JP2001287908A - Silicon sheet manufacturing apparatus and solar cell using silicon sheet by the apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon sheet manufacturing apparatus capable of stably mass-producing a silicon substrate having a thin and uniform thickness at a low cost. SOLUTION: This silicon sheet manufacturing apparatus is equipped with a partition wall 9 made of a heat insulating material between a heating and melting part 16 and a cooling part 17. Namely, heat insulating walls 6 are spread all over the inside of a container 5 and a pair of right and left heaters 2 are arranged at the lower part of the inside of the container 5. A square crucible 3 is vertically movably arranged between the heaters 2 and a raw material containing silicon 3 is melted in the crucible 3. A cylindrical rotary cooling body 1 is supported by a revolving shaft 2 at the upper part of the container 5. The partition wall 9 has a square opening 9a into which the rotary cooling body 1 is inserted and fixed to opposing right and left heat insulating walls 6 at a position a little higher than the lower end part of the rotary cooling body 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a silicon sheet which can be used mainly for solar cells, etc.
And a solar cell manufactured using a silicon sheet obtained by the manufacturing apparatus.

[0002]

2. Description of the Related Art Conventionally, crystalline silicon used for semiconductors such as solar cells has been produced by a pulling method (CZ method) by the Czochralski method or a melt-solidification method in which silicon in a crucible is melted and then solidified. (Cast method) is generally adopted.

[0003] In the CZ method, a single crystal silicon piece serving as a seed is brought into contact with a silicon melt and pulled upward while directly contacting the silicon melt, thereby obtaining a cylindrical single crystal mass. On the other hand, in the casting method, a silicon raw material is placed in a crucible, temporarily melted by heating, and then cooled from the crucible bottom to obtain a polycrystalline silicon lump.

[0004] For the technique of the CZ method, see Phys. Rev .. 96, 833 (1954), using a high quality Si raw material;
High-precision temperature control is required for crystal growth at a purity level that does not affect properties even if segregation occurs. CZ with applied magnetic field
In the method, temperature control of ± 0.1 ° C. is performed in the vicinity of the solution surface. Here, high-precision control is also required to stabilize the shape of the silicon crystal to be taken out. Furthermore, the key point of the growth is to stabilize thermally by rotation of the pulling seed crystal and rotation of the crucible.

In the casting method, as disclosed in Japanese Patent Application Laid-Open No. 6-64913, a high-purity silicon material to which a dopant such as phosphorus or boron is added in an inert atmosphere is heated and melted in a crucible to melt the silicon. The liquid is poured into another mold and cooled slowly to obtain a polycrystalline ingot. By slicing this ingot using a wire saw or an inner peripheral blade method, a wafer usable for a solar cell or the like can be obtained.

[0006] As a method of growing ribbon silicon, EF is used.
There are a G method and a WEB method. The EFG method is a method in which a carbon die is placed so as to be immersed in the surface of a silicon melt and pulled up from the die to produce a polycrystalline sheet.
However, according to this method, the growth rate is slow, a jig called a die is required, and there is contamination from the die. The WEB method is a method for growing dendrite crystals directly from the surface of a supercooled silicon melt.
According to this method, since a die is not required, relatively high quality silicon can be obtained.

As a new ribbon silicon growth method, there is a cooling body surface growth method (Japanese Patent Publication No. 61-275119). The method disclosed in Japanese Patent Publication No. 61-275119 is a method in which a rotary cooling body is directly immersed in a silicon melt and rapidly cooled to grow a silicon thin plate on the surface of the rotary cooling body.

[0008]

Although high quality silicon can be obtained by the CZ method, it is necessary to use high-purity raw material silicon and to use a seed crystal. There's a problem. Further, since the silicon thin plate is processed through the slicing process, the cut portion is wasted, and the cost for the slicing process should be considered.

In the casting method, since single crystallization is unnecessary,
Since silicon with a large amount of impurities such as scrap can be used, cost reduction can be achieved.However, many metal impurities are unevenly distributed due to unidirectional solidification from the crucible bottom, and slicing processing is required. Is the problem.

[0010] In the EFG method and the WEB method, since the melt surface is directly cooled to extract crystalline silicon, the contact point between the cooling part and the silicon melt is a seed crystal or a guide. Since the melt surface is cooled through the solidified silicon, there is a problem that the drawing speed is relatively low, about 1 to 3 cm / min.

Coolant surface growth method (Japanese Patent Publication No. 61-2751)
No. 19), the rotating cooling body absorbs the radiant heat and radiant heat from the heating part and the silicon melt surface, lowering the crucible heating efficiency and causing the melt surface to drop in temperature and solidify. Changes, affecting crystal quality. Also, the separation of crystalline silicon grown on the surface of the cooling body is considered to be caused by mechanical wedges or the like, and contamination from the jig material affects the crystal quality.

As described above, it has been difficult for the conventional techniques to stably obtain a high silicon extraction speed and to easily remove crystalline silicon.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and a silicon sheet manufacturing apparatus capable of stably obtaining a high silicon pull-out speed and easily removing crystalline silicon, and a silicon sheet produced thereby. The purpose is to provide solar cells using sheets

[0014]

According to one aspect of the present invention, there is provided a heating / melting section which includes a crucible and a heater for heating and melting a silicon-containing raw material in a crucible and heating with the heater; A rotary cooling body provided above the crucible in the section and rotatable by the substantially horizontal rotation axis, and the rotary cooling body is immersed in the molten silicon in the crucible obtained in the heating and melting section. And a cooling section, wherein a silicon crystal layer generated on the surface of the immersed rotary cooling body is drawn out by rotation of the rotary cooling body to produce a silicon sheet. Silicon sheet production characterized in that a part of the body is covered with a shield made of a heat insulating material to reduce the influence of heat from the heater in the heat melting part. Location is provided.

The silicon sheet manufacturing apparatus is provided in a chamber sealed in, for example, an argon gas atmosphere.

In the heating and melting section, the silicon-containing raw material put in the crucible is heated and melted by the heater for heating.
As this crucible, for example, one made of high-density graphite or high-density carbon is used. As the heater, for example, a heater provided with a high-frequency heating coil is used.

The cooling section includes a rotary cooling body mounted on a substantially horizontal rotating shaft above the crucible in the heating and melting section. As the rotating cooling body, for example, a cooling layer in which a surface layer is provided on a drum made of high-density graphite having good heat conductivity and a cooling gas flows inside the drum is used. Due to the downward movement of the rotary cooling body or the upward movement of the crucible, or the approaching movement of the two, a part of the surface layer of the drum is melted in the crucible obtained in the heating and melting section. Immerse in silicon.

On the surface of the rotary cooling body immersed in the molten silicon, a silicon crystal layer is formed by cooling the molten silicon. Then, the silicon crystal layer is pulled out by the rotation of the rotary cooling body, whereby a silicon sheet is manufactured.

The first extraction of the silicon crystal layer is performed, for example, as follows. A carbon net is previously wound around the surface of the rotary cooling body, for example, the surface layer of the drum, and the net is drawn out of the apparatus. When the cooling progresses and solid silicon begins to deposit on the carbon net, the rotating cooling body is rotated. Then, the carbon net is pulled out in synchronization with this rotation.

[0020] The silicon sheet manufacturing apparatus according to the present invention comprises:
A part of the rotary cooling body in the cooling unit is covered with a heat insulating material shield. This shield is to reduce the influence of heat from the heater and the molten silicon in the crucible in the heating and melting part by minimizing the exposure of the surface of the rotary cooling body.

According to this shield, the radiant heat from the heater and the radiant heat from the molten silicon in the crucible to the rotary cooling body can be minimized, thereby keeping the surface temperature of the rotary cooling body low. The unnecessary temperature drop of the heater and the molten silicon is prevented, and the power consumption and the cooling gas flow rate can be reduced.

Here, regarding the surface temperature of the rotary cooling body, when the silicon sheet manufacturing apparatus according to one embodiment of the present invention is compared with a similar apparatus without the shield, the former has a maximum temperature compared to the latter. At about 160 ° C.

Therefore, according to the present invention, a stable continuous high-speed growth of the silicon sheet becomes possible, and the durability of the rotary cooling body is increased, and at the same time, the thermal expansion of the material on the surface of the rotary cooling body and the crystalline silicon sheet. Since the contrast of the difference in the rate can be increased, the removability of the crystalline silicon sheet from the rotating cooling body is improved.

Further, according to the present invention, since the silicon sheet peels off under a relatively high temperature atmosphere on the surface of the molten liquid in the crucible, when the rotary cooling body and the crystalline silicon sheet do not peel off to near room temperature as in the conventional case. Cracks and crystal defects caused by the difference in the coefficient of thermal expansion, which occur in the above, can be obtained to obtain a high quality silicon sheet.

As a result, the fluctuation of the heating power and the change of the melt temperature are relatively small, the stability during crystal growth is increased, the surface temperature of the rotary cooling body is kept low, and the columnar growth high quality silicon sheet is obtained. Can be manufactured with good reproducibility.

In the silicon sheet manufacturing apparatus according to the present invention, the shielding body is a box body opened downward and composed of two side walls, two end walls, and one upper wall, and one of the side walls has It is preferable to have an opening for pulling out a silicon sheet.

[0027] In this configuration, since the rotary cooling body is covered by the box except for the lower part thereof, the mutual temperature influence between the rotary cooling body and the molten silicon in the crucible is further reduced. The cooling capacity of the rotary cooling body is further enhanced, and the silicon sheet can be more preferably extracted by extracting the silicon sheet from the opening for extracting the silicon sheet provided on a part of one of the side walls.

The silicon sheet manufacturing apparatus according to the present invention comprises:
The shielding body is a box body that opens downward and includes two side walls, two end walls, and one upper wall, and has an opening for pulling out a silicon sheet in a part of the upper wall. Is preferred.

[0029] In this configuration, since the rotary cooling body is covered by a box except for its lower part, the mutual temperature influence between the rotary cooling body and the molten silicon in the crucible is further reduced. The cooling ability of the rotary cooling body is further enhanced, and the silicon sheet can be more preferably extracted by extracting the silicon sheet from the opening for extracting the silicon sheet provided in a part of the upper wall.

In the silicon sheet manufacturing apparatus of the present invention, the shield is a frame which is open upward and downward and has two side walls and two end walls, and the silicon sheet is moved from the inside of the frame. Preferably, it is adapted to be pulled upward.

In this configuration, the rotary cooling body is covered by the frame except for the upper and lower portions, so that the rotary cooling body and the molten silicon in the crucible are less affected by the mutual temperature. In other words, the cooling ability of the rotary cooling body is further enhanced, and the pulling out of the silicon sheet from the inside of the frame body can be performed more favorably.

According to the present invention, there is provided a silicon sheet manufacturing apparatus in which a rotary cooling body is opened downward and is covered by a heat insulating box (heat insulating case) composed of two side walls, two end walls and one upper wall. Using a conventional silicon sheet manufacturing apparatus without such a box, one confirmation experiment was performed by changing the cooling gas flow rate. That is, the temperature at which the crucible was to be heated was set to a temperature equal to the melting point of silicon, 1430 ° C., and the surface temperature of the upper part of the rotary cooling body when the silicon-containing raw material in the crucible was melted was measured. FIG. 9 shows the measurement results.

As can be seen from FIG. 9, the temperature of the silicon sheet manufacturing apparatus of the present invention is reduced by about 160 ° C. at the maximum as compared with the conventional silicon sheet manufacturing apparatus without such a box. And the growth form of the silicon sheet was a column shape without dendrite, and the reaction between the rotary cooling body and the molten silicon in the crucible was suppressed, so that a high quality silicon sheet could be manufactured. Also, the 30 kW resistance heating output at the set temperature was reduced from 96% to 91%, and the heating power used could be saved.

In this confirmation experiment, the size of the high-density carbon rotary cooling body used for growing crystalline silicon was φ150 mm.
× 120 mm. Regarding the coefficient of thermal expansion between the surface material of the rotating cooling body and the crystalline silicon, carbon is about 7 × 10 ^−6.
/.Degree. C. and about 5.times.10.sup.- ⁶ / .degree. C. for silicon, which differs by about 40%. For this reason, when the surface temperature of the rotary cooling body decreases by about 200 ° C.,
A deviation of about 40 μm was generated per 0 cm, and the removability of the crystalline silicon from the rotary cooling body was improved.

According to another aspect of the present invention, there is provided a solar cell manufactured using a silicon sheet by the silicon sheet manufacturing apparatus according to one aspect of the present invention.

In such a solar cell, as shown in Table 1, the short-circuit current density is increased by about 10% as compared with a solar cell using a silicon sheet manufactured by a conventional silicon sheet manufacturing apparatus. It was confirmed from experiments by the present inventors that the conversion efficiency was improved by about 10%.

[0037]

[Table 1]

Inspection of the cross section of this silicon sheet revealed that the crystallinity was improved by columnar growth. That is, in a solar cell using a silicon sheet by a conventional silicon sheet manufacturing apparatus, a silicon crystal that grows on the surface of a rotary cooling body is mainly formed by dendrite, and is therefore desired for crystalline silicon for solar cells. It is difficult to obtain a columnar growth cross section. In contrast,
In the solar cell using the silicon sheet by the silicon sheet manufacturing apparatus of the present invention, since the silicon sheet mainly having columnar growth is used as the material by improving the cooling effect of the rotary cooling body, the solar cell characteristics can be improved. I was able to plan. In addition, since the power input during the production of the silicon sheet can be saved, the production cost of the solar cell can be reduced.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, three embodiments of the present invention will be described with reference to the drawings. The present invention is not limited by these.

Embodiment 1 A silicon sheet manufacturing apparatus according to Embodiment 1 shown in FIGS. 1 to 3 includes a heating / melting unit 11 and a cooling unit 12.

That is, in this silicon sheet manufacturing apparatus, a box (first heat insulating box) 9 made of a heat insulating material is arranged inside a container (not shown) made of stainless steel. A square crucible 1 made of high-purity graphite and constituting a part of a heat-melting unit 11 is provided below the inside of the box 9 so that a raw material containing silicon 3 is melted in the crucible 1. I have.

Above the inside of the box 9, the resistance heating heater 2 constituting a part of the heating / melting section 11 is provided.
A silicon additional charging section 7 for additionally charging a raw material containing silicon 3 is provided from above the outside of the box 9 to the heater 2.

At the upper part of the container 5, a cylindrical rotary cooling body 1
Are supported by the horizontal rotation shaft 2. Rotary cooling body 1
Is a device in which a surface layer is provided on a drum made of high-density graphite having good heat conductivity, and a cooling gas is caused to flow inside the drum. The partition wall 9 is a rotary cooling body 1
Has a rectangular opening 9a through which the lower portion of the rotary cooling body 1 penetrates the opening 9a. It is fixed horizontally to the heat insulating wall 6.

As shown in FIGS. 2 and 3, the partition wall 9 is provided with a raw material inlet 8 so that additional raw materials can be injected into the crucible 1 from the upper outside of the apparatus. The inside of the device surrounded by the heat insulating wall 6 is sealed so as to be maintained in an argon gas atmosphere.

As shown in FIG. 3, when the surface layer of the rotary cooling body 1 comes into contact with the melted silicon 3 melt, the silicon melt adheres to the surface layer and grows as crystals. Surface management and temperature management are performed so that Also, this silicon sheet manufacturing equipment includes
A transport mechanism for taking out the silicon sheet 10 on which the crystal has been grown is provided.

The partition wall 9 may have one or both sides reinforced with a heat-resistant plate or the like. The opening 9a of the partition wall 9
Need to be provided in consideration of a portion overlapping with the rotary cooling body 1. However, depending on the transport mechanism for taking out the silicon sheet 10, it is necessary to make the size and shape so as not to hinder the taking out function.

The apparatus for manufacturing a silicon sheet thus constituted was used as follows. First, as shown in FIG.
A raw material containing silicon 3 was charged into a crucible 1 and heated and melted by a heater 2. Next, the crucible 1 is raised and a part of the surface layer of the drum in the rotary cooling body 1 is immersed in the molten silicon 3 as shown in FIG. The silicon sheet 10 grown on the surface of No. 1 was taken out. Here, when the inside of the apparatus was observed through a peephole (not shown) until the immersion treatment, the melt of silicon 3 did not solidify, and the silicon sheet 10 could grow stably with a uniform thickness of 280 μm. Was.

Second Embodiment A silicon sheet manufacturing apparatus according to a second embodiment shown in FIGS. 4 and 5 has the same structure as that of the silicon sheet manufacturing apparatus according to the first embodiment, but also includes a rotary cooling body penetration opening 9a. There is further provided a closing member 11 made of a heat insulating material for partially closing the opening member downwardly, and a holding rod 12 made of graphite for holding the closing member 11 so as to be movable horizontally.

In this silicon sheet manufacturing apparatus,
As shown in FIG. 4, when the silicon-containing raw material is heated and melted, the closing member 11 is operated by the holding rod 12 to close the opening 9a. Thereby, heat transfer from the melt of the heater 2, crucible 1 or silicon 3 to the rotary cooling body 1 during heating and melting can be further reduced.

Then, as shown in FIG. 5, only when the crucible 1 rises and the rotary cooling body 1 is immersed in the molten silicon 3, the opening 9a is opened by the operation of the closing member 11.

A part of the surface layer of the drum in the rotary cooling body 1 was immersed in the molten silicon 3, and the silicon sheet 10 grown on the surface of the rotary cooling body 1 was taken out while rotating the rotary cooling body 1. Here, when the inside of the apparatus was observed through a peephole (not shown) until the immersion treatment,
The melt of silicon 3 does not solidify, and the silicon sheet 10
Was able to grow stably.

Embodiment 3 The silicon sheet manufacturing apparatus according to Embodiment 3 shown in FIGS. 6 and 7 differs from the silicon sheet manufacturing apparatus according to Embodiment 1 in that the heating / melting unit and the cooling unit are vertically arranged. A movable partition wall 15 for partitioning is provided.

That is, as shown in FIG. 6, a movable partition wall 15 for partitioning the rotary cooling body 1 from the crucible 1 heater (not shown) has a rotary cooling body penetration opening 15 a directly above the crucible 1. The crucible 1 is fixed to the upper edge of the crucible 1 in a state where the crucible 1 is moved up and down.

The upper surface of the partition wall 15 has an opening 15a.
A cover member (lid) 13 made of a heat insulating material having a size enough to cover the space is provided so as to be horizontally slidable. The lid 13 is opened and closed by a heat-resistant rope 14 such as a graphite string.

The material containing silicon 3 is filled in the crucible 1 and heated with a heater with the lid 13 closed to melt the silicon 3.

Next, as shown in FIG.
4, the lid 13 was opened, the crucible 1 and the partition wall 15 fixed thereto were raised, and a part of the surface layer of the drum in the rotary cooling body 1 was immersed in the molten silicon 3.

Then, while rotating the rotary cooling body 1,
The silicon sheet 10 grown on the surface of the rotary cooling body 1 was taken out. Here, when the inside of the apparatus was observed through a peephole (not shown) until the immersion treatment, the silicon sheet 10 could be grown stably without solidifying the melt of silicon 3.

Conventional Embodiment In a silicon sheet manufacturing apparatus according to a conventional embodiment shown in FIG. 8, first, a crucible 1 filled with silicon 3 was heated by a heater 2 to melt the silicon 3.

Next, the crucible 1 is raised, a part of the surface of the rotary cooling body 1 is immersed in the molten silicon 3, and the silicon sheet 10 grown on the surface is rotated while rotating the rotary cooling body 1. I took it out. When the inside of the apparatus was observed through a peephole (not shown) until the immersion treatment, the vicinity of the wall of the crucible 1 on the surface of the melt of silicon 3 was up to 2 cm.
It was confirmed that the solidified material had a width of.

Next, solar cells were manufactured using the silicon sheets obtained by the silicon sheet manufacturing apparatuses of the first to third embodiments.

It has been found that these solar cells have higher short-circuit power density and fill factor and improved conversion efficiency as compared with solar cells using silicon sheets obtained by a conventional silicon sheet manufacturing apparatus. . It is considered that this is because the improvement of the cooling effect by the partition walls 9 and 15 has caused silicon crystal growth to be mainly columnar growth.

From these results, in the silicon sheet manufacturing apparatus of the present invention, solidification of the silicon melt can be suppressed and the temperature distribution is improved as compared with the conventional silicon sheet manufacturing apparatus. Further, since the heater output under the same conditions is lower than in the past, it is possible to save the heating power used for melting the silicon.

[0063]

According to the first aspect of the present invention, there is provided a silicon sheet manufacturing apparatus including a crucible and a heater for heating, a heating / melting section for putting a silicon-containing raw material into a crucible and heating and melting with a heater; And a rotating cooling body rotatable by the rotating shaft, the rotating cooling body being immersed in the molten silicon in the crucible obtained in the heating and melting part. In a silicon sheet manufacturing apparatus in which a silicon crystal layer formed on the surface of a immersed rotary cooling body is drawn out by rotation of the rotary cooling body to produce a silicon sheet, a heating / melting unit and a cooling unit are provided. Between them, there is provided a heat insulating partition wall having an opening for penetrating the rotary cooling body and partitioning them. Therefore, heat transfer from the heater or crucible to the cooling body or heat transfer from the silicon melt to the cooling body can be reduced as compared with the case without the partition wall, so that heating power is wasted and cooling gas is consumed. Problems such as an increase in the flow rate of silicon, solidification of the silicon melt and uneven temperature distribution, and unstable shape of the grown silicon can be largely solved.

In the silicon sheet manufacturing apparatus according to the second aspect, the partition wall is provided within a range from the upper end to the lower end of the rotary cooling body. Therefore, in addition to the effect of the silicon sheet manufacturing apparatus according to claim 1, the height of the silicon sheet manufacturing apparatus is reduced as compared with the case where the partition wall is provided below the lower end of the rotary cooling body. be able to.

In the silicon sheet manufacturing apparatus according to a third aspect of the present invention, a closing member made of a heat insulating material is further provided to partially or entirely open the opening, and the rotary cooling body is immersed in the molten silicon. The opening is opened only when the closing member is actuated. Therefore, in addition to the effect of the silicon sheet manufacturing apparatus according to claim 1 or 2, the heating and melting of the silicon-containing raw material is performed by closing the rotary cooling body penetration opening by the closing member during heating and melting. The heat transfer from the crucible or the silicon melt to the cooling body can be further reduced.

In the silicon sheet manufacturing apparatus according to the fourth aspect, the crucible is provided so as to be vertically movable, and the partition wall is located below the rotary cooling body when the silicon-containing raw material is heated and melted. When the rotary cooling body is immersed, it is provided so as to be movable up and down so as to be located within the range of its height. In the case of heating and melting, the opening is closed by the closing member and the crucible and the partition wall are provided. Move downward, and when immersed, the opening is opened by the operation of the closing member, and the crucible and the partition wall move upward. Therefore, in addition to the effect of the silicon sheet manufacturing apparatus according to claim 3, the operation of the closing member and the vertical movement of the crucible and the partition wall combine to cool the heater, crucible or silicon melt during heating and melting. Heat transfer to the body can be further reduced.

A solar cell according to a fifth aspect is manufactured using a silicon sheet by the manufacturing apparatus according to any one of the first to fourth aspects. Therefore, compared with a solar cell using a silicon sheet manufactured by a conventional silicon sheet manufacturing apparatus in which a heat-melting part and a cooling part are not separated by a heat insulating material partition wall, the short-circuit current density and the fill factor are increased. Manufacturing costs can be reduced while improving efficiency.

[Brief description of the drawings]

FIG. 1 is a front vertical sectional view of a silicon sheet manufacturing apparatus according to Embodiment 1 of the present invention when raw silicon is melted.

FIG. 2 is a side longitudinal sectional view of the silicon sheet manufacturing apparatus of FIG. 1 when raw silicon is melted.

FIG. 3 is a side longitudinal sectional view of the silicon sheet manufacturing apparatus of FIG. 1 when a rotary cooling body is immersed.

FIG. 4 is a front vertical sectional view of a silicon sheet manufacturing apparatus according to Embodiment 2 of the present invention when raw silicon is melted.

5 is a side longitudinal sectional view of the silicon sheet manufacturing apparatus of FIG. 4 when the rotary cooling body is immersed.

FIG. 6 is a front vertical sectional view of a silicon sheet manufacturing apparatus according to Embodiment 3 of the present invention when raw silicon is melted.

7 is a side longitudinal sectional view of the silicon sheet manufacturing apparatus in FIG. 6 when the rotary cooling body is immersed.

FIG. 8 is a front vertical sectional view of a conventional silicon sheet manufacturing apparatus when raw silicon is melted.

FIG. 9 is a graph showing the temperature distribution in the depth direction of the silicon melt when the silicon-containing raw material in the crucible is melted by the silicon sheet manufacturing apparatus according to the first embodiment of the present invention to keep the temperature inside the apparatus constant. It is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating cooling body 2 Rotating shaft 3 Crucible 4 Silicon 5 Container 6 Insulating wall 7 Heater 8 Raw material input port 9 Partition wall 9a Opening 10 Silicon sheet 11 Closing member 12 Holding rod 13 Closing member (lid) 14 Heat resistant rope 15 Partition wall 15a Opening 16 Heating and melting part 17 Cooling part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toru Fui 22-22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 4G072 AA01 BB02 GG04 GG05 MM38 UU02 5F051 AA02 BA14 CB06

Claims (5)

[Claims] 1. A heating / melting unit including a crucible and a heater for heating, melting and heating a silicon-containing raw material into a crucible by a heater, and a substantially horizontal rotating shaft provided above the crucible in the heating / melting unit. And a cooling unit that includes a rotating cooling body rotatable by the rotating shaft, and a cooling unit that is immersed in the molten silicon in the crucible obtained in the heating and melting unit. In a silicon sheet manufacturing apparatus in which a silicon crystal layer formed on the surface of a body is drawn out by rotation of a rotary cooling body to produce a silicon sheet, a part of the rotary cooling body in a cooling unit is provided inside a heater and a crucible in a heating and melting unit. A silicon sheet manufacturing apparatus, wherein the silicon sheet manufacturing apparatus is covered with a shield made of a heat insulating material for reducing a thermal effect from molten silicon. 2. A box, wherein the shield is a downwardly open box comprising two side walls, two end walls and one upper wall,
The manufacturing apparatus according to claim 1, further comprising an opening for pulling out a silicon sheet in a part of the one side wall. 3. A box, wherein the shield is a downwardly opening box comprising two side walls, two end walls and one upper wall,
2. The manufacturing apparatus according to claim 1, wherein a part of the upper wall has an opening for pulling out a silicon sheet. 4. A shield, which opens upward and downward, and
2. The manufacturing apparatus according to claim 1, wherein the frame includes two side walls and two end walls, and the silicon sheet is drawn upward from inside the frame. 5. A solar cell manufactured by using the silicon sheet by the manufacturing apparatus according to claim 1. Description: