JP2023040998A - Method for producing single crystal, device for producing single crystal and crucible - Google Patents

Abstract

To reduce impurity crystals generated in the solution.SOLUTION: A method for producing a single crystal includes: a first heating step of heating a solution so as to increase temperature of the solution coming into contact with a side face of a crucible to be higher than temperature of the solution coming into contact with a bottom face of the crucible; and a second heating step of heating the solution so as to increase temperature of the solution coming into contact with the bottom face of the crucible to be higher than temperature of the solution coming into contact with the side face of the crucible, where the first heating step and the second heating step are switched alternately.SELECTED DRAWING: Figure 5

Description

TECHNICAL FIELD The present invention relates to a single crystal manufacturing technique, a single crystal manufacturing apparatus, and a crucible made of silicon carbide, and relates to a technique effectively applied to, for example, a single crystal manufacturing technique by a solution method.

Japanese Patent No. 5746362 (Patent Document 1) describes a technique for controlling the degree of carbon supersaturation on the crystal surface by switching the temperature gradient in the solution during the growth of the single crystal.

Japanese Patent Application Laid-Open No. 2018-184324 (Patent Document 2) describes a technique of heating the bottom surface of a crucible for a long time.

Japanese Patent Application Laid-Open No. 2-217388 (Patent Document 3) describes a technique for heating a crucible with a side heater and a bottom heater.

Japanese Patent Application Laid-Open No. 2012-136388 (Patent Document 4) discloses a technique related to an induction heating device including an upper coil portion arranged around an upper storage chamber and a lower coil portion arranged around a lower storage chamber. Are listed.

Japanese Patent Laying-Open No. 7-25694 (Patent Document 5) describes a technique relating to a crucible having a projection projecting from the bottom surface.

Japanese Patent No. 5746362 JP 2018-184324 A JP-A-2-217388 JP 2012-136388 A JP-A-7-25694

For example, inverter circuits are used as circuits for controlling motors included in automobiles, home appliances, and the like. Power semiconductor elements typified by power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors) are used in this inverter circuit.

Such power semiconductor devices are required to have, for example, low on-resistance and low switching loss in addition to high withstand voltage. Here, the current mainstream of power semiconductor devices is a field effect transistor formed on a semiconductor substrate whose main component is silicon, but this power semiconductor device is approaching its theoretical performance limit.

In this regard, a semiconductor device (hereinafter referred to as a wide bandgap power semiconductor device) including a field effect transistor formed on a semiconductor substrate whose main component is a semiconductor material having a bandgap larger than that of silicon has attracted attention.

This is because a large bandgap means high dielectric breakdown strength, which makes it easier to achieve a high withstand voltage.

If the semiconductor material itself has a high dielectric breakdown strength, the breakdown voltage can be ensured even if the drift layer that maintains the breakdown voltage is thin. , the on-resistance of the power semiconductor element can be reduced.

That is, the wide bandgap power semiconductor device is excellent in that it can achieve both an improvement in breakdown voltage and a reduction in on-resistance, which are in a trade-off relationship. Therefore, wide bandgap power semiconductor devices are expected as semiconductor devices capable of achieving high performance.

Examples of semiconductor materials having a bandgap larger than that of silicon include silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga ₂ O ₃ ), and diamond. In the following, description will be made focusing on silicon carbide.

A single crystal made of silicon carbide (hereinafter referred to as a silicon carbide single crystal) is manufactured by using, for example, a solution method. In the solution method, a seed crystal attached to the tip of a shaft is brought into contact with a solution containing carbon and silicon contained in a crucible, thereby growing a silicon carbide single crystal on the seed crystal and pulling up the shaft. , a method for producing a silicon carbide single crystal.

Here, in the solution method, it is important to reduce miscellaneous crystals generated in the solution accommodated in the crucible. This is because miscellaneous crystals are, for example, aggregates of silicon carbide grains of about 1 mm to 3 mm, and if these miscellaneous crystals adhere to the seed crystal, the crystal growing on the seed crystal will not be a single crystal. Therefore, in the solution method, from the viewpoint of growing a silicon carbide single crystal on a seed crystal, it is desired to find a way to reduce miscellaneous crystals generated in the solution.

In one embodiment of the method for producing a single crystal, (a) a shaft having a seed crystal attached to its tip portion is moved downward to displace the lower surface of the seed crystal into a solution containing carbon and silicon contained in a crucible. and (b) growing a single crystal made of silicon carbide on the lower surface of the seed crystal.

Here, the single crystal manufacturing method includes (c1) a first heating step of heating the solution so that the temperature of the solution in contact with the side surface of the crucible is higher than the temperature of the solution in contact with the bottom surface of the crucible; a second heating step of heating the solution so that the temperature of the solution in contact with the bottom surface becomes higher than the temperature of the solution in contact with the side surface of the crucible, and the first heating step and the second heating step are alternately switched. .

A single crystal manufacturing apparatus according to one embodiment can arrange a crucible containing a solution containing carbon and silicon in a container. Then, the single crystal manufacturing apparatus includes a pedestal arranged inside the container, a first heating section for heating the crucible arranged on the pedestal, a second heating section for heating the pedestal, and supply to the first heating section. and a control unit that controls power to be supplied to the second heating unit.

Here, the control unit adjusts the power supplied to the first heating unit and the power supplied to the second heating unit so that the temperature of the solution in contact with the side surface of the crucible is higher than the temperature of the solution in contact with the bottom surface of the crucible. The power supplied to the first heating unit and the power supplied to the second heating unit are adjusted so that the temperature of the solution in contact with the bottom surface of the crucible is higher than the temperature of the solution in contact with the side surface of the crucible. The second operation to adjust and the second operation are alternately switched.

The crucible in one embodiment can contain a solution containing carbon and silicon. Here, the crucible includes a main body for containing the solution, and a heat transfer section protruding from the bottom of the main body.

According to one embodiment, miscellaneous crystals generated in the solution can be reduced.

It is a figure which shows the structure of the single-crystal manufacturing apparatus in embodiment. FIG. 10 is a diagram illustrating an example of dimensions of main parts of the pedestal and the crucible; It is a figure for demonstrating operation|movement of a single-crystal manufacturing apparatus. It is a figure for demonstrating operation|movement of a single-crystal manufacturing apparatus. It is a figure which shows the switching example of a 1st operation|movement and a 2nd operation|movement by a control part. It is a figure which shows the temperature distribution of the solution implement|achieved by 1st operation|movement. It is a figure which shows the temperature distribution of the solution implement|achieved by 2nd operation|movement. It is a figure which shows another example which switches a 1st operation|movement and a 2nd operation|movement. It is a figure which shows the structural example which heats the bottom face of a crucible. FIG. 4 is a diagram showing a configuration for heating the bottom surface of a crucible in an embodiment; (a) is a schematic diagram showing power supplied to the first coil when power is continuously supplied to the first coil, and (b) is a case where power is continuously supplied to the second coil. is a schematic diagram showing the power supplied to the second coil in . (a) is a schematic diagram showing power supplied to the first coil when power is discontinuously supplied to the first coil, and (b) is a schematic diagram showing power discontinuously supplied to the second coil. It is a schematic diagram which shows the electric power supplied to the 2nd coil in the case where it does. 4 is a block diagram showing the configuration of a heating unit in the embodiment; FIG. (a) is a schematic diagram showing power supplied to the first coil when power is discontinuously supplied to the first coil, and (b) is a schematic diagram showing power discontinuously supplied to the second coil. It is a schematic diagram which shows the electric power supplied to the 2nd coil in the case where it does. (a) is a schematic diagram showing power supplied to the first coil when power is discontinuously supplied to the first coil, and (b) is a schematic diagram showing power discontinuously supplied to the second coil. It is a schematic diagram which shows the electric power supplied to the 2nd coil in the case where it does. 4 is a graph showing the power supply current supplied to the first coil in an experiment; 7 is a graph showing the power supply current supplied to the second coil in an experiment; FIG. 3 is a cross-sectional view of a crucible containing a solidified solution in side heating. FIG. 10 is a cross-sectional view of a crucible containing a solidified solution during bottom heating. FIG. 10 is a cross-sectional view of a crucible containing a solidified solution in switching heating.

In principle, the same members are denoted by the same reference numerals throughout the drawings for describing the embodiments, and repeated description thereof will be omitted. In order to make the drawing easier to understand, even a plan view may be hatched.

<Consideration of improvement>
When a silicon carbide single crystal is grown by a solution method, it is necessary to create a supersaturated state in the solution in order to deposit the crystal. Therefore, in the solution method for growing silicon carbide single crystals, a temperature gradient is formed in the solution in order to create a supersaturated state. In this case, a high-temperature region and a low-temperature region are formed in the solution, and a supersaturated state is realized in the low-temperature region. Therefore, a crystal can be grown on the seed crystal by forming a temperature gradient in the solution so that the region of the solution in contact with the seed crystal becomes a low-temperature region where a supersaturated state is achieved.

When a crystal having the same structure and orientation as the seed crystal grows on the surface of the seed crystal, a desired silicon carbide single crystal grows from the seed crystal as a starting point. On the other hand, even in the case of crystal growth on the surface of a seed crystal, a crystal grown whose structure or orientation differs from that of the seed crystal is called miscellaneous crystal, and this miscellaneous crystal grows on the surface of the seed crystal. Then, the growth of the silicon carbide single crystal is impeded. Therefore, in the solution method, from the viewpoint of growing a silicon carbide single crystal on a seed crystal, it is desired to find a way to reduce miscellaneous crystals generated in the solution.

In addition to the miscellaneous crystals that are generated directly on the surface of the seed crystal, there are also miscellaneous crystal nuclei generated on the side wall and bottom of the crucible that float in the solution and adhere to the seed crystal and grow. do.

Since such miscellaneous crystals hinder the growth of silicon carbide single crystals starting from the seed crystal, it is desired to suppress the adhesion of miscellaneous crystals to the seed crystal. In other words, it is basically acceptable for miscellaneous crystals to be generated not on the seed crystal but on the crucible side wall or bottom surface itself. There is an increased possibility that some of the miscellaneous crystals separated from the crystals will float in the solution. For this reason, in order to reduce miscellaneous crystals floating in the solution and adhering to the seed crystal, it is desired to suppress enlargement of miscellaneous crystals generated on the side wall and bottom surface of the crucible. Furthermore, the enlargement of the miscellaneous crystals generated on the sidewall and bottom of the crucible causes a decrease in the raw material for growing the silicon carbide single crystal on the seed crystal and a decrease in the growth rate of the silicon carbide single crystal. .

Therefore, when a silicon carbide single crystal is grown by a solution method, it is necessary to suppress enlargement of miscellaneous crystals generated on the sidewall and bottom of the crucible. Therefore, in the present embodiment, it is possible to reduce the miscellaneous crystals generated in the solution and to suppress the enlargement of the miscellaneous crystals generated on the sidewall and bottom of the crucible.

In the following, the technical idea of this embodiment with this ingenuity will be described.

<Basic idea in the embodiment>
As described above, in the technique of growing silicon carbide single crystals by the solution method, it is necessary to create a supersaturated state in the solution in order to precipitate the crystal. is being done. Therefore, the solution contained in the crucible contains a mixture of high-temperature regions and low-temperature regions, and while crystals precipitate in the low-temperature region, crystals do not precipitate in the high-temperature region. From this, it can be considered that, for example, if the low-temperature region where crystals precipitate is changed to a high-temperature region, the precipitated crystals will dissolve again (knowledge).

By paying attention to this finding, the present inventors have found that it is possible to reduce the miscellaneous crystals generated in the solution, and to suppress the enlargement of the miscellaneous crystals generated on the sidewall and bottom of the crucible. This basic idea will be explained below.

The basic idea of the present embodiment is to switch the high-temperature region and the low-temperature region accommodated in the crucible to change the low-temperature region where miscellaneous crystals precipitate to a high-temperature region, thereby dissolving the precipitated miscellaneous crystals. be. According to this basic idea, it is possible to suppress the continuous precipitation of miscellaneous crystals, and as a result, it is possible to reduce the miscellaneous crystals and suppress the enlargement of the miscellaneous crystals.

Specifically, assuming that the miscellaneous crystals are basically generated on the side wall and the bottom surface of the crucible, the basic idea in the present embodiment is to change the temperature of the solution in contact with the side surface of the crucible to a first heating step of heating the solution so as to be higher than the temperature; a second heating step of heating the solution so that the temperature of the solution in contact with the bottom surface of the crucible is higher than the temperature of the solution in contact with the side surface of the crucible; and alternately switching between the first heating step and the second heating step.

According to this basic idea, in the first heating step, miscellaneous crystals precipitate on the bottom surface of the crucible, while miscellaneous crystals precipitated on the side surface of the crucible dissolve. On the other hand, in the second heating step, miscellaneous crystals deposited on the bottom surface of the crucible are dissolved, while miscellaneous crystals are deposited on the side surface of the crucible. As a result, by alternately switching between the first heating step and the second heating step, precipitation of miscellaneous crystals is not continuously performed. It is possible to suppress the enlargement of crystals. A single crystal manufacturing technique embodying this basic concept will be described below.

<Configuration of Single Crystal Manufacturing Apparatus>
FIG. 1 is a diagram showing the configuration of a single-crystal manufacturing apparatus 100 according to this embodiment.

In FIG. 1 , a single crystal manufacturing apparatus 100 has a container 10 . The internal space of the container 10 is filled with argon gas, for example. A heat insulating member 13c is provided inside the container 10, and a horizontally rotatable pedestal 11 is arranged inside surrounded by the heat insulating member 13c. The container 10 is made of, for example, a ferrous material such as SUS.

As a filling structure for argon gas, for example, a quartz tube is passed between the heat insulating member 13c and the coil 14a and between the heat insulating member 13c and the coil 14b, and the upper and lower ends of the quartz tube are sealed with flanges. A structure filled with gas can also be adopted.

Next, a crucible 12 is arranged on the pedestal 11 . The crucible 12 is made of, for example, graphite, and contains a high-temperature solution 20 containing silicon (Si). Specifically, the crucible 12 includes a main body capable of containing the solution 20 containing carbon and silicon, and a heat transfer section 12a protruding from the bottom of the main body.

In the crucible 12 configured in this manner, the heat transfer section 12a also functions as a "leg", so the heat transfer section 12a also has a secondary function of stably standing the crucible 12 upright. It can be said that there is The heat transfer portion 12a is configured to contact a pedestal 11 on which the crucible 12 can be placed. For example, as shown in FIG. 1, the base 11 has a first region R1 in contact with the heat transfer section 12a, a second region R2 surrounded by the first region R1, and a third region R3 surrounding the first region R1. , and a heat insulating member 13a is provided so as to be in contact with the second region R2, and a heat insulating member 13b is provided so as to be in contact with the third region R3.

The pedestal 11 is connected to a crucible holding shaft 18 that holds the pedestal 11 . The crucible holding shaft 18 is configured to be vertically movable, and is configured to be rotatable either clockwise or counterclockwise. Thus, the pedestal 11 attached to the crucible holding shaft 18 and the crucible 12 placed on the pedestal 11 can be vertically moved and horizontally rotated by the crucible holding shaft 18 . The crucible holding shaft 18 has a hollow structure inside, and is configured so that a thermocouple or a radiation thermometer can be inserted to measure the temperature.

A coil through which a high-frequency current flows is provided on the outer periphery of the container 10 of the single-crystal manufacturing apparatus 100, and the crucible 12 is heated by induction heating based on the high-frequency current flowing through the coil. Specifically, the single-crystal manufacturing apparatus 100 has a heating section 25a and a heating section 25b. The heating part 25a is configured to heat the crucible 12 by an induction heating phenomenon caused by applying a high-frequency current to the coil 14a provided at a position facing the side surface of the crucible 12. As shown in FIG. In other words, since the coil 14a functions as a heating portion 25a that heats the crucible 12, the heating portion 25a is also shown in FIG. 1 for the coil 14a. On the other hand, the heating part 25b is configured to heat the pedestal 11 by an induction heating phenomenon caused by applying a high-frequency current to a coil 14b provided at a position facing the pedestal 11 that supports the crucible 12. As shown in FIG. Then, the crucible 12 is heated by heat conduction from the heated pedestal 11 . Specifically, heat is transferred from the pedestal 11 heated by the heating part 25b to the heat transfer part 12a, and then heat is transferred from the heat transfer part 12a to the crucible 12 (main body part), whereby the crucible 12 is heated. In this way, the heating part 25b indirectly heats the crucible 12 through the pedestal 11 by an induction heating phenomenon caused by applying a high-frequency current to the coil 14b provided at a position facing the pedestal 11 that supports the crucible 12. is configured to Because of this, the coil 14b functions as a heating portion 25b that heats the crucible 12, so in FIG. Although not shown in FIG. 1, the coils 14b and 14a are configured to allow cooling water to flow therein.

As described above, single crystal manufacturing apparatus 100 is configured such that crucible 12 is heated not only by heating portion 25a but also by heat conduction from pedestal 11 heated by heating portion 25b. Therefore, it can be said that the heat transfer portion 12a of the crucible 12 has a function of conducting heat from the base 11 heated by the heating portion 25b to the main body portion.

Here, in order to facilitate heating of the pedestal 11 by the heating portion 25b, the thickness of the pedestal 11 is increased so that the portion facing the coil 14b is large. This pedestal 11 can be integrated with the crucible 12. However, considering the need to replace the crucible 12 each time a silicon carbide single crystal is manufactured and the manufacturing cost of the integrated product is high, the pedestal 11 and the crucible 12 is desirably constructed separately. When the pedestal 11 and the crucible 12 are configured as separate bodies, the heat transfer portion 12a of the crucible 12 may be arranged on the pedestal 11, or the heat transfer portion 12a may be fitted into the pedestal 11. The pedestal 11 can also be constructed.

These heating unit 25 a and heating unit 25 b are controlled by the control unit 50 . That is, the single-crystal manufacturing apparatus 100 has a control section 50 that controls power supplied to the heating section 25a and power supplied to the heating section 25b. For example, a power source that supplies power to the heating unit 25a and a power source that supplies power to the heating unit 25b are separate power sources, and the control unit 50 controls the heating units 25a and 25b with different power sources. configured to be controlled.

The control unit 50 controls the power supplied to the heating unit 25a and the power supplied to the heating unit 25b so that the temperature of the solution 20 in contact with the side surface of the crucible 12 is higher than the temperature of the solution 20 in contact with the bottom surface of the crucible 12. The power supplied to the heating unit 25a and the power supplied to the heating unit 25b so that the temperature of the solution 20 in contact with the bottom surface of the crucible 12 is higher than the temperature of the solution 20 in contact with the side surface of the crucible 12. and the second operation for adjusting the above can be alternately switched.

The solution 20 contained in the crucible 12 heated by the heating units 25a and 25b has a high temperature, and the graphite (C) that constitutes the crucible 12 is dissolved. will include A crucible lid 15 is attached to the crucible 12. The crucible lid 15 has a tubular member 15a and a connecting member 15b connected to the tubular member 15a. The connecting member 15b has a function of fixing and supporting the cylindrical member 15a, and is configured to be able to contact with the crucible 12, for example.

Next, the single crystal manufacturing apparatus 100 is provided with a vertically movable crystal holding shaft 16 . Like the crucible holding shaft 18, the crystal holding shaft 16 may also be configured to be rotatable clockwise or counterclockwise. In other words, the crystal holding shaft 16 and the crucible holding shaft 18 may or may not have a rotating mechanism.

A seed crystal (not shown in FIG. 1) made of silicon carbide is attached to the tip of the crystal holding shaft 16 . Further, the crystal holding shaft 16 has a fin structure 16 a attached so as to intersect the extending direction of the crystal holding shaft 16 . Furthermore, the inside of the crystal holding shaft 16 has a hollow structure, and a thermocouple 17 is inserted inside the crystal holding shaft 16 for measuring the temperature near the seed crystal. The temperature in the vicinity of the seed crystal can also be measured by arranging a radiation thermometer having a measurement diameter smaller than the inner diameter of the crystal holding shaft 16 at the upper end of the crystal holding shaft 16 instead of inserting the thermocouple 17 .

The control unit 50 of the single crystal manufacturing apparatus 100 is also configured to perform control such that the crystal holding shaft 16 having the fin structure 16a is vertically moved. Specifically, the control unit 50 is configured to control the crystal holding shaft 16 so that the crystal holding shaft 16 having the fin structure 16a moves vertically through the interior of the tubular member 15a. . The control unit 50 is configured to bring the lower surface of the seed crystal into contact with the surface of the solution 20 contained in the crucible 12 by moving the crystal holding shaft 16 having the seed crystal attached to the tip thereof downward. In addition, after bringing the lower surface of the seed crystal into contact with the surface of the solution 20, by moving the crystal holding shaft 16 upward, a single crystal made of silicon carbide can be grown on the lower surface of the seed crystal. It is configured. For example, FIG. 1 shows a silicon carbide single crystal 40 growing on the bottom surface of the seed crystal. In addition, the seed crystal may be brought into contact with the solution 20 , but it is particularly desirable to bring it into contact with the surface of the solution 20 .

It should be noted that the configuration in which a single crystal made of silicon carbide can be grown on the lower surface of the seed crystal by moving the crystal holding shaft 16 upward is an example. In the (maintained) state, a single crystal made of silicon carbide may be grown on the lower surface of the seed crystal. It can also be configured to grow a single crystal made of. This configuration takes into account that, for example, evaporation of the solution 20 may lower the surface of the solution 20 . That is, when the surface of the solution 20 recedes due to the evaporation of the solution 20, the single crystal can be reliably grown on the seed crystal by growing the single crystal while moving the crystal holding shaft 16 downward. .

The single crystal manufacturing apparatus 100 is configured as described above.

2A and 2B are diagrams illustrating examples of dimensions of main portions of the pedestal 11 and the crucible 12. FIG.

The dimensions of the main parts shown in FIG. 2 are, for example, as follows.
(1) “L1” = φ150mm
(2) “L2” = φ250mm
(3) “L3” = φ100mm
(4) “L4” = φ190mm
(5) "T1" = 100mm
(6) "T2" = 80mm
(7) "T3" = 30mm
(8) "T4" = 250mm
(9) "A1" = 90 mm
(10) "A2" = φ330mm

<Modification 1>
In single-crystal manufacturing apparatus 100 shown in FIG. The part 25b is not limited to this, and may be composed of a resistance heater provided below the base 11, for example.

However, when the heating part 25b is composed of a resistance heater, it is necessary to provide a "hole" in the heat insulating material in order to route a pair of wires used for energizing the resistance heater. In particular, in the case of a structure in which the crucible 12 itself is rotated, the heat insulating material needs to be provided with a circular opening in order to route the pair of wires. As a result, it may become difficult to ensure the high temperature retention characteristics of the crucible 12 . Therefore, from the viewpoint of enhancing the heat insulating effect of the heat insulating material and from the viewpoint of simplifying the configuration of the single crystal manufacturing apparatus 100, the heating unit 25b for heating the pedestal 11 should be induction heating using the induction heating phenomenon as shown in FIG. Preferably, it consists of a heater.

<Operation of Single Crystal Manufacturing Apparatus (Single Crystal Manufacturing Method)>
Next, the operation of single crystal manufacturing apparatus 100 will be described.

3 and 4 are diagrams for explaining the operation of the single crystal manufacturing apparatus 100. FIG.

In FIG. 3, the controller 50 first lowers the crystal holding shaft 16 with the seed crystal 30 attached to the tip. As a result, the seed crystal 30 attached to the crystal holding shaft 16 passes through the cylindrical member 15a provided in the crucible lid 15, and then adheres to the surface of the solution 20 containing carbon and silicon contained in the crucible 12. Contact. At this time, the fin structure 16a attached to the crystal holding shaft 16 is arranged at a position facing the inner wall of the tubular member 15a.

Next, in FIG. 4, the controller 50 slowly raises the crystal holding shaft 16 . Thereby, silicon carbide single crystal 40 grows on the lower surface of seed crystal 30 that is pulled up. At this time, the fin structure 16a attached to the crystal holding shaft 16 moves while maintaining the opposition to the inner wall of the cylindrical member 15a. After that, when continuing the crystal growth, the pulling operation of the crystal holding shaft 16 is continued. On the other hand, when terminating the crystal growth, control unit 50 further pulls up crystal holding shaft 16 to separate silicon carbide single crystal 40 and solution 20 . This completes the growth of silicon carbide single crystal 40 . At this time, the fin structure 16a attached to the crystal holding shaft 16 is maintained in a position facing the inner wall of the tubular member 15a.

By operating single-crystal manufacturing apparatus 100 as described above, a silicon carbide single crystal can be manufactured. Although it has been described that the crystal growth is completed by further pulling up the crystal holding shaft 16 to separate the silicon carbide single crystal 40 from the solution 20, the present invention is not limited to this. , the silicon carbide single crystal 40 and the solution 20 can be separated by pulling down the crucible holding shaft 18, and the crystal growth can be completed.

<<Operation by control section>>
As described above, single-crystal manufacturing apparatus 100 manufactures silicon carbide single crystals by the “solution method”. At this time, in the single crystal manufacturing method of the present embodiment, the first heating step of heating the solution 20 so that the temperature of the solution 20 in contact with the side surface of the crucible 12 is higher than the temperature of the solution 20 in contact with the bottom surface of the crucible 12. and a second heating step of heating the solution 20 so that the temperature of the solution 20 in contact with the bottom surface of the crucible 12 is higher than the temperature of the solution 20 in contact with the side surface of the crucible 12 are alternately switched.

In the present embodiment, these steps are realized by control of heating section 25a and heating section 25b by control section 50 of single-crystal manufacturing apparatus 100. FIG. Specifically, the control unit 50 adjusts the power supplied to the heating unit 25 a and the power supplied to the heating unit 25 b to adjust the temperature of the solution 20 in contact with the side surface of the crucible 12 to the temperature of the solution 20 in contact with the bottom surface of the crucible 12 . and the power supplied to the heating unit 25a and the power supplied to the heating unit 25b are adjusted to increase the temperature of the solution 20 in contact with the bottom surface of the crucible 12 to the side surface of the crucible 12. A second action of increasing the temperature of the solution 20 is alternated.

For example, when the first operation is performed by the control unit 50, the temperature of the solution 20 in contact with the side surface of the crucible 12 is the temperature at which miscellaneous crystals dissolve, while the temperature of the solution 20 in contact with the bottom surface of the crucible 12 is the temperature at which miscellaneous crystals dissolve. This is the temperature at which crystals precipitate. On the other hand, when the second operation is performed by the control unit 50, the temperature of the solution 20 in contact with the bottom surface of the crucible 12 is the temperature at which miscellaneous crystals are dissolved, while the temperature of the solution 20 in contact with the side surface of the crucible 12 is , the temperature at which miscellaneous crystals precipitate.

As a result, by repeating alternate switching between the first operation and the second operation, the precipitated miscellaneous crystals can be dissolved again. In addition, it is possible to suppress the enlargement of miscellaneous crystals.

FIG. 5 is a diagram showing an example of switching between the first operation and the second operation by the control unit 50. As shown in FIG.

In FIG. 5, "A" indicates the period during which the first action is performed, while "B" indicates the period during which the second action is performed. In FIG. 5, the solid line indicates the power (coil output) supplied to the coil 14a of the heating section 25a. On the other hand, the dashed line indicates the power (coil output) supplied to the coil 14b of the heating section 25b.

In FIG. 5, the first operation (“A”) and the second operation (“B”) are switched while growing the crystal. That is, in FIG. 5, in the step of growing the silicon carbide single crystal 40 on the lower surface of the seed crystal while moving the crystal holding shaft 16 upward (see FIG. 4), switching between the first operation and the second operation is performed. An iterative example is shown.

For example, in the first operation, the power supplied to the coil 14a is large, while the power supplied to the coil 14b is small. This means that the amount of heating of the side surfaces of crucible 12 is greater than the amount of heating of the bottom surface of crucible 12 , thereby increasing the temperature of solution 20 in contact with the side surfaces of crucible 12 to the temperature of solution 20 in contact with the bottom surface of crucible 12 . A temperature distribution is achieved that is higher than the temperature. In contrast, in the second operation, the power supplied to the coil 14a is decreased while the power supplied to the coil 14b is increased. This means that the amount of heating of the bottom surface of the crucible 12 is greater than the amount of heating of the side surfaces of the crucible 12 , thereby increasing the temperature of the solution 20 contacting the bottom surface of the crucible 12 to the temperature of the solution 20 contacting the side surfaces of the crucible 12 . A temperature distribution is achieved that is higher than the temperature.

Note that FIG. 5 shows an example in which the power supplied to the coil 14a is greater than the power supplied to the coil 14b not only in the first operation but also in the second operation. However, depending on the configuration of the crucible 12, the power supplied to the coil 14a is required to achieve a temperature distribution in which the temperature of the solution 20 in contact with the bottom surface of the crucible 12 is higher than the temperature of the solution 20 in contact with the side surface of the crucible 12. , may be smaller than the power supplied to the coil 14b. That is, in the second operation, if a temperature distribution is realized in which the temperature of the solution 20 in contact with the bottom surface of the crucible 12 is higher than the temperature of the solution 20 in contact with the side surface of the crucible 12, electric power (or current) and power (or current) supplied to the coil 14b.

Since all members constituting the single-crystal manufacturing apparatus 100 have a heat capacity, the temperature distribution of the solution 20 transitions with a delay with respect to changes in all control conditions including adjustment of power supplied to each of the coils 14a and 14b. do. While the temperature distribution of the solution 20 is transitioning, it is not necessarily in a state suitable for single crystal growth.

For example, regarding switching from the first operation to the second operation, if the transition time from the end of the first operating condition until the temperature distribution of the solution 20 attaining the second operation reaches a steady state, the first transition time is A temperature distribution different from the temperature distribution achieved by the first operation and the temperature distribution achieved by the second operation is achieved in one transition time.

A plurality of methods are conceivable for controlling the temperature distribution of the solution 20 in the first transition time to a desired state. As a first example, there is a method of immediately shifting to the second action after the end of the first action. This method has the advantage that the temperature distribution of the solution 20 achieved by the second operation can be achieved in a short period of time, so that silicon carbide single crystals can be grown under stable conditions for a longer period of time. is particularly effective in Another advantage is that the power control conditions are simple and clear compared to the second and third examples described later, and that it can be implemented in a single crystal manufacturing apparatus that does not have a complicated control mechanism. .

As a second example, there is a method of gently changing the power supplied to each of the coils 14a and 14b between the end of the first operation and the start of the second operation so as to absorb the transition delay due to heat capacity. . In this method, the temperature distribution of the solution 20 during the first transition time can be changed in a quasi-stable manner, and the temperature distribution of the solution 20 can be almost controlled by the power supplied to each of the coils 14a and 14b. It has the advantage of being As a result, since the first transition time substantially coincides with the time from the end of the first operation to the start of the second operation, it is the first priority to realize a temperature distribution suitable for growing silicon carbide single crystals during the first transition time. and the third example described later.

As a power change process of the second example, a method of maintaining a constant power change speed from the end of the first operation to the start of the second operation as shown in FIG. 5 is conceivable. On the other hand, the power change rate may be increased or decreased at one time point or two or more time points between the end of the first operation and the start of the second operation. Since the coil 14a and the coil 14b are characterized by being able to be controlled independently, in the latter, for example, the power change speed of one of them is increased compared to the first example, and the power change speed of the other is set to that of the first example. It is also possible to adjust to make it smaller than .

As a third example, the power supplied to the coil 14a during a certain period of time between the end of the first operation and the start of the second operation is set to be smaller than the power supplied to the coil 14a under the second operating condition, and at the same time, the coil 14b is is greater than the power supplied to the coil 14b under the second operating condition. This method is called overshoot and has the effect of canceling out the state change delay due to heat capacity. The advantage of the power change method using this overshoot is that the temperature distribution of the solution 20, in which the second operation is realized earlier than in the first example, reaches a steady state in a single crystal manufacturing apparatus with a large heat capacity.

So far, regarding the switching from the first operation to the second operation, the method of controlling the temperature distribution of the solution 20 in the first transition time to a desired state has been described. It goes without saying that the same method can be applied to

FIG. 6 is a diagram showing the result of simulating the temperature distribution of the solution 20 realized by the first operation. For the simulation, software called "CGSim | STR Japan Co., Ltd. <Crystal growth analysis simulation software> (str-soft.co.jp)" was used.

In FIG. 6, it can be seen that a temperature distribution is realized in which the temperature (K) of the solution 20 in contact with the side surface of the crucible is higher than the temperature (K) of the solution 20 in contact with the bottom surface of the crucible. At this time, since the temperature of the solution 20 in contact with the side surface of the crucible is high, miscellaneous crystals are dissolved. On the other hand, since the temperature of the solution 20 in contact with the bottom surface of the crucible is low, miscellaneous crystals are generated (precipitated).

FIG. 7 is a diagram showing the result of simulating the temperature distribution of the solution 20 realized by the second operation. In FIG. 7, it can be seen that a temperature distribution is achieved in which the temperature (K) of the solution 20 in contact with the bottom surface of the crucible is higher than the temperature (K) of the solution 20 in contact with the side surface of the crucible. At this time, since the temperature of the solution 20 in contact with the bottom surface of the crucible is high, miscellaneous crystals are dissolved. On the other hand, since the temperature of the solution 20 in contact with the side surface of the crucible is low, miscellaneous crystals are generated (precipitated).

Therefore, when alternate switching between the first operation and the second operation is repeated, the temperature distribution shown in FIG. 6 and the temperature distribution shown in FIG. 7 are alternately switched. As a result, a redissolution phenomenon of the precipitated miscellaneous crystals occurs, and the precipitation of the miscellaneous crystals does not occur continuously. can be suppressed.

Next, timing for switching between the first operation and the second operation will be described.

Ideally, it is desirable to switch between the first operation and the second operation when the size of miscellaneous crystals exceeds a predetermined size. This is because if the switching timing is determined in this way, it is possible to effectively suppress the enlargement of miscellaneous crystals.

However, it is difficult to measure the size of miscellaneous crystals during the process of manufacturing silicon carbide single crystals. For this reason, the control method of switching between the first operation and the second operation when the size of miscellaneous crystals exceeds a predetermined size is not realistic. Therefore, for example, it is realistic to alternately switch between the first operation and the second operation at predetermined time intervals.

Here, when the first operation and the second operation are alternately switched at predetermined time intervals, in order to effectively suppress the enlargement of the miscellaneous crystals, for example, the time interval and the miscellaneous crystal size It is conceivable to construct a database in which data indicating the relationship between is accumulated, and to set the optimum time interval based on the data accumulated in this database.

<Modification 2>
Although FIG. 5 illustrates an example of switching between the first operation and the second operation while performing crystal growth, an example of switching between the first operation and the second operation by the control unit 50 is not limited to this. For example, one of the first operation and the second operation is performed at the stage of crystal growth after the seed crystal is brought into contact with the surface of the solution, while the other of the first operation and the second operation is the seed crystal. The silicon carbide single crystal grown on the lower surface of is separated from the surface of the solution.

FIG. 8 is a diagram showing an example (modification 2) of switching between the first operation and the second operation.

FIG. 8 shows an example in which crystal growth is stopped when the first operation is performed, while the second operation is performed while crystal growth is being performed. That is, as an example of switching between the first operation and the second operation by the control unit 50, the switching operation shown in FIG. 8 can be employed.

In this case, the following advantages can be obtained.

For example, in FIG. 6 showing the temperature distribution of the solution by performing the first operation, the surface temperature of the solution 20 with which the seed crystal contacts is high.

Here, in order to grow the silicon carbide single crystal on the lower surface of the seed crystal, it is desirable to set the surface temperature of the solution contacting the seed crystal to the lower temperature in the temperature distribution of the solution. This is because the silicon carbide single crystal grows in a supersaturated state, and the supersaturated state is realized in a low temperature region. Considering this, the temperature distribution of the solution obtained by performing the first operation cannot necessarily be said to be a temperature condition suitable for growing a silicon carbide single crystal. This is because, in the temperature distribution shown in FIG. 6, since the degree of supersaturation is small, the crystal growth rate slows down, and as a result, the temperature distribution cannot necessarily be said to be suitable for crystal growth.

On the other hand, in FIG. 7 showing the temperature distribution of the solution by performing the second operation, the surface temperature of the solution 20 with which the seed crystal contacts is low. Therefore, it can be said that the temperature distribution of the solution obtained by performing the second operation is a temperature condition suitable for growing a silicon carbide single crystal. That is, the temperature distribution of the solution by performing the second operation has a large degree of supersaturation, and as a result, the crystal growth rate is increased. can be called a temperature distribution.

From the above, the temperature distribution of the solution obtained by performing the first operation cannot necessarily be said to be a temperature condition suitable for growing silicon carbide single crystals, and the temperature distribution of the solution obtained by performing the second operation is It can be said that these temperature conditions are suitable for the growth of silicon carbide single crystals.

Therefore, as shown in FIG. 8, when the first operation is performed, the crystal growth is stopped, while the second operation is performed while the crystal is grown, temperature conditions suitable for growing the silicon carbide single crystal are obtained. It is possible to grow a silicon carbide single crystal only by As a result, Modification 2 shown in FIG. 8 has the advantage of being able to produce silicon carbide single crystals of excellent quality. On the other hand, in the switching example shown in FIG. 5, since the first operation and the second operation are alternately performed while crystal growth is performed, an advantage of being able to shorten the manufacturing time of the silicon carbide single crystal is obtained.

As described above, a method of determining the switching time between the first operation and the second operation based on a database constructed in advance is conceivable. However, from the viewpoint of shortening the crystal growth time, it is more desirable to shorten the implementation time of the first operation than the implementation time of the second operation. As a condition suitable for obtaining a switching time that satisfies this purpose, for example, the dissolution rate of miscellaneous crystals in the solution 20 in contact with the side surface of the crucible 12 during the first operation is less than the dissolution rate of miscellaneous crystals at the same position during the second operation. is higher than the deposition rate of As a method of satisfying this condition, the power supplied to the coils 14a and 14b is adjusted so that the temperature distribution of the solution 20 during the first operation has a larger temperature gradient than the temperature distribution during the second operation. can be considered.

In both the first operation and the second operation, the power supplied to the coil need not be completely constant, and may be gradually decreased. The first operation and the second operation in the second and subsequent rounds do not necessarily have to have exactly the same output power supply as in the first round. For example, it is possible to slightly lower the output power supply than in the first round, or to slightly lower the power supply only for the coil 14a. These methods take into account the fact that the amount of solution to be heated decreases as the crystal grows, and the power supplied to the coil is reduced in order to create the same temperature distribution as in the first round. .

<Features of the embodiment>
Next, feature points in this embodiment will be described.

A first characteristic point of the present embodiment is that, for example, as shown in FIGS. A first operation (“A”) for making the temperature of the solution 20 in contact with the bottom surface of the crucible 12 higher than the temperature of the solution 20 in contact with the bottom surface of the crucible 12, and adjusting the power supplied to the heating unit 25a and the power supplied to the heating unit 25b. , the temperature of the solution 20 in contact with the bottom surface of the crucible 12 is alternately switched to the second operation (“B”) in which the temperature of the solution 20 in contact with the side surface of the crucible 12 is made higher. Thereby, for example, the temperature of each of the solutions 20 in contact with the side and bottom surfaces of the crucible 12 can be periodically changed between the temperature at which miscellaneous crystals precipitate and the temperature at which miscellaneous crystals dissolve. This means that the precipitated miscellaneous crystals can be reduced and the enlargement of the miscellaneous crystals can be suppressed, thereby suppressing deterioration in quality of the silicon carbide single crystal caused by the miscellaneous crystals.

Next, the second characteristic point of the present embodiment is that the crucible 12 is provided with a heat transfer portion 12a protruding from the bottom portion of the body portion of the crucible 12, as shown in FIG.

The technical significance of this second feature point will be described below.

For example, in the second operation of raising the temperature of the solution 20 in contact with the bottom surface of the crucible 12 to a temperature at which miscellaneous crystals dissolve, it is important to raise the temperature of the bottom surface of the crucible 12 uniformly. This is because, if the temperature of the bottom surface of the crucible 12 cannot be raised uniformly, there is a high probability that there will be a low temperature region where the miscellaneous crystals do not dissolve even if the second operation is performed. This is because you will not be able to

As a configuration for heating the bottom surface of the crucible 12, for example, the configuration shown in FIG. 9 can be considered. In FIG. 9, a crucible 12 is placed on a pedestal 11, and the pedestal 11 is configured to be heated by an induction heating phenomenon from a heating portion 25b including a coil 14b. In this case, the heat from the heated pedestal 11 is conducted to the bottom surface of the crucible 12 that is in direct contact with the pedestal 11, but in the induction heating by the coil 14b, the outer portion of the pedestal 11 is more likely to be heated than the central portion. has the property of For this reason, in the configuration shown in FIG. 9, the outer bottom surface of the crucible 12 is mainly heated (see arrows in FIG. 9), making it difficult to heat the central portion of the bottom surface of the crucible 12 . That is, with the configuration shown in FIG. 9, it is difficult to uniformly raise the temperature of the bottom surface of crucible 12 .

On the other hand, in the present embodiment, as shown in FIG. 1, the crucible 12 is provided with a heat transfer portion 12a projecting from the bottom portion of the main body portion of the crucible 12 . In this case, as shown in FIG. 10, heat is preferentially conducted to the central portion of the bottom surface of the crucible 12 via the heat transfer portion 12a from the pedestal 11 heated by the induction heating phenomenon from the heating portion 25b including the coil 14b. be able to. As a result, according to the present embodiment, the temperature of the bottom surface of crucible 12 can be raised uniformly. That is, it can be said that the heat transfer portion 12 a has a function of preferentially guiding the heat from the heated pedestal 11 to the center portion of the bottom surface of the crucible 12 .

From the viewpoint of improving the temperature uniformity of the entire bottom surface of the crucible 12, for example, as shown in FIG. It is desirable to provide a heat insulating member 13b.

In order to uniformly raise the temperature of the bottom surface of the crucible 12, the formation position of the heat transfer section 12a is important. Considering this point, for example, the dimensions of the main portions shown in FIG. 2 are determined. .

In particular, from the viewpoint of causing miscellaneous crystals to melt over the entire bottom surface by uniformly raising the temperature of the entire bottom surface of the crucible 12, "L3" is smaller than "L1", and "L4" is " It is important that it is greater than "L1" and less than "L2". This arrangement avoids preferential heating of the sides of the crucible 12 .

<Consideration of further improvement>
For example, in the present embodiment, as shown in FIG. 1, the crucible 12 is heated by induction heating by supplying power to the coil 14a, and the base 11 is heated by induction heating by supplying power to the coil 14b. is configured to heat the

Here, the feature of this embodiment is that, for example, as shown in FIGS. 5 and 8, by adjusting the power supplied to the coil 14a and the power supplied to the coil 14b, By adjusting the first operation (“A”) to make the temperature of the solution 20 higher than the temperature of the solution 20 in contact with the bottom surface of the crucible 12 and the power supplied to the coil 14a and the power supplied to the coil 14b, the crucible The second operation (“B”) of making the temperature of the solution 20 in contact with the bottom surface of the crucible 12 higher than the temperature of the solution 20 in contact with the side surface of the crucible 12 is alternately switched.

At this time, as shown in FIGS. 5 and 8, power is supplied to both the coil 14a and the coil 14b in both the first operation (“A”) and the second operation (“B”). . This means that high-frequency currents are simultaneously flowing through both the coils 14a and 14b in both the first operation (“A”) and the second operation (“B”). Therefore, for example, the electromagnetic field generated by the high-frequency current flowing in the coil 14a adversely affects the circuit including the coil 14b, while the electromagnetic field generated by the high-frequency current flowing in the coil 14b causes the coil 14a to may adversely affect the circuits containing it. That is, in both the first operation (“A”) and the second operation (“B”), high-frequency currents are flowing through both the coils 14a and 14b at the same time. It is feared that such an event will occur and adverse effects such as malfunction of the circuit will be exerted.

Therefore, in the present embodiment, measures are taken to suppress the above-described adverse effects. In the following, the technical idea of this embodiment with this ingenuity will be described.

<Technical idea in the embodiment>
The technical idea of the present embodiment is based on the assumption that power is discontinuously supplied to each of the coils 14a and 14b instead of continuously supplying power to each of the coils 14a and 14b. The idea is to exclusively control the power supply so that the period during which power is supplied to the coil 14a and the period during which power is supplied to the coil 14b do not overlap. That is, the period for supplying power to the coil 14a is a period during which power is not supplied to the coil 14b, while the period for supplying power to the coil 14b is a period during which power is not supplied to the coil 14a. As a result, when power is supplied to one coil, power is not supplied to the other coil, thereby preventing high-frequency current from flowing through both coils at the same time. As a result, it is possible to suppress electromagnetic interference caused by high-frequency currents flowing through both coils at the same time, thereby suppressing malfunction of the circuit.

For example, FIG. 11A is a schematic diagram showing power supplied to the coil 14a when power is continuously supplied to the coil 14a. On the other hand, FIG. 11B is a schematic diagram showing power supplied to the coil 14b when power is continuously supplied to the coil 14b. In particular, FIG. 11(a) shows the power supplied to the coil 14a in the first operation (“A”) of FIG. 5, and FIG. 11(b) shows the power supplied to the first operation (“A ) shows the power supplied to the coil 14b. In this case, it can be seen that both coils 14a and 14b are energized simultaneously, as shown in FIGS. 11(a) and 11(b). Therefore, in a configuration in which power is continuously supplied to coils 14a and 14b, respectively, as shown in FIGS. , it can be seen that there is concern that electromagnetic interference resulting from this will result in adverse effects typified by circuit malfunction.

In FIG. 11A, when power is continuously supplied to the coil 14a, the instantaneous power supply P1H to the coil 14a is equal to the average power supply <P1H> to the coil 14a. Similarly, in FIG. 11(b), when power is continuously supplied to the coil 14b, the instantaneous power supply P2L to the coil 14b is equal to the average power supply <P2L> to the coil 14b.

On the other hand, for example, FIG. 12A is a schematic diagram showing power supplied to the coil 14a when power is discontinuously supplied to the coil 14a. On the other hand, FIG. 12(b) is a schematic diagram showing power supplied to the coil 14b when power is discontinuously supplied to the coil 14b. In particular, FIG. 12(a) shows the power supplied to the coil 14a in the first operation (“A”) of FIG. 5, and FIG. 12(b) shows the power supplied to the coil 14a in the first operation 1 (“ A") shows the power supplied to the coil 14b. In this case, as shown in FIGS. 12(a) and 12(b), control can be performed so that power is not supplied to the coil 14b during a period in which power is being supplied to the coil 14a. That is, as shown in FIGS. 12(a) and 12(b), if a configuration is adopted in which power is discontinuously supplied to each of the coils 14a and 14b, power is supplied to both the coils 14a and 14b at the same time. It turns out that it can be controlled so that it is not supplied. Therefore, if the configuration as shown in FIGS. 12(a) and 12(b) is adopted to discontinuously supply electric power to each of the coils 14a and 14b, both the coils 14a and 14b are simultaneously supplied with high-frequency current. flow can be prevented. As a result, it is possible to suppress the occurrence of electromagnetic interference caused by high-frequency currents flowing through both the coils 14a and 14b at the same time, thereby suppressing adverse effects such as circuit malfunction.

However, in FIG. 12A, when power is discontinuously supplied to the coil 14a, the instantaneous power supply P1H to the coil 14a is higher than the average power supply <P1H> to the coil 14a. Similarly, in FIG. 12B, when power is discontinuously supplied to the coil 14b, the instantaneous power supply P2L to the coil 14b is higher than the average power supply <P2L> to the coil 14b. That is, by adopting the technical concept of the present embodiment, it is possible to prevent high-frequency currents from flowing through both the coil 14a and the coil 14b at the same time, while the instantaneous power supply becomes higher than the average power supply. However, considering that it is possible to suppress electromagnetic interference caused by high-frequency current flowing through both coils at the same time, thereby suppressing malfunction of the circuit, the technical idea of the present embodiment is a very large technology. It can be said that it has a significant meaning.

<Embodiment mode>
In the following, an embodiment that embodies the technical idea described above will be described.

The implementation mode of the present embodiment assumes that power is discontinuously supplied to each of the coils 14a and 14b instead of continuously supplying power to each of the coils 14a and 14b. In this mode, the first inverter for supplying power to the coil 14a and the second inverter for supplying power to the coil 14b are operated exclusively. That is, when the first inverter for supplying power to the coil 14a is turned on, the second inverter for supplying power to the coil 14b is turned off, while the second inverter for supplying power to the coil 14b is turned off. is turned on, the first inverter for supplying power to the coil 14a is turned off. As a result, when power is supplied to one coil, power is not supplied to the other coil, thereby preventing high-frequency current from flowing through both coils at the same time. As a result, it is possible to suppress electromagnetic interference caused by high-frequency currents flowing through both coils at the same time, thereby suppressing malfunction of the circuit.

<<Configuration and Operation of Heating Unit>>
FIG. 13 is a block diagram showing the configuration of the heating section in this embodiment.

FIG. 13 shows a configuration example of the heating section 25a and the heating section 25b.

In FIG. 13, the heating unit 25a includes a first AC/DC converter 201a, a first inverter 202a, a first transformer 203a, and a coil 14a, and is configured to be controlled by a control unit 210. In the heating unit 25a configured as described above, first, a signal (that is, a target output signal) for setting the target output power <<P1>> is input to the control unit 210. As shown in FIG. Then, control unit 210 outputs target inverter voltage <<Vi1>> for achieving input power PA to first inverter 202a to first AC/DC converter 201a. Next, first AC/DC converter 201a converts AC power from first commercial power supply 200a into DC power based on target inverter voltage <<Vi1>> input from control unit 210 . As a result, input power PA from first AC/DC converter 201a to first inverter 202a is output. Subsequently, the first inverter 202a receives the input power PA output from the first AC/DC converter 201a and outputs the output power <P1>. Specifically, the DC current converted by the first AC/DC converter 201a is converted into a high-frequency current (for example, 10 kHz) by the first inverter 202a. Then, the output voltage from the first inverter 202a is reduced in pressure by the first transformer 203a, and then high-frequency current (output power <P1>) is supplied to the coil 14a. That is, in order to prevent electric leakage and arcing in the heating furnace, the voltage is reduced by the first transformer 203a (transformer), and a corresponding large current is supplied to the coil 14a to heat the heating furnace. Here, the controller 210 controls on/off of the first inverter 202a. As a result, the coil 14a has a period during which power is supplied and a period during which power is not supplied. Then, the coil 14a performs induction heating to the crucible 12 based on the supplied output power <P1>. Thus, the crucible 12 is heated by the heating part 25a.

Next, the heating unit 25b includes a second AC/DC converter 201b, a second inverter 202b, a second transformer 203b, and a coil 14b, and is configured to be controlled by the control unit 210. FIG. In the heating unit 25b configured in this way, first, a signal to set the target output power <<P2>> is input to the control unit 210. As shown in FIG. Then, control unit 210 outputs target inverter voltage <<Vi2>> for realizing input power PB to second inverter 202b to second AC/DC converter 201b. Next, second AC/DC converter 201b converts AC power from second commercial power supply 200b into DC power based on target inverter voltage <<Vi2>> input from control unit 210 . As a result, the input power PB from the second AC/DC converter 201b to the second inverter 202b is output. Subsequently, the second inverter 202b receives the input power PB output from the second AC/DC converter 201b and outputs the output power <P2>. Specifically, the DC current converted by the second AC/DC converter 201b is converted into a high-frequency current (for example, 10 kHz) by the second inverter 202b. After the output voltage from the second inverter 202b is reduced by the second transformer 203b, the coil 14b is supplied with a high-frequency current (output power <P2>). That is, in order to prevent electric leakage and arcing in the heating furnace, the voltage is reduced by the second transformer 203b (transformer), and a corresponding large current is supplied to the coil 14b to heat the heating furnace. Here, the controller 210 controls on/off of the second inverter 202b. As a result, the coil 14b has a period during which power is supplied and a period during which power is not supplied. Then, in the coil 14b, induction heating to the pedestal 11 is performed based on the supplied output power <P2>. Thus, the base 11 is heated by the heating portion 25b.

Thus, rather than continuously powering each of coils 14a and 14b, in an implementation, power is discontinuously supplied. At this time, the first inverter 202a for supplying power to the coil 14a and the second inverter 202b for supplying power to the coil 14b are operated exclusively by the control unit 210. 2 inverter 202b is controlled. That is, when the first inverter 202a for supplying power to the coil 14a is turned on, the second inverter 202b for supplying power to the coil 14b is turned off, while the second inverter 202b for supplying power to the coil 14b is turned off. When turning on the second inverter 202b, the first inverter 202a for supplying power to the coil 14a is turned off. As a result, when power is supplied to one coil, power is not supplied to the other coil, thereby preventing high-frequency current from flowing through both coils at the same time. As a result, it is possible to suppress electromagnetic interference caused by high-frequency currents flowing through both coils at the same time, thereby suppressing malfunction of the circuit.

<<Specific waveform example>>
Next, specific waveform examples will be described.

FIG. 14(a) is a schematic diagram showing power supplied to the coil 14a when power is discontinuously supplied to the coil 14a. On the other hand, FIG. 14(b) is a schematic diagram showing power supplied to the coil 14b when power is discontinuously supplied to the coil 14b. In particular, FIG. 14(a) shows the power supplied to the coil 14a in the first operation (“A”) of FIG. 5, and FIG. 14(b) shows the power supplied to the first operation (“A ) shows the power supplied to the coil 14b. The lower part of FIG. 14(a) also shows the waveform of the current flowing through the coil 14a, and the lower part of FIG. 14(b) also shows the waveform of the current flowing through the coil 14b.

Here, the symbols in FIGS. 14(a) and 14(b) have the following meanings.
P1H: Instantaneous power supply to coil 14a P2L: Instantaneous power supply to coil 14b <P1H>: Average power supply to coil 14a <P2L>: Average power supply to coil 14b fa: ON/OFF switching frequency fs1: Coil Frequency fs2 of the current flowing through the coil 14a: Frequency d1 of the current flowing through the coil 14b: ON time ratio of the coil 14a d2: ON time ratio of the coil 14b Note that the relationship d1+d2<1 is established. That is, there is a period during which the first inverter and the second inverter are turned off at the same time.

FIG. 15(a) shows the power supplied to the coil 14a in the second operation (“B”) of FIG. 5, and FIG. 15(b) shows the second operation (“B”) of FIG. shows the power supplied to the coil 14b. FIG. 15(a) also shows the waveform of the current flowing through the coil 14a, and FIG. 15(b) also shows the waveform of the current flowing through the coil 14b.

Here, the symbols in FIGS. 15(a) and 15(b) have the following meanings.
P1L: Instantaneous power supply to coil 14a P2H: Instantaneous power supply to coil 14b <P1L>: Average power supply to coil 14a <P2H>: Average power supply to coil 14b fa: ON/OFF switching frequency fs1: Coil Frequency fs2 of current flowing through coil 14a: Frequency of current flowing through coil 14b d3: On-time ratio of coil 14a d4: On-time ratio of coil 14b The relationship d3+d4<1 is established. That is, there is a period during which the first inverter and the second inverter are turned off at the same time.

14, "d1", "d2", "P1H" and " P2L", the first operation ("A") in FIGS. 5 and 8 can be realized. Similarly, in FIG. 15, <P1L> is aligned with the solid lines in FIGS. 5 and 8, and <P2H> is aligned with the dashed lines in FIGS. ' and 'P2H', the second operation ('B') in FIGS. 5 and 8 can be realized.

In this embodiment, the power supply operation to the coils 14a and 14b is intermittent operation. temperature change. Also, the switching frequency of the first inverter 202a (frequency fs1 of the current flowing through the coil 14a) and the switching frequency of the second inverter 202b (frequency fs2 of the current flowing through the coil 14b) must be sufficiently higher than the on/off switching frequency fa. induction heating becomes possible.

From the above, as shown in FIGS. 5 and 8, when the output of one coil exists, the output of the other coil is not zero, but the exclusive operation shown in FIG. 14 or 15 can be performed. 5 and 8, the power supply to one coil can be stopped while power is being supplied to the other coil. Therefore, by exclusively operating the first inverter 202a that supplies current to the coil 14a and the second inverter 202b that supplies current to the coil 14b, malfunction of the first inverter 202a or the second inverter 202b due to electromagnetic interference can be avoided. As a result, stable operation becomes possible. Further, according to the present embodiment, since electromagnetic interference can be suppressed, there is no need to provide a magnetic shield between the coil 14a and the coil 14b, so the cost of the single crystal manufacturing apparatus can be reduced.

<Other features>
Next, other features of this embodiment will be described.

In the single-crystal manufacturing apparatus 100 of the present embodiment, for example, as shown in FIG. The portion 25b includes a coil 14b provided at a position facing the pedestal 11 positioned below the crucible 12 containing the solution 20 . Regarding this point, another feature of the present embodiment is that the coil 14b is provided at a position facing the pedestal 11 arranged below the solution 20 contained in the crucible 12 .

Thereby, the heating part 25 b can heat the base 11 by an induction heating phenomenon caused by applying a high-frequency current to the coil 14 b provided at a position facing the base 11 . Then, the bottom surface of the crucible 12 can be heated by heat conduction from the heated pedestal 11 .

Specifically, heat is transferred from the pedestal 11 heated by the heating unit 25b to the heat transfer unit 12a, and then the heat is transferred from the heat transfer unit 12a to the crucible 12 (main body). is heated. That is, the heating part 25b heats the bottom surface of the crucible 12 in contact with the solution through the pedestal 11 by an induction heating phenomenon caused by applying a high-frequency current to the coil 14b provided at a position facing the pedestal 11 that supports the crucible 12. configured for indirect heating. In this way, another feature is that the coil 14b is placed in the crucible 12 so that the bottom surface of the crucible 12 in contact with the solution 20 can be heated by the coil 14b arranged on the outer side surface of the heat insulating member 13c. The point is that it is provided at a position facing the pedestal 11 arranged below 20 .

As a result, according to other features, the pedestal 11 is heated by an induction heating phenomenon that occurs when a high-frequency current is passed through the coil 14b, and heat conduction from the heated pedestal 11 causes the bottom surface of the crucible 12 to come into contact with the solution 20. can be indirectly heated. In other words, the technical significance of the other characteristic points is that the coil 14b is arranged at a position facing the pedestal 11 instead of directly heating the bottom surface of the crucible 12 in contact with the solution 20 (other characteristic points), By adopting a configuration in which the pedestal 11 on which the crucible 12 is placed is heated instead of the crucible 12 itself, the bottom surface of the crucible 12 is indirectly heated via the pedestal 11 .

<Further features>
As described above, the first characteristic point of the present embodiment is that, for example, as shown in FIGS. A first operation (“A”) for making the temperature of the solution 20 in contact with the side surface of the crucible 12 higher than the temperature of the solution 20 in contact with the bottom surface of the crucible 12, and power supplied to the heating unit 25a and power supplied to the heating unit 25b. and a second operation (“B”) for making the temperature of the solution 20 in contact with the bottom surface of the crucible 12 higher than the temperature of the solution 20 in contact with the side surface of the crucible 12 by adjusting the above.

Regarding this point, the present embodiment has another feature in that the power supplied to the heating unit 25a and the power supplied to the heating unit 25b are adjusted. That is, still another characteristic point is that the electric power supplied to the heating unit 25a and the electric power supplied to the heating unit 25b are made different so as to realize the first operation and the second operation described above. In other words, still another characteristic point is that the first operation and the second operation described above are realized only by adopting a configuration in which the power supplied to the heating unit 25a and the power supplied to the heating unit 25b are different. at the point. As a specific example, as shown in FIGS. 5 to 8, in realizing the first operation, the "first power" supplied to the heating unit 25a is replaced by the "second power" supplied to the heating unit 25b. make it larger than On the other hand, in realizing the second operation, the "third electric power" supplied to the heating unit 25a is made larger than the "fourth electric power" supplied to the heating unit 25b. At this time, the "first power" is greater than the "third power" and the "second power" is less than the "fourth power". Thereby, in a specific example, each of the first operation and the second operation can be realized.

As described above, according to still another characteristic point, the temperature of each of the solution 20 in contact with the side surface and the bottom surface of the crucible 12 can be adjusted simply by changing the power supplied to the heating unit 25a and the power supplied to the heating unit 25b. The temperature can be periodically changed between the temperature at which miscellaneous crystals precipitate and the temperature at which miscellaneous crystals dissolve. As a result, according to the present embodiment, it is possible to reduce the precipitated miscellaneous crystals and suppress the enlargement of the miscellaneous crystals, thereby suppressing deterioration in quality of the silicon carbide single crystal caused by the miscellaneous crystals.

<Verification of effects based on experimental results>
Next, based on actual experimental results rather than simulation results, it will be described that according to the present embodiment, miscellaneous crystals generated in the solution can be reduced.

A feature of this embodiment is that, for example, as shown in FIGS. 5 and 8, by adjusting the power supplied to the heating unit 25a and the power supplied to the heating unit 25b, the solution that is in contact with the side surface of the crucible 12 is heated. By adjusting the first operation (“A”) to make the temperature of the solution 20 higher than the temperature of the solution 20 in contact with the bottom surface of the crucible 12 and the power supplied to the heating unit 25a and the power supplied to the heating unit 25b, The point is to alternately switch between the second operation (“B”) in which the temperature of the solution 20 in contact with the bottom surface of the crucible 12 is made higher than the temperature of the solution 20 in contact with the side surface of the crucible 12 .

Here, hereinafter, the above-described first operation (first heating process) will be referred to as "side surface heating", and the above-described second operation (second heating process) will be referred to as "bottom surface heating"). Further, the operation of alternately switching between the first operation and the second operation (characteristic of the present embodiment) is called "heating switching".

FIG. 16 is a graph showing the power supply current supplied to the coil 14a in the experiment. In FIG. 16, the horizontal axis indicates time (hour), while the vertical axis indicates the value (A) of the power supply current supplied to the coil 14a.

In FIG. 16, the solid line indicates the relationship between power supply current and time in "side heating". The dotted line indicates the relationship between power supply current and time in "bottom heating", and the dashed line indicates the relationship between power supply current and time in "heating switching".

FIG. 17 is a graph showing the power supply current supplied to the coil 14b in the experiment. In FIG. 17, the horizontal axis indicates time (hour), while the vertical axis indicates the value (A) of the power supply current supplied to the coil 14a.

In FIG. 17, the solid line indicates the relationship between power supply current and time in "side heating". The dotted line indicates the relationship between power supply current and time in "bottom heating", and the dashed line indicates the relationship between power supply current and time in "heating switching".

Experiments were conducted under the conditions shown in FIGS. 16 and 17 described above. The switching of the power supply current was performed so that the timing was 6 hours for side heating, 10 minutes for switching, 5 hours for 50 minutes for bottom heating, 10 minutes for switching, 5 hours for 50 minutes for side heating, 10 minutes for switching, and 5 hours for 50 minutes for bottom heating. Then, after the solution contained in the crucible was cooled and solidified, a cross-sectional view of the whole crucible was obtained. The experimental results will be described below using cross-sectional views obtained in this way.

FIG. 18 is a cross-sectional view of crucible 12 containing solidified solution 20 in "side heating". In FIG. 18, no miscellaneous crystals were observed in the region RA on the side surface of the crucible 12, and it was confirmed that the side surface of the crucible 12 was melted by a maximum of about 3 mm. On the other hand, in the region RB on the bottom surface of the crucible 12, miscellaneous crystals of about 2 mm were confirmed.

This is because the temperature of the solution 20 in contact with the side surface of the crucible 12 is higher than the temperature of the solution 20 in contact with the bottom surface of the crucible 12 in the "side heating", so miscellaneous crystals are dissolved on the side surface of the crucible 12, This can be qualitatively understood from the fact that miscellaneous crystals are deposited on the bottom surface of the crucible 12 .

Next, FIG. 19 is a cross-sectional view of the crucible 12 containing the solidified solution 20 in "bottom heating". In FIG. 19, it was confirmed that miscellaneous crystals having a large size of about 5 mm were found in the area RA on the side surface of the crucible 12 . On the other hand, no miscellaneous crystals were observed in the region RB on the bottom surface of the crucible 12, and it was confirmed that the bottom surface of the crucible 12 was melted by a maximum of about 4 mm. Furthermore, in the region RC on the bottom surface of the crucible 12, miscellaneous crystals of about 1 mm were confirmed.

This means that in the "bottom heating", the temperature of the solution 20 in contact with the bottom of the crucible 12 is higher than the temperature of the solution 20 in contact with the side of the crucible 12. This can be understood qualitatively because even if crystals are generated, they are small-sized miscellaneous crystals, while large-sized miscellaneous crystals tend to precipitate on the side surface of the crucible 12 .

Next, FIG. 20 is a cross-sectional view of the crucible 12 containing the solidified solution 20 in "heating switching". In FIG. 20, it was confirmed that small-sized miscellaneous crystals were observed in the region RA on the side surface of the crucible 12 and that the side surface of the crucible 12 was melted by about 1 mm at maximum. On the other hand, in the region RB on the bottom surface of the crucible 12, no miscellaneous crystals were observed, and it was confirmed that the bottom surface of the crucible 12 was melted by a maximum of about 2 mm. Also, in the region RC on the bottom surface of the crucible 12, miscellaneous crystals of about 1 mm were observed.

In the “heating switching”, the first operation is to raise the temperature of the solution 20 in contact with the side surface of the crucible 12 higher than the temperature of the solution 20 in contact with the bottom surface of the crucible 12, and the temperature of the solution 20 in contact with the bottom surface of the crucible 12 is increased to A second operation of increasing the temperature of the solution 20 in contact with the side surface is alternated. Therefore, in the "heating switching", the temperature of each of the solutions 20 in contact with the side and bottom surfaces of the crucible 12 can be periodically changed between the temperature at which miscellaneous crystals precipitate and the temperature at which miscellaneous crystals dissolve. . Therefore, as shown in the experimental results shown in FIGS. 18 to 20, "heating switching" can reduce the miscellaneous crystals that precipitate and suppress the enlargement of miscellaneous crystals more than "side heating" and "bottom heating". It can be qualitatively understood that the melting of the crucible 12 can be suppressed.

Based on the above experimental results, according to "heating switching", it is possible to reduce the miscellaneous crystals that precipitate and suppress the enlargement of miscellaneous crystals more than "side heating" and "bottom heating". , that the dissolution of the crucible 12 can also be suppressed. Therefore, according to experimental results, the basic concept of the present embodiment is that it is possible to suppress quality deterioration of silicon carbide single crystals caused by miscellaneous crystals (for example, it is possible to obtain silicon carbide single crystals free of miscellaneous crystals). point) has been proved to be an effective technical idea.

Although the invention made by the present inventor has been specifically described based on the embodiment, the invention is not limited to the above embodiment, and can be variously modified without departing from the gist of the invention. Needless to say.

Reference Signs List 10 container 11 pedestal 12 crucible 12a heat transfer section 13a heat insulating member 13b heat insulating member 13c heat insulating member 14a coil 14b coil 15 crucible lid 15a cylindrical member 15b connecting member 16 crystal holding shaft 16a fin structure 17 thermocouple 18 crucible holding shaft 20 Solution 25a Heating Unit 25b Heating Unit 30 Seed Crystal 40 Silicon Carbide Single Crystal 50 Control Unit 100 Single Crystal Manufacturing Apparatus 200a First Commercial Power Supply 200b Second Commercial Power Supply 201a First AC/DC Converter 201b Second AC/DC Converter 202a First Inverter 202b Second inverter 203a First transformer 203b Second transformer 210 Control unit

Claims (20)

(a) bringing the lower surface of the seed crystal into contact with the solution containing carbon and silicon contained in the crucible by moving downward a shaft having a seed crystal attached to the tip thereof;
(b) growing a single crystal made of silicon carbide on the lower surface of the seed crystal;
A single crystal manufacturing method comprising
(c1) a first heating step of heating the solution so that the temperature of the solution in contact with the side surface of the crucible is higher than the temperature of the solution in contact with the bottom surface of the crucible;
(c2) a second heating step of heating the solution so that the temperature of the solution in contact with the bottom surface of the crucible is higher than the temperature of the solution in contact with the side surface of the crucible;
has
A method for manufacturing a single crystal, wherein the first heating step and the second heating step are alternately switched. In the single crystal manufacturing method according to claim 1,
A single crystal manufacturing apparatus for carrying out the single crystal manufacturing method includes:
a first heating unit that heats the crucible by applying a high-frequency current to a first coil provided at a position facing the side surface of the crucible;
a second heating unit that heats the pedestal by applying a high-frequency current to a second coil provided at a position facing the pedestal that supports the crucible;
has
In the first heating step, the temperature of the solution in contact with the side surface of the crucible is adjusted to the bottom surface of the crucible by adjusting the power supplied to the first heating unit and the power supplied to the second heating unit. above the temperature of the solution in contact with
In the second heating step, by adjusting the power supplied to the first heating unit and the power supplied to the second heating unit, the temperature of the solution in contact with the bottom surface of the crucible is adjusted to the side surface of the crucible. A method for producing a single crystal, wherein the temperature is higher than the temperature of the solution in contact with. In the single crystal manufacturing method according to claim 1 or 2,
In the first heating step, the temperature of the solution in contact with the side surface of the crucible is the temperature at which miscellaneous crystals dissolve, while the temperature of the solution in contact with the bottom surface of the crucible is the temperature at which miscellaneous crystals precipitate. can be,
In the second heating step, the temperature of the solution in contact with the bottom surface of the crucible is a temperature at which miscellaneous crystals dissolve, while the temperature of the solution in contact with the side surface of the crucible is a temperature at which miscellaneous crystals precipitate. A single crystal manufacturing method. In the single crystal manufacturing method according to claim 1,
In the step (b), the first heating step and the second heating step are performed while alternately switching between the first heating step and the second heating step. In the single crystal manufacturing method according to claim 1,
Either one of the first heating step and the second heating step is performed in the step (b) after performing the step (a), while the first heating step and the second heating The other step of the steps is a method for producing a single crystal, wherein the single crystal grown on the lower surface of the seed crystal is separated from the surface of the solution. In the single crystal manufacturing method according to claim 1,
The method for manufacturing a single crystal, wherein alternate switching between the first heating step and the second heating step is performed at predetermined time intervals. In the single crystal manufacturing method according to claim 1,
A single crystal manufacturing apparatus for carrying out the single crystal manufacturing method includes:
a first coil provided at a position facing the side surface of the crucible;
a second coil provided at a position facing the pedestal that supports the crucible;
has
In each of the first heating step and the second heating step, the first coil and the second coil are heated so that a period during which power is supplied to the first coil and a period during which power is supplied to the second coil do not overlap. A single crystal manufacturing method in which power is supplied to each of two coils. In the single crystal manufacturing method according to claim 1,
A single crystal manufacturing apparatus for carrying out the single crystal manufacturing method includes:
a first coil provided at a position facing the side surface of the crucible;
a first inverter for supplying power to the first coil;
a second coil provided at a position facing the pedestal that supports the crucible;
a second inverter for powering the second coil;
a control unit that controls the operation of the first inverter and the operation of the second inverter;
has
The single crystal manufacturing method, wherein each of the first heating step and the second heating step is performed by the exclusive operation of the first inverter and the second inverter by the control unit. In the single crystal manufacturing method according to claim 2,
The method for manufacturing a single crystal, wherein the second coil is provided at a position facing the pedestal arranged below the solution contained in the crucible. In the single crystal manufacturing method according to claim 2,
In the first heating step, the first power supplied to the first heating unit is greater than the second power supplied to the second heating unit,
In the second heating step, the third electric power supplied to the first heating unit is greater than the fourth electric power supplied to the second heating unit,
the first power is greater than the third power,
The method for manufacturing a single crystal, wherein the second power is lower than the fourth power. A single crystal manufacturing apparatus capable of disposing a crucible containing a solution containing carbon and silicon in a container,
a pedestal disposed inside the container;
a first heating unit that heats the crucible placed on the pedestal;
a second heating unit that heats the pedestal;
a control unit that controls power supplied to the first heating unit and power supplied to the second heating unit;
with
The control unit
The power supplied to the first heating unit and the power supplied to the second heating unit are adjusted so that the temperature of the solution in contact with the side surface of the crucible is higher than the temperature of the solution in contact with the bottom surface of the crucible. a first action to
power supplied to the first heating unit and power supplied to the second heating unit so that the temperature of the solution in contact with the bottom surface of the crucible is higher than the temperature of the solution in contact with the side surface of the crucible; a second operation to adjust
A single crystal manufacturing device that alternately switches between In the single crystal manufacturing apparatus according to claim 11,
The first heating unit induction-heats the crucible,
The single crystal manufacturing apparatus, wherein the second heating unit induction-heats the pedestal. In the single crystal manufacturing apparatus according to claim 11 or 12,
The crucible is
a main body that houses the solution;
a heat transfer portion protruding from the bottom of the main body;
has
In the single crystal manufacturing apparatus, by bringing the heat transfer section into contact with the pedestal, the crucible is heated by heat conduction from the pedestal heated by the second heating section via the heat transfer section. Crystal manufacturing equipment. In the single crystal manufacturing apparatus according to claim 13,
The pedestal is
a first region in contact with the heat transfer section;
a second region surrounded by the first region;
a third region surrounding the first region;
including
The single crystal manufacturing apparatus has a heat insulating member in contact with at least one of the second region and the third region. In the single crystal manufacturing apparatus according to claim 11,
The first heating unit includes a first coil,
The second heating unit includes a second coil,
Each of the first operation of the control unit and the second operation of the control unit is performed such that a period for supplying power to the first coil and a period for supplying power to the second coil do not overlap. A single crystal manufacturing apparatus that can be performed by supplying power to each of the first coil and the second coil. In the single crystal manufacturing apparatus according to claim 11,
The first heating unit is
a first coil;
a first inverter for supplying power to the first coil;
including
The second heating unit is
a second coil;
a second inverter for powering the second coil;
including
Each of the first operation of the control unit and the second operation of the control unit can be performed by exclusive operation of the first inverter and the second inverter by the control unit. Device. In the single crystal manufacturing apparatus according to claim 11,
The first heating unit includes a first coil provided at a position capable of facing the side surface of the crucible that can be arranged above the pedestal,
The single-crystal manufacturing apparatus, wherein the second heating unit includes a second coil provided at a position facing the pedestal on which the crucible containing the solution can be arranged. In the single crystal manufacturing apparatus according to claim 11,
In the first operation performed by the control unit, the first power supplied to the first heating unit is greater than the second power supplied to the second heating unit,
In the second operation performed by the control unit, the third power supplied to the first heating unit is greater than the fourth power supplied to the second heating unit,
the first power is greater than the third power,
Said 2nd electric power is a single-crystal manufacturing apparatus smaller than said 4th electric power. A crucible capable of containing a solution containing carbon and silicon,
a main body that houses the solution;
a heat transfer portion protruding from the bottom of the main body;
A crucible. A crucible according to claim 19,
The crucible, wherein the heat transfer section has a function of conducting heat from the heated pedestal to the main body section.

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