JPWO2010073413A1 - Spherical semiconductor manufacturing equipment - Google Patents

Abstract

A conventional spherical semiconductor manufacturing apparatus and manufacturing method have obtained a spherical semiconductor by melting a semiconductor material in a floating state and dropping it in a drop tube. This method is not suitable for manufacturing a large amount of spherical semiconductors because each semiconductor material is floated, melted, and dropped. Accordingly, in the present invention, a hopper having a funnel capable of dropping semiconductor material melted by electromagnetic induction heating and melting little by little, and an induction disposed so as to surround a semiconductor loading region of the hopper in order to apply the electromagnetic force. A heating coil, a drop tube for cooling and spheronizing the molten semiconductor material dropped from the hopper, and a receiving part for receiving the spherical semiconductor that has fallen into the drop tube and cooled to a solid state; The manufacturing apparatus of the spherical semiconductor which has this. This makes it possible to easily manufacture a large amount of spherical semiconductors.

Description

  The present invention relates to a method for producing a spherical semiconductor, which makes it possible to produce a large amount of spherical semiconductors used in solar cell panels in a short time.

  The solar cell panels that are currently mainstream are generally those using flat single crystal silicon, polycrystalline silicon, amorphous silicon, or the like. However, these solar cell panels have low power generation efficiency, and raising the power generation efficiency of this solar cell panel is a problem.

Therefore, in recent years, a spherical silicon solar cell using spherical silicon has been proposed. The spherical silicon type solar cell is a solar cell in which an infinite number of spherical silicon particles and a concave mirror for increasing the light collecting ability are combined. This spherical silicon solar cell can achieve higher power generation efficiency than amorphous silicon with a silicon usage amount of about 1/5 compared to the above-described flat plate solar cell. This spherical silicon solar cell is expected to be a solar cell production method that is less affected by the supply status of silicon as a raw material by reducing the amount of silicon used.
JP2002-348194 JP 2005-162609 A JP-A-10-33969

  As a method of manufacturing a spherical semiconductor used in such a spherical silicon solar cell, a manufacturing method as shown in Patent Document 1 has been invented. In the manufacturing method disclosed in Patent Document 1, a method is disclosed in which silicon, which is a semiconductor material, is irradiated with a laser and preheated to float and melt. Patent Document 1 describes that high-purity silicon as a raw material is floated and melted by applying a high frequency. Since high-purity silicon has extremely low electrical conductivity, it is extremely difficult to float and melt at high frequencies.

  Patent Document 2 describes a method of melting silicon using a melting crucible. As described above, since silicon has extremely low electrical conductivity, it is difficult to float and melt. Therefore, Patent Document 2 describes a method of melting using a crucible without floating. However, in melting using a crucible, the melted silicon comes into contact with the inner surface of the crucible, so that impurities may be mixed into the melted silicon.

  Patent Document 3 describes a method of melting an inorganic material, which is a semiconductor material, in a floating state, but in order to produce a large amount of spherical semiconductors in order to float and melt inorganic materials one by one, A lot of time is required.

  Accordingly, the present invention provides a method for solving the above-described problems and manufacturing a spherical semiconductor in a large amount and in a short time without contamination of impurities. That is, as a first invention, a semiconductor material can be loaded and a hopper having a funnel in which a semiconductor material melted in an electromagnetic induction heating and melting state in a floating state by an external electromagnetic force can be dropped little by little, and the electromagnetic force is applied. For this purpose, an induction heating coil arranged so as to surround the semiconductor loading area of the hopper, a drop tube for cooling and spheroidizing the molten semiconductor material dripped from the hopper, and dropping in the drop tube to be cooled. There is provided a spherical semiconductor manufacturing apparatus having a receiving portion for receiving a spherical semiconductor in a solid state.

  In a second aspect of the invention, the induction heating coil is configured to generate an electromagnetic force such that the funnel surface of the hopper and the semiconductor material to be melted and dropped are hardly contacted by the generated electromagnetic force. An apparatus for producing a spherical semiconductor according to the invention is provided.

  As a third invention, there is further provided an inert gas blowing portion for blowing out an inert gas for pressurizing the inside of the hopper so that the semiconductor material electromagnetically heated and melted in the hopper is dropped little by little from the funnel. A spherical semiconductor manufacturing apparatus according to one invention or the second invention is provided.

  As a fourth invention, according to any one of the first to third inventions, further comprising a current control unit for controlling a current flowing through the induction heating coil so that a semiconductor material to be loaded is floated and melted in a supercooled state. An apparatus for producing a spherical semiconductor as described in 1 above is provided.

  According to a fifth aspect of the invention, the drop length at which the dropped semiconductor material falls freely is shorter than the drop length necessary for cooling the same semiconductor material melted in a non-supercooled state into a solid state. A spherical semiconductor manufacturing apparatus according to any one of the first to fourth inventions, wherein the drop tube is configured as described above.

  According to a sixth aspect of the invention, there is provided a conductive material attaching step for attaching a conductive material to the surface of the semiconductor material, and the semiconductor material to which the conductive material is attached in the conductive material attaching step is floated by electromagnetic force and is in a floating state. A melting step for melting this by electromagnetic induction heating, a supercooling temperature control step for maintaining the temperature of the molten semiconductor material at the supercooling temperature after melting in the melting step, and the supercooling temperature control A method for producing a spherical semiconductor comprising: a dropping step of dropping a semiconductor material controlled to a supercooling temperature in a step by a small amount so that a sufficient dropping time can be secured so that the semiconductor material is cooled and becomes solid. To do.

  The spherical semiconductor manufacturing apparatus of the present invention can manufacture a large amount of spherical semiconductors having a small particle diameter by providing a funnel in a hopper and dropping a floating and melted semiconductor material little by little from the tip of the funnel. In addition, by dropping a supercooled semiconductor material onto a drop tube, the same semiconductor material that is melted in a non-supercooled state is cooled and has a length shorter than the drop length required to become a solid state. The semiconductor material can be solidified, and a compact spherical semiconductor manufacturing apparatus can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, this invention should not be limited to these embodiments at all, and can be implemented in various modes without departing from the gist thereof.

  The first embodiment mainly relates to claim 1, claim 2, claim 3, and the like.

  The second embodiment mainly relates to claims 4 and 5.

  The third embodiment mainly relates to claim 6 and the like.

<Embodiment 1>
<Overview of Embodiment 1>

This embodiment is a spherical semiconductor manufacturing apparatus characterized in that a semiconductor material is heated and melted in an electromagnetically suspended state, and the molten semiconductor material is dropped into a drop tube from a funnel, spheroidized, and cooled. It is.
<Configuration of Embodiment 1>

  FIG. 1 shows a conceptual diagram of a spherical semiconductor manufacturing apparatus of the present embodiment. The spherical semiconductor manufacturing apparatus according to the present embodiment can be loaded with a semiconductor material, and has a hopper (0101) having a funnel (0101) capable of dripping small portions of a semiconductor material that has been electromagnetically heated and melted in a floating state by electromagnetic force from outside. ), An induction heating coil (0103) arranged so as to surround the semiconductor loading area of the hopper to apply the electromagnetic force, and a drop for cooling and spheronizing the molten semiconductor material dropped from the hopper A tube (0104) and a receiving part (0105) for receiving the spherical semiconductor that has fallen into the drop tube and cooled to a solid state.

  The “hopper” can be loaded with a semiconductor material that is a spherical semiconductor material, and has an induction heating coil for floating and melting the semiconductor material by electromagnetic force, and a funnel for dropping the molten semiconductor material. Yes. FIG. 2 shows a photograph (a) of the outer appearance of the hopper of the spherical semiconductor manufacturing apparatus of the present embodiment and a conceptual diagram (b) inside the hopper. Inside the hopper, a funnel (0201) for dropping molten semiconductor material is disposed, and an induction heating coil (0202) is disposed so as to surround the funnel and the semiconductor loading region into which the semiconductor material is loaded. In addition, the hopper has a wiring (0203) for supplying power to the dielectric heating coil, a control device (0204), a radiation temperature measuring device for measuring the temperature of the semiconductor material, and a pressure gauge for measuring the internal pressure. Etc. may be arranged. The hopper is provided with a door for loading a semiconductor material in the semiconductor loading area, and the semiconductor loading area can be loaded with the semiconductor material by opening and closing the door from the outside of the hopper.

  The funnel provided inside the hopper is configured to drop the semiconductor material floated and melted by the electromagnetic force generated by the induction heating coil little by little toward the drop tube. As shown in FIG. 2, the funnel is disposed so as to be surrounded by the dielectric heating coil. The funnel has a cylindrical shape with a circular cross section, and is configured such that the diameter of the cross section gradually decreases toward the drop tube. FIG. 3 shows an example of the funnel used in this embodiment. The total length of the funnel is approximately 100 mm, the maximum inner diameter is approximately 17 mm, and the maximum outer diameter is approximately 29 mm. The upper portion of the funnel approximately 80 mm is approximately 17 mm with no change in the size of the inner diameter. In the lower portion of the funnel, approximately 20 mm, the inner diameter gradually decreases in the lower direction, and the diameter of the funnel tip portion and the opening portion where the molten and floating semiconductor material is dropped is 100 μm.

  Conventionally, in a method for manufacturing a spherical semiconductor in which a molten semiconductor material is floated by electromagnetic force, the semiconductor material in a floating and molten state is dropped as it is into a drop tube to obtain a spherical semiconductor. In other words, the semiconductor material that has been floated and melted falls in the drop tube with its mass (size) as it is to form a solid semiconductor. That is, in the conventional manufacturing method, one spherical semiconductor is obtained by loading a semiconductor material into a hopper, floating and melting it, and dropping it into the drop tube. However, the spherical semiconductor manufacturing apparatus of the present embodiment is configured to drop the semiconductor material that is floated and melted little by little toward the drop tube by providing a funnel inside the hopper. Thereby, it is possible to obtain a large amount of spherical semiconductors by performing the operation of loading the semiconductor material into the hopper, floating and melting it, and dropping it from the tip of the funnel to the drop tube only once.

  Here, in order to drop the semiconductor material from the funnel to the drop tube little by little, an inert gas blowing part (0205) for blowing an inert gas for pressurizing the inside of the hopper may be provided. The inert gas blowing unit pressurizes the inside of the hopper by blowing inert gas into the hopper, and drops the molten semiconductor material from the funnel onto the drop tube. The gas blown out from the inert gas blowing portion does not cause a chemical reaction with the molten semiconductor material, and is, for example, a rare gas element such as helium, neon, argon, krypton, or xenon, or nitrogen. . The gas blown out from the inert gas blowing section is not limited to the above as long as it does not cause a chemical reaction with the semiconductor material melted at a high temperature like the gas exemplified above, and can be changed as appropriate. It is a matter.

  The suspended and melted semiconductor material is dropped from the tip of the funnel to the drop tube without contacting the funnel wall surface. At this time, the melted semiconductor material is dropped into the drop tube (0403) from the funnel tip (0402) of the funnel (0401) as shown in FIG. First, the semiconductor material (0404) in a floating and melted state maintains a substantially spherical shape as shown in (a). Next, when dripping into the drop tube is started, the output of the dielectric heating coil and the amount of inert gas blown into the hopper are controlled so that the semiconductor material in a floating molten state is as shown in (b), It is made to become thin vertically, and finally it is dripped little by little from the lower part of the molten semiconductor material like (c).

  FIG. 5 shows a photographed image taken by a high-speed camera that photographed how the semiconductor material that was melted by floating was dropped from the tip of the funnel to the drop tube. The captured image in FIG. 5 is an image captured by enlarging the funnel tip. The photographed image in FIG. 5 corresponds to the state shown in FIG. In this way, the floating and melted semiconductor material is dropped onto the drop tube without making contact with the inner wall surface of the funnel as much as possible. In the image of FIG. 5, the white portion is the melted semiconductor material (0501), and the portion indicated by the broken line is the dielectric heating coil (0502), which is difficult to confirm with the photograph. (0503) is photographed.

  Here, dripping in the present embodiment means that the molten semiconductor material is dropped onto the drop tube from the initial velocity of 0. In other words, it does not fall into the drop tube with a certain initial velocity that is blown by applying pressure from the funnel tip.

  In semiconductors, it is very important to prevent impurities from being mixed at the time of manufacture, for example, when semiconductors do not exhibit correct performance due to unnecessary impurities. For this reason, in the spherical semiconductor manufacturing apparatus of the present embodiment, the molten semiconductor material is controlled so as not to contact an object such as a funnel as much as possible. Even if the molten semiconductor material comes into contact with the funnel, it is desirable that the funnel is made of a material made of the same element as the semiconductor material so that impurities do not enter. For example, when silicon is used as the semiconductor material, the material constituting the funnel is preferably made of a material containing silicon, such as quartz.

  In addition, since the molten semiconductor material floats without contact with a funnel or the like, it becomes easy to create a supercooled state. Subcooling will be described in detail in the second embodiment.

  The “induction heating coil” causes the semiconductor material to float and melt by electromagnetic force. As shown in FIG. 2, the induction heating coil is disposed so as to surround the semiconductor loading area and the funnel, and the semiconductor material loaded in the semiconductor loading area is floated and melted. At this time, the magnitude of the current flowing through the induction heating coil is controlled to adjust the semiconductor material to float in the semiconductor loading region. Also, the semiconductor material floats and melts in a funnel surrounded by the induction heating coil.

  Here, the induction heating coil needs to float and melt the semiconductor material by a high-periphery magnetic field. For this reason, the semiconductor material needs to have conductivity. However, since a semiconductor material such as silicon (Si) does not have conductivity, it cannot be floated or heated and melted. In such a case, boron (B), carbon (C), or the like, which is a conductive substance, is vapor-deposited in advance on the surface of a non-conductive semiconductor material such as silicon. By evaporating the conductive material on the surface in this manner, the inside of the semiconductor material can be heated and melted by the induction heating coil while maintaining high purity. Further, the conductive substance deposited on the surface is heated and melted by the induction heating coil, thereby diffusing inside the semiconductor material, and the conductive substance is doped as an impurity inside the semiconductor. For example, when silicon is used as the semiconductor material and boron is used as the conductive material, a P-type semiconductor can be obtained.

  Further, the electromagnetic force generated by the induction heating coil is configured to generate an electromagnetic force that does not contact the funnel surface of the hopper and the semiconductor material to be melted and dropped as much as possible. Details of this point will be described later.

  In the example shown in FIGS. 1 and 2, the induction heating coil is composed of one coil. In the induction heating coil shown in FIGS. 1 and 2, a force that opposes gravity is applied to the semiconductor material to suspend the semiconductor material. In addition to this, the induction heating coil may be composed of a plurality of coils. For example, two coils may be arranged above and below so that the semiconductor material floats between them. In this case, a force opposite to the gravity is applied to the semiconductor material from the lower coil, and a force is applied to the semiconductor coil in the same direction as the gravity from the upper coil. The By arranging two upper and lower coils in this manner, when the semiconductor material is dropped from the tip of the funnel, the inert gas is not blown into the hopper, and the force applied by the coil is adjusted to be dropped. Is possible. In addition, regardless of whether the number of coils is one or more, the semiconductor material can be dropped into the drop tube little by little without the need for a funnel by controlling the force applied to the semiconductor material from the coil. It is.

  In the “drop tube”, the molten semiconductor material dropped from the hopper funnel is spheroidized and cooled. As described above, the molten semiconductor material that has been dropped is dropped in a state where no initial speed is applied, and thus is in a free fall state. The molten semiconductor material in a free-fall state is spheroidized by surface tension. Moreover, the inside of the semiconductor material during free fall is under microgravity. Furthermore, the semiconductor material that was in a molten state during free fall is cooled to a solid state. By freely dropping the molten semiconductor material, the semiconductor material is spheroidized using surface tension. The molten semiconductor material is rapidly cooled in the drop tube to crystallize into a semiconductor.

  By making the inside of the drop tube into a vacuum state, the air resistance against the dropped semiconductor material is reduced and the semiconductor material solidifies more spherically. However, in vacuum, the cooling effect is low, so a longer drop tube is required. Become. Further, an inert gas may be allowed to flow in the drop tube in accordance with the dropping speed of the semiconductor material. At this time, since the semiconductor material is gradually accelerated by the gravitational acceleration, it is desirable that the inert gas flowing in the drop tube is adapted to the speed of the semiconductor material. For example, the flow rate of the inert gas may be controlled in accordance with the falling speed of the semiconductor material by gradually reducing the cross-sectional area of the drop tube. By doing in this way, it is possible to reduce the resistance of the inert gas accompanying dropping of the semiconductor material, and it is possible to obtain a more spherical semiconductor material without losing the cooling effect.

  The “receiving portion” receives the spherical semiconductor that has fallen in the drop tube and cooled to a solid state. FIG. 6 shows an image of the spherical semiconductor taken out from the receiving portion. The spherical semiconductor shown in FIGS. 6A and 6B is a drop-shaped spherical semiconductor having a diameter of about 400 μm. Note that the number of spherical semiconductors obtained in one operation varies depending on the amount of semiconductor material initially loaded in the hopper. In addition, the size and amount of the obtained spherical semiconductor change depending on the size of the opening at the tip of the funnel and the initial velocity when dropping from the funnel tip, and the design can be changed in a timely manner according to the target spherical semiconductor. It is a matter. In the spherical semiconductor manufacturing apparatus of this embodiment, the spherical semiconductor is obtained from the receiving portion at a rate of 80% with respect to the amount of the loaded semiconductor material.

The particle size distribution of the spherical semiconductor obtained by the spherical semiconductor manufacturing apparatus of this embodiment is shown in FIG. The particle size distribution shown in FIG. 7 is an example in which a material obtained by depositing boron on silicon is used as a semiconductor material. Moreover, the funnel shown in FIG. 3 was used as the funnel, and the dropping was performed while the inside of the hopper was pressurized with helium at the time of dropping. As a result, most of the obtained spherical semiconductors were obtained with a diameter of about 300 to 500 μm. As described above, the spherical semiconductor manufacturing apparatus of this embodiment can manufacture a large amount of spherical semiconductors having a small particle diameter.
<Embodiment 1 effect>

The spherical semiconductor manufacturing apparatus according to the present embodiment can manufacture a large amount of spherical semiconductors having a small particle diameter by providing a funnel in a hopper and dropping a floating and melted semiconductor material little by little from the tip of the funnel. .
<Embodiment 2>
<Overview of Embodiment 2>

The spherical semiconductor manufacturing apparatus of the present embodiment is characterized in that the semiconductor material can be further controlled to float and melt in a supercooled state in the first embodiment. The supercooled state can be maintained in a very calm and stable state. Therefore, the floating state without contacting the container is a suitable condition for maintaining the supercooled state. In the semiconductor manufacturing apparatus of the present embodiment, the molten semiconductor material is brought into a supercooled state, and this supercooled semiconductor material is dropped from the tip of the funnel onto the drop tube.
<Configuration of Embodiment 2>

  The spherical semiconductor manufacturing apparatus of the present embodiment includes a current control unit that controls a current that flows through the induction heating coil so that a semiconductor material to be loaded is floated and melted in a supercooled state.

  The “current control unit” controls the current flowing through the induction heating coil so that the semiconductor material loaded in the hopper is floated and melted in a supercooled state.

  Here, an advantage of floating and melting a semiconductor material in a supercooled state will be described. Usually, when a molten semiconductor material is solidified to become a solid, cooling is started from the outside of the semiconductor material by placing the semiconductor material in a cooling atmosphere. The supercooled semiconductor material is cooled to a temperature at which the already melted semiconductor material solidifies. For this reason, the semiconductor material is instantaneously solidified and crystallized by an external shock such as an impact. That is, it does not gradually solidify from the outside of the semiconductor material, but solidifies and crystallizes in a short time.

  For this reason, in the spherical semiconductor manufacturing apparatus of this embodiment, the current flowing through the induction heating coil is controlled so that the semiconductor material loaded in the hopper is floated and melted in a supercooled state. By maintaining the semiconductor material in a supercooled state in this manner, the supercooled semiconductor material can be dropped onto the drop tube.

  In addition, when the semiconductor material is brought into a supercooled state, the crystal state of the obtained spherical semiconductor depends on the temperature at which the supercooled state is maintained at a temperature lower than the freezing point of the semiconductor material, that is, the degree of supercooling. It is possible to control. FIG. 8 shows a cooling curve when the semiconductor material is silicon. In the cooling curve of FIG. 8, (a) is the case where the cooling rate is 158 K / s and the degree of supercooling is 21 K, and (b) is the case where the cooling rate is 58 K / s and the degree of supercooling is 70 K. (C) shows a case where the cooling rate is 56 K / s and the degree of supercooling is 150 K. The X-ray diffraction measurement result of the spherical semiconductor obtained at this time is shown in FIG. As a result, it can be seen that as the degree of supercooling increases, diffraction peaks increase and polycrystallization occurs.

  FIG. 10 shows an image of the surface morphology of the manufactured spherical semiconductor by SEM. FIG. 11 shows a cross-sectional structure image of the manufactured spherical semiconductor. Thus, it can be seen that the surface state of the spherical semiconductor to be manufactured, the crystal state of the inner surface, and the state of defects such as cracks change due to the difference in the degree of supercooling. In this way, by controlling the degree of supercooling, it is possible to manufacture a spherical semiconductor that meets the purpose.

  As described in the first embodiment, the spherical semiconductor manufacturing apparatus of the present invention manufactures a large amount of spherical semiconductors having a small particle size by dropping a floating molten semiconductor material from a funnel provided in a hopper. Is possible. Moreover, in the spherical semiconductor manufacturing apparatus of the present embodiment, the semiconductor material dropped on the drop tube is dropped in a supercooled state. As described above, a semiconductor material that melts in a supercooled state rapidly crystallizes and solidifies. For this reason, it is possible to solidify in a short time compared with the time required for dripping and solidifying the molten semiconductor material in a non-supercooled state. Therefore, in the spherical semiconductor manufacturing apparatus of this embodiment, the solidification time can be shortened, so that the length of the drop tube can be shortened compared to the apparatus that drops in a non-supercooled state. is there. Further, in the spherical semiconductor manufacturing apparatus of the present embodiment, a semiconductor material having a smaller particle diameter is dropped onto the drop tube, so that the solidification speed is fast, and the length of the drop tube, that is, the length of free fall is shortened. Is possible. Specifically, when the particle size of the silicon material melted in a supercooled state where the semiconductor material is a silicon material is 200 μm to 1400 μm, the length of the free fall, that is, the length of the drop tube is about 3 m. It's okay. In the case of a conventionally used apparatus for producing a spherical semiconductor by free fall, the length of free fall was required to be about 10 m to 25 m, but in comparison with that, producing a spherical semiconductor with a much shorter length. Is possible.

Therefore, the spherical semiconductor manufacturing apparatus of the present embodiment is a much more compact apparatus than the conventional spherical semiconductor manufacturing apparatus using free fall.
<Embodiment 2 Effect>

The spherical semiconductor manufacturing apparatus of this embodiment is necessary for cooling the same semiconductor material melted in a non-supercooled state to a solid state by dropping the supercooled semiconductor material onto a drop tube. The length is shorter than the drop length. Therefore, a compact spherical semiconductor manufacturing apparatus can be provided.
<Embodiment 3>
<Overview of Embodiment 3>

The present embodiment is a method for manufacturing a spherical semiconductor. The spherical semiconductor manufacturing method of the present embodiment is a manufacturing method in which a floating and melted semiconductor material is spheroidized by free fall, and the molten semiconductor material is maintained in a supercooled state. This is a manufacturing method capable of manufacturing a large amount of a spherical semiconductor having a small particle diameter by allowing a semiconductor material to fall freely little by little.
<Configuration of Embodiment 3>

  FIG. 12 shows a flowchart for explaining the method of manufacturing a spherical semiconductor according to this embodiment. The spherical semiconductor manufacturing method of the present embodiment includes a conductive material attaching step (S1201) for attaching a conductive material to the surface of the semiconductor material, and a semiconductor material to which the conductive material is attached in the conductive material attaching step. A melting step (S1202) in which the molten semiconductor material is floated by electromagnetic induction heating in a floating state and melted in the melting step, and then the supercooling that keeps the temperature of the melted semiconductor material at the supercooling temperature The temperature control step (S1203) and the semiconductor material controlled to the supercooling temperature in the supercooling temperature control step are dropped little by little so as to ensure a sufficient drop time for the semiconductor material to cool and become solid. Dropping step (S1204).

  The “conductive material deposition step” is a step of depositing a conductive material on the surface of the semiconductor material. Specifically, for example, when silicon is used as the semiconductor material, a conductive material such as boron or carbon is deposited on the silicon surface by vacuum deposition. The reason for depositing the conductive material on the surface of the semiconductor material is that, in the case of silicon, it is difficult to float in the melting step described later, and impurities to be doped on the semiconductor material are attached to the surface of the semiconductor material. This is because, in the melting step, the semiconductor material is melted and the deposited conductive material is mixed with the semiconductor material. Thus, by attaching a conductive material to the surface, it becomes possible to easily dope a semiconductor material with a conductive material.

  In the “melting step”, the semiconductor material to which the conductive material is attached is floated by electromagnetic force, and further melted by electromagnetic induction heating in a floating state. In this melting step, the conductive material and the semiconductor material are mixed.

  The “temperature control step” is a step of cooling the melted semiconductor material and keeping the temperature of the semiconductor material at a temperature below the freezing point of the semiconductor material, that is, the supercooling temperature. As described in the second embodiment, it is possible to control the crystal state of the manufactured spherical semiconductor by the degree of supercooling at this time.

In the “dropping step”, the semiconductor material in a supercooled state is dropped little by little so as to ensure a drop time required for the semiconductor material to be cooled and become a solid. At this time, it is possible to obtain a large amount of spherical semiconductors having a small particle diameter by dropping them little by little. Further, by dropping the supercooled semiconductor material, the time until the semiconductor material becomes a cooled solid can be shortened. Furthermore, since the dropped semiconductor material is in a free fall state, the inside of the molten semiconductor material is placed under microgravity, and the conductive material is uniformly distributed in the semiconductor material.
<Effect of Embodiment 3>

  In the method for manufacturing a spherical semiconductor according to the present embodiment, the semiconductor material in a supercooled state is dropped with a drop tube, so that the same semiconductor material melted in a non-supercooled state is cooled to become a solid state. The semiconductor material can be solidified with a length shorter than the drop length, and a spherical semiconductor can be manufactured with a compact spherical semiconductor manufacturing apparatus.

Conceptual diagram for explaining the semiconductor manufacturing apparatus of the first embodiment. Conceptual diagram for explaining the semiconductor manufacturing apparatus of the first embodiment. Conceptual diagram for explaining an example of a funnel of the semiconductor manufacturing apparatus according to the first embodiment. Conceptual diagram for explaining the semiconductor manufacturing apparatus of the first embodiment. Conceptual diagram for explaining the semiconductor manufacturing apparatus of the first embodiment. Photographed image of semiconductor obtained by semiconductor manufacturing apparatus of embodiment 1 Particle size distribution of a semiconductor obtained by the semiconductor manufacturing apparatus of Embodiment 1 Schematic for demonstrating the semiconductor manufacturing apparatus of Embodiment 2. FIG. Schematic for demonstrating the semiconductor manufacturing apparatus of Embodiment 2. FIG. Schematic for demonstrating the semiconductor manufacturing apparatus of Embodiment 2. FIG. Schematic for demonstrating the semiconductor manufacturing apparatus of Embodiment 2. FIG. Flowchart of Semiconductor Manufacturing Method of Embodiment 3

Explanation of symbols

0101 Funnel 0102 Hopper 0103 Induction heating coil 0104 Drop tube 0105 Receiving part

Claims (6)

A hopper having a funnel that can be loaded with a semiconductor material and can drop a small amount of semiconductor material that has been electromagnetically heated and melted in a floating state by electromagnetic force from the outside;
An induction heating coil arranged to surround a semiconductor loading region of the hopper to apply the electromagnetic force;
A drop tube for cooling and spheroidizing the molten semiconductor material dropped from the hopper;
A receiving part for receiving a spherical semiconductor that has fallen into the drop tube and cooled to a solid state;
A spherical semiconductor manufacturing apparatus.   2. The spherical semiconductor according to claim 1, wherein the induction heating coil is configured to generate an electromagnetic force to an extent that the funnel surface of the hopper and the semiconductor material to be melted and dropped are hardly brought into contact by the generated electromagnetic force. Manufacturing equipment.   The inert gas blowing part for blowing out the inert gas which pressurizes the inside of a hopper so that the semiconductor material by which the electromagnetic induction heating fusion was carried out in the said hopper dripped little by little from a funnel is further provided. Spherical semiconductor manufacturing equipment.   The spherical semiconductor manufacturing apparatus according to any one of claims 1 to 3, further comprising a current control unit that controls a current that flows through the induction heating coil so that a semiconductor material to be loaded is floated and melted in a supercooled state.   The drop tube is such that the dropped length of the dropped semiconductor material freely falls is shorter than the drop length required for the same semiconductor material melted in a non-supercooled state to be cooled to become a solid state. The manufacturing apparatus of the spherical semiconductor as described in any one of Claim 1 to 4 by which is comprised. A conductive material deposition step for depositing a conductive material on the surface of the semiconductor material;
A melting step of floating the semiconductor material to which the conductive material is adhered in the conductive material adhesion step by electromagnetic force, and melting the semiconductor material by electromagnetic induction heating in a floating state;
A supercooling temperature control step for maintaining the temperature of the molten semiconductor material at the supercooling temperature after melting in the melting step;
A dropping step of dropping the semiconductor material controlled to the supercooling temperature in the supercooling temperature control step by a small amount so that a sufficient dropping time can be secured for the semiconductor material to be cooled and become solid.
A method for producing a spherical semiconductor comprising: