JP2011098844A - Apparatus and method for producing polycrystalline silicon ingot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for producing a polycrystalline silicon ingot where clumpy silicon raw materials charged in a crucible are efficiently melted and the production efficiency of the polycrystalline silicon ingot is drastically enhanced. <P>SOLUTION: The apparatus 10 for producing the polycrystalline silicon ingot, where a silicon melt is made by melting the silicon raw materials charged in the crucible 20 and the polycrystalline silicon ingot is produced by solidifying the silicon melt, includes the crucible 20 having a cylindrical shape with a bottom, an upper heating part 14 arranged on the upward side of the crucible 20 and a lower heating part 30 arranged downward of the crucible 20. The lower heating part 30 has a table 31 mounted with the crucible 20 and an induction heating coil 32 and an electric current is generated by the induction heating coil 32 in the table 31 and makes the table 31 self-heating. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides a polycrystalline silicon ingot for producing a polycrystalline silicon ingot by melting a silicon raw material contained in a crucible to produce a silicon melt, and solidifying the silicon melt in the crucible. The present invention relates to an apparatus and a method for manufacturing a polycrystalline silicon ingot.

In recent years, as a power generation method with a small environmental load, a solar cell module is attracting attention and is widely used in various fields. Such a solar cell module includes a plurality of cells made of pn-bonded silicon semiconductor plates, and these cells are electrically connected by a solar cell interconnector and a bus bar.
Recently, with the widespread use of solar cell modules, the demand for silicon materials as semiconductor materials is increasing, and there is a shortage of silicon raw materials.

By the way, a polycrystalline silicon ingot that has been unidirectionally solidified in a crucible is widely used as a semiconductor material constituting the solar cell module described above.
As a manufacturing apparatus for producing such a polycrystalline silicon ingot, for example, as shown in Patent Documents 1 and 2, a bottomed cylindrical crucible made of quartz glass or the like is provided in the internal space of the chamber. A cooling plate on which a crucible is placed, an upper heater located above the crucible, and a lower heater located below the crucible have been proposed.

In this polycrystalline silicon ingot manufacturing apparatus, a bulk silicon raw material is charged into a crucible, the inside of the chamber is set to an inert gas atmosphere such as argon gas, and the crucible is inserted from above and below by an upper heater and a lower heater. The silicon raw material in the crucible is melted by heating.
Then, when the silicon raw material in the crucible is completely melted, the silicon melt is cooled from the bottom surface side of the crucible by the cooling plate and the upper part of the crucible is heated by the upper heater. Then, the silicon melt is solidified while growing crystals in one direction along a temperature gradient that increases from the bottom surface of the crucible upward. At this time, impurities in the silicon melt are discharged from the solid phase side to the liquid phase side, and a polycrystalline silicon ingot having high purity and excellent crystallinity is manufactured.

JP 2000-290096 A JP 2000-319094 A

  By the way, in the conventional polycrystalline silicon ingot manufacturing apparatus as disclosed in Patent Documents 1 and 2, a lower heater made of a carbon heater or the like is disposed below the cooling plate. The crucible is held by a reinforcing member made of carbon or the like, and the reinforcing member and the crucible are placed on the cooling plate. Then, by generating heat in the lower heater, the heat is transmitted to the cooling plate, and further, heat is transmitted from the cooling plate to the reinforcing member and the crucible to heat the silicon raw material. Thus, since the heat of the lower heater is transmitted through the cooling plate, the reinforcing member, and the crucible, it takes a long time to dissolve the silicon raw material. For this reason, there was a problem that a polycrystalline silicon ingot could not be produced efficiently. Furthermore, there is a problem that the amount of electric power required for melting the silicon raw material is increased, and the manufacturing cost of the polycrystalline silicon ingot is greatly increased.

  The present invention has been made in view of the above-described circumstances, and can efficiently dissolve a bulk silicon raw material charged in a crucible, and greatly improve the production efficiency of a polycrystalline silicon ingot. An object of the present invention is to provide a polycrystalline silicon ingot manufacturing apparatus and a polycrystalline silicon ingot manufacturing method capable of performing the above.

  In order to solve the above-described problems, the polycrystalline silicon ingot manufacturing apparatus of the present invention generates a silicon melt by melting a silicon raw material charged in a crucible and coagulates the silicon melt to obtain a multi-material. An apparatus for producing a polycrystalline silicon ingot for producing an ingot of crystalline silicon, comprising a crucible having a bottomed cylindrical shape, an upper heating unit disposed above the crucible, and a lower side of the crucible A lower heating unit, and the lower heating unit includes a pedestal on which the crucible is placed and an induction heating coil. The induction heating coil generates an electric current in the pedestal, and the pedestal self-heats. It is the structure made to let it be a feature.

According to the polycrystalline silicon ingot manufacturing apparatus having this configuration, the lower heating unit disposed on the lower side of the crucible has a pedestal on which the crucible is placed and an induction heating coil, and an electric current is supplied to the pedestal by the induction heating coil. Therefore, heat can be efficiently transferred from the pedestal that self-heats to the bottom surface of the crucible, and the melting of the silicon raw material in the crucible can be promoted. In addition, when the silicon raw material is dissolved and a silicon melt is generated, the silicon melt itself can be self-heated.
Therefore, the melting time of the silicon raw material can be shortened, and the production efficiency of the polycrystalline silicon ingot can be improved. In addition, it is possible to reduce the time required for melting the silicon raw material and the amount of electric power required, and it is possible to greatly reduce the manufacturing cost of the polycrystalline silicon ingot.

Here, it is preferable that the induction heating coil has a flat outer shape and is disposed below the pedestal.
In this case, by energizing the induction heating coil, an eddy current can be generated on the entire surface of the pedestal, and the pedestal can be surely and efficiently self-heated.

Moreover, it is preferable that the heat insulation sheet which can be inserted or extracted is interposed between the said induction heating coil and the said base.
When the induction heating coil is energized and the pedestal self-heats, the induction heating coil can be protected from the heat of the pedestal by interposing a heat insulating sheet between the induction heating coil and the pedestal. it can.
Further, since the polycrystalline silicon ingot solidified in the crucible cannot be taken out in a high temperature state, it needs to be cooled in the chamber. Here, when the polycrystalline silicon ingot is cooled, cooling of the bottom surface of the crucible can be promoted by a cooling medium (cooling water or the like) flowing through the induction heating coil by taking out the heat insulating sheet. Therefore, the time for cooling the polycrystalline silicon ingot can be shortened, and the next polycrystalline silicon ingot can be manufactured at an early stage. Therefore, the production efficiency of the polycrystalline silicon ingot can be further improved. Further, when the silicon melt in the crucible is solidified, cooling of the bottom of the crucible is promoted by a cooling medium (cooling water or the like) flowing through the induction heating coil, so that the solidification time of the silicon melt can be shortened. it can.

Furthermore, it is preferable that a coil elevating part for moving the induction heating coil close to and away from the bottom surface of the crucible is provided.
In this case, when melting the silicon raw material, the induction heating coil is separated from the bottom surface of the crucible, so that a space is secured between the pedestal that self-heats and the induction heating coil, and induction heating is performed by the heat of the pedestal. Coil damage can be prevented. Even when the induction heating coil is separated from the pedestal, eddy current can be generated in the pedestal and the pedestal can be self-heated. On the other hand, when the silicon melt is solidified, the crucible is efficiently cooled by a cooling medium (cooling water or the like) flowing through the induction heating coil by keeping the induction heating coil close to the bottom surface of the crucible. be able to. Thereby, it is possible to shorten the solidification time of the silicon melt.

The induction heating coil includes a central heating region that heats a central portion of the bottom surface of the crucible, and a peripheral heating region that heats a peripheral portion of the bottom surface of the crucible, and the central heating region and It is preferable that the peripheral edge heating region can be selected and energized.
In this case, it becomes possible to adjust a heating condition with the center part and peripheral part of the bottom face of a crucible. For example, when solidifying a silicon melt, by heating only the peripheral part of the crucible, heat is radiated from the central part of the bottom surface of the crucible, and solidification proceeds upward, so that the crystallinity is high. A polycrystalline silicon ingot can be produced.

  The method for producing a polycrystalline silicon ingot according to the present invention comprises a method of producing a silicon melt by melting a silicon raw material charged in a crucible, and solidifying the silicon melt to produce a polycrystalline silicon ingot. A method for producing a crystalline silicon ingot, wherein a silicon raw material charging step of charging a silicon raw material into the crucible, an upper heating unit disposed above the crucible, and a lower side of the crucible And a lower heating unit having a pedestal on which the crucible is placed and an induction heating coil, and a heating and melting step for generating a silicon melt by melting the silicon raw material in the crucible, and an upper portion in the upper heating unit Cooling from the bottom side of the crucible while keeping the temperature of the crucible, solidification step of unidirectionally solidifying the silicon melt in the crucible, and cooling to cool the polycrystalline silicon ingot in the crucible Has a degree, and the in heating and melting step, the induced by heating coil to generate a current to the base, the base is self-heating, it is characterized in that it is configured for heating the crucible.

  According to the method for manufacturing a polycrystalline silicon ingot having this configuration, the lower heating unit disposed on the lower side of the crucible has a pedestal on which the crucible is placed and an induction heating coil. In the heating and melting step, Since the induction heating coil generates current in the pedestal, self-heats the pedestal, and heats the crucible, heat can be efficiently transferred from the pedestal that self-heats to the bottom of the crucible. It is possible to promote the dissolution of the silicon raw material in the crucible. In addition, when the silicon raw material is dissolved and a silicon melt is generated, the silicon melt itself can be self-heated.

Here, in the cooling step, the pedestal is preferably cooled by a cooling medium flowing in the induction heating coil.
In the induction heating coil, a cooling medium (cooling water or the like) is circulated in order to protect the induction heating coil itself from heat. Therefore, in the cooling step, it becomes possible to efficiently cool the polycrystalline silicon ingot in the crucible using this cooling medium. Thereby, the cooling time of the polycrystalline silicon ingot can be greatly shortened, and the production efficiency of the polycrystalline silicon ingot can be improved.

The induction heating coil includes a central heating region for heating a central portion of the bottom surface of the crucible and a peripheral heating region for heating a peripheral portion of the bottom surface of the crucible. It is preferable to prevent heat removal from the periphery of the crucible by energizing only the periphery heating region.
In this case, in the solidification step, by supplying current only to the peripheral edge heating region, heat removal from the peripheral edge of the crucible is prevented, so that a crystal can be grown from the bottom surface side of the crucible. It becomes possible to produce a high polycrystalline silicon ingot.

  According to the present invention, an apparatus for producing a polycrystalline silicon ingot that can efficiently dissolve a bulk silicon raw material charged in a crucible and can greatly improve the production efficiency of a polycrystalline silicon ingot, and A method for producing a polycrystalline silicon ingot can be provided.

It is a schematic explanatory drawing of the manufacturing apparatus of the polycrystal silicon ingot which is 1st embodiment of this invention. It is a top view of the high frequency heating coil (induction heating coil) with which the manufacturing apparatus of the polycrystalline silicon ingot shown in FIG. 1 was equipped. It is a schematic explanatory drawing of the manufacturing apparatus of the polycrystalline silicon ingot which is 2nd embodiment of this invention. It is explanatory drawing which shows the state which implements the solidification process in the manufacturing apparatus of the polycrystalline silicon ingot shown in FIG.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
First, a polycrystalline silicon ingot manufacturing apparatus and a polycrystalline silicon ingot manufacturing method according to a first embodiment of the present invention will be described with reference to FIGS.

  The polycrystalline silicon ingot manufacturing apparatus 10 according to the present embodiment includes a chamber 11 capable of holding an internal space in an airtight state. In the internal space of the chamber 11, a crucible 20 having a bottomed cylindrical shape, A carbon heater 14 positioned above the crucible 20, a lower heating unit 30 positioned below the crucible 12, and a heat insulating member 18 covering the outer periphery of the crucible 20 are disposed.

Here, the chamber 11 is supplied with an inert gas supply means (not shown) for supplying an inert gas such as argon gas to the internal space, and cooling water is supplied to the wall portion of the chamber 11 to circulate it. A coolant supply means (not shown) is provided separately.
The crucible 20 is made of quartz glass, and includes a bottom surface portion 20A and a side wall portion 20B erected from the bottom surface portion 20A. The crucible 20 is reinforced by a reinforcing member 21 having a reinforcing plate 21A and a reinforcing wall 21B.

The lower heating unit 30 includes a pedestal 31 disposed on the bottom surface 20 </ b> A side of the crucible 20 and a high-frequency heating coil 32 disposed on the lower side of the pedestal 31.
The pedestal 31 is made of, for example, carbon or silicon carbide, and includes a plate portion 31A having a substantially flat plate shape, and a side tube portion 31B standing from the peripheral portion of the plate portion 31A. Even when the liquid leaks out of the crucible 20, the silicon melt does not reach the high-frequency heating coil 32.
The pedestal 31, the crucible 20, and the reinforcing member 21 are supported by a crucible support member (not shown).
Moreover, between the plate part 31A and the high frequency heating coil 32, the heat insulation sheet 38 is arrange | positioned so that insertion / extraction is possible. The heat insulating sheet 38 is made of a material that does not generate eddy current even when the high frequency heating coil 32 is energized, such as glass wool.

  As shown in FIG. 2, the high-frequency heating coil 32 is formed by arranging copper tubes in a spiral shape, and has a flat plate shape as a whole. A cooling medium (cooling water) is circulated inside the copper pipe. In the present embodiment, the high frequency heating coil 32 is partitioned into two regions, a central region 32A and a peripheral region 32B. One electrode of the power source 33 is connected to the outer peripheral end portion of the peripheral region 32 </ b> B, and the other electrode of the power source 33 is connected to the switching unit 34. The switching unit 34 includes one contact 34A, the other contact 34B, and a switch unit 34C that selects either the one contact 34A or the other contact 34B, and the one contact 34A is in the central region. The other contact 34B of the switching portion 34 is connected to the inner peripheral end portion of the peripheral region 32B.

  Below, the manufacturing method of the polycrystalline silicon ingot using this polycrystalline silicon ingot manufacturing apparatus 10 is demonstrated.

(Silicon raw material charging process)
First, a massive silicon raw material is charged into the crucible 20. Here, as the silicon raw material, a lump called “chunk” obtained by crushing high purity silicon of 11N (purity: 99.99999999999) is used. The particle size of the bulk silicon raw material is, for example, 30 mm to 100 mm.

(Heating and melting process)
The crucible 20 charged with the silicon raw material is accommodated in the reinforcing member 21 placed on the pedestal 31. At this time, a heat insulating sheet 38 is inserted between the base 31 and the high-frequency heating coil 32.
In this state, the coolant is passed through the high-frequency heating coil 32 and energized. At this time, the switch part 34C of the switching part 34 is connected to one contact 34A side, and the inner peripheral end of the central region 32A and the outer peripheral end of the peripheral region 32B of the high-frequency heating coil 32 are connected via a power source. As a result, the entire high-frequency heating coil 32, that is, the central region 32A and the peripheral region 32B is energized.

Then, an eddy current is generated on the surface of the pedestal 31 disposed via the heat insulating sheet 38, and the pedestal 31 itself self-heats due to Joule heat.
Further, the carbon heater 14 disposed above the crucible 20 is energized to generate heat.
The silicon raw material in the crucible 20 is melted by the heat from the carbon heater 14 and the heat from the pedestal 31 that has self-heated to generate a silicon melt.

(Coagulation process)
Next, the switch part 34C of the switching part 34 of the high-frequency heating coil 32 is changed to the other contact 34B side. Then, the inner peripheral end of the peripheral region 32B of the high frequency heating coil 32 and the outer peripheral end of the peripheral region 32B are connected via a power source, and only the peripheral region 32B of the high frequency heating coil 32 is energized. Become. Further, the carbon heater 14 disposed above the crucible is kept energized. At this time, the heat insulating sheet 38 may be extracted.

Then, the temperature of the upper part of the crucible 20 is maintained by the heat from the carbon heater 14. Further, in the lower part of the crucible 20, since the central region 32A of the high frequency heating coil 32 is not energized and the cooling water is circulated inside the high frequency heating coil 32, heat is dissipated from the bottom surface portion 20A side. Will be. As a result, a temperature gradient is provided in the crucible 20 so that the temperature increases from the bottom surface portion 20A side upward, and the silicon melt in the crucible 20 It is solidified in one direction from above.
In addition, since electricity is supplied only to the peripheral region 32B of the high-frequency heating coil 32, the peripheral portion and the side wall portion 20B of the bottom surface portion 20A of the crucible 20 are heated. Thereby, the dissipation of the heat from the side wall part 20B etc. is suppressed.

(Cooling process)
Next, the carbon heater 14 is stopped, and the polycrystalline silicon ingot in the crucible 20 is cooled. At this time, energization of the high frequency heating coil 32 is stopped and the circulation of the cooling water is continued. Thereby, the cooling of the polycrystalline silicon ingot in the crucible 20 is promoted by the cooling water flowing inside the high frequency heating coil 32.
In this way, a unidirectionally solidified polycrystalline silicon ingot is produced.

  According to the polycrystalline silicon ingot manufacturing apparatus 10 and the manufacturing method of the present embodiment configured as described above, the pedestal 31 is self-heated by the high-frequency heating coil 32, and the heat of the pedestal 31 is efficiently transferred. It can be transmitted to the bottom surface portion 20A of the crucible 20, and the melting of the silicon raw material in the crucible can be promoted. Further, when the silicon raw material is melted and a silicon melt is generated, the silicon melt itself can be self-heated. Thereby, the melting time of the silicon raw material can be greatly shortened, and the production efficiency of the polycrystalline silicon ingot can be improved. In addition, it is possible to reduce the time required for melting the silicon raw material and the amount of electric power required, and it is possible to greatly reduce the manufacturing cost of the polycrystalline silicon ingot.

Further, since the pedestal 31 is cooled by the cooling water flowing inside the high frequency heating coil 32 in the cooling process, the polycrystalline silicon ingot in the crucible 20 can be efficiently cooled.
In particular, in the present embodiment, since a heat insulating sheet 38 that can be inserted and removed is interposed between the high frequency heating coil 32 and the pedestal 31, the heat insulating sheet 38 is taken out in the cooling step to thereby remove the heat insulating sheet 38. The heat dissipation from the bottom surface 20A of the crucible 20 can be promoted by the cooling water flowing through the crucible 20, and the cooling time of the polycrystalline silicon ingot can be further shortened. Also in the solidification step, the heat dissipation from the bottom surface portion 20A is promoted, so that the solidification time can be shortened.
Thus, the melting time of the silicon raw material and the cooling time of the polycrystalline silicon ingot can be shortened, and the production efficiency of the polycrystalline silicon ingot can be further improved. In addition, when the pedestal 31 is self-heated by energizing the high-frequency heating coil 32, the high-frequency heating coil 32 can be protected from the heat of the pedestal 31 by interposing a heat insulating sheet 38. Thereby, the lifetime extension of the high frequency heating coil 32 can be aimed at.

  Further, the high frequency heating coil 32 is divided into two regions, a central region 32A and a peripheral region 32B, and the outer peripheral end portion of the peripheral region 32B is connected to one electrode of the power source 33, and the other electrode of the power source 33 is connected to the other region. The switching unit 34 is connected, one contact 34A of the switching unit 34 is connected to the inner peripheral end portion of the central region 32A, and the other contact 34B of the switching unit 34 is connected to the inner peripheral end portion of the peripheral region 32B. Therefore, only the central region 32A and the peripheral region 32B or the peripheral region 32B can be selected and energized.

  Therefore, in the solidification process, only the peripheral region 32B is energized to heat only the peripheral portion of the bottom surface portion 20A of the crucible 20, thereby dissipating heat from the central portion of the bottom surface portion 20A of the crucible 20 and heat from the peripheral portion. The silicon melt in the crucible 20 can be solidified upward from the bottom surface portion 20A side, and a polycrystalline silicon ingot with high crystallinity can be produced. .

  Further, in the present embodiment, the high frequency heating coil 32 is configured such that the copper tube is arranged in a spiral shape and the outer shape is a flat plate shape. Eddy currents can be generated on the entire surface, and the pedestal 31 can be surely and efficiently self-heated. Further, the polycrystalline silicon ingot manufacturing apparatus 10 can be downsized.

  Next, a polycrystalline silicon ingot manufacturing apparatus and manufacturing method according to a second embodiment of the present invention will be described with reference to FIGS.

  The polycrystalline silicon ingot manufacturing apparatus 110 according to the present embodiment includes a chamber 111 capable of holding an internal space in an airtight state. In the internal space of the chamber 111, a crucible 120 having a bottomed cylindrical shape, and the crucible A carbon heater 114 positioned above 120, a lower heating unit 130 positioned below the crucible 120, and a heat insulating member 118 covering the outer periphery of the crucible 120 are disposed.

  The crucible 120 is made of quartz glass, and includes a bottom surface portion 120A and a side wall portion 120B erected from the bottom surface portion 120A. The crucible 120 is reinforced by a reinforcing member 121 including a reinforcing plate 121A and a reinforcing wall 121B.

The lower heating unit 130 includes a pedestal 131 on which the crucible 120 is placed, and a high-frequency heating coil 132 disposed on the lower side of the pedestal 131.
The pedestal 131 is made of, for example, carbon or silicon carbide, and includes a plate portion 131A having a substantially flat plate shape, and a side tube portion 131B erected from the peripheral portion of the plate portion 131A. Even when the melt leaks from the crucible 120, the silicon melt does not reach the high-frequency heating coil 132.
The base 131, the crucible 120, and the reinforcing member 121 are supported by a crucible support member (not shown).

  A heat insulating sheet 138 is detachably disposed between the plate portion 131A and the high frequency heating coil 132. The heat insulating sheet 138 is made of a material that does not generate eddy current, such as glass wool, even when the high-frequency heating coil 132 is energized. In the present embodiment, the thickness of the plate portion 131A of the pedestal 131 is relatively thick, for example, 70 to 100 mm.

The high-frequency heating coil 132 is formed by arranging copper tubes in a spiral shape, and has a flat plate shape as a whole. A cooling medium (cooling water) is circulated inside the copper pipe.
In the present embodiment, the high frequency heating coil 132 is supported by the coil support member 135. The coil support member 135 has an elevating function and is configured such that the high-frequency heating coil 132 can be moved close to and away from the bottom surface portion 120 </ b> A of the crucible 120.

  Below, the manufacturing method of the polycrystalline silicon ingot using this polycrystalline silicon ingot manufacturing apparatus 110 is demonstrated.

(Silicon raw material charging process)
First, a massive silicon raw material is charged into the crucible 120. Here, as the silicon raw material, a lump called “chunk” obtained by crushing high purity silicon of 11N (purity: 99.99999999999) is used. The particle size of the bulk silicon raw material is, for example, 30 mm to 100 mm.

(Heating and melting process)
The crucible 120 charged with the silicon raw material is accommodated in the reinforcing member 121 mounted on the pedestal 131. At this time, a heat insulating sheet 138 is inserted between the base 131 and the high-frequency heating coil 132.
In this state, the coolant is passed through the high-frequency heating coil 132 and energized. Then, an eddy current is generated on the surface of the pedestal 131 disposed via the heat insulating sheet 138, and the pedestal 131 itself generates heat by Joule heat.
Further, the carbon heater 114 disposed above the crucible 120 is energized to generate heat.
The silicon raw material in the crucible 120 is melted by the heat from the carbon heater 114 and the heat from the pedestal 131 that has self-heated to generate a silicon melt.

(Coagulation process)
Next, energization of the high-frequency heating coil 132 is stopped. Further, the cooling water is allowed to flow inside the high frequency heating coil 132. And while extracting the heat insulation sheet 138, the coil support member 135 is raised and the high frequency heating coil 132 is made to contact the lower surface of the base 131. FIG.
The carbon heater 114 disposed above the crucible is left energized.

  Then, the temperature of the upper part of the crucible 120 is maintained by the heat from the carbon heater 114. In addition, since the high-frequency heating coil 132 through which the cooling water is circulated is in contact with the pedestal 131, the bottom surface portion 120A of the crucible 120 is cooled. As a result, a temperature gradient is provided in the crucible 120 so that the temperature increases from the bottom surface portion 120A side upward, and the silicon melt in the crucible 120 flows into the bottom surface portion 120A side of the crucible 120. It is solidified in one direction from above.

(Cooling process)
Next, the carbon heater 114 is stopped and the polycrystalline silicon ingot in the crucible 120 is cooled. At this time, energization of the high-frequency heating coil 132 is stopped and the circulation of the cooling water is continued. Thereby, the cooling of the polycrystalline silicon ingot in the crucible 120 is promoted by the cooling water flowing inside the high frequency heating coil 132.
In this way, a unidirectionally solidified polycrystalline silicon ingot is produced.

  According to the polycrystalline silicon ingot manufacturing apparatus and manufacturing method of the present embodiment configured as described above, the high-frequency heating coil 132 is supported by the coil support member 135, and the bottom surface portion 120 </ b> A of the crucible 120 is supported. In this embodiment, the high-frequency heating coil 132 in which the cooling water is circulated is brought close to the bottom surface portion 120A of the crucible 120 in the cooling process. Then, the crucible 120 can be efficiently cooled by configuring the pedestal 131 so that the high-frequency heating coil 132 is in contact therewith. Thereby, the cooling time of the polycrystalline silicon ingot in the crucible 120 can be significantly shortened. Also in the solidification step, the solidification time can be shortened by promoting the dissipation of heat from the bottom surface portion 120A of the crucible 120.

  In the present embodiment, since the thickness of the plate portion 131A of the pedestal 131 is relatively thick, for example, 70 to 100 mm, the heat spreads in the surface direction by the plate portion 131A in the heating and melting step, and the crucible 120 The bottom surface portion 120A can be uniformly and efficiently heated.

As described above, the polycrystalline silicon ingot manufacturing apparatus and the polycrystalline silicon ingot manufacturing method according to the embodiment of the present invention have been described. However, the present invention is not limited to this and does not depart from the technical idea of the present invention. The range can be changed as appropriate.
For example, 11N high-purity silicon has been described using a bulk silicon raw material having a particle size of 30 to 100 mm, but the present invention is not limited to this, and the particle size, purity, and the like can be appropriately selected. preferable.

Further, the shapes and structures of the chamber, the carbon heater, the heat insulating member, etc. are not limited to this embodiment, and can be appropriately changed in design.
Furthermore, although it demonstrated as what formed the high frequency heating coil (induction heating coil) in the shape of a spiral, it is not limited to this, You may arrange | position in another shape.
Moreover, although the high frequency heating coil (induction heating coil) has been described as being disposed on the lower side of the pedestal, the arrangement of the high frequency heating coil (induction heating coil) is not limited as long as this pedestal can be induction heated.

10, 110 Polycrystalline silicon ingot production equipment 14, 114 Carbon heater (upper heating section)
20, 120 Crucible 20A, 120A Bottom portion 30, 130 Lower heating portion 31, 131 Base 32, 132 High frequency heating coil (induction heating coil)

Claims (8)

A polycrystalline silicon ingot producing apparatus for producing a silicon melt by melting a silicon raw material charged in a crucible and solidifying the silicon melt to produce a polycrystalline silicon ingot,
A crucible having a bottomed cylindrical shape, an upper heating part arranged on the upper side of the crucible, and a lower heating part arranged on the lower side of the crucible,
The lower heating unit includes a pedestal on which the crucible is placed and an induction heating coil, and is configured to generate current in the pedestal by the induction heating coil and cause the pedestal to self-heat. For producing polycrystalline silicon ingot   The apparatus for producing a polycrystalline silicon ingot according to claim 1, wherein the induction heating coil has a flat outer shape and is disposed below the pedestal.   The apparatus for producing a polycrystalline silicon ingot according to claim 2, wherein a heat insulating sheet that can be inserted and removed is interposed between the induction heating coil and the pedestal.   The apparatus for producing a polycrystalline silicon ingot according to any one of claims 2 and 3, further comprising a coil lifting / lowering unit that moves the induction heating coil close to and away from the bottom surface of the crucible. . The induction heating coil has a central heating region for heating the central portion of the bottom surface of the crucible and a peripheral heating region for heating the peripheral portion of the bottom surface of the crucible,
5. The structure according to claim 1, wherein energization can be selectively performed on the central heating area and the peripheral heating area. 6. Polycrystalline silicon ingot manufacturing equipment. A method for producing a polycrystalline silicon ingot in which a silicon raw material charged in a crucible is dissolved to produce a silicon melt, and the silicon melt is solidified to produce a polycrystalline silicon ingot.
A silicon raw material charging step of charging the silicon raw material into the crucible;
An upper heating unit disposed on the upper side of the crucible, a lower heating unit disposed on the lower side of the crucible and having a pedestal on which the crucible is placed and an induction heating coil. A heating and melting step in which a silicon raw material is dissolved to produce a silicon melt;
A solidification step of cooling from the bottom side of the crucible while maintaining the upper part in the upper heating section, and solidifying the silicon melt in one direction in the crucible; and a cooling step of cooling the polycrystalline silicon ingot in the crucible. Have
In the heating and melting step, a current is generated in the pedestal by the induction heating coil, the pedestal is self-heated, and the crucible is heated.   The method for producing a polycrystalline silicon ingot according to claim 6, wherein in the cooling step, the pedestal is cooled by a cooling medium flowing inside the induction heating coil. The induction heating coil has a central heating region for heating the central portion of the bottom surface of the crucible and a peripheral heating region for heating the peripheral portion of the bottom surface of the crucible,
8. The manufacture of a polycrystalline silicon ingot according to claim 6, wherein heat removal from the periphery of the crucible is prevented by energizing only the peripheral edge heating region in the solidification step. Method.

Images