enlarged view of the through hole formed in the peripheral wall part of the 2nd container. It is an enlarged view of the protrusion formed on the outer bottom surface of the bottom plate part of the 2nd container. It is an enlarged cross-sectional view of the through hole formed in the bottom plate part of the 2nd container. It is a flowchart which shows the process process until the silicon crushed piece prepared from the polycrystalline silicon rod which was precipitated by the Siemens method was dried.

Next, one embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the first container 10 made of resin contains the silicon crushed pieces 11 after being washed in the washing step. In the pure water or ultrapure water 13 stored in the water tank 12, a second container 14 made of resin different from the first container 10 is arranged. Examples of the resin material of the second container, which can prevent metal contamination of the contained silicon crushed pieces by making the second container 14 made of resin instead of metal, include polyethylene, polypropylene, and polycarbonate. In the first container 10 containing the silicon crushed pieces 11, the silicon crushed pieces 11 in the container are inclined at the opening 10a of the first container in pure water or ultrapure water 13, and the inclination angle thereof is increased. By dropping the silicon crushed pieces 11 into the second container 14, the silicon crushed pieces 11 are transferred from the first container 10 to the second container 14.

By transferring the silicon crushed piece 11 to the second resin container 14 in water, the container piece (resin piece) adhering to the silicon crushed piece 11 in the first container 10 can be separated from the silicon crushed piece and removed. It is possible to prevent the resin pieces from being brought into the drying process. Further, since the silicon crushed pieces 11 move slowly in water at the time of transfer, the damage caused by the collision of the silicon crushed pieces to the second container is reduced, and the silicon caused by the generation of the container pieces of the first container is reduced. In addition to suppressing contamination of the crushed pieces, damage to the inner surface of the second container due to the silicon crushed pieces can be suppressed, and contamination of the silicon crushed pieces caused by organic substances from the second container can be suppressed. Further, it is possible to suppress the generation of fine powder due to contact or collision between silicons at the time of transfer, and by reducing the fine powder having a surface area, it is possible to avoid surface contamination by pollutants in the air after being taken out of the water. Further, when the weight of the silicon crushed piece is large, the work load at the time of transfer can be reduced.

Pure water refers to water having an electrical resistivity of 0.1 to 15 MΩcm level from which most of the dissolved ions have been removed, and ultrapure water has an electrical resistivity of 15 MΩcm that approaches _{H 2 O as much as possible.} A level of water that exceeds. By changing the water stored in the water tank 12 to pure water or ultrapure water, it is possible to reduce the contamination of the surface of silicon crushed pieces by a small amount of impurities contained in the water. Further, as the material of the first container, it is preferable that the specific gravity is smaller than that of water. In that case, when the container piece (resin piece) adhering to the surface of the silicon crushed piece in the first container separates from the silicon crushed piece, the container piece floats, making it more difficult to reattach to the silicon crushed piece, and the resin. It is possible to prevent the pieces from being brought into the drying process.

In the present embodiment, the area or volume of the opening 18 of the second container 14 is larger than the area or volume of the opening 10a of the first container 10, respectively. With this configuration, the transfer of the crushed silicon pieces in water is facilitated, and at the time of transfer, the crushed silicon pieces come into contact with or collide with the edge of the opening of the second container of the second container. There is no risk of breakage or damage, and there is no risk of scraping of new container pieces, and the falling silicon crushed pieces can be reliably transferred into the second container, and there is a mistake in transferring the silicon crushed pieces to the outside of the second container. Eliminates and improves work efficiency.

The pure water or ultrapure water 13 stored in the water tank 12 is preferably configured to flow. Although not shown, in this flow state, water is supplied from one peripheral wall portion of the water tank 12 and water is discharged from a peripheral wall portion different from the peripheral wall portion, or water is supplied from the bottom plate portion of the water tank 12. It is created by overflowing from the upper edge of the water tank 12. By making the silicon crushed state into a fluid state, the container piece (resin piece) adhering to the surface of the silicon crushed piece can be efficiently desorbed, and contamination of the silicon crushed piece due to organic substances can be suppressed. Regarding the flow of water, it is desirable that the flow of water does not affect the transfer of the silicon crushed pieces into the second container.

The temperature of pure water or ultrapure water in the water tank 12 is preferably set to a temperature of 10 to 70 ° C. It is more preferable to set the temperature to 30 to 70 ° C. By setting the temperature to 30 to 70 ° C., the temperature of the silicon crushed pieces and the second container can be increased during the transfer in water, and by adding the heat capacity, the drying time of the silicon crushed pieces in the next drying step can be increased. Can be further shortened, and contamination of silicon debris caused by organic substances from the second container can be suppressed.

As shown in FIG. 2, the second container 14 is formed into a rectangular parallelepiped box shape by injection molding of synthetic resin, and four peripheral wall portions 17 are integrally erected on a substantially rectangular bottom plate portion 16. It is composed. The four peripheral wall portions 17 form four-sided walls along each of the four sides of the bottom plate portion 16 and form a square cylinder. An opening 18 is formed in the upper part of these peripheral wall portions 17. That is, the second container 14 is formed in a box shape with the upper side open, and the silicon crushed pieces 11 are placed in the internal space 19 (see FIG. 1) of the second container through the opening 18 at the upper portion thereof. It is configured to be supplied or discharged. Although not shown, the first container 10 also has a bottom plate portion and a peripheral wall portion having the same configuration, and the bottom plate portion and the peripheral wall portion have through holes. By forming a through hole in the first container 10, the cleaning liquid in the container moves from the through hole of the first container, so that the first container 10 containing the silicon crushed pieces is moved into water with a reduced transport load. At the same time, since the container piece is discharged from the through hole together with water to the outside of the container, it is possible to reduce that the container piece in the first container is taken into the second container together with the silicon crushed piece.

As shown in FIG. 2, a plurality of through holes 21 and 22 are formed in a grid pattern on the entire surface of the bottom plate portion 16 of the second container 14 and the entire surface of the four peripheral wall portions 17. In FIG. 2, the through hole 22 of the peripheral wall portion 17 is shown only in a part of the peripheral wall portion and is not shown on the entire surface. When the second container 14 is taken out from the water tank 12 through these through holes 21 and 22, the water in the container is discharged. As a result, the second container containing the silicon crushed pieces can be moved to the drying process by reducing the work load, and the temperature at the time of drying is easily transmitted to the silicon crushed pieces through the through holes, so that the drying time of the silicon crushed pieces is easy. Can be shortened. By shortening the drying time, contamination of silicon crushed pieces from the container due to organic substances can be suppressed, and the drying work efficiency can be improved.

In the present embodiment, the through hole 21 formed in the bottom plate portion 16 of the second container 14 is formed in a circular shape, for example, when viewed from the front of the bottom plate portion, as shown in FIG. Although not shown, the through hole 21 may be formed in a square shape when viewed from the front of the bottom plate portion. Further, in the through holes 22 formed in the four peripheral wall portions 17, the peripheral surface of the hole directed upward of the through hole, that is, the peripheral surface of the hole in the lower half of the hole is gradually linearly downward in the front view of the peripheral wall portion 17. Alternatively, it has an inclined surface that slopes in a curved line. As shown in FIGS. 2 and 3A, as an example of having an inclined surface 22a in which the peripheral surface of the hole in which the through hole 22 is directed upward gradually inclines downward, a rhombus is formed in the front view of the peripheral wall portion. Through hole. Further, as shown in FIG. 3B, as an example in which the peripheral surface of the hole in which the through hole 22 is directed upward has an inclined surface 22b in which the peripheral surface of the hole is gradually inclined downward, a circular penetration is seen in the front view of the peripheral wall portion. There is a hole. In such a through hole 22, draining after taking out the second container 14 from the water tank 12 is performed more efficiently, and the amount of water adhering to the second container 14 can be reduced. As a result, the drying time of the silicon crushed piece 11 in the next drying step is further shortened, and the contamination of the silicon crushed piece due to the organic matter from the second container 14 can be suppressed.

The through holes 21 and 22 formed in the bottom plate portion 16 and the peripheral wall portion 17 of the second container 14 have a hole diameter smaller than the size of the silicon crushed piece 11. In the present specification, the shortest part of the silicon fragment in a plan view is referred to as the size of the silicon fragment. Although not shown, the through holes formed in the bottom plate portion and the peripheral wall portion of the first container 10 also have a hole diameter smaller than the size of the silicon crushed piece. By setting the hole diameter of the through hole in this way, it is possible to prevent the silicon crushed piece 11 from falling out from the inside of each of the first container 10 and the second container 14 through the through hole.

Further, in the present embodiment, as shown in FIGS. 4A to 4C, the installation surface of the second container is located on the outer bottom surface 16a where the through hole 21 of the bottom plate portion 16 of the second container 14 is not formed. One or more protrusions 24 are formed that separate the outer bottom surface 16a from the 23. For example, the protrusion 24 has an inclined surface 24a shown in FIG. 4A which is gradually inclined downward in a vertical cross-sectional view. The inclined surface may be the inclined surface 24b or 24c shown in FIG. 4 (b) or (c), which gradually inclines downward in a curved line. By forming the protrusion 24 in this way, a certain space can be secured under the through hole of the bottom plate portion 16, and the container pieces and silicon fine powder brought into the second container 14 are discharged to the outside of the container. By making it easier and making it difficult for the container pieces and silicon fine powder from the outside of the bottom plate of the second container to enter directly, it is possible to reduce the contamination of the silicon crushed pieces. Further, since the protrusion 24 has an inclined surface that gradually inclines downward in a straight line or a curve in the vertical cross-sectional view, the space between the protrusion 24 and the protrusion 24 on the outer bottom surface 16a of the second container is created. It can be taken large, and the silicon fine powder and the relatively large container piece taken into the second container 14 at the time of transfer are discharged into the space between the protrusion 24 and the protrusion 24 on the outer bottom surface 16a. It can also be isolated from the silicon shards inside the container. As a result, contamination of silicon debris caused by organic substances can be suppressed.

Further, in the present embodiment, the through hole 21 formed in the bottom plate portion 16 of the second container 14 is tapered in diameter from the hole edge portion inside the container to the hole edge portion outside the container, as shown in FIG. By having the shape or curvature, the corners are eliminated, the hole edge inside the container is less likely to be scraped by the silicon piece, and the generation of the container piece can be reduced. By forming the through hole 21 in this way, draining after taking out the second container 14 from the water tank 12 is performed more efficiently, and the container pieces and silicon fine powder taken into the container are discharged to the outside through the through hole. It can also be made easier to flow out. The amount of water adhering to the second container 14 can be reduced. As a result, the drying time of the silicon debris in the next drying step is further shortened, and the contamination of the silicon debris caused by the organic matter from the second container 14 can be suppressed.

Further, by using the second container as a holding member made of synthetic resin having low gasogenicity such as polypropylene, polycarbonate, silicone synthetic resin, ethylene / tetrafluoroethylene copolymer, PEEK, PTFE, PFA, FEP, PVDF, etc. Even when the drying temperature is set to 50 ° C. or higher, the amount of organic gas such as a resin additive containing carbon generated from the container itself is small, so that the contamination of the container piece by organic substances can be reduced. .. Although the amount of gas generated by the silicone resin is not smaller than that of the above resins, the generated gas is less likely to adhere to the silicon surface, and the carbon contamination of the crushed fragments can be reduced.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. For example, in the above-described embodiment, the second container has a rectangular parallelepiped box shape, but it may have a cylindrical shape or a polygonal shape of a quadrangle or more. Further, although the inclined surfaces 22a and 22b are formed in all the through holes formed in the peripheral wall portion, they may be formed only in some of the through holes. Further, in the present invention, when transferring the container, bubbling is formed in pure water or ultrapure water, and the container is transferred in a state where the bubbling is in contact with the surface of the silicon crushed piece, and the container piece or the container piece or the container piece is transferred. Abrasion debris may be separated from the silicon debris. Further, the surface of the silicon crushed piece may be irradiated with ultrasonic waves when the container is transferred so that the container piece and the abrasion powder adhering to the surface of the silicon crushed piece are separated from the surface of the silicon crushed piece.

Further, in the present invention, the silicon crushed pieces were dropped and transferred into the second container arranged in the water tank, but when this transfer was performed, the second container was arranged in the third container. In this state, the silicon crushed pieces may be transferred from the first container. In this case, the bottom area of the third container is larger than that of the second container, and when the second container is arranged in the third container, the bottom surface of the third container exists near the bottom surface of the second container. It is good to be arranged so as to. As a result, when the silicon crushed pieces are transferred from the first container to the second container, the silicon crushed pieces that have fallen to the outside of the second container can be stored in the third container, and the silicon that has fallen to the outside of the second container can be stored. The crushed pieces can be easily recovered.

Further, the pure water or ultrapure water in the water tank in the present invention may constitute circulation filtration. In this case, by circulating and filtering pure water or ultrapure water in the water tank, the container pieces and wear debris dispersed in the water can be removed by filtration, and the container pieces and wear debris separated from the silicon crushed pieces can be removed. Can be prevented from reattaching to the silicon debris. Further, in the present invention, the second container is arranged in the water tank, and the silicon crushed pieces in the first container are dropped from the upper part of the second container. A stand may be provided so as to be arranged above. As a result, if container pieces or wear debris enter the second container when the silicon crushed pieces are transferred, the container pieces or wear debris can be easily discharged from the second container by arranging the gantry, and the silicon crushed pieces can be crushed. Container pieces and wear debris can be separated from the pieces more efficiently.

Next, examples of the present invention will be described in detail together with comparative examples.

<Example 1>
As shown in FIG. 1, a water tank 12 made of PVDF (polyvinylidene fluoride) having an inner dimension of about 2000 mm × width × height of about 2000 mm × about 1000 mm × about 1000 mm and an outer dimension of about length × width × height are about. An unused first container 10 made of PE (polyethylene) measuring 155 mm × about 155 mm × about 220 mm and made of PE (polyethylene) having internal dimensions of about 480 mm × about 320 mm × about 140 mm. A second container 14 was prepared. A square through hole having a side of about 5 mm is formed in the bottom plate portion of the first container 10 so that the vertical and horizontal pitches between the through holes are about 4 mm, and the peripheral wall of the first container 10 is formed. A square through hole having a side of about 5 mm was formed in the portion so that the diagonal line of the through hole extends in the vertical direction and the horizontal direction and the pitch between adjacent through holes is about 4 mm. Further, in the bottom plate portion 16 of the second container 14, a circular through hole 21 having a diameter of about 5 mm is formed so that the vertical and horizontal pitches between the through holes 21 are about 4 mm (FIG. 2). In the peripheral wall portion 17 of the second container 14, a square through hole 22 having a side of about 5 mm is provided, and the diagonal lines of the through hole 22 extend in the vertical and horizontal directions, and the pitch between the adjacent through holes 22 is increased. It was formed to be about 4 mm (FIGS. 2 and 3 (a)).

On the other hand, about 25 kg of silicon crushed pieces 11 having a maximum length of about 5.5 mm to 45 mm in a plan view are prepared, and about 25 kg of the silicon crushed pieces 11 are divided into 5 sets of about 5 kg each, and 5 pieces are prepared. Each of the first containers 10 of the above was charged and contained. Here, in the above-mentioned silicon crushed piece, after precipitating a polycrystalline silicon rod by the Siemens method, a silicon lump is formed by cutting and crushing the silicon rod, and further, the silicon lump is made into a predetermined size by a tool such as a hammer. (Fig. 6).

As shown in the flowchart of FIG. 6, first, the silicon crushed piece 11 housed in the first container 10 was etched. This etching treatment was performed by immersing the first container 10 containing about 5 kg of crushed silicon pieces 11 in an etching solution composed of a mixed solution of hydrofluoric acid and nitric acid. Specifically, the first container 10 containing the crushed silicon piece 11 was immersed in the etching solution for 2 minutes, and the first container 10 was shaken 20 times during the immersion. By this etching treatment, impurities adhering to the surface of the silicon crushed piece 11 in the first container 10 were removed. In addition, in order to suppress the variation in the etching amount of the silicon crushed piece 11 to a low level, the temperature and concentration of the etching solution were controlled to stabilize the temperature and concentration of the etching solution. Next, the etched silicon crushed pieces 11 were rinsed while being contained in the first container 10. In this rinsing treatment, the etched silicon crushed pieces 11 are immersed in pure water for 3 minutes while being contained in the first container 10, and the first container 10 is shaken 20 times during the immersion. went. By this rinsing treatment, the acid solution adhering to the surface of the silicon crushed piece 11 in the first container 10 was removed.

Next, the silicon crushed pieces 11 in the five first containers 10 were sequentially transferred to a single second container 14 (transfer treatment). In this transfer treatment, the water tank 12 is filled with pure water (water temperature: about 20 ° C.), and a second container 14 is arranged at the bottom of the water tank 12 with the opening 10a facing upward. In the pure water 13 above the opening 18, the rinsed first container 10 was gradually tilted to move the silicon crushed pieces 11 in the first container 10 into the second container 14. The remaining 4 sets of crushed silicon products 11 were also transferred in the same manner as described above. Then, the second container 14 containing the silicon crushed pieces 11 was taken out from the water tank 12, and the silicon crushed pieces 11 were dried (drying treatment). This drying treatment was carried out by placing the silicon crushed pieces 11 in the vacuum drying treatment device while being housed in the second container 14 and holding the silicon crushed pieces 11 at 70 ° C. for 120 minutes. The silicon crushed piece 11 subjected to these treatments was designated as Example 1.

<Comparative example 1>
The same treatment as in Example 1 was carried out except that the transfer treatment was not carried out, that is, 5 sets of crushed silicon pieces were subjected to an etching treatment, a rinsing treatment and a drying treatment, respectively. Five sets of crushed silicon pieces subjected to these treatments were designated as Comparative Example 1. Since the silicon crushed piece of Comparative Example 1 after the treatment has not been subjected to the transfer treatment, it remains contained in the first container.

<Comparative test 1>
The presence or absence of the container pieces attached to the silicon crushed pieces after the drying treatment of Comparative Example 1 and the presence or absence of the container pieces attached to the silicon crushed pieces after the drying treatment of Example 1 were visually examined. The results are shown in Table 1.

<Evaluation 1>
As is clear from Table 1, in Comparative Example 1 in which the transfer treatment was not performed, several container pieces of about 3 mm or less were attached to the silicon crushed pieces after the drying treatment. On the other hand, in Example 1 in which the transfer treatment was performed, exactly the same treatment as in Comparative Example 1 was performed before the transfer treatment, so that several container pieces adhered to the silicon crushed pieces in each of the five first containers. However, the container pieces did not adhere to the silicon crushed pieces after the drying treatment in a single second container. In the first container used in Example 1 and Comparative Example 1, a plurality of cutting marks which were considered to have been generated when the silicon crushed pieces were in contact were observed on the inner wall surface of the container in which the silicon crushed pieces were in contact.

<Example 2>
In the transfer treatment of Example 1, the silicon crushed pieces in the five first containers were transferred to five other first containers formed in the same shape and size as the first container. In this transfer process, the water tank is filled with pure water, another first container is placed at the bottom of the water tank with the opening facing upward, and in the pure water above the opening of the other first container. This was done by gradually tilting the rinsed first container and transferring the silicon crushed pieces in the first container into another first container. Except for the above, the silicon crushed pieces were treated in the same manner as in Example 1. These treatments were also performed on the remaining 4 sets of crushed silicon products. The silicon crushed piece subjected to these treatments was designated as Example 2.

<Comparative test 2>
The situation during the transfer of the silicon crushed pieces of Example 2 from the first container to another first container was investigated. Specifically, during the above transfer, the number of silicon crushed pieces dropped out of another first container was examined. The results are shown in Table 2. In addition, also in Example 1, the number of silicon crushed pieces that the silicon crushed pieces fell out of the second container during the transfer was also examined. In Table 2, since the “-” in Example 2 was not transferred from the first container to the second container, it is not necessary to check the number of silicon crushed pieces that fell out of the second container. This means that “-” in Example 1 indicates the number of silicon crushed pieces that fell out of the other first container because the transfer process from the first container to another first container was not performed. It means that I didn't have to look it up.

<Evaluation 2>
As is clear from Table 2, in Example 2, when the transfer was performed using another first container, some silicon crushed pieces being transferred fell out of the other first container. Was done. On the other hand, in Example 1, when the silicon crushed pieces were transferred from the first container to the second container, none of them fell out of the second container. From this, it was found that the transfer efficiency of Example 2 was not as good as that of Example 1.

<Example 3>
A single plate (same material as the first container) having a thickness of about 1 mm is attached to the upper surface of the bottom plate portion of the first container of the first embodiment to close all the through holes of the bottom plate portion of the first container. Four plates (the same material as the first container) having a thickness of about 1 mm were attached to the inner surface of the peripheral wall portion of the first container to close all the through holes in the peripheral wall portion of the first container. Further, one plate (the same material as the second container) having a thickness of about 1 mm is attached to the upper surface of the bottom plate portion of the second container of Example 1 to close all the through holes of the bottom plate portion of the second container. , Four plates (the same material as the second container) having a thickness of about 1 mm were attached to the inner surface of the peripheral wall of the second container to close all the through holes in the peripheral wall of the second container. Using these first container and second container, the silicon crushed pieces were treated in the same manner as in Example 1. The silicon crushed piece subjected to these treatments was designated as Example 3.

<Comparative test 3>
The situation in the second container used for the treatment of the silicon crushed pieces of Example 3 was investigated. Specifically, the presence or absence of container pieces in the first container collected in the second container used for treating the crushed silicon pieces was examined. The results are shown in Table 3. In addition, also in Example 1, the presence or absence of the container piece of the first container accumulated in the second container used for the treatment of the silicon crushed piece was examined together.

<Evaluation 3>
As is clear from Table 3, in Example 1, the container pieces of the first container collected in the second container used for the treatment of the silicon crushed pieces were not confirmed. On the other hand, in Example 3, several container pieces of the first container collected in the second container used for the treatment of the crushed silicon pieces were confirmed. This is considered to be based on the following reasons. In the third embodiment, since the through holes on the bottom surface and the side surface of the first container are closed, the container pieces generated in the first container during the etching process and the rinsing process penetrate from the inside of the first container before transfer. It cannot move out of the first container through the hole and easily stays in the first container. Further, when the silicon crushed pieces are transferred from the first container to the second container, if a part of the container pieces in the first container enters the second container together with the silicon crushed pieces, the bottom surface in the second container or Since the through hole on the side surface is closed, the container piece is not discharged from the second container and easily collects in the second container.

<Example 4>
Pure water in the water tank was supplied and discharged by a water supply / discharge mechanism so as to form a gentle flow of about 7 m / min in the vertical direction on the upper part of the water tank of Example 1. In this state, the silicon crushed pieces in the first container were transferred to another first container in the water tank. Except for the above, the same treatment as in Example 2 was performed on the silicon crushed pieces. The silicon crushed piece subjected to these treatments was designated as Example 4.

<Comparative test 4>
It was confirmed whether or not the container pieces adhered to the silicon crushed pieces of Example 4 after the drying treatment. Further, the same confirmation as above was performed for Example 2 in which the flow of pure water in the water tank was not formed (flow velocity: 0 m / min). The results are shown in Table 4.

<Evaluation 4>
As is clear from Table 4, in Example 2 in which the flow velocity of pure water in the water tank was 0 m / min, one container piece of about 3 mm or less was confirmed in the silicon crushed piece, whereas the pure water in the water tank was pure. In Example 4 in which the flow velocity of water was about 7 m / min, no container piece was confirmed in the silicon crushed piece. As a result, by using the pure water in the water tank as running water, it is considered that the container pieces that have fallen from the first container are flowed into the pure water and dispersed, and it is possible to reduce the amount of the container pieces falling into another first container. The flow rate of pure water of about 7 m / min is an example, and is not limited to this. If the flow velocity of pure water in the water tank is too fast, the number of relatively small-sized silicon crushed pieces that fall out of another first container along with the flow of pure water will increase, so the flow velocity should not be too fast. good. On the other hand, if the flow velocity of pure water is slow, the container piece cannot ride on the flow of pure water, and the dispersion effect of the container piece becomes small.

<Example 5>
Silicon crushed pieces were treated in the same manner as in Example 1 except that the temperature of pure water in the water tank of Example 1 was set to about 30 ° C. The silicon crushed piece subjected to these treatments was designated as Example 5.

<Example 6>
Silicon crushed pieces were treated in the same manner as in Example 1 except that the temperature of pure water in the water tank of Example 1 was set to about 50 ° C. The silicon crushed piece subjected to these treatments was designated as Example 6.

<Example 7>
Silicon crushed pieces were treated in the same manner as in Example 1 except that the temperature of pure water in the water tank of Example 1 was set to about 70 ° C. The silicon crushed piece subjected to these treatments was designated as Example 7.

<Comparative test 5>
The time required for the drying treatment of the silicon crushed pieces of Examples 5 to 7 was measured. In addition, the time required for the drying treatment of the silicon crushed pieces of Example 1 in which the temperature of pure water in the water tank was set to 20 ° C. was also measured. Then, the reduction rate of the drying time of Examples 5 to 7 was calculated based on the drying time of Example 1. The results are shown in Table 5. The silicon crushed pieces are dried by putting the silicon crushed pieces in a vacuum drying treatment device to set the pressure to 760 mmHg and keeping the temperature at 70 ° C., purging the nitrogen gas to a pressure of 500 mmHg, and increasing the pressure by 2 mmHg. When it was the following, it was judged that the silicon crushed pieces were dried, and the time from the start of vacuum drying to the purging of nitrogen gas until the pressure increase amount became 2 mmHg or less was defined as the drying time of the silicon crushed pieces.

<Evaluation 5>
As is clear from Table 5, in Examples 5 to 7, the drying time of the silicon crushed pieces could be shortened as compared with Example 1. This is because the silicon crushed pieces after the transfer from the first container to the second container were dried together with the second container while being warmed to near the temperature of pure water, so that the temperature of pure water is about 20 ° C. It is considered that the time required for drying could be shortened as compared with the drying time of the silicon crushed pieces of Example 1. As a result, it is possible to improve the drying treatment efficiency and reduce the generation of gas from the container itself due to the shortening of the drying time, and it is possible to reduce the carbon contamination derived from organic substances in the drying treatment.

<Example 8>
A square through hole having a side of about 5 mm is formed in the peripheral wall of the second container so that the diagonal line extends at an angle of 45 degrees with respect to the vertical direction, that is, the side extends in the vertical direction and the horizontal direction, and It was formed so that the vertical and horizontal pitches between the through holes were about 4 mm. Except for the above, the same second container as in Example 1 was used. This second container was designated as Example 8.

<Example 9>
As shown in FIG. 3B, a circular through hole 22 having a diameter of about 5 mm is provided in the peripheral wall portion 17 of the second container so that the vertical and horizontal pitches between the through holes 22 are about 4 mm. Formed. Except for the above, the same second container as in Example 1 was used. This second container was designated as Example 9.

<Comparative test 6>
After putting the second container of Example 1, Example 8 and Example 9 into the pure water in the water tank, the second container is taken out from the pure water, and the pure water in the second container penetrates the bottom plate portion. After falling through the hole or the through hole of the peripheral wall, pure water (adhered water) adhering to the inner surface of the peripheral wall of the second container travels along the periphery of the through hole of the peripheral wall and becomes water droplets outside the second container. The container was left until it fell and the adhering water did not fall, and the weight of the second container containing the crushed silicon was measured. It was visually judged that the adhering water did not fall. The results are shown in Table 6. In the second container of the first embodiment, as shown in FIG. 3A, the through hole 22 formed in the peripheral wall portion 17 has a square shape having a side of about 5 mm, and the diagonal line thereof is in the vertical direction. The pitch between the through holes 22 extending in the horizontal direction and adjacent to each other was about 4 mm.

<Evaluation 6>
As is clear from Table 6, the weight of the second container of Example 1 having a square through hole whose diagonal line extends vertically and horizontally is the smallest when the adhering water does not fall, and the circular through hole has a circular shape. The second of Example 8 having the next smallest weight when the adhering water of the second container of Example 9 does not fall, and having a square through hole whose diagonal line extends in the direction of 45 degrees with respect to the vertical direction. The weight was the heaviest when the adhering water in the container did not fall. That is, the amount of residual water adhering to the inner surface of the peripheral wall portion was the smallest in the second container of Example 1, the second smallest container of Example 9, and the largest amount of the second container of Example 8. As a result, the second container of Example 8 is most likely to collect water droplets on the lower edge of the through hole, whereas the second container of Example 9 is most likely to collect water droplets on the lower edge of the through hole. It was found that, in the second container of Example 1, water droplets accumulated on the lower edge of the through hole easily flowed down.

<Example 10>
On the lower surface of the bottom plate portion of the second container, a plurality of rectangular parallelepiped plate-shaped protrusions were projected downward. Except for the above, the same second container as in Example 1 was used. This second container was designated as Example 10. The rectangular plate-shaped protrusions had lengths, thicknesses, and heights of 5 mm, 5 mm, and 7 mm, respectively, and were projected at positions where a plurality of through holes formed in the bottom plate portion were not blocked. In addition, four plates (the same material as the second container) having a thickness of about 1 mm were attached to the inner surface of the peripheral wall portion of the second container to close all the through holes in the peripheral wall portion of the second container.

<Example 11>
As shown in FIG. 4A, a plurality of truncated cone-shaped protrusions 24 having a straight inclined surface are projected downward from the lower surface of the bottom plate portion 16 of the second container. Except for the above, the same second container as in Example 1 was used. This second container was designated as Example 11. The truncated cone-shaped protrusion 24 having a straight inclined surface has an upper end diameter, a lower end diameter and a height of 5 mm, 3 mm and 7 mm, respectively, and a plurality of through holes 21 formed in the bottom plate portion 16. Was projected at a position where there was no blockage. In addition, four plates (the same material as the second container) having a thickness of about 1 mm were attached to the inner surface of the peripheral wall portion of the second container to close all the through holes in the peripheral wall portion of the second container.

<Example 12>
As shown in FIG. 4B, a plurality of curved cone-shaped protrusions 24 having an inwardly curved inclined surface are projected downward from the lower surface of the bottom plate portion 16 of the second container. bottom. Except for the above, the same second container as in Example 1 was used. This second container was designated as Example 12. The truncated cone-shaped protrusion 24 having an inclined surface curved inward has an upper end diameter, a lower end diameter and a height of 5 mm, 3 mm and 7 mm, respectively, and is formed on the bottom plate portion 16. A plurality of through holes 21 are projected at positions where they are not blocked. In addition, four plates (the same material as the second container) having a thickness of about 1 mm were attached to the inner surface of the peripheral wall portion of the second container to close all the through holes in the peripheral wall portion of the second container.

<Comparative test 7>
The second container of Examples 10 to 12 is placed on a flat plate made of the same material as the water tank, 5 liters of pure water containing a container piece is put into the second container, and pure through the through hole of the bottom plate of the second container. After the water was no longer discharged, the presence or absence of container pieces in the second container was visually confirmed. The results are shown in Table 7.

<Evaluation 7>
As is clear from Table 7, the inside of the second container of Example 12 having a truncated cone-shaped protrusion whose inclined surface is curvedly inclined, and having a truncated cone-shaped protrusion whose inclined surface is linearly inclined. No container pieces were confirmed in the second container of Example 11, and several container pieces were confirmed only in the second container of Example 10 having a rectangular parallelepiped plate-shaped protrusion. That is, since the flow of pure water that falls from the second container of Example 12 and the second container of Example 11 through the through hole of the bottom plate portion to the outside of the second container is fast, the container pieces are easily discharged, and the example. It is probable that the container pieces were difficult to be discharged because the flow of pure water falling from the second container of No. 10 through the through hole of the bottom plate portion to the outside of the second container was slow.

<Example 13>
As shown in FIG. 5, the through hole 21 formed in the bottom plate portion 16 of the second container is formed in a tapered shape that becomes smaller from the upper side to the lower side. The silicon crushed pieces were treated in the same manner as in Example 1 except that this second container was used. The second container after the treatment was designated as Example 13. The tapered through hole 21 was formed by being curved inward, and the lengths of one side of the square at the upper end and the lower end were 5 mm and 3 mm, respectively.

<Example 14>
The silicon shards were treated in the same manner as in Example 1. The second container after the treatment was designated as Example 14.

<Comparative test 8>
After the treatment, the wear state of the bottom plate portion of the second container of Examples 13 and 14, that is, the state of scraping of the bottom plate portion and the scraping of the peripheral edge of the through hole inside the bottom plate portion was visually examined. Further, pure water containing a container piece is put into the second container of Examples 13 and 14, and the behavior of the container piece or the like in the pure water from the bottom plate portion of the second container, that is, it is caught on the peripheral edge of the through hole. The presence or absence of container pieces and the condition of water droplets accumulated on the upper surface of the bottom plate were visually inspected. The results are shown in Table 8.

<Evaluation 8>
As is clear from Table 8, in the second container of Example 14 in which the through hole of the bottom plate portion was formed in a rectangular parallelepiped shape, the bottom plate portion was scraped and the peripheral edge of the through hole inside the bottom plate portion was scraped relatively much. In the second container of Example 13 in which the through hole of the bottom plate portion was formed in a tapered shape, the scraping of the bottom plate portion and the scraping of the peripheral edge of the through hole inside the bottom plate portion were relatively small. Further, in the second container of Example 14, a container piece or the like was caught on the peripheral edge of the rectangular parallelepiped through hole of the bottom plate portion, whereas in the second container of Example 13, the container was placed on the peripheral edge of the tapered through hole of the bottom plate portion. One piece was not caught. Further, in the second container of Example 14, a relatively large amount of water droplets were accumulated on the upper surface of the bottom plate portion, whereas in the second container of Example 13, the amount of water droplets accumulated on the upper surface of the bottom plate portion was relatively small.

The method for cleaning the surface of crushed silicon of the present invention can be used between cleaning and drying the crushed silicon, which is a raw material for single crystal silicon produced by the CZ method.

10 1st container 11 Silicon crushed pieces 12 Water tank 13 Pure water or ultra-pure water 14 2nd container 16 Bottom plate of 2nd container 17 Peripheral wall of 2nd container 18 Opening of 2nd container 21 Bottom plate of 2nd container Through hole 22 Through hole 22a, 22b of the peripheral wall portion of the second container Inclined surface of the through hole of the peripheral wall portion of the second container 23 Installation surface of the second container 24 Protrusions 24a to 24c of the bottom plate portion of the second container Second container Inclined surface of the protrusion of the bottom plate of

Claims (10)

Before drying the silicon crushed pieces after being housed in the resin first container and washed, the silicon crushed pieces are transferred from the first container to the resin second container in pure water or ultrapure water. A method for cleaning the surface of crushed silicon, which is characterized by replacement. The first container and the second container are containers having an opening at the upper part, respectively, and the transfer arranges the second container in pure water or ultrapure water of a water tank with the upper part facing upward. Then, in the pure water or ultrapure water, the silicon crushed pieces after being housed in the first container and washed are dropped into the inside of the second container by inclining the opening of the first container. The method for cleaning the surface of crushed silicon according to claim 1. The method for cleaning the surface of crushed silicon according to claim 1 or 2, wherein the opening area of the second container is larger than that of the first container, or the volume thereof is larger than the volume of the first container. The silicon crushed piece according to any one of claims 1 to 3, wherein a plurality of through holes having a diameter smaller than the size of the silicon crushed piece are formed in the peripheral wall portion and the bottom plate portion of the first container and the second container, respectively. Surface cleaning method. The method for cleaning the surface of crushed silicon according to any one of claims 1 to 4, wherein the pure water or ultrapure water is water in which the ultrapure water flows. The method for cleaning the surface of crushed silicon according to any one of claims 1 to 5, wherein the pure water or ultrapure water is set to a temperature of 10 to 70 ° C. The fourth aspect of claim 4, wherein the through hole formed in the peripheral wall portion of the second container has an inclined surface in which the peripheral surface of the lower half of the hole is gradually inclined downward linearly or curvedly in a front view of the peripheral wall portion. How to clean the surface of silicon shards. One or two or more protrusions that separate the outer bottom surface from the installation surface of the second container are formed on the outer bottom surface portion where the through hole of the bottom plate portion of the second container is not formed, and the vertical section of the protrusion portion is formed. The method for cleaning the surface of silicon crushed pieces according to claim 4, which has an inclined surface that gradually slopes downward linearly or curvedly in a plan view. The fourth or eight claim, wherein the through hole formed in the bottom plate portion of the first container or the second container has a tapered shape or a curvature by reducing the diameter from the hole edge portion inside the container to the hole edge portion outside the container. A method for cleaning the surface of crushed silicon. The second container is made of one or more synthetic resins selected from the group consisting of polypropylene, polycarbonate, silicone synthetic resin, ethylene / ethylene tetrafluoride copolymer, PEEK, PTFE, PFA, FEP and PVDF. The method for cleaning the surface of crushed silicon according to any one of claims 1 to 4 or 7 to 9.

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