JP4868757B2 - Manufacturing method of semiconductor ingot - Google Patents

Description

The present invention relates to the production how the semiconductor ingot, especially after heated and melted by supplying semiconductor material into the mold, about the production how the semiconductor ingot for producing an ingot for a solar cell solidifying.

  Solar cells are expected to be put to practical use in a wide range of fields, from small households to large-scale power generation systems, as a clean petroleum alternative energy source. These are classified into crystalline, amorphous, and compound types depending on the type of raw materials used, and most of them currently on the market are crystalline silicon solar cells. This crystalline silicon solar cell is further classified into a single crystal type and a polycrystalline type. Single crystal silicon solar cells have the advantage that the conversion efficiency is easy to increase because the quality of the substrate is good, but the disadvantage is that the manufacturing cost of the substrate is high.

  On the other hand, polycrystalline silicon solar cells have been distributed in the market for a long time, but in recent years, the demand is increasing as interest in environmental issues is increasing, and higher conversion efficiency is required at lower cost. . In order to cope with such a demand, it is necessary to reduce the cost and quality of the polycrystalline silicon substrate, and it is required to manufacture a high-purity silicon ingot with a high yield.

  A polycrystalline silicon substrate used for a polycrystalline silicon solar cell is generally manufactured by a method called a casting method. In this casting method, a silicon melt heated and melted at a high temperature in a mold coated with a release material is poured into the mold and solidified from the bottom of the mold, or after silicon material is placed in the mold and once melted, it is again This is a method of forming a silicon ingot by solidifying from the bottom. The ends of the silicon ingot are removed, cut into a desired size and cut into a block shape, and the cut silicon block is sliced to a desired thickness to obtain a polycrystalline silicon substrate for forming a solar cell.

  In order to manufacture such a polycrystalline silicon ingot, a melting furnace is provided to melt a silicon raw material, and the molten silicon melt is poured into a mold and solidified. In the semiconductor ingot manufacturing apparatus, It is necessary to prepare the coagulation part separately, which increases the size of the apparatus. However, in the method using in-mold melting, in which the silicon raw material is melted in the mold and solidified in the mold as it is, there is no need to provide a melting furnace, so the apparatus does not become large, and an expensive member such as a high-purity quartz crucible Therefore, it is more advantageous to produce a polycrystalline silicon ingot using a method described later.

  Here, a conventional apparatus for manufacturing a semiconductor ingot in melting in a mold is shown in FIG. In FIG. 3, 21 is a mold made of graphite or silica, 22 is a cooling means, 23 is a heat insulating wall made of graphite, 24 is a mold heating means, 25 is a silicon raw material (silicon melt), and 28 is a mold release material. In this semiconductor ingot manufacturing apparatus, a mold release material 28 mainly composed of silicon nitride, silicon carbide, silicon dioxide or the like is formed on the inner wall surface of a mold 21, and a silicon raw material 25 is supplied into the mold 21. The raw material 25 is melted by heating it to about 1500 ° C. with the mold heating means 24, and the mold is gradually lowered to cool the silicon melt away from the mold heating means 24, or the mold position is kept as it is. The temperature is lowered by means 22 for cooling, and the silicon melt is solidified in the mold 21 to form a silicon ingot (see, for example, Patent Document 1 and Non-Patent Document 1). The silicon ingot is taken out from the mold 21 by breaking the mold 21 or taken out by disassembling the mold 21. These are all arranged in a vacuum vessel (not shown).

The bulk density of the silicon raw material 25 used in such a method for producing a silicon ingot is usually 1.0 to 1.5, which is about half of the specific gravity of silicon 2.33. Therefore, in the conventional semiconductor ingot manufacturing apparatus as shown in FIG. 3, the height of the silicon ingot formed by solidifying the silicon melt is only about half of the mold. The mold 21 and the release material 28 applied to the inner wall surface of the mold are expensive consumables and have a large proportion of the running cost. Therefore, the conventional technique has a problem that the required mold 21 is large with respect to the size of the silicon ingot, and the mold 21 and the release material 28 around the weight of the silicon ingot are expensive. FIG. 4 shows a conventional semiconductor material supply type manufacturing apparatus. To solve this problem, as shown in FIG. 4, a movable door 33b is provided above the heat insulating wall 33a on the mold 31, and a raw material supply means 36 is provided on the movable door 33b. The silicon raw material 35 can be supplied into 31 (for example, refer to Patent Document 2). As the silicon raw material 35 filled in the mold 31 is melted in this way, a new silicon raw material is additionally supplied into the mold 31 after the bulk of the silicon raw material 35 is reduced, so that the mold 31 around the weight of the silicon ingot and The cost of the release material 38 can be reduced.
U.S. Pat. No. 3,898,051 Japanese Patent Laid-Open No. 10-139586 5th International PVSEC p303-305

  However, in the conventional new silicon raw material supply method, the silicon raw material previously charged in the mold is heated to about 1500 ° C. and melted. When a new silicon raw material is additionally supplied from the raw material supply means 36 to the silicon melt in the mold that has been melted in this state, the silicon melt is rapidly cooled. There is a problem that the phenomenon of being mixed in occurs or the mold release material is peeled off so that the mold material comes into contact with the silicon melt, and the silicon ingot is cracked to reduce the product yield. In addition, when a new silicon raw material is introduced, there is a problem that the crystal quality is deteriorated by drastically lowering the temperature of the silicon melt.

  The inventor, when a new silicon raw material is charged, the temperature in the furnace is drastically decreased, or the silicon melt adheres to the inner surface of the mold due to the scattering of the silicon melt at the time of charging, and solidifies by cooling. As a result, the mold material and the release material coated on the mold material are peeled and damaged due to the difference in thermal expansion coefficient between the mold material and the mold release material due to a rapid thermal history, and enter the silicon melt in the mold. It was found that this was a factor that greatly reduced the product yield.

The present invention was invented in view of such problems of the conventional apparatus, and it is possible to manufacture a silicon ingot by effectively using the height of the mold, and to the semiconductor melt melted in the mold. when adding provide a new semiconductor material, intended to release material of the mold is peeled off or damaged, provides manufacturing how the semiconductor ingot to solve the problems of reducing the yield by the incorporation of cracks and release material ingot And

In order to achieve the above object, in a method for manufacturing a semiconductor ingot according to an embodiment of the present invention, a semiconductor raw material is heated and melted by a mold heating means in a mold, and then a new semiconductor raw material is supplied and melted. In the method of manufacturing a semiconductor ingot obtained by solidifying the obtained semiconductor melt, a new semiconductor raw material is supplied into the mold in a preheated state, and the new semiconductor raw material is reduced in temperature of the semiconductor melt. There is provided upon reaching below the specified value 70 ° C. and said Rukoto stopped.

  Further, the new semiconductor material is preheated by the mold heating means.

  Furthermore, a new semiconductor material is preheated separately by a material heating means for heating a new semiconductor material.

As described above, according to the manufacturing how a semiconductor ingot according to the present invention, in a mold, the semiconductor material on the heated melted by the mold heating means, and supplies a new semiconductor material, obtained by melting In a method for manufacturing a semiconductor ingot obtained by solidifying a semiconductor melt, a new semiconductor material is supplied into a mold in a preheated state. Thus, by melting the semiconductor raw material charged in the mold and then supplying a new semiconductor raw material, it is possible to manufacture a semiconductor ingot that effectively uses the height of the mold. In addition, when supplying the semiconductor raw material, since there is no sudden temperature drop, it can prevent the release material peeling damage at the time of the semiconductor raw material supply, the release damaged release material is taken into the silicon melt, It is possible to eliminate the problem that the crystal quality is lowered by cracking the semiconductor ingot, or when the temperature of the semiconductor melt is drastically lowered when a new silicon raw material is added, Since the supply amount of the semiconductor raw material can be increased, the manufacturing time of the semiconductor ingot can be shortened and the productivity can be improved.

  In addition, a new semiconductor material is supplied into the silicon melt, and when the temperature drop of the silicon melt at that time reaches a specified value, the supply of the semiconductor material is stopped to prevent peeling damage to the release material. However, the semiconductor raw material can be supplied into the silicon melt more efficiently.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing an embodiment of a semiconductor ingot manufacturing apparatus according to the present invention, wherein 1 is a mold, 2 is a cooling means, 3a is a heat insulating wall, 3b is a movable door, and 4a is a mold upper heating means. 4b is a mold side heating means, 5 is a semiconductor raw material or a semiconductor melt formed by melting a semiconductor raw material, 6 is a raw material supply means, 6a is an introduction member, 6b is an opening and closing port, 6c is a raw material supply tank, 7 Is a new semiconductor material, 8 is a mold release material, 9 is a temperature measuring means, 10 is a display, 11 is a calculator, and 12 is a material supply control means. As a semiconductor raw material, silicon that is frequently used for solar cell substrates is generally used.

  The mold 1 is made of graphite, silicon dioxide, or the like, and is configured as an integral structure mold. Such a monolithic mold is disposable to destroy and remove the mold 1 when the semiconductor ingot is taken out, and after the semiconductor raw material in the mold is melted to effectively use the height of the mold, a new one is formed. It is desirable to supply semiconductor raw materials.

  A mold release material 8 is applied to the inner surface side of the mold 1 shown in FIG. 1. After the semiconductor melt 5 inside the mold 1 is solidified by the mold release material 8, the semiconductor ingot can be taken out. At this time, if the release material 8 is not present, the semiconductor ingot and the mold 1 are fused and occupy an important position because cracks and cracks occur when taken out.

  As such a release material 8, each powder of silicon nitride, silicon carbide, silicon oxide or the like or mixed powder is mixed and stirred in a solution composed of an appropriate organic binder and solvent to form a slurry, and a spatula. The inner surface of the mold 1 is coated and dried by using a brush, a brush or a spray. Common binders include PVA (polyvinyl alcohol), PVB (polyvinyl butyral), PEG (polyethylene glycol), MC (methyl cellulose), CMC (carboxymethyl cellulose), EC (ethyl cellulose), HPC (hydroxypropyl cellulose), wax and the like. Used for. Further, when the release material 8 mixed with the organic binder solution to form a slurry is coated, the heat decomposable product of the organic binder solution is prevented from being mixed into the silicon melt 5 by the subsequent heating. A degreasing process is performed. Further, as a drying method, the mold release material can be bonded to the mold 1 by performing a degreasing treatment by natural drying or drying using a conventionally known method such as a hot plate or an oven. In addition, the mold release material may be applied to the inner surface of the mold 1 not only by applying a slurry, but also by directly using a plasma spraying machine or the like.

  And the casting_mold | template 1 is arrange | positioned inside the heat insulation wall 3a which consists of graphite. In addition, the silicon raw material 5 is charged into the mold and heated by the heating means 4 to obtain a silicon melt 5. Next, an additional silicon raw material 7 is supplied into the mold 1 by the raw material supply means 6 provided on the upper part of the mold 1. The mold 1, the heat insulating wall 3a, the mold heating means 4, and the raw material supply means 6 are installed in a vacuum container (not shown).

  The raw material supply means 6 is provided with a raw material supply tank 6c for holding a new semiconductor raw material 7 made of, for example, stainless steel or graphite, and underneath it is for introducing the new semiconductor raw material 7 to the mold 1. An introduction member 6a is provided. The introduction member 6a has a through hole, and an opening / closing port 6b is provided between the through hole and the raw material supply tank 6c.

  When a new semiconductor raw material 7 is supplied into the mold 1, the new semiconductor raw material 7 can be supplied through the introduction member 6 a by opening the opening / closing port 6 b from the raw material supply tank 6 c.

  The mold heating means 4 is a resistance heating type heater or induction heating type coil.

  In this way, the semiconductor raw material in the mold 1 is heated by the mold heating means 4 to be in a melt state, and then a new semiconductor raw material 7 is supplied. Therefore, the mold coated with the release material 8 having a high running cost is applied. In-mold melting using the height of 1 effectively is made possible.

In this case, the density of the silicon ingot (solid) is 2.33 g / cm ³ whereas the density of the silicon melt (liquid) is 2.55 g / cm ^3, when moving from a liquid to a solid In consideration of the volume expansion of about 9% occurring in the above, it is desirable to introduce a new semiconductor material 7 so that the silicon melt is about 90% of the height of the mold 1.

  In order to use the semiconductor melt 5 thus formed as a semiconductor ingot, the mold 1 is removed from the bottom. By removing heat from the lower part of the mold 1, unidirectional solidification of the semiconductor ingot is realized. However, when the semiconductor melt 5 is a silicon melt, when the heating is stopped by the mold heating means 4b, the silicon melt in the mold has a large heat removal from the liquid surface. If the silicon melt is solidified and the silicon melt is left in the interior, the silicon melt left behind is solidified and expands, and the surface of the silicon ingot is erupted and the silicon ingot is cracked. In order to prevent this problem, it is desirable to heat the liquid surface of the silicon melt by the mold upper heating unit 4a located above the silicon melt so as not to solidify the liquid surface of the silicon melt in the mold.

  In this way, the semiconductor melt 5 can be unidirectionally solidified by removing heat from the lower part of the mold 1 by contacting or approaching the cooling means 2 provided at the lower part of the mold 1. At this time, as the cooling means 2, for example, a metal plate such as stainless steel (SUS) can be used, and a coolant such as water is circulated inside the mold 1, so that it is effectively removed from the semiconductor melt 5 inside the mold 1. It is desirable to configure so that heat can be removed. A semiconductor ingot obtained by cooling and solidification is cut and washed to a desired size and used as a polycrystalline silicon substrate material for solar cells.

  The method for manufacturing a semiconductor ingot according to the present invention is characterized in that a new semiconductor raw material is supplied into a mold in a preheated state.

  Conventionally, since the temperature of the new semiconductor raw material 7 supplied into the mold is low, when it is supplied into the mold, the temperature in the mold 1 rapidly decreases, and the mold release material coated on the inner surface of the mold 1 is used. Takes a very heavy load. For example, when the output of the mold upper heating means 4a is increased more than necessary to melt the semiconductor raw material 5, the inner surface of the mold 1 is heated more than necessary by the radiation of the mold upper heating means 4a. It is in a state. When a new semiconductor raw material 7 is supplied in this state, the mold material and the mold release material, which have been thermally expanded by being heated by the mold heating means 4, suddenly fall due to a temperature drop caused by supplying the new semiconductor raw material 7. As a result, shrinkage occurs and the release material is peeled off.

  However, the mold material which has been thermally expanded by suppressing the temperature drop of the semiconductor melt when the new semiconductor raw material is supplied by supplying the new semiconductor raw material into the semiconductor melt 5 in a preheated state. Since the mold release material does not shrink rapidly, the mold release material can be prevented from being damaged by peeling, and the mold release material damaged by peeling can be taken into the silicon melt or the silicon ingot can be cracked. When the silicon raw material is charged, the problem that the crystal quality is deteriorated due to a rapid decrease in the temperature of the silicon melt can be suppressed. Furthermore, when a large amount of new semiconductor raw material 7 is supplied, the temperature of the semiconductor melt 5 is drastically decreased. However, even if the supply amount of the semiconductor raw material is increased once by preheating, the drastic temperature decrease does not occur. The manufacturing time of the silicon ingot can be shortened. The same applies when a new semiconductor material 7 is supplied again.

  As a preheating method, it is preferable to heat by the mold heating means 4 which heats the semiconductor raw material in the mold. As shown in FIG. 1, since the heat insulating wall is not provided between the mold heating means 4 and the raw material supply means 6, the amount of heat of the mold heating means 4 for heating the semiconductor raw material in the mold is increased in the new semiconductor raw material 7. As a result, new semiconductor materials are preheated. Therefore, even when the output of the mold upper heating means 4a is increased more than necessary in order to melt the semiconductor raw material 5, the new semiconductor raw material is also heated at the same time, and the semiconductor melt 5 is rapidly heated. The temperature drop is suppressed, peeling damage of the release material can be prevented, and the melting time of the semiconductor raw material can be shortened. Further, if the heat from the mold heating unit 4 is larger than necessary, the life of the raw material supply unit 6 is shortened, which is not preferable. Therefore, a thin heat insulating wall is partially provided between the mold heating unit 4 and the raw material supply unit 6. Thus, the heat to the raw material supply means 6 may be reduced.

  Further, as shown in FIG. 2, a raw material heating means 13 for heating a new semiconductor raw material 7 may be provided. Thus, by directly heating the new semiconductor raw material 7, the semiconductor raw material can be preheated to a higher temperature, and the supply amount of the semiconductor raw material can be increased once.

  Further, it is desirable that the preheating temperature of the new semiconductor raw material 7 is measured by the raw material temperature measuring means 14, heated to a certain temperature, for example, 500 ° C. or higher, and then supplied into the silicon melt. Considering the cost-effectiveness of attaching the raw material heating means 13 for heating a new semiconductor raw material, the supply amount of the semiconductor raw material at one time is more than twice that of the case where the raw material heating means 13 is not attached. Since it is considered desirable to supply, heating to 500 ° C. or higher is desirable. In addition, in order to suppress the temperature drop during semiconductor raw material supply, it is better to heat the semiconductor raw material close to the melting point of the semiconductor raw material. However, if the temperature is too high, safety and heat resistance of the raw material supply tank are taken into consideration. The need arises. Silicon has a very high melting point of 1412 ° C., and in order to achieve a structure that can be heated to close to the melting point, it is necessary to cool a large tank or require a large-capacity heater power supply. It is for not getting. Therefore, the preheating temperature is desirably 800 ° C. or lower.

  Further, the casting apparatus is normally maintained in a vacuum or an inert atmosphere, and the raw material supply tank 6c is also maintained in a vacuum or an inert atmosphere, and used in such an atmosphere. Since the heater which can do is limited, it is preferable that it can heat from the outside of a tank. When the raw material heating means 13 is provided, a heater shape that matches the tank shape is desired, but a heater such as carbon has a low degree of freedom in shape. Therefore, it is preferable to use a Kanthal line or the like having a relatively high degree of freedom and a maximum temperature of 1200 ° C. Depending on the temperature, nichrome wire or the like can be used.

further,
The supply of new semiconductor raw material is stopped when the temperature drop of the semiconductor melt at the time of supply reaches a specified value. As shown in FIG. 1, the temperature measuring means 9 is provided, and the measured temperature T1 of the semiconductor melt 5 before supplying the new semiconductor raw material 7 is taken into the computing unit 11 through the display 10, and then the raw material supply control means 12 is provided. Thus, the opening / closing port 6b of the raw material supply means 6 is opened to supply a new semiconductor raw material 7. The measured temperature T2 of the semiconductor melt 5 when the semiconductor raw material 7 is being supplied is taken into the computing unit 11, and the computing unit 11 calculates the temperature difference T1-T2. When the temperature difference T1-T2 reaches a predetermined value, the raw material supply control means 12 sends an open / close signal to the raw material supply means 6 so that the open / close port 6b is closed. Thus, the surface temperature of the semiconductor melt 5 is measured by the temperature measuring means 9 such as a radiation thermometer with an emissivity of 1.0, and the temperature drop of the semiconductor melt when a new semiconductor material is supplied is specified. By stopping the supply when the value reaches the value, the mold material and the mold release material that were thermally expanded do not contract rapidly. Problems such as being taken into the liquid or cracking in the semiconductor ingot can be suppressed. For example, in the case of a release material coated and dried by applying slurry, supply is stopped when the temperature drop of the semiconductor melt when supplying a new semiconductor raw material 7 is 70 ° C. or lower, preferably 50 ° C. or lower. Is preferable. When the temperature drop is larger than 70 ° C., the mold material and the mold release material which have been thermally expanded rapidly contract. Therefore, the mold release material is peeled and damaged, and the mold release material damaged by the peel is taken into the semiconductor melt. Ingots may be cracked. For example, when preheating of a new semiconductor raw material is not performed, if the amount of one supply is 8.3% or less with respect to the weight of the silicon melt before supply, the temperature drop of the semiconductor melt is 70 ° C. or less. It can be. Further, as temperature measuring means 9, in order to monitor the temperature, it is possible to indirectly estimate the temperature drop of the silicon melt by contacting the mold with a thermocouple and measuring the temperature of the mold. However, since it is very difficult because the absolute value of the temperature varies depending on the heat insulating property of the mold, it is desirable to directly measure the temperature drop of the silicon melt using a radiation thermometer.

  Since the decrease in the temperature of the silicon melt is determined by the heat capacity of the new semiconductor raw material 7, the size of the silicon raw material is not particularly defined. However, when the size of the new semiconductor raw material 7 is smaller than necessary, the semiconductor raw material 7 Therefore, problems such as being unable to enter the mold 1 or adhering to the release material occur. If it is larger than necessary, the release material may be damaged by the impact when the semiconductor raw material 7 collides with the release material, or when the semiconductor raw material 7 is supplied, the semiconductor melt 5 scatters and adheres to the release material. It is not preferable because a problem such as a reduction in yield or an accelerated damage due to adhesion to the mold heating means 4 or the heat insulating wall 3 occurs.

  When all the semiconductor raw materials are melted by the method for producing a semiconductor ingot according to the present invention, the output of the mold heating means is lowered and the semiconductor ingot is cooled by the cooling means. For example, in the case of a silicon ingot, if the additional supply is repeated so that the amount of the melt when all the silicon raw materials are melted is 90% of the effective depth of the mold, the silicon ingot is about Since the 10% bulk is large, the height of the completed silicon ingot is ideally the same as the effective depth of the mold 1.

  It should be noted that the embodiment of the present invention is not limited to the above-described example, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

  For example, the position where the new semiconductor material 7 is supplied need not be located in the center of the mold 1, and may be anywhere as long as the mold 1 and the semiconductor material 7 do not collide and the semiconductor material does not spill from the mold.

  In addition, the mold used in the manufacturing apparatus may be a divided mold, and even when such a divided mold is used, in order to effectively use the release material applied to the inner wall surface of the upper part of the mold. It is desirable to supply the semiconductor raw material after dissolving the silicon raw material in the mold, and the effects of the present invention can be obtained by using the silicon casting method of the present invention.

As shown in FIG. 5, a mold having an inner dimension of 350 mm square and a depth of 250 mm was prepared, and a release material layer made of silicon nitride was formed on the inner surface thereof to produce a silicon casting mold. After 36 kg of silicon raw material was charged into the obtained mold, the mold was supplied into a casting furnace equipped with a raw material supply means and heated and melted. After the silicon raw material charged in the mold was completely dissolved, a new silicon raw material was supplied from the raw material supply means. At this time, as shown in Table 1, the supply amount of the silicon raw material and the temperature of the silicon raw material before the supply were changed, and the temperature drop of the silicon melt due to the supply of the silicon raw material and the release material layer damage on the inner surface of the mold were observed.

  When the semiconductor raw material was supplied without heating, the No. in Table 1 was obtained. As the supply amount of the semiconductor material increases from 1 to 4, the temperature drop of the silicon melt increases, and when the supply amount is 3 kg or less, the release material is not damaged, but when the supply amount is 4 kg or more, the release material It can be seen that there is damage. Further, when the supply amount of the semiconductor raw material is 3 kg, it becomes 8.3% with respect to the weight of the silicon melt 36 kg before supply.

  In Table 1, No. 5-8, no. 9-12, no. 13-16 and no. From comparison of 17 to 21, since the temperature drop of the silicon melt is smaller when the temperature of the silicon raw material before supply is increased when the same silicon raw material is supplied, there is no peeling damage of the release material. The semiconductor raw material which can be increased can be increased.

  Furthermore, when the temperature drop at the time of damage of a mold release material is seen, it is No .. 3 was 89 ° C. 4 was 115 ° C., No. 4 8 was 87 ° C., no. No. 12, 77 ° C., No. 12 16 is 84 ° C., no. No. 21 was 90 ° C., and there was no damage to the release material, and the temperature drop was the largest. Compared with 20 of 68 ° C, it can be seen that the release material is damaged at 70 ° C.

  When the temperature of the semiconductor raw material before supply is 400 ° C. (No. 9-12) and 500 ° C. (No. 13-16), the supply limit amount when the heating temperature is 400 ° C. is 5 kg, 500 The supply limit amount at 6 ° C. is 6 kg. As the additional supply amount increases, the number of additional supplies can be reduced. Therefore, when considering productivity, the supply limit amount is 500 ° C. or more, which is twice the supply limit amount 3 kg when the semiconductor raw material is not heated. It can be said that it is preferable.

It is a figure which shows one Embodiment of the casting apparatus which concerns on this invention. It is a figure which shows other embodiment of the casting apparatus which concerns on this invention. It is a figure which shows the conventional casting apparatus. It is a figure which shows the conventional casting apparatus. It is a figure which shows the casting apparatus used in the Example which concerns on this invention.

Explanation of symbols

1: Mold 2: Cooling means 3, 3a: Thermal insulation wall 3b: Movable door 4: Mold heating means 4a: Mold upper heating means 4b: Mold side heating means 5: Silicon raw material (silicon melt)
6: Raw material supply means 6a: Funnel 6b: Opening / closing port 6c: Raw material supply tank 7: New semiconductor raw material 8: Release material 9: Temperature measuring means 10: Display 11: Calculator 12: Raw material supply control means 13: Raw material heating Means 14: Raw material temperature measuring means

Claims (2)

In a method for producing a semiconductor ingot, in which a semiconductor raw material is heated and melted by a mold heating means in a mold, a new semiconductor raw material is supplied, and a semiconductor melt obtained by melting is solidified.
New semiconductor material is supplied in said mold in the preheating state, the new semiconductor material is supplied is stopped when the temperature drop of the semiconductor melt reaches below specified value 70 ° C. Rukoto A method for producing a semiconductor ingot characterized by the above.   The method for manufacturing a semiconductor ingot according to claim 1, wherein the new semiconductor raw material is preheated by the mold heating unit.

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