JP2003001162A - Device for manufacturing crystal sheet, method for manufacturing crystal sheet, substrate, and solar battery cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for manufacturing a crystal sheet capable of manufacturing a flat and uniform crystal sheet at a low cost, a method for manufacturing the crystal sheet, a substrate manufactured by using the method for manufacturing the crystal sheet, and a solar battery using the substrate. SOLUTION: The device 1 for manufacturing the crystal sheet is provided with a rotation body having the outer peripheral face, and base bodies 4a-4f and 5a-5f supported on the outer peripheral face of the rotation body rotatably around an axis which is parallel to a rotation axis 6 of the rotation body and having surfaces on which a crystal sheet 21 is formed by being immersed in a melt liquid 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal sheet manufacturing apparatus, a crystal sheet manufacturing method, a substrate, and a solar cell, and more specifically, a crystal sheet manufacturing method for manufacturing a crystal sheet (plate-shaped substrate) from a melt. The present invention relates to an apparatus, a crystal sheet manufacturing method, a substrate manufactured by using the crystal sheet manufacturing method, and a solar cell using the substrate.

[0002]

2. Description of the Related Art A polycrystalline silicon substrate used for a solar cell or the like is conventionally manufactured by the following method. That is, first, a high-purity silicon material is prepared. This high-purity silicon material added with a dopant such as phosphorus or boron is melted by overheating in a crucible placed in an inert gas atmosphere to form a melt. A polycrystalline silicon ingot is obtained by pouring the melt into a mold and cooling it. A slicing step of slicing this polycrystalline silicon ingot with a wire saw or the like is performed. Thus, the silicon substrate (silicon wafer) used for the solar cell can be obtained.

[0003]

However, in the method of manufacturing a silicon substrate as described above, the slicing step is costly and the cutting margin for slicing results in loss of silicon material. Therefore, in order to reduce the cost of the silicon substrate, a method of directly producing a silicon substrate (silicon sheet) from a silicon melt has been proposed. For example, in Japanese Patent Application No. 11-369299, by rotating a rotating body, a substrate placed on the side surface of the rotating body is immersed in a silicon melt for a certain period of time to solidify and grow silicon on the surface of the substrate. Disclosed are a crystal sheet manufacturing method and a crystal sheet manufacturing apparatus.

Referring to FIG. 10, Japanese Patent Application No. 11-3692
The crystal sheet manufacturing method disclosed in No. 99 will be described. FIG. 10 is a schematic diagram for explaining a crystal sheet manufacturing method as a technique related to the present invention.

Referring to FIG. 10, Japanese Patent Application No. 11-3692
The crystal sheet manufacturing apparatus disclosed in Japanese Patent No. 99 has a rotating shaft 10
6, which is rotatable about 6, and bases 105a to 105f arranged on the side wall of the rotor 103.
And a crucible 110 holding a melt 109 of silicon. The crucible 110 is arranged on a crucible stand 111. In the crucible 110, the bases 105a to 105f are the melt 10
9 is held at a position where it can be immersed. Rotating body 103
Is rotatable about the rotation shaft 106 in a direction indicated by an arrow 128. As the rotator 103 rotates, the bases 105a to 105f are successively immersed in the melt 109 held in the crucible 110. Substrate 1 to melt 109
05a-105f are immersed in the substrate 105a-
Silicon solidifies and grows on the outer peripheral surface of 105f. Since the outer peripheral surfaces of the bases 105a to 105f are formed substantially flat, a flat silicon substrate can be grown on this flat outer peripheral surface.

However, as a result of the inventor's detailed examination of the above-mentioned method for producing a crystal sheet, it was found that the following problems exist. That is, referring to FIG. 10, the central portion 137 of the outer peripheral surfaces of the bases 105 a to 105 f moves on the locus 127 as the rotating body 103 rotates. on the other hand,
As the rotating body 103 rotates, the bases 105a to 105f
One end portion 129a and the other end portion 129b of the outer peripheral surface of move along the locus 126. As you can see from Figure 10,
The locus 127 is a distance R1 about the rotation axis center 140.
Draw a circle with radius as. On the other hand, the locus 126 draws a circle centered on the rotation axis center 140 and having a radius of the distance R2. The distance R2 is longer than the distance R1 by the distance D. Therefore, in the melt 109, the one end portion 129a and the other end portion 129b of the outer peripheral surface are immersed by a distance D to a position deeper than the central portion 137 of the outer peripheral surface of the bases 105a to 105f.

Here, the rotation axis center 140 of the rotating body 103
To the outer peripheral surface central portion 137 of the bases 105a to 105f is 350 mm, and the width W of the bases 105a to 105f is 150 mm. In this case, the distance D is about 8 mm. The distance D is equal to the bases 105a to 105f.
The larger the width W is, the larger.

As described above, in the bases 105a to 105f, there is a difference in the immersion depth between the central portion 137 of the outer peripheral surface and the one end 129a and the other end 129b (hereinafter referred to as the end). The temperature condition which is one of the growth conditions of the silicon substrate on the outer peripheral surface of 105f is
The outer peripheral surface central portion 137 and the end portion are different. As a result, the central portion 137 and the end portions of the outer peripheral surfaces of the bases 105a to 105f have different thicknesses and crystal states of the growing silicon substrate, and it is difficult to obtain a uniform silicon substrate.

The present invention has been made to solve such problems, and an object of the present invention is to provide a crystal sheet manufacturing apparatus and a crystal sheet manufacturing apparatus capable of manufacturing a flat and uniform crystal sheet at low cost. A crystal sheet manufacturing method, a substrate manufactured by using the crystal sheet manufacturing method, and a solar cell using the substrate.

[0010]

A crystal sheet manufacturing apparatus according to one aspect of the present invention includes a rotating body having an outer peripheral surface,
On the outer peripheral surface of the rotator, there is provided a substrate which is rotatably supported around an axis parallel to the rotation axis of the rotator and has a surface on which a crystal sheet is formed by being immersed in the melt.

According to this structure, when the rotating body is rotated while the surface of the substrate is immersed in the melt, the substrate rotates about the above-mentioned axis so that the surface of the substrate becomes the liquid surface of the melt. The angles of the substrates can be changed so that they are substantially parallel. In other words, the immersion depth in the melt can be made substantially equal over the entire surface of the base. As a result, the growth conditions of the crystal sheet on the surface of the substrate can be made substantially equal, so that a uniform crystal sheet can be formed on the surface of the substrate.

In the crystal sheet manufacturing apparatus according to the above aspect 1, the surface of the substrate may include a flat surface portion.

In this case, the crystal sheet formed on the surface portion of the substrate is a flat sheet that reflects the flat surface condition of this surface portion. Therefore, a flat crystal sheet can be easily obtained.

It is preferable that the crystal sheet manufacturing apparatus in the above aspect 1 further comprises a substrate fixing means for determining a rotation angle of the substrate rotated about an axis parallel to the rotation axis of the rotating body.

In this case, the angle (penetration angle) formed by the surface of the substrate with respect to the liquid surface of the melt when the substrate is dipped in the melt can be determined by the substrate fixing means. Therefore,
By adjusting the base fixing means, it becomes possible to arbitrarily change the penetration angle of the base with respect to the liquid surface of the melt.

In the crystal sheet manufacturing apparatus according to the above aspect 1, the base fixing means is such that the end of the surface is located on the locus drawn by the central part of the surface of the base when the rotating body rotates about the rotation axis. It is preferable to determine the rotation angle of the substrate.

In this case, when the rotation angle of the base body is fixed by the base body fixing means, the central portion and the end portion of the surface of the base body are located on the same locus about the rotation axis of the rotating body. . Therefore, when the end of the substrate is immersed in the melt in this state, the end of the surface of the substrate is immersed in the melt, and the center of the surface is immersed in the melt. Can be about the same. As a result, it is possible to prevent the immersion depth of the end portion of the surface of the substrate in the melt from becoming deeper than the immersion depth of the central portion of the surface. Therefore, it is possible to suppress the growth conditions of the crystal sheet on the surface of the substrate from locally changing due to the difference in the immersion depth.

In the crystal sheet manufacturing apparatus according to the above aspect 1, the base fixing means may include a fixing member that comes into contact with the base so that the base is kept rotated by a predetermined rotation angle. The fixing member may include cooling means for cooling the substrate.

In this case, the rotation angle of the base can be reliably determined by bringing the fixing member into contact with the base. Further, since the heat of the substrate can be removed through the fixing member, the crystal sheet manufacturing apparatus can be simplified in structure as compared with the case where a cooling device for cooling the substrate is installed separately from the fixing member.

In the crystal sheet manufacturing apparatus according to the above aspect 1, it is preferable that a plurality of substrates are arranged on the outer peripheral surface of the rotating body.

In this case, a plurality of substrates can be continuously immersed in the melt by rotating the rotating body. As a result, the crystal sheet can be continuously manufactured. Therefore, the production efficiency of the crystal sheet can be improved.

The crystal sheet manufacturing apparatus in the above aspect 1 may further include a sheet take-out means for removing the crystal sheet formed on the surface of the substrate from the substrate.

In this case, the crystal sheet can be continuously produced by removing the crystal sheet from the substrate by the sheet take-out means, then rotating the rotating body and immersing the substrate again in the melt. As a result, the production efficiency of the crystal sheet can be improved.

In the crystal sheet manufacturing method according to another aspect of the present invention, the crystal sheet is formed on the surface of the substrate by immersing the substrate arranged on the outer peripheral surface of the rotating body in a melt which is a raw material of the crystal sheet. A method for producing a crystal sheet, comprising: rotating the rotating body to immerse the surface of the substrate in the melt; and rotating the rotating body while the surface of the substrate is immersed in the melt. And the step of forming a crystal sheet on the surface of the substrate with the inclination angle of the surface of the substrate with respect to the liquid surface of the melt being substantially constant.

With this configuration, when the crystal sheet is formed on the surface of the substrate, the inclination angle of the surface of the substrate with respect to the liquid surface of the melt is kept substantially constant (for example, the surface of the substrate is melted). Since the surface of the substrate is held so as to be substantially parallel to the liquid surface), the growth conditions of the crystal sheet can be made substantially the same for the entire surface of the substrate. Therefore, a crystal sheet having a uniform thickness and film quality can be formed on the surface of the substrate.

In the crystal sheet manufacturing method according to the other aspect described above, it is preferable that the surface of the substrate includes a flat surface portion.

In this case, the crystal sheet formed on the surface portion of the substrate is a flat sheet that reflects the flat surface condition of this surface portion. Therefore, a flat crystal sheet can be easily obtained.

In the crystal sheet manufacturing method according to another aspect, the substrate may be rotatable about an axis extending in a direction substantially parallel to the rotation axis of the rotating body. In the step of forming a crystal sheet, it is preferable that the central part and the end part of the surface of the substrate that is immersed in the melt have substantially the same immersion depth from the surface of the melt.

In this case, when the rotating body is rotated while the surface of the substrate is immersed in the melt, the substrate rotates about the above-mentioned axis so that the surface of the substrate becomes substantially parallel to the liquid surface of the melt. The angle of the substrate can be changed so that That is, the immersion depth from the melt surface can be easily made equal to each other in the central portion and the end portion of the surface of the base body (the immersion depth to the melt can be made substantially equal to the entire surface of the base body). ).

The crystal sheet manufacturing method according to another aspect may include a step of determining a rotation angle of the substrate rotated about an axis substantially parallel to the rotation axis of the rotating body.

In this case, the angle (penetration angle) formed by the surface of the substrate with respect to the liquid surface of the melt when the substrate is immersed in the melt can be determined by the step of determining the rotation angle of the substrate. Therefore, by adjusting the rotation angle of the substrate, it is possible to arbitrarily change the penetration angle of the substrate with respect to the liquid surface of the melt.

In the method of manufacturing a crystal sheet according to another aspect described above, the step of determining the rotation angle of the base body includes the step of determining the rotation angle of the base body on the locus drawn by the central portion of the surface of the base body when the rotating body rotates about the rotation axis. The rotation angle of the substrate may be determined so that the parts are located.

In this case, by carrying out the step of determining the rotation angle of the substrate, the central portion and the end portion of the surface of the substrate are located on the same locus with the rotation axis of the rotating body as the center. Therefore, if the end of the substrate is immersed in the melt in this state, the end of the surface of the substrate is immersed in the melt, and the center of the surface is immersed in the melt. And can be almost the same. As a result, it is possible to prevent the immersion depth of the end portion of the surface of the substrate in the melt from becoming excessively deeper than the immersion depth of the central portion of the surface. Therefore, it is possible to suppress local changes in the growth conditions of the crystal sheet on the surface of the substrate due to the difference in the immersion depth.

The method for producing a crystal sheet according to another aspect described above may include a step of cooling the substrate.

In this case, it is possible to prevent the temperature of the substrate from rising excessively by cooling the substrate while the substrate is immersed in the melt. Therefore, since the surface temperature of the substrate can be kept sufficiently low, the growth of the crystal sheet on the surface of the substrate can be promoted. In addition, since it is possible to prevent the temperature of the substrate from rising excessively, it is possible to mitigate thermal shock when the substrate is pulled out of the melt.

The crystal sheet manufacturing method according to the other aspect described above may further include a step of removing the crystal sheet formed on the surface of the substrate from the substrate.

In this case, the crystal sheet can be continuously produced by removing the crystal sheet from the substrate and then rotating the rotor to immerse the surface of the substrate in the melt again. . As a result, the production efficiency of the crystal sheet can be improved.

A substrate according to another aspect of the present invention is manufactured by using the crystal sheet manufacturing method according to the above-mentioned other aspect.

In this way, it is possible to easily obtain a substrate of low thickness and uniform thickness and film quality.
Further, if the surface of the base is flat, a flat substrate can be easily obtained.

A solar cell according to another aspect of the present invention uses the substrate according to another aspect described above.

If, for example, a silicon melt is used as the melt, the crystal sheet manufacturing method according to the present invention can be used to manufacture a silicon substrate as a crystal sheet. The silicon substrate as the semiconductor substrate has a uniform thickness and film quality as described above, and the manufacturing cost thereof can be kept low. Further, since the substrate is flat and the film thickness and film quality are uniform, the substrate can be used as it is as a substrate for a solar cell without performing a grinding process or a polishing process on the surface of the substrate other than cutting the end face. Therefore, by applying such a substrate to a solar cell, the manufacturing cost of the solar cell can be reduced.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and the description thereof will not be repeated.

FIG. 1 is a schematic view showing a crystal sheet manufacturing apparatus according to the present invention. A crystal sheet manufacturing apparatus according to the present invention will be described with reference to FIG.

Referring to FIG. 1, a crystal sheet manufacturing apparatus 1
Is a chamber 2, a rotor 3 arranged inside the chamber 2, a crucible 10 for holding a melt 9, and a chamber 2
A front chamber 13 disposed adjacent to the front chamber 13, a sheet take-out device 15 disposed inside the front chamber 13, and a sheet take-out device 1
And a stocker 20 for storing the crystal sheet 22 taken out by No. 5. The inside of the chamber 2 can be in a high vacuum state. A heat insulating material is installed on the inner wall surface of the chamber 2. The rotating body 3 is rotatable about the rotating shaft 6 in the direction of arrow 28. A plurality of support arms 8 are installed on the outer peripheral surface of the rotating body 3. On the support arm 8, the support substrates 4a to 4f are attached to the pins 2 respectively.
It is rotatably connected by 4. This support substrate 4a
Substrates 5a to 5f are provided on the outer peripheral surfaces of to 4f, respectively. The supporting substrates 4a to 4f and the bases 5a to 5f form the base of the present invention. Further, tilt stopper members 7a to 7f as base body fixing means are arranged in a region located between the support arms 8 on the outer peripheral portion of the rotating body 3.

In the region located below the rotor 3, the melt 9
A crucible 10 for holding is placed. A silicon melt is used as the melt 9. The crucible 10 is the crucible stand 1
It is installed on 1. The lifting motor 1 is mounted on the crucible table 11.
2 is connected, and the crucible base 11 can be moved up and down in the direction indicated by the arrow 25 by the operation of the lifting motor 12.

A sheet take-out device 15 is installed in the front chamber 13. The sheet take-out device 15 is rotatable about a rotation shaft 18. And the sheet take-out device 1
The sheet take-out rod 16 of No. 5 is the sheet take-out device 15
It is expandable and contractable in the direction indicated by arrow 38 from the main body. A suction pad 17 is attached to the tip of the sheet take-out rod 16.
Is installed. With the suction pad 17, the base 5a
The crystal sheet 21 formed on the surface of ~ 5f can be adsorbed and held. The sheet take-out device 15 allows the crystal sheet 21 to be stored inside the stocker 20 after the crystal sheet 21 is removed from the substrates 5a to 5f as described later.

Inside the rotating body 3, from the inside of the rotating shaft 6, the rotating body 3, the supporting substrates 4a to 4f and the bases 5a to 5 are formed.
A cooling medium such as a cooling gas or a cooling liquid for cooling f is supplied. The cooling gas or the cooling liquid supplied to the rotating body 3 circulates through the medium passage formed inside the rotating body 3, and then rotates again from the discharge port (not shown) formed on the rotating shaft 6. It is discharged to the outside of the body 3. By providing such a cooling function, it is possible to prevent the rotating body 3 from being heated more than necessary.

Further, as will be described later, the support substrates 4a-4
Since f is rotatably installed on the support arm 8, the end portions of the support substrates 4a to 4f are inclined stopper members 7a to 7a installed on the outer peripheral portion of the rotating body 3 as the rotating body 3 rotates.
Contact 7f. Therefore, when the crystal sheet is formed on the surfaces of the bases 5a to 5f, the heat accumulated in the bases 5a to 5f and the supporting substrates 4a to 4f is removed from the tilt stopper member 7a.
It can be removed by this cooling gas or cooling liquid via ~ 7f.

As the material of the substrates 5a to 5f, a graphite-based material having excellent heat resistance is used. However, the material of the substrates 5a to 5f may be any material having a melting point higher than the temperature of the melt 9. Since a silicon melt is used as the melt 9 here, a material having a melting point higher than the temperature of the melt 9 of silicon can be used as the material of the substrates 5a to 5f. Further, it is more preferable that the materials of the bases 5a to 5f are materials that have little reactivity with the melt 9. For example, when a silicon melt is used as the melt 9, silicon carbide, quartz, silicon nitride, alumina, zirconium oxide, or the like can be used as the material of the substrates 5a to 5f.

The distance between the liquid surface of the melt 9 held in the crucible 10 and the bases 5a to 5f installed on the rotating body 3 is determined by using the lifting motor 12 to set the crucible table on which the crucible 10 is installed. 1
It can be easily controlled by changing the height of 1.

Hereinafter, the crystal sheet manufacturing apparatus 1 shown in FIG.
The operation of will be briefly described. In the crystal sheet manufacturing apparatus 1 shown in FIG. 1, as the rotating body 3 rotates in the direction of arrow 28, the base bodies 5a to 5f are partially and sequentially dipped in the melt 9 held inside the crucible 10. . Substrate 5a to melt 9
In the state where 5f is immersed, the crystal sheet 21 in which the melt is solidified is formed on the surfaces of the substrates 5a to 5f. As the rotating body 3 rotates, the substrates 5a to 5f having the crystal sheet 21 formed on the surface thereof are pulled up from the melt 9. Then, the crystal sheet 21 formed on the surfaces of the bases 5a to 5f is removed from the bases 5a to 5f by the sheet take-out device 15.

The sheet take-out device 15 is rotatable about a rotary shaft 18. A motor (not shown) as a driving unit is connected to the rotary shaft 18. By driving this motor, the sheet take-out device 15 can be rotated about the rotating shaft 18. Sheet ejection device 1
The antechamber 13 in which 5 is installed is installed adjacent to the chamber 2, and the interior of the antechamber 13 is kept airtight so that a high vacuum state can be realized like the inside of the chamber 2. There is. A shutter 14 is installed between the chamber 2 and the antechamber 13. By opening and closing the shutter 14, the inside of the chamber 2 and the inside of the antechamber 13 can be separated. When taking out the crystal sheet 21 using the sheet taking-out device 15, the shutter 14 is opened.

The operation of the sheet take-out device 15 is roughly as follows. That is, when taking out the crystal sheet 21 from the inside of the chamber 2, the shutter 14 is first opened. Then, the sheet take-out device 15 rotates about the rotation shaft 18 until the sheet take-out device 15 has an angle as shown in FIG. Then, the sheet take-out rod 16 extends in a direction approaching the rotating body 3 so that the suction pad 17 installed at the tip end portion of the sheet take-out rod 16.
Comes into contact with the crystal sheet 21 formed on the surface of the substrate 5d.

At this time, the base 5d and the supporting substrate 4d
Is rotatably attached to the support arm 8 arranged on the outer peripheral surface of the rotating body 3, so that the inclination angle of the base body 5d can be changed so that the suction pad 17 surely contacts the crystal sheet 21. (By pressing the suction pad 17 against the crystal sheet 21 formed on the surface of the base body 5d, the inclination angles of the base body 5d and the support substrate 4d are changed so that the suction pad 17 surely contacts the surface of the crystal sheet 21. ). After that, the crystal sheet 2 is removed by the suction pad 17.
1 is adsorbed, and the crystal sheet 21 is held by the adsorption pad 17. Next, the crystal sheet 21 can be removed from the base 5d by retracting the sheet take-out rod 16 in the direction away from the rotating body 3.

After the sheet take-out rod 16 is sufficiently retracted while the crystal sheet 21 is held by the suction pad 17,
The sheet take-out device 15 is rotated about the rotating shaft 18. At this time, the crystal sheet 21 held by the suction pad
Until the sheet is positioned on the stocker 20.
5 rotates. After that, the sheet take-out rod 16 extends downward (toward the stocker 20). The crystal sheet 21 is placed inside the stocker 20 by releasing the suction operation of the suction pad 17 with the crystal sheet 21 arranged inside the stocker 20. After that, the sheet take-out rod 16 retracts in the direction of the rotating shaft 18. In this way, the crystal sheet 21 can be arranged inside the stocker 20. Inside the stocker 20, a plurality of crystal sheets 22 which are sequentially removed from the substrates 5a to 5f by the above-mentioned steps are held.

After storing a predetermined number of crystal sheets 22 in the stocker 20, the shutter 19 provided on the side wall 23 of the front chamber 13 is opened, and the stocker 20 is taken out of the front chamber 13 through this opening. It Then, the crystal sheet 22 held inside the stocker 20 is conveyed to another processing apparatus in order to carry out a predetermined step such as a post step of forming a solar cell.

In the crystal sheet manufacturing apparatus 1 shown in FIG.
The support substrates 4a to 4f and the base body 5a are provided on the side surface of the rotating body 3.
~ 5f is rotatably installed so that the base 5
A crystal sheet 21 having a uniform thickness and film quality can be formed on the surface of a to 5f. Hereinafter, referring to FIGS.
The step of solidifying and growing the crystal sheet 21 on the surface of a to 5f will be described in detail. 2 to 6 are schematic diagrams for explaining the steps of solidifying and growing the crystal sheet. In FIGS. 2 to 6 below, one of the bases 5a to 5f installed on the side surface of the rotating body 3 is 5a which is one base.
The operation of the crystal sheet manufacturing apparatus will be described by paying attention to.

As shown in FIG. 2, when the rotating body 3 rotates in the direction of the arrow 28, the support substrate 4a and the base body 5a before being dipped in the melt 9 held in the crucible 10 are attached to the support arm 8. It rotates counterclockwise around the pin 24 which is the connected connecting portion. One end 30a of the support substrate 4a is in contact with the tilt stopper member 7a as the base fixing means. Thus, the one end 30a of the support substrate 4a comes into contact with the tilt stopper member 7a,
The inclination angles of the support substrate 4a and the base 5a are fixed.

With this arrangement, the angle (entry angle) formed by the surface 31 of the substrate 5a with respect to the liquid surface 32 of the melt 9 when the substrate 5a is dipped in the melt 9 is tilted as the substrate fixing means. It can be determined by the stopper member 7a. Therefore, by adjusting the position of the surface of the tilt stopper member 7a that contacts the support substrate 4a, the liquid surface 32 of the melt 9 is adjusted.
It is possible to arbitrarily change the penetration angle of the base body 5a with respect to.

At this time, one end 29a of the base body 5a
Are located on the locus 27 drawn by the central portion 37 of the base body 5a as the rotating body 3 rotates. By rotating the rotating body 3 in the direction of the arrow 28 in such a state, the base body 5a is immersed in the melt 9 from the one end portion 29a of the base body 5a.

In this case, when the rotation angle of the base body 5a is fixed by the tilt stopper member 7a, the surface 3 of the base body 5a is fixed.
The central portion 37 and the one end portion 29a of 1 are located on the same locus 27 around the rotation axis 6 of the rotating body 3 as described above. Therefore, when the one end 29a of the base 5a is immersed in the melt 9 by rotating the rotating body 3 in this state, the one end 29a of the surface 31 of the base 5a is melted by the melt 9
The immersion depth in which the central portion 37 of the surface 31 is immersed in the melt 9 can be made substantially the same. As a result, the surface 3 of the substrate 5a in the melt 9
It is possible to prevent the immersion depth of the one end portion 29a in 1 from becoming deeper than the immersion depth of the central portion 37 of the surface 31. Therefore, the growth condition of the crystal sheet on the surface 31 of the substrate 5a can be suppressed from locally changing due to the difference in the immersion depth.

Here, in the crystal sheet manufacturing apparatus shown in FIG. 10, one end portion 1 of the base 105a is more than the central portion 137.
Since 29a has a longer immersion time in the melt 109 (and a deeper immersion depth in the melt 109), the temperature of the one end 129a tends to be higher than the temperature of the central part 137 of the base 105a. It was Therefore, in the crystal sheet manufacturing apparatus shown in FIG.
It was difficult to obtain a uniform crystal sheet because the thickness and surface condition of the crystal sheet formed at the one end portion 129a of a were different from those of the other regions. In order to solve such a problem, the crystal sheet manufacturing apparatus 1 according to the present invention
Then, the heat applied to the one end 29a of the base body 5a is transferred to the tilt stopper member 7a as a fixing member installed on the rotating body 3 via the support substrate 4a, so that the one end 29a of the one end 29a is transferred. It prevents the temperature from rising excessively.

As described above, the tilt stopper member 7a determines the tilt angle of the surface 31 of the base body 5a and, at the same time, acts as a cooling means for removing heat from the base body 5a. Therefore, the device configuration of the crystal sheet manufacturing apparatus can be simplified as compared with the case where a separate cooling device or the like is provided to cool the substrate 5a.

Next, when the rotating body 3 further rotates in the direction of the arrow 28, as shown in FIG. 3, the supporting substrate 4a and the base body 5a whose inclination angles have been determined by the inclination stopper member 7a are melted. The liquid surface 32 of the liquid 9 is substantially parallel to the liquid surface 32. Then, when the rotating body 3 further rotates in the direction of the arrow 28 from the state shown in FIG. 3, the support substrate 4a and the base body 5a are rotatably connected to the support arm 8 by the pin 24. And base 5
and a rotate about the pin 24 in the clockwise direction by its own weight. As a result, as the rotating body 3 rotates, the base 5
The substrate 5 a moves in the melt 9 while the surface 31 of a is kept substantially parallel to the liquid surface 32 of the melt 9.

In this way, the immersion depth in the melt 9 can be made substantially equal over the entire surface 31 of the base 5a. As a result, the growth conditions of the crystal sheet on the surface 31 of the substrate 5a can be made substantially equal, so that a uniform crystal sheet can be formed on the surface of the substrate 5a.

Next, as shown in FIG. 4, when the central portion 37 of the substrate 5a reaches the deepest position from the liquid surface 32 of the melt 9, the rotation speed of the rotating body 3 is reduced. At this time, the rotating body 3 may be temporarily stopped in the state as shown in FIG. By doing so, the central portion 3 of the base 5a is
7, the one end 29a and the other end 29b are arranged in a position substantially parallel to the liquid surface 32 of the melt 9 (that is, the surface 31 of the substrate 5a is almost the same as the liquid surface 32 of the melt 9). Parallel state). As a result, the substrate 5a
It is possible to obtain the best condition for growing the crystal sheet on the surface 31 of. By stopping the rotating body 3, the crystal growth state can be made particularly stable,
It is possible to promote the growth of a crystal sheet having a uniform film thickness and film quality. In this way, the step of forming a crystal sheet is carried out.

Next, at the timing when the crystal sheet has grown sufficiently on the surface of the substrate 5a, the rotating body 3 is further rotated in the direction of arrow 28. At this time, in the support substrate 4 a and the base body 5 a, the surface 31 of the base body 5 a is the liquid surface 3 of the melt 9.
While maintaining a state substantially parallel to 2, the pin 24 rotates about the pin 24 due to its own weight moment. The pin 24 is connected to approximately the center of the support substrate 4a. Therefore, it is possible to keep the surface 31 of the base body 5a in a horizontal direction (that is, in a direction substantially parallel to the liquid surface 32 of the melt 9) by the self-weight moment.

Then, as the rotating body 3 further rotates, the supporting substrate 4a and the base body 5a rotate clockwise with respect to the rotating body 3, so that the other end 30b of the supporting substrate 4a is moved as shown in FIG. It contacts the surface of the tilt stopper member 7f. In this way, when the other end 30b comes into contact with the surface of the tilt stopper member 7f, the other end 29 of the base body 5a.
b is located on the locus 27 drawn by the central portion 37 of the base body 5a.

Next, the rotating body 3 further rotates in the direction of the arrow 28, so that the substrate 5a is pulled up from the melt 9 as shown in FIG. A crystal sheet (not shown) is formed on the surface of the base body 5a. At this time, the support substrate 4
Since the other end 30b of a is in contact with the tilt stopper member 7f acting as a cooling member, the heat of the base body 5a can be removed by the tilt stopper member 7f via the support substrate 4a. As a result, it is possible to mitigate the thermal shock caused by the sudden temperature drop when the substrate 5a is taken out from the melt 9.

As described above, when the base body 5a is pulled up from the melt 9, the other end 29b of the base body 5a is located on the locus 27 drawn by the central portion 37 of the base body 5a. On the other hand, it is possible to prevent the other end portion 29b from being immersed in a deep region of the melt 9 (region indicated by the locus 26). Therefore, a crystal sheet having a uniform film quality can be formed on the surface of the substrate 5a. The locus 26 is the rotating body 3 when the positions of the one end 29a and the other end 29b of the base body 5a are fixed in the state shown in FIG.
Is a locus drawn by one end 29a and the other end 29b when rotating.

As shown in FIGS. 2 to 6, in the crystal sheet manufacturing apparatus 1 according to the present invention, while the substrate 5a is immersed in the melt 9, that is, as shown in FIGS. The surface 31 of the substrate 5a can be kept parallel to the liquid surface 32 of the melt 9 for a time. Therefore, the crystal growth conditions for forming the crystal sheet on the surface 31 of the substrate 5a can be made uniform over the entire surface 31 of the substrate 5a. As a result, a crystal sheet having a uniform thickness and film quality can be obtained.

When a silicon crystal sheet produced by the crystal sheet production apparatus 1 according to the present invention is used as a material for a solar cell, the power generation efficiency of the solar cell is about 1.
It was 2%.

Since the surfaces 31 of the substrates 5a to 5f are flat, the crystal sheet obtained by the crystal sheet production apparatus 1 according to the present invention has a flat shape from the stage of production. Therefore, as the post-treatment of the crystal sheet obtained by the crystal sheet manufacturing apparatus 1 according to the present invention, necessary minimum processing such as end face cutting may be performed (that is, flatness such as polishing and grinding of the substrate surface is ensured). It is not necessary to carry out the steps for doing so). Therefore, in order to obtain a flat crystal sheet, a crystal sheet having a curved surface (for example, a part of the side surface of a cylindrical rotary cooling body is immersed in a silicon melt, and the rotary cooling body is rotated to solidify on a cylindrical surface. Since it is possible to omit the step of processing the silicon crystal sheet obtained by continuously pulling out the silicon ribbon) into a flat shape, the manufacturing cost of the crystal sheet can be reduced.

Further, the crystal sheet manufacturing apparatus 1 shown in FIG.
Then, a plurality of support substrates 4a to 4f are provided on the outer peripheral surface of the rotating body 3.
Since the bases 5a to 5f are arranged, the crystal sheet can be continuously produced on the surfaces of the bases 5a to 5f by rotating the rotating body 3. Therefore, the production efficiency of the crystal sheet can be improved.

Further, in the crystal sheet manufacturing apparatus shown in FIG. 1, since the sheet take-out device 15 as the sheet take-out means is installed, the substrates 5a to 5 on which the crystal sheet is formed.
By sequentially taking out the crystal sheets from f by the sheet take-out device 15, the crystal sheets can be continuously produced.

The surface 31 of the substrates 5a to 5f may be a smooth surface, but as shown in FIGS.
An uneven shape may be formed on the surface. 7 to 9 are schematic partial perspective views for explaining modified examples of the crystal sheet manufacturing apparatus according to the present invention. 7 to 9 show the surface 3 of the bases 5a to 5f.
1 is an enlarged view of a part of 1.

As shown in FIG. 7, a plurality of protrusions 33 extending in a predetermined direction may be formed on the surface 31 of the substrate 5a.
The cross-sectional shape of the convex portion 33 is substantially triangular. For example, in the base body 5a shown in FIG. 7, the V-shaped grooves 35 are formed on the surface thereof under the condition that the pitch is 1 mm and the depth is 1 mm. By doing so, the structure shown in FIG. 7 can be easily obtained. The direction in which the groove 35 extends (the direction in which the convex portion 33 extends) may be arranged so as to extend parallel to the rotation direction of the rotating body 3. Further, the extending direction of the groove 35 may be arranged so as to extend substantially perpendicular to the rotating direction of the rotating body 3.

Further, as shown in FIG. 8, a plurality of semicircular grooves 35 may be formed on the surface 31 of the substrate 5a so as to extend in a predetermined direction. By doing so, it is possible to form a plurality of convex portions 34 extending in a predetermined direction.

Further, as shown in FIG. 9, a plurality of quadrangular pyramidal projections 36 may be formed in a matrix on the surface 31 of the substrate 5a.

In this way, the convex portions 33, 34, 36
Is the starting point of the crystal growth of the crystal sheet. As a result, in the crystal sheet 21, a portion having a contact with the surface of the base body 5a can be formed with a periodic corrugated (corrugated) surface structure along the shapes of the protrusions 33, 34, and 36. . By thus forming the corrugated structure on the surface of the crystal sheet 21, the mechanical strength of the crystal sheet 21 can be increased. As a result, when the crystal sheet 21 is handled in a later step or the like, the crystal sheet 21 is insufficient in strength, so that the crystal sheet 2
It is possible to suppress the occurrence of the problem that 1 is missing.

When the substrate 5a as shown in FIG. 9 is used, the convex portion 3 which becomes the starting point of the crystal growth of the crystal sheet 21.
Since 6 are distributed almost uniformly in a matrix on the surface of the substrate 5a, columnar crystals having a substantially uniform crystal grain size are formed in the crystal sheet 21. That is, if the substrate 5a having the surface structure as shown in FIG. 9 is used, the effect of suppressing the generation of dendrites that disturb the shape of the crystal sheet 21 is high.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above-described embodiments but by the scope of the claims, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope.

[0083]

As described above, according to the present invention, a crystal sheet provided with a base body that is installed on the outer peripheral surface of a rotating body and is rotatably supported around an axis parallel to the rotation axis of the rotating body. By using the manufacturing apparatus, the immersion depth in the melt can be made substantially uniform over the entire surface of the substrate. For this reason, the process conditions for forming the crystal sheet on the surface of the substrate can be kept substantially uniform. As a result, a crystal sheet having a uniform film thickness and film quality can be easily obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a crystal sheet manufacturing apparatus according to the present invention.

FIG. 2 is a schematic diagram for explaining a first step of a step of solidifying and growing a crystal sheet.

FIG. 3 is a schematic diagram for explaining a second step of the step of solidifying / growing a crystal sheet.

FIG. 4 is a schematic diagram for explaining a third step of the steps of solidifying and growing a crystal sheet.

FIG. 5 is a schematic diagram for explaining a fourth step of the steps of solidifying and growing a crystal sheet.

FIG. 6 is a schematic diagram for explaining a fifth step of solidifying / growing a crystal sheet.

FIG. 7 is a schematic partial perspective view for explaining a modified example of the crystal sheet manufacturing apparatus according to the present invention.

FIG. 8 is a schematic partial perspective view for explaining a modified example of the crystal sheet manufacturing apparatus according to the present invention.

FIG. 9 is a partial perspective schematic view for explaining a modified example of the crystal sheet manufacturing apparatus according to the present invention.

FIG. 10 is a schematic diagram for explaining a crystal sheet manufacturing method as a technique related to the present invention.

[Explanation of symbols]

1 crystal sheet manufacturing apparatus, 2 chambers, 3 rotating bodies,
4a to 4f Support substrate, 5a to 5f Base body, 6 Rotating shaft, 7a to 7f Tilt stopper member, 8 Support arm,
9 melt, 10 crucible, 11 crucible stand, 12 lift motor, 13 front chamber, 14 shutter, 15 sheet take-out device, 16 sheet take-out rod, 17 suction pad, 18
Rotating shaft, 20 stockers, 21,22 crystal sheets,
23 side wall, 24 pin, 25, 28, 38 arrow, 2
6,27 locus, 29a one end, 29b other end, 30a one end of support substrate, 30b other end of support substrate, 31 surface, 32 liquid surface, 33, 34, 36
Convex part, 35 groove, 37 central part.

Continued front page    (72) Inventor Toru Nunoi             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company F-term (reference) 4F040 AA02 AA12 AB06 AC01 BA45                       CC07 CC15 CC20 DB10 DB15                       DB30                 4G072 AA01 BB02 BB12 GG01 GG03                       GG04 GG05 HH01 NN01 UU02                 5F051 AA03 CB04 CB30                 5F053 AA03 BB04 BB08 DD01 GG02                       HH05 LL05 RR01 RR05

Claims (16)

[Claims] 1. A rotating body having an outer peripheral surface, and rotatably supported on the outer peripheral surface of the rotating body around an axis parallel to the rotation axis of the rotating body, and immersed in a melt. A crystal sheet manufacturing apparatus, comprising: a substrate having a surface on which a crystal sheet is formed. 2. The crystal sheet manufacturing apparatus according to claim 1, wherein the surface of the substrate includes a flat surface portion. 3. The crystal sheet manufacturing apparatus according to claim 1, further comprising a substrate fixing unit that determines a rotation angle of the substrate rotated about an axis parallel to the rotation axis of the rotating body. 4. The base body fixing means is configured such that when the rotary body rotates about a rotation axis, an end portion of the surface is located on a locus drawn by a central portion of the surface of the base body. The crystal sheet manufacturing apparatus according to claim 3, wherein the rotation angle of the crystal sheet is determined. 5. The base fixing means includes a fixing member that is in contact with the base so that the base is kept rotated by a predetermined rotation angle, and the fixing member includes cooling means for cooling the base. Prepare,
The crystal sheet manufacturing apparatus according to claim 3. 6. The crystal sheet manufacturing apparatus according to claim 1, wherein a plurality of the bases are arranged on the outer peripheral surface of the rotating body. 7. The crystal sheet manufacturing apparatus according to claim 1, further comprising a sheet takeout unit that removes the crystal sheet formed on the surface of the substrate from the substrate. 8. A method for producing a crystal sheet, which comprises forming a crystal sheet on the surface of the substrate by immersing the substrate arranged on the outer peripheral surface of the rotating body in a melt which is a raw material of the crystal sheet, A step of immersing the surface of the base body in the melt by rotating the rotator; and a step of transporting the base body by rotating the rotator in a state where the surface of the base body is immersed in the melt. And a step of forming a crystal sheet on the surface of the substrate with the inclination angle of the surface of the substrate with respect to the liquid surface of the melt being substantially constant. 9. The method for producing a crystal sheet according to claim 8, wherein the surface of the substrate includes a flat surface portion. 10. The substrate is rotatable about an axis extending in a direction substantially parallel to the rotation axis of the rotating body, and in the step of forming the crystal sheet, a surface of a surface of the substrate immersed in the melt is formed. The crystal sheet manufacturing method according to claim 8 or 9, wherein the central portion and the end portions have substantially the same immersion depth from the melt surface. 11. The method for producing a crystal sheet according to claim 10, further comprising the step of determining a rotation angle of the substrate rotated about an axis substantially parallel to a rotation axis of the rotating body. 12. The step of determining the rotation angle of the substrate is such that the end portion of the surface is positioned on a locus drawn by the central portion of the surface of the substrate when the rotating body rotates about a rotation axis. 12. The rotation angle of the base body is determined according to claim 11.
The method for producing a crystal sheet according to 1. 13. The method for producing a crystal sheet according to claim 8, further comprising a step of cooling the substrate. 14. The method for producing a crystal sheet according to claim 8, further comprising the step of removing the crystal sheet formed on the surface of the base body from the base body. 15. A substrate manufactured by using the crystal sheet manufacturing method according to claim 8. 16. A solar cell using the substrate according to claim 15.