JPH0246048Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a manufacturing tray used for manufacturing polycrystalline silicon wafers used in solar cells, other photoelectric conversion elements, and the like.

[Conventional technology]

Conventionally, the most common method for producing the above-mentioned polycrystalline silicon wafers is to once cast an ingot of a predetermined shape from a silicon base material and then slice the ingot to obtain the wafer.

As methods that do not involve slicing, a ribbon method and a casting method have already been implemented.

However, with the slicing method mentioned above, not only does the slicing process take a lot of time, but also about 50% of the ingot is lost during slicing.
The product cost is high and mass production is not possible.

In addition, the above-mentioned ribbon method and casting method have the disadvantage of not being able to obtain large solar cell materials, and furthermore, the casting method cannot obtain satisfactorily large silicon crystal grains, so The photovoltaic conversion efficiency of the resulting solar cell also has the drawback of being somewhat low.

Therefore, the applicant has already developed a method for manufacturing polycrystalline silicon wafers that can improve the defects of the above-mentioned methods, by melting a silicon base material and using this melt as a method of manufacturing polycrystalline silicon wafers made of quartz or carbon and in a rotating state. A method in which a thin layer of melt with a desired expanded diameter is layered by dripping onto a production plate, etc. by effectively utilizing centrifugal force, and this is peeled off from the production plate after solidification (hereinafter referred to as the spin method) ) was proposed.

Regarding this spin method, the applicant has already proposed a production plate for mass production as shown in FIG.

That is, a lid b made of carbon or the like and having approximately the same size as the main body a is stacked on the top surface of a dish body a made of carbon or the like, and both a and b are placed in a state where they face each other. A plurality of cavities d, d... are formed between the dish main body a and the lid body b by screwing them with carbon screws c, c... applied at the locations where . In addition, a pouring hole e is erected in the center of the lid b so as to communicate with these cavities d, d, . . . .

When carrying out the spin method, this production plate is placed on a turntable and a rotating centrifugal force is applied to it, and the silicon base material is melted from the pouring hole e under conditions such as high temperature and an argon gas atmosphere. As a result, the melt flows into the four cavities d, d... in the case shown in the figure, and by predetermining the amount of the melt, it is possible to form rectangular cavities as shown in the figure. A thin layer of melt that is exactly full is formed at d, d, . . . , and by cooling and solidifying this, a polycrystalline silicon wafer can be manufactured.

However, in the case of the above-mentioned manufactured plates made of carbon, a mold release agent such as Si ₃ N ₄ powder is applied so that the product can be peeled off. Small irregularities may occur on the surface, and in such a case, the lid b as a whole will be distorted considerably, and a gap will be created between the surfaces a and b that should be in contact. Such a phenomenon makes it difficult to completely correct the distortion of the lid body b, no matter how strongly the carbon screws C, C, . . . are tightened.

As a result, when the solution silicon is injected as described above, not only does the silicon protrude from the outer peripheral end of the cavities d, d, .

Therefore, in order to avoid such leakage of the melt, it is impossible to increase the rotation speed of the turntable, so it is necessary to reduce the thickness of the cavity to manufacture thin polycrystalline silicon wafers. However, it cannot be easily manufactured.

[Problem that the invention attempts to solve]

This invention was developed in consideration of the above-mentioned difficulties with the conventional manufacturing plates.
The lid body is not made of a single piece, but is constructed by abutting properly divided small pieces, and the size is made as small as possible, and each piece is divided into pieces. Separately, by screwing it to the main body of the dish, it is possible to prevent distortion in one place on the lid from spreading to the entire body and increasing the gap.
The individual divided bodies can be strongly screwed together to suppress the occurrence of gaps as much as possible, improve the above-mentioned protrusion and chipping problems, and improve the productivity of thin products due to high-speed rotation. The purpose is to reduce raw material costs by suppressing seepage.

[Means for solving problems]

In order to achieve the above object, the present invention stacks the lid on the dish body and fastens it with screws, so that the melt of the silicon base material injected from the pouring hole in the center of the lid rotates. A plurality of cavities in which polycrystalline silicon wafers are manufactured by flowing in by centrifugal force to form a thin layer of melt and solidifying it are formed between the dish body and the lid,
a centrally divided small body in which the lid body has the pouring hole;
and a cavity segmented body that contacts this to close the cavity, and all of these segmented bodies are stacked so as to partially close the dish body,
In addition, a manufacturing tray for polycrystalline silicon wafers is provided in which each divided small body is screwed.

〔Example〕

The present invention will be described in detail with reference to the embodiment shown in FIG.
Even in the same device, the dish body 1 and the lid 2 made of a high melting point material such as carbon are fixed by locking screws 3, 3, etc., as in the conventional example, so that the central part of the lid 2 is fixed. A plurality of cavities 5, 5, .

In the illustrated example, the cavities 5, 5...
In order to form a circular central injection groove ₆₁ on the surface of the dish body 1 as shown in FIG. 1(b),
Four cavity grooves 6 ₂ recessed on the outer circumferential side,
6 ₂ ... and the injection groove 6 ₁ are connected to the narrow grooves 6 ₃ , 6 ₃ that communicate with each other.
..., and on the smooth surface 7 where these grooves are not provided, cavity grooves 6 ₂ , 6 ₂ ... are formed on both sides of the central injection groove 6 ₁ .
Screw holes 8, 8, . . . are formed on both sides in the circumferential direction, respectively.

Here, in the present invention, the above-mentioned lid body 2 is not formed in one piece as in the conventional example, but has an upright opening that tapers downward and has a larger diameter, as clearly shown in Figures a and c. The center divided small body 2 ₁ is provided with the pouring hole 4, and the cavity divided small bodies 2 ₂ , 2 ₂ . It is divided by.

In the illustrated example, the central divided body 2 ₁ is formed into a rectangular tube shape, and this is connected to the central injection groove 6 ₁ and the narrow grooves 6 ₃ , 6 _{3 .}
... is partially closed, and each side of the divided small body 2 ₁ corresponds to one side of the cavity divided small bodies 2 ₂ , 2 ₂ . This causes the small bodies to form the communicating narrow grooves 6 ₃ , 6 ₃ . . .
The remaining portion of the cavity grooves 6 ₂ , 6 ₂ . . . are closed.

Then, each divided small body 2 ₁ , 2 ₂ , 2 ₂ . . . is attached to the dish main body 1.
When stacking..., the lid body 2 does not completely close the smooth surface 7 of the dish body 1 as shown in figure a, but the divided small pieces are arranged so that a part of the same surface 7 is exposed. is made as small as possible, and set screws 3, 3, etc. made of carbon or the like can be inserted diagonally into the centrally divided small body ₂₁ .
In the cavity segmented bodies 2 ₂ , 2 _{2 .} . ., protrusions 9, 9 are provided on both sides, and the same screws 3, 3 .
are inserted into the screw holes 8, 8, . . . .

In the above embodiment, it is divided into five divided small bodies, but the central divided small body 2 ₁ is configured such that one cavity divided small body 2 ₂ is connected to the illustrated small body 2 ₁ . In the illustrated example, the plate body 1 is used to form the cavities 5, 5...
Although a groove is provided on the lower surface of the lid body 2, it goes without saying that the groove may be formed on the lower surface of the lid 2 side.

For the configuration shown, Si ₃ N ₄
By dissolving the powder in alcohol and spraying it, a release agent layer is formed, and the dish body 1 is 36 cm in diameter, the cavities 5, 5... are 10 cm x 10 cm, and the production dish is maintained at the melting point of silicone. After pouring the molten silicon through the pouring hole 4, the rotation speed of the production plate was gradually increased, and as a result, in the conventional example,
At 360 rpm, the melt leaked out and scattered around, but in this case it was possible to prevent melt leakage up to 600 rpm.

[Effect of idea]

Since the present invention is constructed and implemented as described above, even if distortion occurs in one segmented body due to the above-mentioned unevenness, this will not affect other segmented bodies. Therefore, the gap between the dish body and the lid body does not become large, and each divided body is screwed independently, and the contact area between the dish body and the divided bodies is small, so the screws do not need to be tightened. The contact pressure due to tightening can be approximately 10 times that of the conventional method, and as a result, it is possible to dramatically improve the problem of molten silicon extrusion and product chipping. Since this can be done safely, even thin polycrystalline silicon wafers, that is, those with a thickness of 0.2 mm or less, can be manufactured easily.

[Brief explanation of the drawing]

FIG. 1 shows a manufacturing dish according to the present invention, in which a is a plan view, b is a plan view of the main body of the dish, and c is a longitudinal sectional front view of a.
FIG. 2 shows a conventional manufacturing tray, a is a plan view thereof,
b is a longitudinal sectional front view thereof. 1... Dish body, 2... Lid body, 3... Set screw, 2
₁ ... Center divided body, 2 ₂ ... Cavity segmented body, 4... Pouring hole, 5... Cavity.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) By stacking the lid on the dish body and securing it with screws, the molten silicon base material poured into the center of the lid through the pouring hole is rotated. A plurality of cavities in which polycrystalline silicon wafers are manufactured by flowing in by centrifugal force to form a thin layer of melt and solidifying it are formed between the dish body and the lid, The lid body is composed of a central divided body having the pouring hole, and a cavity divided body that comes into contact with the central divided body to close the cavity, and these divided bodies partially cover the dish body. A manufacturing tray for polycrystalline silicon wafers, which is stacked so as to be closed and is screwed to each divided body. (2) Scope of Utility Model Registration Claim 1, in which the centrally divided small body of the lid body is formed by connecting a central part provided with a pouring hole and a cavity part that closes one cavity. The manufacturing dish for polycrystalline silicon wafers described above.