JP2008071977A - Thin plate manufacturing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide thin plate manufacturing equipment in which a carbide of a crude material is removed from a molten crude material which is to be accommodated in a first crucible for growing a thin plate-shaped polycrystal, and which scarcely contains the carbide, and has a uniform quality, a high mechanical strength, and a good characteristic. <P>SOLUTION: The thin plate manufacturing equipment 1 contains a first melting heating furnace 2, a second melting heating furnace 3, a solid crude material supply means 4, a not-shown molten crude material supply means, a first cooling member 5, a not-shown first holding means, a second cooling member 6, a not-shown second holding means, and a not-shown first cooling member conveying means. The second cooling member 6 is dipped in a molten crude material 8 containing the carbide to be accommodated in the first crucible 10 included in the first melting heating furnace 2, whereby the carbide is adhered to a surface of the second cooling member 6 to remove the carbide. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thin plate manufacturing apparatus.

  Conventionally, a silicon thin plate-like polycrystalline body (hereinafter simply referred to as “thin plate-like polycrystalline body”) has been widely used as a substrate material for solar cells and the like. The thin plate-like polycrystalline body is produced, for example, by a method including a slicing step of slicing a polycrystalline ingot with a wire saw, an inner peripheral blade or the like. In addition, a polycrystalline ingot is obtained by, for example, heating and melting a high-purity silicon material to which a dopant such as phosphorus or boron is added in an inert atmosphere in a crucible, and obtaining a silicon melt (hereinafter referred to as “molten silicon”). It is manufactured by a method including a silicon casting process in which the material is poured into a mold and cooled (see, for example, Patent Document 1). In such a method for manufacturing a thin plate-like polycrystalline body, in addition to the silicon casting process, a slicing process requiring high cost is required, and in the slicing process, material loss more than the thickness of the wire or the inner peripheral blade is generated. This is a major obstacle to producing a thin plate-like polycrystalline body at a low cost.

  In order to solve this problem, a method for manufacturing a thin plate-like polycrystalline body in which silicon is attached to and grown on the thin plate generation surface of the cooling body by immersing and pulling up the cooling body in the molten silicon contained in the crucible is proposed. (For example, see Patent Documents 2 to 4). In these production methods, as the production of the thin plate-like polycrystalline body proceeds, the molten silicon in the crucible is consumed and gradually decreases. Therefore, the formation of the thin plate-like polycrystalline body is stopped when the molten silicon is reduced to some extent. The structure which replenishes silicon is taken. For replenishment of silicon, silicon (solid matter, hereinafter referred to as “solid silicon”) is directly supplied to the crucible, or solid silicon is previously melted in the second crucible, and the obtained molten silicon is the first crucible which is the main crucible. It is conceivable to supply the crucible into the crucible.

  Various apparatuses for directly supplying solid silicon to the crucible are proposed. For example, an apparatus including a circular crucible, a partition plate, solid silicon supply means, and heating means is proposed (see, for example, Patent Documents 5 to 6). Here, the partition plate extends in the vertical direction in the vicinity of the radial end portion of the crucible, is spaced apart from the bottom surface of the crucible, and is provided so as to partition the liquid level of the molten silicon in the crucible into two. . The solid silicon supply means supplies solid silicon to a portion surrounded by the side wall of the crucible in the radial direction and the partition plate (hereinafter referred to as “silicon supply portion”). The heating means mainly heats the silicon supply section to a temperature suitable for melting solid silicon. According to the apparatus of Patent Document 5, a partition plate is provided, and solid silicon and molten silicon are prevented from being mixed in the entire crucible, thereby enabling direct supply of solid silicon. Various apparatuses for supplying a melting raw material such as molten silicon to a crucible are also proposed (see, for example, Patent Documents 7 to 9). In the apparatuses of Patent Documents 7 to 9, solid silicon is melted in a second crucible provided vertically above the first crucible, and the obtained molten silicon is dropped downward in the vertical direction and supplied to the first crucible. The structure to do is taken.

Japanese Unexamined Patent Publication No. 6-64913 Japanese Patent Laid-Open No. 10-29895 JP 2002-175996 A JP 2003-59849 A JP 61-361197 A Japanese Patent Laid-Open No. 5-117077 JP-A-2-279582 JP-A-8-252650 JP 11-43318 A

  In the above prior art, since the production of the thin plate-like polycrystalline body is stopped during the replenishment of silicon, if the silicon replenishment takes a long time, the operating rate of the apparatus is lowered and the production efficiency is deteriorated. In particular, when supplying solid silicon directly into the crucible, the temperature in the crucible is raised to a temperature necessary for melting the solid silicon and the temperature in the crucible is lowered to a temperature suitable for producing a thin plate-like polycrystalline body. Since more time is required, the time during which production stops is even longer. Further, due to frequent production stoppage, the quality of the produced thin plate-like polycrystalline body may vary.

  On the other hand, when the molten silicon is supplied to the first crucible, the time for raising the temperature and the time for lowering the temperature are not necessary, and the production stop time is shortened accordingly. In this case, as a second crucible for obtaining molten silicon, a carbon crucible that can be efficiently heated by a high-frequency induction heating furnace or the like and has high productivity of molten silicon is mainly used. There is a problem that carbon is eluted. From the silicon-carbon phase diagram, it is known that a saturated amount of carbon is eluted in molten silicon. In a carbon crucible, when solid silicon is melted at a temperature sufficiently higher than the melting temperature of silicon, carbon is eluted into the generated molten silicon, and the first crucible is saturated or Molten silicon containing a near amount of carbon is supplied. By the way, in the first crucible, in order to obtain a thin plate-like polycrystalline body having a desired plate thickness, the temperature in the crucible is controlled in the vicinity of the melting temperature of silicon. Accordingly, the temperature of the molten silicon liquid is lowered from a temperature sufficiently higher than the melting temperature of silicon to around the melting temperature of silicon when fed from the carbon crucible as the second crucible to the first crucible. . As the liquid temperature of the molten silicon decreases, the saturation concentration of carbon relative to the molten silicon also decreases, so that an amount of carbon atoms that can no longer be dissolved in the molten silicon is deposited in the form of SiC. Further, since the molten silicon in the first crucible is consumed immediately and the molten silicon containing carbon is supplied from the second crucible to the first crucible, the circulation is repeatedly performed. The amount of SiC gradually increases. SiC is also mixed in the thin plate-like polycrystalline body to be produced, and causes deterioration of the quality of the thin plate-like polycrystalline body. Therefore, it is difficult to produce a thin plate-like polycrystalline body having no variation in quality even in a configuration in which molten silicon is supplied to the first crucible.

In view of the above problems, it is conceivable to use, as the second crucible, a SiO ₂ crucible that hardly elutes carbon and other substances into molten silicon. However, since the heating efficiency is reduced in the SiO ₂ crucible, a huge amount of electric power is required rather than melting the solid silicon in the carbon crucible, and the increase in manufacturing cost is inevitable.

  An object of the present invention is to obtain a molten raw material by heating a solid raw material in a second crucible made of a carbon material, and supplying the molten raw material to the first crucible. An object of the present invention is to provide an apparatus for producing a thin plate which can be efficiently removed and can produce a uniform thin plate-like polycrystalline body of a quality containing almost no carbide in a stable and industrially advantageous manner.

The present invention
A first melting furnace comprising: a first crucible having a recess for accommodating a melting raw material; and a heating means for heating the first crucible;
A second melting heating furnace comprising a second crucible made of carbon material having a recess for accommodating a melting raw material, and a heating means for heating the second crucible;
Solid raw material supply means for supplying a solid raw material to the recess of the second crucible;
A melt raw material feeding means for feeding the melt raw material accommodated in the recess of the second crucible to the recess of the first crucible;
A first cooling member provided so as to be dipped in the melt raw material housed in the recess of the first crucible, and having a thin plate formed by solidifying the melt raw material on its surface;
A first holding means for holding the first cooling member and immersing the first cooling member in the melt raw material housed in the recess of the first crucible and pulling it up;
A second cooling member provided so as to be immersed in the melt raw material housed in the recess of the first crucible;
The second cooling member is held, and the second cooling member is immersed in the molten raw material accommodated in the recess of the first crucible, and the carbide in the molten raw material is adsorbed on the surface while maintaining the immersed state. A thin plate manufacturing apparatus including a second holding means to be pulled up later.

Moreover, the thin plate manufacturing apparatus of the present invention is
The second holding means is
The second cooling member is immersed in a melt raw material accommodated in the recess of the first crucible, and is pulled up after maintaining the immersed state for at least 30 seconds.

Furthermore, the thin plate manufacturing apparatus of the present invention is
The second holding means is
The second cooling member is immersed in the molten raw material accommodated in the recess of the first crucible without the first cooling member being immersed by the first holding means.

  Furthermore, the thin plate manufacturing apparatus of the present invention further includes heating means for heating the second cooling member.

  Furthermore, the thin plate manufacturing apparatus of the present invention further includes a cooling means for cooling the second cooling member.

  Furthermore, the thin plate manufacturing apparatus of the present invention is characterized in that the second cooling member is made of a carbon material.

Furthermore, the thin plate manufacturing apparatus of the present invention is
The second cooling member includes a heat insulating layer provided on at least a part of the surface thereof.
Furthermore, the thin plate manufacturing apparatus of the present invention is characterized in that the second cooling member is a plate-like member.

  According to the present invention, the first melting heating furnace, the second melting heating furnace, the solid raw material supply means, the molten raw material supply means, the first cooling member, the first holding means, and the second A thin plate manufacturing apparatus including the cooling member and the second holding means is provided. The first melt heating furnace includes a first crucible having a recess for accommodating a melt raw material, and a heating means for heating the first crucible. The second melt heating furnace includes a second crucible made of a carbon material having a recess for accommodating the melt raw material, and a heating means for heating the second crucible. The solid raw material supply means supplies the solid raw material to the recess of the second crucible. The molten raw material feeding means feeds the molten raw material accommodated in the recess of the second crucible to the recess of the first crucible. The first cooling member is provided so as to be dipped in the molten raw material accommodated in the recess of the first crucible, and a thin plate formed by solidifying the molten raw material is formed on the surface thereof. The first holding means holds the first cooling member and immerses and pulls up the first cooling member in the molten raw material accommodated in the recess of the first crucible. The second cooling member is provided so as to be immersed in the melt raw material accommodated in the recess of the first crucible. The second holding means holds the second cooling member, immerses the second cooling member in the molten raw material accommodated in the recess of the first crucible, and maintains the immersed state in the molten raw material. Pull up after adsorbing carbide on its surface.

  In the thin plate manufacturing apparatus of the present invention, even if a molten raw material containing a carbon material is supplied from the second crucible to the first crucible, and carbide of the raw material is generated in the molten raw material due to a decrease in liquid temperature, Since the holding means adsorbs and removes the carbide using the second cooling means, the first crucible always contains the molten raw material containing almost no carbide. Therefore, according to the thin plate manufacturing apparatus of the present invention, it is possible to stably manufacture a thin plate-like polycrystalline body that hardly contains carbides and has very little quality variation.

  According to the present invention, the second holding means is configured to immerse the second cooling member in the molten raw material accommodated in the recess of the first crucible and pull it up after maintaining the immersed state for at least 30 seconds. By doing so, a sufficient amount of carbide is adsorbed and removed by the second cooling member, so that a thin plate-like polycrystalline body with less variation in quality and uniform characteristics can be stably produced.

  According to the present invention, the second holding means does not immerse the first cooling member by the first holding means with respect to the molten raw material accommodated in the recess of the first crucible. By comprising so that 2 cooling members may be immersed, the carbide | carbonized_material in a molten raw material can be removed efficiently, performing the thin plate formation in the 1st cooling member surface smoothly.

  According to the present invention, the thin plate manufacturing apparatus of the present invention further includes heating means for heating the second cooling member, so that the temperature of the second cooling member is prevented from excessively decreasing, and the temperature is adjusted to an appropriate temperature. It becomes possible to control. As a result, when the second cooling member is immersed in the molten raw material, only the carbide is selectively adsorbed on the surface of the second cooling member and the carbide can be efficiently removed, and partial solidification of the molten raw material can be prevented. If a part of solidified material is mixed in the melt raw material, a thin plate-like polycrystalline body having a uniform structure cannot be obtained.

  According to the present invention, the thin plate manufacturing apparatus of the present invention further includes the cooling means for cooling the second cooling member, so that the temperature of the second cooling member is prevented from excessively rising, and the temperature is adjusted to an appropriate temperature. It becomes possible to control. As a result, when the second cooling member is immersed in the molten raw material, the temperature of the molten raw material existing around the second cooling member temporarily rises, and the carbide to be removed is dissolved and removed again in the molten raw material. It can be prevented from becoming impossible. Therefore, the carbide can be reliably removed, and the quality of the manufactured thin plate-like polycrystalline body can be reliably made uniform.

  According to the present invention, since the second cooling member is formed of a carbon material, the melting raw material accommodated in the first crucible is not contaminated with unnecessary atoms other than the carbon material. A thin plate-like polycrystalline body can be produced.

  According to the present invention, by providing a heat insulating layer on at least a part of the surface of the second cooling member, it is possible to prevent heat dissipation more than necessary in the second cooling member, so that the carbide on the surface of the second cooling member At the same time as the precipitation, the solidification of the silicon can be greatly reduced.

  According to the present invention, a thin plate-like polycrystalline body for producing a thin plate-like polycrystalline body by immersing the first cooling member in the first crucible by making the second cooling member into a plate-like member. The production processing region and the second cooling member occupation region in which the second cooling member is immersed can be set so that mutual interference does not occur. Therefore, it is not necessary to form the first crucible with an unnecessarily large size, and the area occupied by the device in the manufacturing plant can be narrowed and the production efficiency can be improved.

  FIG. 1 is a cross-sectional view schematically showing a configuration of a thin plate manufacturing apparatus 1 according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view schematically showing a configuration of a main part of the thin plate manufacturing apparatus 1 shown in FIG. FIG. 3 is a drawing showing an immersion region of the first cooling member 5 in the first crucible 22. FIG. 3A is a top view showing an immersion region of the first cooling member 5. FIG. 3B is a cross-sectional view showing the immersion operation of the first cooling member 5. FIG. 4 is a drawing showing an immersion region of the first cooling member 5 and an immersion region of the second cooling member 6. FIG. 4A is a top view showing the immersion region of the first cooling member 5 and the immersion region of the second cooling member 6. FIG. 4B is a cross-sectional view showing the immersion state of the second cooling member 6. The thin plate manufacturing apparatus 1 includes a first melting heating furnace 2, a second melting heating furnace 3, a solid raw material supply means 4, a molten raw material supply means (not shown), a first cooling member 5, and a first cooling member (not shown). 1 holding means, a second cooling member 6, a second holding means (not shown), and a first cooling member transport means (not shown).

  The first melting furnace 2 includes a first crucible 10, a heating means 11, and a power source (not shown). The first crucible 10 is a container-like member having a recess 10a that opens upward in the vertical direction. The first crucible 10 is formed of, for example, a carbon material such as graphite. A heat insulating layer and / or an insulating layer (not shown) may be formed on the side surface in the vertical direction of the first crucible 10. The heat insulating layer is formed of a heat insulating material such as carbon felt, for example. The insulating layer is formed of an insulating material such as alumina fiber, for example. The recess 10a is a space formed from at least a part of the upper surface of the first crucible 10 in the vertical direction downward in the vertical direction, and serves as a molten raw material storage tank. In the present embodiment, the diameter of the recess 10a is about 700 mm. The melt raw material 8 is accommodated in the recess 10a. The melt raw material 8 contains a saturated amount of carbon. Carbon elutes from a second crucible 15 described later, and when the first crucible 10 is formed of a carbon material as described above, it elutes from the first crucible 10 as well. The carbon atoms 15 exceeding the saturation amount are precipitated in the molten raw material 8 and react with the molten raw material 8 to float in the molten raw material 8 as carbide particles 13 of the raw material. Since the carbide particles 12 usually have a higher melting point than the raw material itself, the carbide particles 12 exist as a solid in the molten raw material 8 maintained at a temperature near the melting point of the raw material. If molten raw material 8 is molten silicon, carbide particles 12 are silicon carbide particles. If the carbide particles 12 are allowed to float as they are, they will be mixed into the thin plate-like polycrystalline body 9 and cause the mechanical strength, characteristics, etc. of the thin plate-like polycrystalline body 9 to be lowered. Is removed from the molten raw material 8 using

  The heating means 11 is provided around the first crucible 10 so as to be spaced apart in parallel with the vertical side wall of the first crucible 10, and at a constant temperature so that the melt raw material 8 does not solidify. Heat to. The heating temperature is a temperature near or slightly higher than the melting point of the raw material. In the present embodiment, a high frequency induction coil is used as the heating means 11. In the present embodiment, the high frequency induction coil has an inner diameter of about 800 mm. A power source (not shown) is provided outside the thin plate manufacturing apparatus 1 to supply power for heating to the heating means 11. The temperature control of the liquid temperature of the melt raw material 8 is not shown, for example, by using the heating means 11 and a thermocouple (not shown) provided on the lower surface in the vertical direction of the first crucible 10 to control the entire operation of the thin plate manufacturing apparatus 1. This is done by the control means. The thermocouple detects the liquid temperature of the melt raw material 8. The control means includes a storage unit, a calculation unit, and a control unit. In the storage unit, the set temperature of the liquid temperature of the melt raw material 8 is written in advance, and further the detection result by the thermocouple is written. The calculation unit retrieves the set temperature and detection result of the melt raw material 8 from the storage unit, and determines whether or not the detection result is lower than the set temperature. Then, when it is determined that the calculation unit is lower than the set temperature or lower than the set temperature in a short time of about several minutes, the control unit supplies heating power to the heating unit 11 according to the determination result by the calculation unit. A control signal is sent to a power source (not shown) that supplies power to control the power supply from the power source to the heating means 11. Thereby, the liquid temperature of the melt raw material 8 is maintained at the set temperature. Although the liquid temperature of the melt raw material 8 is appropriately selected according to various conditions in producing the thin plate-like polycrystalline body, it is preferably near the melting point of the raw material, and is a temperature that is about 30 to 100 ° C. higher than the melting point of the raw material. Is more preferable. When the melting raw material 8 is a molten silicon, about 1440-1600 degreeC is preferable in consideration of melting | fusing point (1412 degreeC) of silicon.

  According to the first melt heating furnace 2, when starting the first melt heating furnace 2, the solid raw material 7 filled so as to fill the recess 10 a is melted to obtain a melt raw material 8. Further, when the molten raw material 8 is accommodated in the recess 10a, the liquid temperature of the molten raw material 8 is set to a temperature near or slightly higher than the melting point of the raw material 8 so that the molten raw material 8 does not solidify. Hold on.

  The second melting furnace 3 includes a second crucible 13, a heating means 14, and a power source (not shown), and is provided above the first melting furnace 2 in the vertical direction. The second melting furnace 3 is supported so as to be tiltable in the direction of the arrow 16 by a melt raw material supply means (not shown). That is, when the second melt heating furnace 3 is tilted in the direction of the arrow 16 by the melt raw material supply means, the melt raw material 8 stored in the second crucible 13 is changed into the first crucible 13 in the second crucible 13. It arrange | positions so that it may fall to the perpendicular direction downward from the upper end part nearest to the fusion heating furnace 2, and may be supplied in the recess 10a in the 1st crucible 10. FIG. The second crucible 13 is a container-like member made of carbon material having a recess 13a that opens upward in the vertical direction on the upper surface in the vertical direction. The second crucible 13 is formed of a carbon material such as graphite. A heat insulating layer and / or an insulating layer (not shown) may be formed on the side surface in the vertical direction of the second crucible 13. The heat insulating layer is formed of a heat insulating material such as carbon felt, for example. The insulating layer is formed of an insulating material such as alumina fiber, for example.

  The recess 13a is a space formed from at least a part of the upper surface of the second crucible 13 in the vertical direction downward in the vertical direction, and becomes a solid raw material melting tank. The solid material 7 is supplied from the solid material supply means 4 to the recess 13a. The solid raw material 7 supplied to the recess 13 a is melted by being heated to a temperature sufficiently higher than the melting point of the solid raw material 7 by the heating means 16, and stored as the molten raw material 8 in the recess 13 a. In the molten raw material 8, carbon 15 is eluted from the inner wall surface of the recess 13 a, and exists at or near the saturated concentration with respect to the molten raw material 8 at that temperature. Although carbon 15 is indicated by a circle in FIG. 1, the carbon 15 is actually dissolved in the molten raw material 8 and is not observed in the form of particles. The melt raw material 8 stored in the recess 13 a is supplied to the first melt heating furnace 2 according to the consumption status of the melt raw material 8 in the first melt heating furnace 2. Therefore, in the second melting heating furnace 3, the carbide of the raw material is rarely generated in the molten raw material 8.

The heating means 14 is provided around the second crucible 13 so as to be spaced apart from and parallel to the vertical side wall of the second crucible 13. The heating means 14 heats the solid raw material 7 supplied to the second crucible 13. Thereby, the melt raw material 8 is obtained. The heating temperature is a temperature sufficiently higher than the melting point of the raw material, preferably a temperature higher by 100 to 250 ° C. When the melting raw material 8 is molten silicon, since the melting point of silicon is 1412 ° C., the heating temperature is preferably maintained at about 1550 to 1650 ° C., more preferably around 1600 ° C. In the present embodiment, a high frequency induction coil is used as the heating means 14. In the present embodiment, the high frequency induction coil has an inner diameter of about 300 mm and a height of about 200 mm. A power source (not shown) is provided outside the thin plate manufacturing apparatus 1 and is connected to copper wires (not shown) at both ends of the high-frequency induction coil via flanges (not shown) provided on the outer wall of the thin plate manufacturing apparatus 1. Supply power for. Although the maximum output of the power supply can be appropriately selected according to the size of the second crucible 13, it is 100 kW in the present embodiment. The power value (W) supplied from the power source to the heating means 14 is the cross-sectional area (cm ² ) in the direction perpendicular to the axial direction of the heating wire (copper wire) constituting the high-frequency induction coil. The value divided by is preferably selected to be 20 W / cm ² or more, and more preferably selected to be 50 W / cm ² or more. Thereby, the solid raw material 7 in the second crucible 13 is efficiently melted. The heating temperature in the second crucible 13 is controlled by the control means using a heating means and a thermocouple (not shown) provided on the lower surface in the vertical direction of the second crucible 13. The control itself is performed in the same manner as the control of the heating temperature in the first melt heating furnace 2. In the present embodiment, a high frequency induction coil is used as the heating means 14. According to the second melt heating furnace 3, the solid raw material 7 supplied from the solid raw material supply means 4 to the second crucible 13 is heated by the heating means 14 to become the molten raw material 8.

  For the raw material supply means 4, for example, a shooter can be used. The upper portion of the shuta is inserted into the upper outer wall of the thin plate manufacturing apparatus 1 and protrudes upward from the outer wall in the vertical direction, and the lower portion of the vertical direction has an angle with respect to the vertical direction inside the thin plate manufacturing apparatus 1. It is the hollow member provided so that it may incline. A gate valve (not shown) is connected to the upper upper end of the vertical direction of the shuter, and the solid material 7 is supplied from the gate valve into the shooter. The solid raw material 8 slides down the inner surface of the shooter and is discharged from the opening at the lower end in the vertical direction of the shooter. The lower end portion in the vertical direction of the shuter is positioned above the one end portion of the recess 13a in the vertical direction, and is arranged so that the solid raw material 7 discharged from the lower end portion is reliably supplied to the recess 13a. For the solid material 7, for example, a semiconductor material, a metal material, or the like can be used. In this embodiment, silicon is used.

  The melt raw material supply means (not shown) supports the second melt heating furnace 3 so as to be tiltable, and tilts the second melt heating furnace 3 in the direction of the arrow 16, thereby forming the recess 13 a of the second crucible 13. The molten raw material 8 stored in is supplied to the recess 10 a of the first crucible 10. A general tilting device can be used as the melt raw material supply means. As a specific example of the tilting device, for example, tiltable support means for tiltingly supporting the second melting heating furnace 3 in the direction of the arrow 16 and tilting power in the direction of the arrow 16 in the second melting heating furnace 3. And a tilting device that includes a hydraulic cylinder that imparts. Also, a trunnion ring fixed to the outer peripheral surface of the second melting furnace 3, a bearing that rotatably supports the support shaft of the trunnion ring, a bull gear fixed to the support shaft, and a drive gear that drives the bull gear; And a tilting device including a drive mechanism (such as a motor) for rotationally driving the drive gear. Further, a support frame (not shown) that supports the second melting heating furnace 3 is supported along a fixed frame that pivots along a vertical surface (vertical side surface) so as to be tiltable, and an arc centered on the pivot portion. There is a tilting device including a rack provided on the side surface of the frame, a pinion meshing with the rack, a speed reduction mechanism provided on the fixed frame side for reducing the rotational force of the motor and transmitting it to the pinion, and a motor.

  The first cooling member 5 is a substrate for growing a thin plate-like polycrystalline body such as silicon on the surface of the lower surface in the vertical direction, and is supported by a first holding means (not shown). After confirming that the liquid temperature of the melt raw material 8 accommodated in the recess 10a of the first crucible 10 is stable, the cooling member 5 is moved by the first holding means, for example, in the direction of the arrow 20, that is, the circle. It is immersed in the melt raw material 8 in the recess 10a in an orbital or elliptical orbit. As shown in FIG. 3A, the first cooling member 5 has a first crucible 10 with respect to the immersion region 21 in the liquid surface of the molten raw material 8 accommodated in the recess 10 a of the first crucible 10. Is dipped from one end in the longitudinal direction and pulled up from the other end. A pyramidal protrusion (not shown) is regularly formed on the surface of the first cooling member 5. When the first cooling member 5 is immersed in the melt raw material 8, crystals grow from the apex of the pyramidal protrusion. A thin plate-like polycrystalline body 9 is formed on the lower surface in the vertical direction of the first cooling member 5. The first cooling member 5 is pulled up from the melt raw material 8 after the thin plate-like polycrystalline body 9 is grown. In the thickness direction of the first cooling member 5, a convex portion is formed on the surface opposite to the growth surface of the thin plate-like polycrystalline body 9 (hereinafter referred to as “opposite side surface”). The convex portion is formed so as to extend from one end portion of the first cooling member 5 to the other end portion in the lateral direction of the opposite side surface. The convex portion is preferably formed near the central portion in the longitudinal direction of the opposite side surface. The convex portion is formed so that a cross section perpendicular to the direction in which the convex portion extends is trapezoidal. In the cross section, the convex portion is formed such that a line in contact with the opposite side surface is parallel to a line separated from the opposite side surface, and a line in contact with the opposite side surface is shorter than a line separated from the opposite side surface.

  The first holding means (not shown) includes, for example, a fixing member, horizontal direction moving means, vertical direction moving means, and slide means. The fixing member supports the first cooling member 5 by a mechanism that engages with the cooling member 5 in an uneven shape. A recess corresponding to the convex portion of the first cooling member 5 is formed on one surface in the thickness direction of the fixing member. The concave portion of the fixing member has a trapezoidal shape in which the cross section in the direction perpendicular to the direction in which the concave portion extends corresponds to the convex portion of the first cooling member 5, and the bottom of the concave portion becomes the upper side of the trapezoid. The dimension in the direction perpendicular to the direction in which the recess of the opening portion extends is the lower side of the trapezoid, and the lower side has a longer dimension than the upper side. The fixing member supports the first cooling member 5 by fitting the recess and the convex portion of the first cooling member 5. The horizontal direction moving means supports the fixing member so as to be movable in the horizontal direction. The vertical direction moving means supports the fixing member so as to be movable in the vertical direction. For the horizontal direction moving means and the vertical direction moving means, for example, a motor, a biaxial robot, a triaxial robot or the like can be used. The sliding means slides the cooling member 5 in the direction in which the convex portion extends or in the opposite direction. As a result, the cooling member 5 is detached from the fixing member. Such holding means are described in, for example, Japanese Patent Application Laid-Open Nos. 2003-59849, 2003-183015, 2003-277187, and the like.

  The second cooling member 6 is supported by a second holding means (not shown) so that its axis coincides with the vertical direction and is movable in the vertical direction, and is at least a lower end in the vertical direction (hereinafter simply referred to as “lower end” unless otherwise specified). Is a columnar member made of a carbon material provided so as to be immersed in the melt raw material 8 accommodated in the recess 10a of the first crucible 10. For the carbon material forming the second cooling member 6, for example, graphite can be used. When the lower end portion of the second cooling member 6 is immersed in the molten raw material 8, an appropriate temperature drop of the molten raw material 8 occurs around the lower end portion immersed in the molten raw material 8. Thereby, the carbon atom 15 melt | dissolved in the melt raw material 8 adheres to a lower end part surface with the form of a carbide | carbonized_material. If the second cooling member 6 is pulled up from the molten raw material 8 in this state, the carbon atoms 15 can be removed from the molten raw material 8. The second cooling member 6 is in the same area as the immersion area 21 of the first cooling member 5 shown in FIG. 3A on the liquid surface of the melt raw material 8 accommodated in the recess 10a of the first crucible 10. In consideration of the temperature distribution of the melt raw material 8, the stability of the liquid surface of the melt raw material 8, etc., it is preferable to immerse in the central portion of the immersion region 21. Moreover, as shown to Fig.4 (a), you may immerse in the area | region different from the immersion area | region 21 of the 1st cooling member 5. FIG. Accordingly, the first cooling member 5 and the second cooling member 6 are not affected by each other, so that the first cooling member 5 and the second cooling member 6 are immersed in the melt raw material 8 at the same time. obtain. Moreover, the function of the 1st cooling member 5 and the 2nd cooling member 6 is exhibited efficiently. However, in this case, in order to sufficiently widen the immersion region 21 of the first cooling member 5 so that the first cooling member 5 can be immersed and pulled up easily, the first crucible 10 is used. In addition, it is necessary to enlarge the dimension of the recess 10 a in the direction of the arrow 22.

  The second cooling member 6 is required to have an appropriate heat absorption capability (cooling capability). For example, if the endothermic capacity is too large, a significant temperature drop occurs when immersed in the molten raw material 8, and a relatively large amount of the molten raw material 8 is solidified around the second cooling member 6. As a result, efficient removal of the carbon atoms 15 becomes difficult. On the other hand, if the endothermic capacity is too low, a sufficient temperature drop does not occur, and it takes a long time to remove carbon atoms, thereby reducing the production efficiency of the thin plate-like polycrystalline body. Therefore, in the present invention, the surface of the second cooling member 6 that is not immersed in the melt raw material 8 is provided with the heat insulating layer 18 to adjust the heat absorption amount of the second cooling member 6 to an appropriate value. The heat insulating layer 18 is formed of a heat insulating material such as carbon felt, for example. Furthermore, a cooling unit that cools the second cooling member 6, a heating unit that heats the second cooling member 6, and the like may be provided. By providing these, the heat absorption capability of the second cooling member 6 can be adjusted to a more appropriate range, so that the carbon atoms 15 can be removed more efficiently.

  The immersion time of the second cooling member 6 in the melt raw material 8 can be appropriately selected from a wide range according to the liquid temperature and type of the melt raw material 8, the material of the second cooling member 6, and the like. In consideration of removal, it is 30 seconds or longer, preferably 30 seconds to 10 minutes.

  The second holding means (not shown) includes, for example, a support means and a vertical direction moving means. The support means detachably supports the second cooling member 6. The vertical moving means supports the supporting means for supporting the second cooling member 6 so as to be movable in the vertical direction. The lower end of the second cooling member 6 supported by the supporting means is immersed in the molten raw material 8 in the recess 10a of the first crucible 10 by the vertical movement means, and after a predetermined time has passed, It is raised from. For example, a two-axis robot can be used as the second holding means.

  The removal of the carbon atoms 15 from the melting raw material 8 is performed as follows using the second cooling member 6 and the second holding means, for example. When the lower end portion of the second cooling member 6 is immersed in the melt raw material 8, the second cooling member 6 functions as a kind of heat absorbing member, so that the temperature of the melt raw material 8 around the lower end portion is lowered, thereby melting As the specific gravity of the raw material 8 increases, a part of the molten raw material 8 is solidified, and the carbon atoms dissolved in the molten raw material 8 react with the molten raw material 8 and precipitate in the form of carbides of the raw material. The molten raw material 8 containing solidified material and carbide and having a high specific gravity sinks into the bottom surface of the recess 10a in the first crucible 10 and moves by moving the bottom surface of the recess 10a toward the inner surface of the recess 10a. Heated by the means 11, rises to the liquid level of the melt raw material 8, and further flows toward the lower end of the second cooling member 6. That is, convection in the direction of the arrow 19 occurs in the melt raw material 8 in the recess 10a. And as for the contact part with the liquid level of the melting raw material 8 in the lower end part of the 2nd cooling member 6, the fall of temperature is especially remarkable. For this reason, a raw material carbide lump 18 (hereinafter referred to as “carbide lump 18”) grows with the solidified raw material as a binder, centering on the contact portion. When the melting raw material 8 is silicon, the raw material carbide is silicon carbide. In order to grow the carbide lump 18, stable convection in the direction of the arrow 19 is necessary. For this purpose, it is desirable to immerse the second cooling member 6 in the molten raw material 8 for 30 seconds or more.

  When the carbide lump 18 has grown to some extent on the surface of the second cooling member 6, the second cooling member 6 is pulled up from the molten raw material 8, and the carbide lump 18 attached to the lower end of the second cooling member 6 is removed. . The removal of the carbide lump 18 may be performed inside the thin plate manufacturing apparatus 1 or may be performed outside. When implemented inside the thin plate manufacturing apparatus 1, the means for removing the carbide lump 18 from the second cooling member 6, the storage means for storing the removed carbide lump 18, and the carbide lump 18 in the storage means are thinned. Discharging means for discharging to the outside of the manufacturing apparatus 1 is provided. The detaching means includes, for example, a clamping means such as an arm and a driving means such as a motor. The clamping means 18 applies a tensile force to the clamping means while holding the carbide lump 18 by the clamping means. This is a device for removing the carbide lump 18 from the cooling member 6. When applying the tensile force, vibration may be added. Further, the detaching means includes a clamping means and an impact applying means. The carbide mass 18 is applied from the second cooling member 6 by applying an impact to the clamping means by the impact applying means while holding the carbide mass 18 by the clamping means. It is a device to remove. The removal means is not limited to these, and an apparatus used for removing the ceramic pieces adhering to the solid material can be used as appropriate. The removing means conveys the carbide lump 18 to the storage means while sandwiching it. When a predetermined amount of carbide lump 18 is stored in the storage means, the conveying means carries out the storage means itself from a dedicated opening (not shown) formed in the thin plate manufacturing apparatus 1, and the carbide lump 18 in the storage means is discarded. Thereafter, the storage means is carried into the thin plate manufacturing apparatus 1 from the opening. Moreover, when it implements outside the thin plate manufacturing apparatus 1, the conveyance means which conveys the 2nd cooling member 6 to which the carbide lump 18 adheres to the exterior of the thin plate manufacturing apparatus 1 is provided. The second cooling member 6 to which the carbide lump 18 adheres is carried out of the thin plate manufacturing apparatus 1 by a conveying means from a dedicated opening (not shown) formed in the thin plate manufacturing apparatus 1. Then, the second cooling member 6 from which the carbide lump 18 is removed or the new second cooling member 6 is carried into the thin plate manufacturing apparatus 1 from the opening and transferred to the second holding means by the conveying means. In this way, the carbon atoms 15 in the molten raw material 8 are removed from the molten raw material 8 as a carbide lump 18 that is a reaction product of the raw material and the carbon atoms 15.

  The first cooling member conveying means (not shown) carries the first cooling member 5 from the outside into the thin plate manufacturing apparatus 1 and transfers it to the first holding means, whereby the thin plate-like polycrystalline body 9 is formed. The cooling member 5 is received from the first holding means and carried out of the thin plate manufacturing apparatus 1. The first cooling member transport means includes, for example, a rotating roller that is rotatably driven by a driving means (not shown), and a plurality of driven members that are rotatably driven by the rotational driving of the rotating roller and have the same diameter as the rotating roller. There is a first cooling member conveying means including a roller, and the rotating roller and the plurality of driven rollers are arranged so that the respective axis centers are included in one horizontal plane. The first cooling member conveying means conveys the first cooling member 5 placed on the rotating roller and the driven roller to a receiving port (not shown) of the thin plate manufacturing apparatus 1 by the rotation of the rotating roller and the driven roller. . Then, the first cooling member 5 is fitted to the fixing member by the slide mechanism of the first holding means, and after being immersed and pulled up, is conveyed to a delivery port (not shown) of the thin plate manufacturing apparatus 1 and is removed from the fixing member by the sliding means. Detached, placed again on the transport means, and transported to the next step.

  According to the thin plate manufacturing apparatus 1 of the present invention, for example, the thin plate-like polycrystalline body 9 is manufactured as follows. First, the solid raw material 7 is filled in the recess 10 a of the first crucible 10 in the first melting heating furnace 2 and heated by the heating means 11 to become the molten raw material 8. The molten raw material 8 is maintained at a temperature near or slightly higher than the melting point of the raw material. On the other hand, also in the second melting furnace 3, the solid raw material 7 is supplied from the raw material supply means 4 to the recess 13 a in the second crucible 13. The solid raw material 7 is heated to a temperature sufficiently higher than the melting point of the raw material by the heating means 14, becomes a molten raw material 8, and is stored in the recess 13a. At this time, the carbon atoms 15 are eluted from the inner wall surface of the recess 13 a into the melt raw material 8. The elution of carbon atoms 15 is continued until a saturation amount at that temperature is reached. In this state, the first cooling member 5 is carried into the thin plate manufacturing apparatus 1 by the first cooling member conveying means. The first cooling member 5 is transferred to a first holding means (not shown) and is immersed in the molten raw material 8 accommodated in the recess 10a of the first crucible 10 in the direction of the arrow 20 and pulled up. . A thin plate-like polycrystal 9 is deposited on the lower surface of the pulled up first cooling member 5 in the vertical direction. The first cooling member 5 is transferred again from the first holding means to the first cooling member conveying means, and is carried out of the thin plate manufacturing apparatus 1 for use in the next process. Thereafter, a thin plate-like polycrystalline body 9 is formed on the surface of the first cooling member 5 in the same manner.

  When the melting raw material 8 accommodated in the recess 10a of the first crucible 10 is consumed and it becomes difficult to immerse the first cooling member 5, the first cooling member 5 enters the thin plate manufacturing apparatus 1 inside. Loading is temporarily stopped. Then, the first crucible 10 is supplied with the melt raw material 8 containing carbon atoms 15 from the second crucible 13 in the second melting furnace 3. After replenishment of the molten raw material 8, the solid raw material 7 is supplied from the raw material supply means 4 to the recess 13 a of the second crucible 13. This solid raw material 7 is heated in the same manner as described above to become a molten raw material 8. Carbon atoms 15 are also eluted in the melt raw material 8. On the other hand, the temperature of the molten raw material 8 supplied from the second crucible 13 to the first crucible 10 is lowered due to the difference in holding temperature between the two crucibles 10 and 13. For this reason, carbon atoms are precipitated in the molten raw material 8, react with the molten raw material 8 and float in the form of carbide particles 12. In order to remove the carbide particles 12, the lower end of the second cooling member 6 is immersed in the molten raw material 8, and the carbide particles 12 are attached around the lower end, and then the second cooling member 6 is placed in the molten raw material 8. The carbide particles 12 are removed from the molten raw material 8 by pulling up from the melt. Then, carrying in of the 1st cooling member 5 to the thin plate manufacturing apparatus 1 is restarted, and the thin plate-like polycrystal 9 is manufactured. By repeatedly executing these operations, the thin plate-like polycrystalline body 9 can be efficiently produced without causing a decrease in mechanical strength, characteristics and the like.

  In the present embodiment, the second cooling member 6 that is a columnar member is used. However, the shape of the second cooling member 6 is not limited to the columnar shape, and the second cooling member 6 having another shape is used. Can be used. FIG. 5 is a perspective view showing a state in which the second cooling member 25 according to another embodiment is immersed in the melt raw material 8 accommodated in the recess 10 a of the first crucible 10. FIG. 6 is a view showing a state in which the second cooling member 25 is immersed in the melt raw material 8 accommodated in the recess 10 a of the first crucible 10. FIG. 6A is a top view. FIG. 6B is a cross-sectional view. 5 and 6, the illustration of the heat insulating layer provided on the surface of the second cooling member 25 is omitted. The second cooling member 25 is a plate-like member. The second cooling member 25 is formed to have the same length as that of the second cooling member 6 in the length of the portion in contact with the liquid surface of the melt raw material 8. As a result, it is possible to clearly show that there is an advantage due to the difference in shape as described below even though the carbide removal ability is the same.

  Similarly to the second cooling member 6, the second cooling member 25 is normally immersed in the substantially central portion of the immersion region 21 shown in FIG. 3A, but is not limited thereto. For example, as shown in FIGS. 5 and 6, the first cooling member 5 can be immersed outside the immersion region 21. Since the second cooling member 25 is plate-shaped, it is not necessary to enlarge the dimensions of the first crucible 10 and the recess 10a even if the immersion region is provided in a portion outside the immersion region 21 of the first cooling member 5. However, there is an advantage that the cost increase due to the provision of the second cooling member 25 is small. Thereby, even if the 1st cooling member 5 and the 2nd cooling member 6 are immersed in the melt raw material 8 simultaneously, they do not interfere with each other. Therefore, the immersion region 21 of the first cooling member 5 can be sufficiently widened, and the first cooling member 5 can be immersed and pulled up without contacting the second cooling member 6 and the carbide particles 12 present in the vicinity thereof. A thin plate-like polycrystalline body that is executed reliably and has a uniform structure is obtained. Further, since the functions of the first cooling member 5 and the second cooling member 6 are sufficiently exhibited, the thin plate-like polycrystalline body 9 having a very low carbide content can be obtained.

  Further, in the present embodiment, the first crucible 10 whose shape viewed from above in the vertical direction is substantially rectangular is used, and accordingly, the second cooling member whose shape viewed from above in the vertical direction is planar. However, the present invention is not limited to this, and the shape of the second cooling member can be changed according to the shapes of the first crucible 10 and the recess 10a. For example, if the shape viewed from above in the vertical direction is circular, a second cooling member having an arc shape, an annular shape, or the like may be used. So

It is sectional drawing which shows typically the structure of the thin plate manufacturing apparatus which is 1st Embodiment of this invention. It is an expanded sectional view which shows typically the structure of the principal part of the thin plate manufacturing apparatus shown in FIG. It is drawing which shows the immersion area | region of the 1st cooling member in a 1st crucible. It is drawing which shows the immersion area | region of a 1st cooling member, and the immersion area | region of a 2nd cooling member. It is a perspective view which shows the state which immersed the 2nd cooling member which is another form in the melt raw material. It is drawing which shows the state which immersed the 2nd cooling member shown in FIG. 5 in the melt raw material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thin plate manufacturing apparatus 2 1st fusion heating furnace 3 2nd fusion heating furnace 4 Solid raw material supply means 5 1st cooling member 6,25 2nd cooling member 7 Solid raw material 8 Melting raw material 9 Thin plate-like polycrystal 10 1st crucible 10a Recess 11, 14 Heating means 12 Carbide particle 13 2nd crucible 15 Carbon atom 16, 19, 20 Arrow 17 Heat insulation layer 18 Carbide 21 Immersion area

Claims (8)

A first melting furnace comprising: a first crucible having a recess for accommodating a melting raw material; and a heating means for heating the first crucible;
A second melting heating furnace comprising a second crucible made of carbon material having a recess for accommodating a melting raw material, and a heating means for heating the second crucible;
Solid raw material supply means for supplying a solid raw material to the recess of the second crucible;
A melt raw material feeding means for feeding the melt raw material accommodated in the recess of the second crucible to the recess of the first crucible;
A first cooling member provided so as to be dipped in the melt raw material housed in the recess of the first crucible, and having a thin plate formed by solidifying the melt raw material on its surface;
A first holding means for holding the first cooling member and immersing the first cooling member in the melt raw material housed in the recess of the first crucible and pulling it up;
A second cooling member provided so as to be immersed in the melt raw material housed in the recess of the first crucible;
The second cooling member is held, and the second cooling member is immersed in the molten raw material accommodated in the recess of the first crucible, and the carbide in the molten raw material is adsorbed on the surface while maintaining the immersed state. A thin plate manufacturing apparatus including a second holding means to be pulled up later. The second holding means is
2. The apparatus for producing a thin plate according to claim 1, wherein the second cooling member is immersed in a melt raw material accommodated in a recess of the first crucible and pulled up after maintaining the immersed state for at least 30 seconds. The second holding means is
The second cooling member is immersed in the molten raw material accommodated in the recess of the first crucible in a state where the first cooling member is not immersed by the first holding means. Item 3. A thin plate manufacturing apparatus according to item 1 or 2.   The thin plate manufacturing apparatus according to any one of claims 1 to 3, further comprising a heating unit that heats the second cooling member.   The thin plate manufacturing apparatus according to claim 1, further comprising a cooling unit that cools the second cooling member. The second cooling member is
It forms with a carbon material, The thin plate manufacturing apparatus as described in any one of Claims 1-5 characterized by the above-mentioned. The second cooling member is
The thin plate manufacturing apparatus according to any one of claims 1 to 6, wherein a heat insulating layer is provided on at least a part of the surface. The second cooling member is
It is a plate-shaped member, The thin plate manufacturing apparatus as described in any one of Claims 1-7 characterized by the above-mentioned.

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