Cleaning Basket

Abstract

To provide a washing basket in which the amount of silicon pieces spilled from a washing basket is reduced and the amount of liquid carried in is reduced.SOLUTION: Provided is a washing basket (10X) that is used to wash polycrystalline silicon lump, and in which a plurality of holes (H) having a hole diameter of 1 mm or more and 10 mm or less are formed in a receiving region (RB) located below the washing basket (10X) and in which the polycrystalline silicon lump is received, and a plurality of slits (S) having a groove width of 1 mm or more and 10 mm or less are formed in an upper region (RT) above the receiving region (RB).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a cleaning basket for use in cleaning polycrystalline silicon. [Background technology]

[0002] The Siemens process is known as a method for producing high-purity polycrystalline silicon. In the Siemens process, trichlorosilane is produced by reacting metal silicon with hydrogen chloride gas, and the trichlorosilane is then hydrogen-reduced or thermally decomposed to precipitate silicon on a silicon core wire, producing cylindrical polycrystalline silicon. The polycrystalline silicon rod thus produced is cut into short lengths or crushed into small chunks of silicon material. The chunks of silicon material are etched and cleaned by being immersed in a cleaning basket filled with a mixture of hydrofluoric acid and nitric acid. The cleaning basket is then washed with pure water and dried.

[0003] The washing basket used for the above-mentioned applications usually has a plurality of through holes in the side and bottom plates for passing liquid into the washing basket. For example, the basket (washing basket) described in Patent Document 1 has a plurality of round through holes in the bottom and side plates. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-106914 A Summary of the Invention [Problem to be solved by the invention]

[0005] It is preferable that the cleaning basket carries a small amount of liquid when it is moved between cleaning liquid tanks and when it is brought to the drying process. On the other hand, if silicon pieces fall out of the through-hole, the life of the cleaning liquid will be shortened, so it is preferable that the amount of silicon pieces that fall out of the through-hole is small. Therefore, there is room for improving the through-hole in order to reduce the amount of liquid carried in while reducing the amount of polycrystalline silicon pieces that fall out of the through-hole during cleaning.

[0006] An object of one aspect of the present invention is to provide a cleaning basket that reduces the amount of polycrystalline silicon pieces that spill out of the cleaning basket and reduces the amount of liquid carried over. [Means for solving the problem]

[0007] In order to solve the above problems, a cleaning basket according to one embodiment of the present invention is a cleaning basket used for cleaning polycrystalline silicon chunks, which is located below the cleaning basket and has a storage area in which the polycrystalline silicon chunks are stored, in which a plurality of holes having a diameter of 1 mm or more and 10 mm or less are formed, and in an upper area above the storage area, a plurality of slits having a groove width of 1 mm or more and 10 mm or less are formed. Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to realize a cleaning basket that reduces the amount of polycrystalline silicon pieces that spill out of the cleaning basket and reduces the amount of liquid carried over. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic perspective view of a cleaning basket according to a first embodiment of the present invention. [Diagram 2] FIG. 1 is an exploded view of a cleaning basket according to a first embodiment of the present invention. [Diagram 3] FIG. 11 is a schematic perspective view of a cleaning basket according to a second embodiment of the present invention. [Figure 4] FIG. 11 is an exploded view of a cleaning basket according to a second embodiment of the present invention. [Diagram 5]FIG. 11 is a plan view of a cleaning basket according to a second embodiment of the present invention as viewed from above. [Figure 6] FIG. 11 is a side view of a cleaning basket according to a second embodiment of the present invention, as viewed from the first side plate 11 side. [Figure 7] FIG. 11 is a side view of a cleaning basket according to a second embodiment of the present invention, as viewed from the second side plate side. [Figure 8] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The cleaning basket according to the present invention will be described below, but first, for the sake of understanding, a situation in which the cleaning basket according to the present invention is used will be described.

[0011] Polycrystalline silicon can be obtained by precipitating polycrystalline silicon on a silicon core by the Siemens process. The polycrystalline silicon rod thus obtained is usually cut into short pieces or crushed, and then placed in a cleaning cage in the form of polycrystalline silicon chunks (hereinafter referred to as silicon chunks) and subjected to a cleaning process.

[0012] The cleaning process includes, for example, an etching step using fluoronitric acid as a cleaning liquid, a water washing step using water as a cleaning liquid, a drying step, and a cooling step. The cleaning process is not limited to this example, and may include a cleaning step using another cleaning liquid.

[0013] The etching process is a cleaning process that removes contaminants present on the surface of the silicon block. An oxide film containing contaminants can be formed on polycrystalline silicon by natural oxidation, usually with a thickness of several nm. The following reaction occurs when polycrystalline silicon is brought into contact with hydrofluoric nitric acid. The surface of the polycrystalline silicon is etched and the oxide film present on the surface is removed, mainly due to the action of hydrofluoric acid. Meanwhile, a new oxide film is formed on the surface of the polycrystalline silicon, mainly due to the action of nitric acid. The removal of the oxide film and the formation of the oxide film proceed simultaneously, so that the polycrystalline silicon is etched and contaminants attached to the surface of the polycrystalline silicon and contaminants incorporated in the polycrystalline silicon are removed. The etching process may be composed of multiple cleaning tanks.

[0014] The water washing step is a washing step for removing the fluoronitric acid washing solution used in the etching step and contaminants. The water used in the water washing step is preferably purified water containing less contaminants, and more preferably ultrapure water. The water washing step may be composed of a plurality of washing tanks.

[0015] The drying process is a process in which the silicon chunks that have been washed with various cleaning solutions are dried by passing hot air or the like through them.

[0016] The cooling step is a step of cooling the silicon chunks heated in the drying step.

[0017] In the above-mentioned cleaning process, the etching step and the water washing step can be performed by immersing a cleaning basket containing silicon chunks in a cleaning tank filled with each cleaning liquid. In addition, while the cleaning basket is immersed, the cleaning basket may be moved up and down or swung to improve the contact efficiency with the cleaning liquid.

[0018] The washing basket according to the present invention is for use in the washing process as described above.

[0019] [Embodiment 1] <Composition of cleaning basket 10X> Hereinafter, one embodiment of the present invention will be described with reference to Figures 1 and 2. The following description is provided for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified. Furthermore, unless otherwise specified, the shape, structure, and positional relationship of each member are not limited to the examples in each figure. In this specification, the expression "A to B" means "A or more and B or less" unless otherwise specified.

[0020] FIG. 1 is a schematic perspective view of the cleaning basket 10X. Note that FIG. 1 is a schematic view of the outer shape of the cleaning basket 10X, and the holes H and slits S of the cleaning basket 10X are omitted. FIG. 2 is a development of the cleaning basket 10X. The view indicated by reference numeral 2001 in FIG. 2 is a development including the bottom plate 14 (bottom), the first side plate 11X (side wall), and the second side plate 12X (side wall). The view indicated by reference numeral 2002 in FIG. 2 is a plan view of the partition plate 15X. It should be understood that the development of FIG. 2 is a schematic development, and the size, number, arrangement, etc. of the holes H and slits S differ from the actual configuration.

[0021] As shown in FIGS. 1 and 2, the cleaning basket 10X includes a bottom plate 14 (bottom portion), a first side plate 11X (side wall portion), a second side plate 12X (side wall portion), and a partition plate 15X.

[0022] The cleaning basket 10X is a basket capable of accommodating a plurality of silicon chunks. The cleaning basket 10X has, for example, a substantially rectangular parallelepiped shape and may be made of a resin with good drainage, such as polypropylene resin (PP), polyvinyl chloride resin (PVC), or polyvinylidene fluoride resin (PVDF). The capacity of the cleaning basket 10X is, for example, 1 L to 300 L, preferably 150 L to 290 L. The length of the long side when the cleaning basket 10X is viewed from above in a plan view is 10 cm to 100 cm, preferably 40 cm to 90 cm. The length of the short side when the cleaning basket 10X is viewed from above in a plan view is 10 cm to 100 cm, preferably 40 cm to 90 cm. The height of the cleaning basket 10X is 10 cm to 70 cm, preferably 30 cm to 60 cm. The shape of the cleaning basket 10X is not limited to a rectangular parallelepiped shape.

[0023] The bottom plate 14 is a member located at the bottom of the cleaning cage 10X. In Fig. 1, the bottom plate 14 is configured as a rectangular flat plate, but is not limited to this shape and may be a square flat plate. The bottom plate 14 may also be curved so as to be convex downward.

[0024] When the cleaning basket 10X has a substantially rectangular parallelepiped shape, the first side plate 11X (side wall portion) is a member connected to the short side of the bottom plate 14 and extending upward from the bottom plate 14. The second side plate 12X (side wall portion) is a member connected to the long side of the bottom plate 14 and extending upward from the bottom plate 14. In FIG. 1, the first side plate 11X and the second side plate 12X extend in a direction perpendicular to the surface of the bottom plate 14, but this is not limited to this embodiment. For example, the first side plate 11X and the second side plate 12X may be inclined upward and outward with respect to the surface of the bottom plate 14 to an extent that silicon chunks can be contained therein.

[0025] The partition plate 15X is provided inside the cleaning cage 10X and is a member for reducing the uneven distribution of silicon chunks in the cleaning cage 10X. The cleaning cage 10X may include multiple partition plates 15X as necessary. In the example shown in FIG. 1 and FIG. 2, the partition plate 15X has a rectangular shape, but the shape of the partition plate X can be designed arbitrarily to match the shape of the cleaning cage 10X. The partition plate 15X is provided with multiple through holes for liquid passage between two areas in the cleaning cage 10X separated by the partition plate X. The shape and size of the through holes provided in the partition plate 15X are not particularly limited as long as they are large enough to ensure the passage of liquid without allowing silicon chunks to pass through. For example, multiple slits S, which will be described later, may be formed.

[0026] As shown in FIG. 1, in the cleaning basket 10X, the area located at the bottom where the silicon chunks are accommodated is defined as the accommodation area RB, and the area above the accommodation area RB is defined as the upper area RT. As shown in FIG. 2, the first side plate 11X has an area 11B that is an area included in the accommodation area RB, and an area 11T that is an area included in the upper area RT. Similarly, the second side plate 12X has an area 12B that is an area included in the accommodation area RB, and an area 12T that is an area included in the upper area RT. The bottom plate 14 has an area 14B that is included in the accommodation area RB. The boundary position between the accommodation area RB and the upper area RT can be set arbitrarily depending on the capacity of the cleaning basket 10X, etc. For example, the boundary position between the accommodation area RB and the upper area RT can be set to be one-quarter to two-thirds from the bottom in the height direction of the cleaning basket 10X.

[0027] In the storage area RB, the cleaning basket 10X has a plurality of holes H, which are substantially circular through holes having a diameter of 1 mm or more and 10 mm or less, preferably 2 mm or more and 6 mm or less. More specifically, the cleaning basket 10X has a plurality of holes H having a diameter of 1 mm or more and 10 mm or less, preferably 2 mm or more and 6 mm or less, in areas 11B, 12B, and 14B. The holes H in the cleaning basket 10X may all have the same diameter, or may have different diameters as long as the diameters are within the above range. If the holes H are all the same diameter, processing is easy.

[0028] When cleaning silicon chunks using a cleaning basket, it is common to move the cleaning basket up and down or rock to improve the flow of liquid in the cleaning basket. This up and down movement or rocking of the cleaning basket can cause the silicon chunks in the basket to come into contact or collide with each other, which can result in the generation of small polycrystalline silicon pieces. Since such silicon pieces include fine pieces, they tend to spill (drop) from the cleaning basket into the cleaning liquid. If the silicon pieces fall into the cleaning liquid, they will react with the cleaning liquid, particularly in a cleaning process that uses a chemical solution such as an etching process, and the life of the cleaning liquid will be shortened.

[0029] By setting the hole diameter to 1 mm or more and 10 mm or less, the amount of silicon pieces that fall from the washing basket into the washing liquid can be reduced. When considering the liquid permeability and the amount of falling, it is more preferable to set the hole diameter to 2 mm or more and 6 mm or less.

[0030] In the cleaning basket 10X, the hole H is formed in an area included in the containing area RB below the bottom plate 14 and side walls (first side plate 11X and second side plate 12X) of the cleaning basket 10X. By forming the hole H in the area included in the containing area RB, the amount of silicon pieces spilling into the cleaning liquid can be effectively reduced.

[0031] The opening ratio, which is the ratio of the total opening area of ​​the holes H to the surface area of ​​the washing basket 10X in the storage area RB of the washing basket 10X, is 10% to 20%, preferably 12% to 18%. The diameter and number of the holes H can be appropriately determined so that the opening ratio in the storage area RB is within the above range.

[0032] By setting the aperture ratio of the accommodation region RB having the holes H to 10% or more and 20% or less, it is possible to reduce the amount of silicon pieces falling while suppressing the amount of cleaning liquid brought in. When considering the liquid permeability and the amount of falling, it is more preferable to set the aperture ratio to 12% or more and 18% or less. Moreover, it is more preferable that the aperture ratio of each of the regions 11B, 12B, and 14B constituting the accommodation region RB is 10% or more and 20% or less, preferably 12% or more and 18% or less.

[0033] In the upper region RT, the washing basket 10X has a plurality of slits S, which are elongated through holes. The groove width of the slits S is 1 mm or more and 10 mm or less, preferably 2 mm or more and 4 mm or less. More specifically, the washing basket 10X has a plurality of slits S extending perpendicularly to the tangent between the bottom plate 14 and the first side plate 11X in the region 11T of the first side plate 11X. Similarly, the washing basket 10X has a plurality of slits S extending perpendicularly to the tangent between the bottom plate 14 and the second side plate 12X in the region 12T of the second side plate 12X. In other words, the slits S are formed in a region included in the upper region RT above the side wall of the washing basket 10X. The slits S extend perpendicularly to the tangent between the bottom of the washing basket 10X and the side wall in which the slits S are formed. The length of the slit S is not particularly limited, but may be, for example, 20 mm to 150 mm, preferably 50 mm to 130 mm. The groove widths of the slits in the cleaning cage 10X may all be the same, or may be different within the above range. If the groove widths are the same, processing is easy.

[0034] When using a cleaning basket to clean silicon chunks, it is preferable that the amount of cleaning liquid carried over when the cleaning basket is moved from the first cleaning liquid tank to the second cleaning liquid tank is small. Comparing the hole H and the slit S, if the opening rate is the same, the smaller the hole diameter of the hole H, the more susceptible it is to the effect of surface tension, and the more likely it is that the liquid passage is poor. By providing the slit S in the upper region RT, the amount of cleaning liquid carried over when the cleaning basket 10X is moved from the first cleaning liquid tank to the second cleaning liquid tank can be reduced. This makes it easier to control the concentration of the cleaning liquid, and also reduces the deterioration of the cleaning liquid. In addition, when the cleaning basket is brought from the cleaning liquid tank to the drying process, the amount of cleaning liquid carried over is reduced, thereby improving the drying efficiency.

[0035] The opening ratio, which is expressed as the ratio of the total opening area of ​​the multiple slits S to the surface area of ​​the washing basket 10X in the upper region RT of the washing basket 10X, is 10% to 40%, preferably 12% to 28%. The groove width, length and number of the slits S can be appropriately determined so that the opening ratio in the upper region RT is within the above range.

[0036] By setting the aperture ratio in the upper region RT having the slits S to 10% or more and 40% or less, it is possible to reduce the amount of silicon pieces falling while suppressing the amount of cleaning liquid brought in. When considering the liquid permeability and the amount of falling, it is more preferable to set the aperture ratio to 12% or more and 28% or less. Moreover, it is more preferable that the aperture ratio in each of the regions 11T and 12T constituting the upper region RT is 10% or more and 40% or less, preferably 12% or more and 28% or less. Furthermore, the opening ratio, which is defined as the ratio of the total opening area of ​​holes H and slits S in cleaning basket 10X to the entire inner area of ​​cleaning basket 10X (excluding partition plate 15X), is 13% to 20%, preferably 15% to 18%. This allows the effect of the present invention to be fully exerted, which is to reduce the amount of silicon pieces falling while suppressing the amount of cleaning liquid carried over.

[0037] The cleaning cage 10X is located below the cleaning cage 10X, and in a storage area RB in which silicon chunks are stored, a plurality of holes H having a diameter of 1 mm or more and 10 mm or less are formed. In addition, the cleaning cage 10X has a plurality of slits having a groove width of 1 mm or more and 10 mm or less formed in an upper area RT above the storage area RB.

[0038] With the above-described configuration, it is possible to realize a cleaning basket that reduces the amount of silicon pieces that spill out of the cleaning basket and reduces the amount of liquid carried over.

[0039] [Embodiment 2] Other embodiments of the present invention will be described below. For convenience of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0040] FIG. 3 is a schematic perspective view of the cleaning basket 10 according to the second embodiment. FIG. 3 is a schematic view of the outer shape of the cleaning basket 10, and the holes H and slits S of the cleaning basket 10 are omitted. FIG. 4 is a development of the cleaning basket 10X. It should be understood that the development of FIG. 4 is a schematic development, and the size, number, and arrangement of the holes H and slits S differ from the actual configuration. FIG. 5 is a plan view of the cleaning basket 10 as viewed from above. FIG. 6 is a side view of the cleaning basket 10 as viewed from the first side plate 11 side. FIG. 7 is a side view of the cleaning basket 10 as viewed from the second side plate 12 side. FIG. 8 is a cross-sectional view taken along the line VII-VII in FIG. 5.

[0041] 3 and 4, the cleaning basket 10 includes a bottom plate 14 (bottom portion), a first side plate 11 (side wall portion), a second side plate 12 (side wall portion), an inclined plate 13 (inclined portion), and a partition plate 15. The cleaning basket 10 differs from the cleaning basket 10X of the first embodiment in that the cleaning basket 10 includes an inclined plate 13 between the bottom plate 14 and the first side plate 11. Also, as shown in FIG. 3, the cleaning basket 10 may include a rib 121 connected to the upper end of the second side plate 12. The presence of the rib 121 can reduce the possibility of silicon chunks falling from the upper portion of the cleaning basket 10.

[0042] As shown in FIG. 3, the cleaning basket 10 has a storage area RB and an upper area RT, similar to the cleaning basket 10X of the first embodiment.

[0043] The inclined plate 13 is a member connected to the bottom plate 14 and the second side plate 12, and inclined upward and outward with respect to the surface of the bottom plate 14. In the cleaning cage 10, the inclined plate 13 has an area 13B included in the storage area RB. A plurality of holes H are formed in the area 13B. Depending on the boundary position between the storage area RB and the upper area RT, the inclined plate 13 may have an area 13T included in the upper area RT. In that case, the area 13T may have a plurality of slits S. The cleaning cage 10 has the inclined plate 13 between the bottom plate 14 and the second side plate 12, but may also have the inclined plate 13 between the bottom plate 14 and the first side plate 11. Alternatively, the inclined plate 13 may be provided both (i) between the bottom plate 14 and the second side plate 12 and (ii) between the bottom plate 14 and the first side plate 11.

[0044] In the cleaning basket 10, the second side panel 12 only has an area 12T that is included in the upper region RT, but depending on the boundary position between the storage region RB and the upper region RT, the second side panel 12 may also have an area 12B that is included in the storage region RB.

[0045] The first side plate 11 has an area 11B and an area 11T. As shown in Fig. 4, the first side plate 11 may have a hexagonal shape including sides connected to the bottom plate 14, the inclined plate 13, and the second side plate 12 in a plan view of the first side plate 11. Alternatively, the first side plate 11 may have legs 112 as shown in Fig. 6 to improve the stability of the cleaning basket 10 when placed on a support stand.

[0046] The partition plate 15 has a similar configuration to the partition plate 15X of the first embodiment, except that the partition plate 15 has a hexagonal shape in a plan view.

[0047] As shown in Fig. 6, the holes H and slits S may be provided regularly and at approximately equal intervals. Alternatively, as shown in Fig. 5, in order to ensure the strength of the cleaning basket 10, the holes H may be formed so that the areas without holes H intersect.

[0048] The cleaning basket 10 includes an inclined plate 13 between a bottom plate 14 and a side wall portion (first side plate 11 and / or second side plate 12) of the cleaning basket 10. The inclined plate 13 is connected to the bottom plate 14 and the side wall portion, and is inclined upward and outward with respect to the surface of the bottom plate 14. A plurality of holes H are formed in the inclined plate 13 in an area included in the storage area RB.

[0049] By having an inclined plate 13 between the bottom plate 14 and the second side plate 12 and / or the first side plate 11, the occurrence of liquid pooling at the bottom can be reduced, and the amount of cleaning liquid carried over can be further reduced.

[0050] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0051] <Demonstration test> Below, a demonstration test will be described in which the amount of liquid carryover and the amount of silicon spillage are compared between examples within the scope of the present invention and comparative examples.

[0052] Examples 1 and 2 are results obtained by using the cleaning basket 10 of the above-mentioned embodiment 2. The hole H in the cleaning basket 10 of Example 1 has a diameter of 4 mm, and the groove width of the slit S is 2 mm (length 90 mm). The hole H in the cleaning basket 10 of Example 2 has a diameter of 6 mm, and the groove width of the slit S is 3 mm (length 90 mm). For Comparative Example 1 and Comparative Example 2, a cleaning basket having an external shape similar to that of the cleaning basket 10 shown in FIG. 3 was used. In the cleaning basket A of Comparative Example 1, all of the through holes in the first side plate 11, the second side plate 12, the inclined plate 13, the bottom plate 14, and the partition plate 15 are slits with a groove width of 2 mm and a length of 90 mm. In the cleaning basket B of Comparative Example 2, all of the through holes in the first side plate 11, the second side plate 12, the inclined plate 13, the bottom plate 14, and the partition plate 15 are holes with a diameter of 4 mm.

[0053] For each comparative example and example, the inner area is 992685 mm 2The same washing operation was carried out by placing 30 kg of silicon chunks in each of the washing baskets having the same outer shape (capacity about 90 L). The silicon chunks were prepared by crushing polycrystalline silicon rods produced by the Siemens process in a reduction reactor with a metal hammer to obtain crushed chunks. The silicon chunks were prepared by crushing the crushed chunks so that the major axis of at least 90 mass% of the total amount of the crushed chunks was within the range of 10 mm to 120 mm.

[0054] Table 1 shows the inner area (mm 2 ), the inner area of ​​the upper region RT and the containing region RB (mm 2 ), the open area ratio (%) in the upper region RT and the storage region RB, and the open area ratio (%) of the entire cage are shown. Also shown are the results of measuring the amount of liquid carried over (kg) and the amount of silicon spilled (g) for each comparative example and example.

[0055] [Table 1]

[0056] First, Comparative Example 1 is compared with Examples (Examples 1 and 2). As shown in Table 1, it was demonstrated that the amount of silicon spillage was significantly reduced in the Examples within the scope of the present invention, which combined slits and holes, compared to Comparative Example 1, in which all the through holes were slits with a groove width of 2 mm.

[0057] Next, Comparative Example 2 is compared with the Examples. As shown in Table 1, it was demonstrated that the amount of liquid carried over was significantly reduced in the Examples within the scope of the present invention, which combined slits and holes, compared to Comparative Example 3, in which all the through-holes were slits with a hole diameter of 4 mm.

[0058] From the above, it has been demonstrated that a cleaning basket within the scope of the present invention can realize a cleaning basket that reduces the amount of silicon pieces spilling out of the cleaning basket and reduces the amount of liquid carried over. [Explanation of symbols]

[0059] 10, 10X... Cleaning basket 11, 11X...1st side plate (side wall part) 12, 12X...2nd side plate (side wall part) 13... Inclined plate (inclined part) 14, 14X...Bottom plate (bottom) 15, 15X... Partition plate H...hole S...Slit RT...upper area RB...containment area

Claims

1. 1. A washing basket used for washing polycrystalline silicon chunks, comprising: a plurality of holes having a diameter of 1 mm or more and 10 mm or less are formed in a storage area located below the cleaning basket and in which the polycrystalline silicon chunks are stored; In an upper region above the storage region, a plurality of slits each having a groove width of 1 mm or more and 10 mm or less and a length of 20 mm or more and 150 mm or less are formed, the slit is formed in a region included in the upper region above the side wall portion of the cleaning basket, The slit extends in a direction perpendicular to a tangent between the bottom of the washing basket and the side wall in which the slit is formed.

2. The cleaning basket of claim 1 , wherein the hole is formed in an area below the bottom and sidewalls of the cleaning basket that is included in the storage area.

3. A slope is provided between the bottom and the side wall of the cleaning basket, the inclined portion is connected to the bottom and the sidewall and inclined upward and outward with respect to a surface of the bottom; The cleaning basket according to claim 1 or 2, wherein a plurality of the holes are formed in the inclined portion in a region included in the storage region.

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