JPH0314769B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stacked manufacturing tray used for solar cells and other photoelectric conversion elements.

Conventionally, polycrystalline silicon wafers have been manufactured by various methods, and the most common method is to cast an ingot in a predetermined shape from a silicon base material and then obtain the wafer by slicing the ingot. However, not only does the slicing process take a lot of time, but about 50% of the ingot is lost during slicing, making the product expensive and impossible to mass produce.

Therefore, the ribbon method and casting method (casting method) have already been implemented as methods that do not involve slicing, but in the ribbon method, for example, molten silicon is sprayed onto the peripheral surface of a rotating drum, and a ribbon-shaped wafer is placed on the peripheral surface of the drum. When using this method, it is actually possible to manufacture ribbons with a width of only a few mm, which has the disadvantage that large-sized solar cell materials cannot be obtained.

In addition, in the above-mentioned casting method, the silicon base material is heated to form a melt, which is poured into a mold according to the dimensions of the product wafer, and then the melt is pressed and molded by the movable parts of the mold. However, when this method is used, wafers of a predetermined shape can be obtained at once, and desirable results can be expected in terms of mass production.As mentioned above, the melt is pressed down from all sides. It turns out.

For this reason, in this method, the upper and lower surfaces and side surfaces of the mold suppress the growth of silicon crystal grains (grains) when the melt solidifies, and the areas near the parts of the solidified product that contact the above-mentioned surfaces are extremely The crystal grains become fine and large crystal grains cannot be obtained, and the requirement for large crystal grain generation, which is considered desirable for silicon wafers for solar cells, etc., cannot be satisfied. The photovoltaic conversion efficiency of solar cells is also extremely poor at 2 to 3%.

Therefore, the applicant has already developed a method for manufacturing polycrystalline silicon wafers that can significantly improve the defects of the above methods by melting a silicon base material, and using this melt to form a polycrystalline silicon wafer made of quartz or carbon and in a rotating state. A method of forming a thin layer of melt with a desired diameter expansion state by effectively utilizing centrifugal force, and then peeling off this silicone sheet from the production plate after solidifying the same layer (hereinafter referred to as a method) , called the spin method).
proposed.

Although this spin method has many excellent features, there is a limit to the number of wafers that can be manufactured in one manufacturing process, and as a result, the operating efficiency of the rotating equipment is poor, resulting in high product costs. There was a problem.

That is, regarding the currently used spin method, as shown in FIG. The bottom surface of the groove 2 is used as a wafer forming plane 3, and four rectangular wafer forming parts 4 are formed on the terminal side of the groove 2, and a through hole 6 is provided in the center as shown in FIG. The resulting lid 5 is fitted over the manufacturing tray 1 as shown in FIG. 4, and the wafer molding space surrounded by the lid 5 and the manufacturing tray 1 is
It is proposed that the melt thin layer 7 be formed by injecting and filling the melt through the through hole 6.
However, even with this method, only about four silicon wafers, not just one product, can be obtained in one manufacturing process, as described above, which is not satisfactory from the point of view of mass production.

This invention was devised in view of the current situation, and its purpose is to make it possible to form a large number of silicon wafers in one manufacturing process by using an appropriate heavy-duty structure, and thereby to improve manufacturing equipment. The present invention aims to provide a stacked manufacturing tray that can significantly improve the operating efficiency of wafers and, as a result, reduce the cost of wafers.

In order to achieve this object, in the present invention, a melt of a silicon base material is supplied onto a rotating wafer forming plane in a desired atmosphere, and the centrifugal force generated by the rotation is applied in the direction of diameter expansion. A manufacturing dish used for manufacturing polycrystalline silicon wafers, in which a thin layer of melt of a desired size is formed by the melt and solidified by flowing the melt into It consists of a dish body and a lid stacked on top, and a concave groove is formed on the top surface of each dish body, the bottom surface of which serves as the wafer forming plane, and the uppermost part of the dish body The main body of the dish is provided with a through hole approximately in the center thereof, and the lid body is provided with an inflow hole approximately in the center thereof so as to communicate with each other, and the required number of layers is formed between the lid body and each plate body. The wafer molding space formed in the wafer molding space is opened to the through hole and the inlet port above the wafer molding space, respectively, so that a required number of the melt thin layers can be simultaneously formed.

Hereinafter, the present invention will be described in detail based on the embodiments shown in the accompanying drawings. As shown in FIG.
The manufacturing dish A according to the present invention is constituted by the dish bodies 10, 20, and 30 stacked in three layers and the lid body B placed on the top layer, and these members have little reactivity with silicon. Quartz (SiO ₂ ) or carbon C
It is formed by etc.

As clearly shown in FIGS. 6 and 7, the dish main body 10 placed at the top has a cross-shaped groove 11 formed on its top surface 16, and its bottom surface is a wafer forming plane 12. And on the terminal side of the same groove 11,
In the illustrated embodiment, four rectangular wafer forming portions 13 are formed. The connecting portion 14 connecting each of these wafer forming portions 13 is formed narrower than the forming portion 13, and a constricted portion 15 is formed at a continuous portion of both portions 13 and 14. It is equivalent to that shown in FIG. 1 above.

As shown in FIGS. 8 and 9, the second layer of the dish body 20 stacked on the top surface 16 of the dish body 10 also has a cross-shaped concave groove 21 in its top surface 26, as shown in FIGS. 8 and 9. , whose bottom surface is a wafer forming plane 22 , and four rectangular wafer forming parts 23 are formed on the terminal side of the groove 21 , and a connecting part 24 connecting each wafer forming part 23 is as follows: Same formation part 2
3, and a constricted portion 25 is formed at a continuous portion of both portions 23 and 24.

However, in the case of the dish main body 20, a through hole 27 that penetrates vertically is opened in the approximate center thereof, and a weir portion 28 is formed to bulge at the upper end periphery of the through hole 27, and a concave groove is formed. It is formed at the same height as the upper surface 26 to prevent the melt injected into the through hole 27 from flowing down. Furthermore, the bottom surface 29 of the dish 20 is formed to be smooth so as to be in close contact with the top surface 16 of the dish body 10.

The third layer of the plate body 30 stacked on the upper surface 26 of the plate body 20 is also similar to the first and second layer plate bodies 10 and 20, as shown in FIGS. 10 and 11. A concave groove 31 in the shape of a plane cross is formed on the upper surface 36.
, with its bottom surface serving as a wafer forming plane 32,
In addition, four rectangular wafer forming portions 33 are formed on the terminal side of the groove 31, and a connecting portion 34 connecting each of these wafer forming portions 33 is formed narrower than the forming portion 33. A constricted portion 35 is formed at a continuous portion of both portions 33 and 34. A through hole 37 that vertically passes through the plate 30 like the plate main body 20 is formed in the approximate center of the plate 30.
The diameter of the through hole 37 is larger than the outer circumferential diameter of the through hole 37, and a bulge 38 is formed on the upper edge of the through hole 37 in the same manner as the dish body 20, so that the melt injected into the groove 31 can be removed. The tray 30 is formed at the same height as the top surface 36 so that the liquid does not flow out from the through hole 37, and the bottom surface 39 of the tray 30 is smooth so as to come into close contact with the top surface 26 of the tray body 20.

The lid body B is formed to have approximately the same external shape as each of the dish bodies 10, 20, and 30, and as shown in FIGS. 12 and 13, the lid body B has an inlet passage hole 4 that penetrates vertically in the approximately central portion thereof.
Weir part 3 formed in dish main body 30 where 1 is the top
The bottom surface 40 of the lid body B is formed to have a larger diameter than the outer circumferential diameter of the tray body 30.
It is formed smoothly so that it comes into close contact with the

Each plate main body 10, 20, 3 configured in this way
0 and the lid body B to form the stacked manufacturing tray A, as shown in FIG. The second layer of plate bodies 20 is stacked on the top surface 16 of the main body 10, and then the third layer of plate bodies 30 is stacked on the top surface 26 of the plate body 20, and finally the plate bodies 30 are stacked on top of each other. It is sufficient to stack the lid B on the top surface,
In this case, the through hole 27 of the dish main body 20, the through hole 37 of the dish main body 30, and the inflow hole 41 of the lid B
are arranged concentrically. Therefore, in the above assembled state, the concave groove 11 of the dish body 10 and the dish body 20
A first stage wafer molding space S defined by the bottom surface 29 of the plate body 20 is formed.
A second stage wafer molding space S' defined by the concave groove 21 and the bottom surface 39 of the dish main body 30 is formed,
Furthermore, a third stage wafer molding space S'' defined by the groove 31 of the dish body 30 and the bottom surface 40 of the lid body B is formed, and in this case, a first stage wafer molding space S'' is formed. S communicates with the through hole 27 of the dish main body 20, and the hole 27 and the second stage wafer forming space
S' is configured to communicate with the through hole 37 of the dish body 30, and the hole 37 and the third stage wafer forming space S'' are configured to communicate with the through hole 41 of the lid C.

Next, the process of manufacturing the same wafer using the manufacturing plate A according to the above embodiment will be explained with reference to FIG. While rotating,
The silicon base material melt may be injected through the inflow hole 41 of the lid B, but at this time, in the illustrated example, the silicon base material is put into the crucible 50 and is heated and melted by a melting heat source (not shown). Then, the melt is discharged into the funnel 51 by the rolling of the crucible 50, and further, the melt is dripped from the eccentric position of the through hole 41 from the outlet 52 as shown by the dotted line in the figure. good.

If the melt is supplied from the inflow port 41 in this way, the melt will be injected into each wafer forming space S, S', S'', and the melt will be affected by the centrifugal force of the rotating production plate A. Therefore, the diameter expands and flows on each wafer forming plane 12, 22, 32 from each connecting part 14, 24, 34 to each wafer forming part 13, 23, 33, and all the same forming parts 13, 23, 33 A thin melt layer D filled with the melt is formed, and by cooling and solidifying this, each dish body 10, 2 is formed.
A total of 12 wafers, 4 wafers at 0 and 30, can be formed simultaneously. Note that this wafer has wafer forming parts 13, 23, 33 and connecting parts 14, 24, 3.
By folding the wafer at locations corresponding to the constricted portions 15, 25, and 35 provided at the boundary with the wafer 4, the product wafer is divided into rectangular product wafers.

The silicon base material is made of metal grade silicon, semiconductor grade high purity silicon, etc. It is possible to melt this by heating with the melting temperature of 1420°C in mind, and the heat source can be an electric heating wire, a high frequency heating device, etc. Of course, the heating can be stopped at an appropriate time,
It is desirable to be able to control the heating conditions.

The product wafer obtained in this way has its front and back surfaces and its outer peripheral surface
0 grooves 11, 21, 31 and each plate body 20, 30
and the bottom surfaces 29, 39, and 40 of the lid body B, so generally when the same thin layer D cools and solidifies,
Although irregularities occur on the free surface due to small protrusions,
Since this is suppressed by the bottom surfaces 29, 39, and 40, a wafer having a smooth surface can be formed. Further, the wafer forming portions 13, 23, 3
The remaining portion of the thin melt layer D formed by materials other than 3 is peeled off from the production plate A, and then melted again and used.

In the above-mentioned embodiments, the production plate A has been described as having a three-layer structure, but the present invention is of course not limited to this, and may be formed of two or more layers.

As mentioned above, according to the present invention, the problems of the conventional ingot slicing method and ribbon method are of course solved, and the material is not pressed down by the sides of the mold unlike the existing casting method. Since multiple products can be manufactured in a single manufacturing process, equipment operating efficiency can be greatly improved and product costs can be reduced.

[Brief explanation of the drawing]

Fig. 1 is an explanatory plan view of a manufacturing tray already proposed by the applicant, Fig. 2 is an explanatory longitudinal cross-sectional view of the same plate, Fig. 3 is a plan view of a lid fitted onto the plate, and Fig. 4 is an explanatory plan view of the manufacturing plate already proposed by the applicant. FIG. 5 is a vertical cross-sectional view showing the assembled state of the lid and the plate, FIG. 5 is a vertical cross-sectional view showing the stacked production plate according to the present invention, and FIG. FIG. 7 is an explanatory plan view of the dish body, FIG. 8 is an explanatory plan view of the dish body related to the second layer, FIG. 9 is an explanatory longitudinal view of the dish, and FIG. 11 is an explanatory plan view of the dish body related to the third layer, FIG. 11 is an explanatory longitudinal view of the dish, FIG. FIG. 14 is a longitudinal sectional view showing a state in which melt is being injected into the wafer molding space formed in each dish body, and FIG. 15 is an enlarged vertical sectional view within the circle of FIG. 14. A... stacking type production plate, B... lid, D... melt thin layer, S, S', S''... wafer molding space, 10, 2
0, 30... Dish body, 11, 21, 31... Concave groove, 27, 37... Through hole, 41... Inflow hole.

Claims (1)

[Claims] 1. In a desired atmosphere, a melt of silicon base material is supplied onto a rotating wafer forming plane, and the centrifugal force generated by the rotation causes the melt to flow in the direction of diameter expansion. This is a manufacturing pan used for manufacturing polycrystalline silicon wafers, in which a thin layer of melt of a desired size is formed by the melt, and this is solidified. A concave groove is formed on the upper surface of each of the dish bodies, and the bottom surface thereof serves as the wafer forming plane, and the dish body for stacking among the dish bodies is A through hole is provided in the approximately central portion of the lid body, and an inlet passage hole is provided approximately in the central portion of the lid body so as to communicate with each other, and a wafer molding space formed by the required number of layers is formed between the lid body and each dish body. ,
A stacked production plate characterized in that the above-mentioned through hole and inflow port are respectively opened in the upper part of the plate. 2. The inflow hole in the lid body is formed to have a large diameter and is concentric with the through hole in the dish body, and when having multiple through holes, the through hole should be formed so that it has a large diameter toward the upper dish body. 1. A stackable manufacturing pan according to claim 1. 3. The stacked manufacturing dish according to claim 1 or 2, wherein the upper end peripheral edge of the through hole is at the same height as the upper surface of the dish main body.