JP7732480B2 - Silicon single crystal manufacturing method and silicon single crystal manufacturing apparatus - Google Patents

Description

The present invention relates to a method for producing silicon single crystals and a silicon single crystal production apparatus.

The MCZ (magnetically coupled Czochralski) method, in which a horizontal magnetic field is applied to a silicon melt, is sometimes used as a method for producing silicon single crystals. When a horizontal magnetic field is applied to a silicon melt using the MCZ method, the direction of convection in the silicon melt in a virtual plane perpendicular to the direction of application of the horizontal magnetic field can be clockwise (hereinafter sometimes referred to as "right-vortex mode") or counterclockwise (hereinafter sometimes referred to as "left-vortex mode").

Whether the convection mode is right-handed or left-handed is random, and the concentration of oxygen incorporated into the silicon single crystal varies depending on the convection mode and the furnace environment. To obtain silicon single crystals with a stable oxygen concentration, it is important to control the convection mode of the silicon melt during pulling. For this reason, various methods for controlling the convection mode of the silicon melt in the crucible have been investigated (see, for example, Patent Document 1).

Patent Document 1 discloses a method of fixing the convection mode to either the right-handed or left-handed vortex mode by making the thermal environment inside the furnace of a manufacturing device asymmetrical with respect to the central axis of the crucible, thereby eliminating variations in oxygen concentration due to the convection mode. Specifically, Patent Document 1 discloses a method using a heating unit in which the heat generation amount of a first heating region on one side of an imaginary plane perpendicular to the direction in which a horizontal magnetic field is applied within the silicon melt is set to different values from the heat generation amount of a second heating region on the other side.

Patent document 1 discloses a method for differentiating the heat generation amounts of the first heating area and the second heating area by differentiating the contact resistance values of the power supply unit that supplies power to the heat generation elements of each of the first and second heating areas.
The methods disclosed for varying the contact resistance values include varying the total number of electrical resistance adjustment members interposed between the terminals and electrodes connected to the heat generating parts of the first and second heating regions, varying the fastening force of the fastening means that fasten the terminals and electrodes connected to the heat generating parts of the first and second heating regions, and varying the material or thickness of the adhesive layer that joins the terminals and electrodes connected to the heat generating parts of the first and second heating regions.

Patent Document 1 also discloses another method for differentiating the heat generation amounts of the first and second heating regions, which involves varying at least one of the length and total number of slits provided in the first and second heating regions.

Japanese Patent Application Laid-Open No. 2022-102247

However, with the method of varying the contact resistance value disclosed in Patent Document 1, when achieving the desired contact resistance value, there is a possibility that the convection mode of the silicon melt may deviate from the desired state due to factors such as variations in work processes and deterioration of components. Furthermore, the method of varying at least one of the length and total number of slits disclosed in Patent Document 1 requires a heating unit with a special shape.

The present invention aims to provide a silicon single crystal manufacturing method and silicon single crystal manufacturing apparatus that can produce silicon single crystals with a stable oxygen concentration without significantly modifying the conventional equipment configuration.

The silicon single crystal manufacturing method of the present invention is a method for pulling a silicon single crystal while applying a horizontal magnetic field to a silicon melt using a silicon single crystal manufacturing apparatus, wherein the silicon single crystal manufacturing apparatus comprises: a crucible that contains the silicon melt; a heater that is formed in a cylindrical shape surrounding the crucible and is arranged so that the central axis of the cylinder is coaxial with the central axis of the crucible; and first, second, third, and fourth support electrodes that are formed in a rod shape from a conductive material and support the heater; the heater comprises a first heating portion, a second heating portion, a third heating portion, and a fourth heating portion that have the same heating characteristics and are aligned in the circumferential direction of the crucible; the first support electrode connects the first heating portion and the second heating portion to the positive terminal of a power source; the second support electrode connects the second heating portion and the third heating portion to the negative terminal of the power source or ground; The electrodes connect the third heating element and the fourth heating element to the positive electrode, and the fourth support electrode connects the fourth heating element and the first heating element to the negative electrode or the ground. At least one of the first, second, third, and fourth support electrodes is configured as a thin-diameter support electrode, at least a portion of which is thinner than the remaining support electrodes. The silicon single crystal manufacturing method includes a silicon melt generating step of heating the silicon raw material in the rotating crucible while the heater has a non-uniform heat distribution to generate the silicon melt, a magnetic field application step of starting to apply the horizontal magnetic field to the silicon melt, and a growing step of growing the silicon single crystal by pulling up a seed crystal immersed in the silicon melt once the direction of convection of the silicon melt in an imaginary plane perpendicular to the central magnetic field line of the horizontal magnetic field has been fixed in one direction.

In the silicon single crystal manufacturing method of the present invention, the silicon single crystal manufacturing apparatus preferably includes a cylindrical heat insulating material surrounding the heater and configured to provide a non-uniform heat transfer distribution to the heater.

In the method for producing silicon single crystals of the present invention, it is preferable that the heat insulating material be configured to have uniform thermal conductivity throughout, and be arranged so that the central axis of the heat insulating material is not coaxial with the central axis of the crucible.

In the method for producing silicon single crystals of the present invention, it is preferable that the heat insulating material is configured so that the thermal conductivity of one portion is different from the thermal conductivity of the other portion, and that the central axis of the heat insulating material is positioned coaxially with the central axis of the crucible.

In the method for producing a silicon single crystal of the present invention, it is preferable that the first support electrode, the second support electrode, the third support electrode, the fourth support electrode, and the heat insulating material are configured such that, when the rotation speed of the crucible when the horizontal magnetic field is applied to the silicon melt is R (rpm), and the time from the start of application of the horizontal magnetic field until the horizontal magnetic field, having a magnetic field strength at which the direction of convection is fixed, acts on the silicon melt is T (minutes), a maximum heating temperature position, where the heating temperature for the crucible is the highest in a planar view, is located on the opposite side of the rotation direction of the crucible with respect to a first horizontal imaginary line that is perpendicular to the central magnetic field line and includes the central axis of the crucible, and an angle θ (°) formed by a second horizontal imaginary line connecting the central axis of the crucible and the maximum heating temperature position and the first horizontal imaginary line satisfies the following formula (1):
θ=360×R×T… (1)

The silicon single crystal manufacturing apparatus of the present invention is a silicon single crystal manufacturing apparatus that pulls a silicon single crystal while applying a horizontal magnetic field to a silicon melt, and includes: a crucible that contains the silicon melt; a heater that is formed in a cylindrical shape surrounding the crucible and is arranged so that the central axis of the cylinder is aligned with the central axis of the crucible; and first, second, third, and fourth support electrodes that are formed in a rod shape from a conductive material and support the heater. The heater has first, second, third, and fourth heating elements that have the same heating characteristics and are aligned in the circumferential direction of the crucible. The device includes a heating section, wherein the first support electrode connects the first heating section and the second heating section to the positive electrode of a power source, the second support electrode connects the second heating section and the third heating section to the negative electrode of the power source or to earth, the third support electrode connects the third heating section and the fourth heating section to the positive electrode, and the fourth support electrode connects the fourth heating section and the first heating section to the negative electrode or earth, and at least one of the first, second, third, and fourth support electrodes is configured as a thin-diameter support electrode, at least a portion of which is thinner than the remaining support electrodes.

The silicon single crystal manufacturing apparatus of the present invention preferably includes a cylindrical heat insulating material surrounding the heater and configured to provide a non-uniform heat transfer distribution to the heater.

In the silicon single crystal manufacturing apparatus of the present invention, it is preferable that the heat insulating material is configured to have a uniform thermal conductivity throughout, and is positioned so that the central axis of the heat insulating material is not coaxial with the central axis of the crucible.

In the silicon single crystal manufacturing apparatus of the present invention, it is preferable that the heat insulating material is configured so that the thermal conductivity of one portion is different from the thermal conductivity of the other portion, and that the central axis of the heat insulating material is positioned coaxially with the central axis of the crucible.

In the silicon single crystal manufacturing apparatus of the present invention, the first support electrode, the second support electrode, the third support electrode, the fourth support electrode, and the heat insulating material are preferably configured such that, when R (rpm) is the rotation speed of the crucible when the horizontal magnetic field is applied to the silicon melt, and T (minutes) is the time from when the application of the horizontal magnetic field starts until the horizontal magnetic field acts on the silicon melt, the horizontal magnetic field having a magnetic field strength at which the direction of convection of the silicon melt is fixed in an imaginary plane perpendicular to the central magnetic field line of the horizontal magnetic field, the maximum heating temperature position at which the heating temperature for the crucible is highest in a planar view is located on the opposite side of the rotation direction of the crucible with respect to a first horizontal imaginary line that is perpendicular to the central magnetic field line of the horizontal magnetic field and includes the central axis of the crucible, and the angle θ (°) formed by the first horizontal imaginary line and a second horizontal imaginary line connecting the central axis of the crucible and the maximum heating temperature position satisfies the following formula (2):
θ=360×R×T… (2)

1 is a vertical cross-sectional view showing a schematic configuration of a silicon single crystal manufacturing apparatus according to an embodiment. FIG. 2 is a plan view schematically illustrating a heater, a heat insulating material, and a magnetic field applying unit according to the embodiment. FIG. 1 is a perspective view of a heater according to an embodiment. FIG. 2 is a side view showing a low resistance support electrode and a high resistance support electrode according to the embodiment. FIG. 3 is an equivalent circuit diagram of a heater and a power supply unit according to the embodiment. 1A and 1B are explanatory diagrams of preferred configurations of first to fourth support electrodes and heat insulating materials according to an embodiment, in which (A) is a plan view showing the position of the highest heating temperature, and (B) is a graph showing the relationship between the elapsed time from the start of application of a horizontal magnetic field and the magnetic field strength. 1 is a block diagram of a main part of a silicon single crystal manufacturing apparatus according to an embodiment. 1 is a flowchart showing a method for manufacturing a silicon single crystal according to an embodiment. FIG. 10 is a plan view showing the position of a high-temperature melt region according to an embodiment. 1A and 1B are graphs showing the incidence rates of each convection mode in the comparative example and examples 1 to 8, and FIG. 1B shows the incidence rates of each convection mode in the comparative example and examples 9 to 16.

[Embodiment]
[Configuration of silicon single crystal manufacturing equipment]
First, the configuration of a silicon single crystal manufacturing apparatus according to an embodiment of the present invention will be described.
FIG. 1 is a vertical cross-sectional view showing the schematic configuration of a silicon single crystal manufacturing apparatus. FIG. 2 is a plan view schematic showing a heater, a heat insulating material, and a magnetic field application unit. FIG. 3 is a perspective view of a heater. FIG. 4 is a side view showing a low-resistance support electrode and a high-resistance support electrode. FIG. 5 is an equivalent circuit diagram of a heater and a power supply unit. FIG. 6 is an explanatory diagram of a preferred configuration of first to fourth support electrodes and a heat insulating material, where (A) is a plan view showing the maximum heating temperature position, and (B) is a graph showing the relationship between the elapsed time from the start of application of a horizontal magnetic field and the magnetic field strength. FIG. 7 is a block diagram of the main parts of a silicon single crystal manufacturing apparatus.

The silicon single crystal manufacturing apparatus 1 shown in Figure 1 is an apparatus for manufacturing silicon single crystals SM using the MCZ method, and pulls up a silicon single crystal SM having a neck portion SM1, a shoulder portion SM2, a straight body portion SM3, and a tail portion (not shown) while applying a horizontal magnetic field to silicon melt M. The silicon single crystal manufacturing apparatus 1 includes a chamber 2 that forms the outer shell, a crucible 3 located in the center of the chamber 2, a heater 4 located around the inside of the crucible 3, and a temperature measurement unit 15.

Crucible 3 has a double structure consisting of an outer graphite crucible 3A and an inner quartz crucible 3B, with silicon melt M contained in quartz crucible 3B. Graphite crucible 3A and quartz crucible 3B are cylindrical containers with bottoms that are circular in plan view from vertically above. Crucible 3 is fixed to the upper end of support shaft 5, which can rotate and move up and down.

The heater 4 is a graphite heater formed in a roughly cylindrical shape and placed around the crucible 3. A cylindrical heat insulator 6 is provided on the outside of the heater 4 and along the inner surface of the chamber 2. The heat insulator 6 is configured to provide uniform thermal conductivity throughout.

Above the crucible 3, a pulling shaft 7 is arranged coaxially with the support shaft 5. The pulling shaft 7 is made of wire or the like. A seed crystal SC is attached to the lower end of the pulling shaft 7.

A cylindrical heat shield 8 is disposed in the chamber 2 above the silicon melt M in the crucible 3 to surround the silicon single crystal SM being grown.
The thermal shield 8 blocks radiant heat from the silicon melt M, the sidewall of the crucible 3, and the heater to the silicon single crystal SM during growth, thereby suppressing a temperature rise of the silicon single crystal SM.

A gas inlet 2A is provided at the top of chamber 2, through which an inert gas such as argon gas is introduced into chamber 2. An exhaust port 2B is provided at the bottom of chamber 2, through which gas within chamber 2 is sucked in and exhausted by a vacuum pump (not shown).

The temperature measurement unit 15 measures the temperatures at the first measurement point P1 and the second measurement point P2. The radial positions of the first measurement point P1 and the second measurement point P2 are between the outer peripheral surface of the silicon single crystal SM to be grown and the inner peripheral surface of the opening of the thermal shield 8. As will be described later, the convection mode of the silicon melt M can be confirmed by measuring the temperatures at the first measurement point P1 and the second measurement point P2. For example, if the convection direction of the silicon melt M is fixed to clockwise in FIG. 1 by heating the silicon melt M with the heater 4, that is, if the convection mode of the silicon melt M becomes a right-handed vortex mode, the measured temperature at the first measurement point P1 will be higher than the measured temperature at the second measurement point P2. On the other hand, if the convection direction of the silicon melt M is fixed to counterclockwise by heating the silicon melt M with the heater 4, that is, if the convection mode becomes a left-handed vortex mode, the measured temperature at the first measurement point P1 will be lower than the measured temperature at the second measurement point P2.

The temperature measurement unit 15 includes a pair of reflecting units 15A and a pair of radiation thermometers 15B.
The reflecting section 15A is installed inside the chamber 2. The reflecting section 15A is preferably installed so that the angle between the reflecting surface 15C and the horizontal plane is 40° or more and 50° or less.
The radiation thermometer 15B is installed outside the chamber 2. The radiation thermometer 15B receives radiant light L incident through a quartz window 2C (see FIG. 1) provided in the chamber 2, and measures the temperatures of the first measurement point P1 and the second measurement point P2 in a non-contact manner.

As shown in FIG. 2 , the silicon single crystal manufacturing apparatus 1 further includes a magnetic field application unit 16 .
The magnetic field application unit 16 includes a first magnetic body 16A and a second magnetic body 16B, each of which is formed by an electromagnetic coil. The first magnetic body 16A and the second magnetic body 16B are disposed outside the chamber 2 so as to face each other across the crucible 3. The magnetic field application unit 16 applies a horizontal magnetic field such that, in a plan view, a central magnetic field line 16C passing through the central axis of the coil intersects with a central axis 3C of the crucible 3 (hereinafter, sometimes referred to as the "crucible central axis 3C") and is directed from the second magnetic body 16B toward the first magnetic body 16A (the upward direction indicated by the arrow indicating the central magnetic field line 16C in FIG. 2, and the direction from the front to the back of the page in FIG. 1).

The heater 4 is positioned so that its central axis 4C (hereinafter sometimes referred to as the "heater central axis 4C") is coaxial with the crucible central axis 3C. Meanwhile, the insulating material 6 is positioned so that its central axis 6C (hereinafter sometimes referred to as the "insulating material central axis 6C") is not coaxial with the crucible central axis 3C and the heater central axis 4C. In other words, the heater 4 is positioned so that the gap between it and the crucible 3 is uniform in the circumferential direction of the crucible 3. Furthermore, the insulating material 6 is positioned so that the gap between it and the heater 4 is nonuniform in the circumferential direction of the heater 4. Due to this arrangement of the heater 4 and insulating material 6, the heat removal distribution from the heater 4 by the insulating material 6 is nonuniform in the circumferential direction of the crucible 3.

As shown in Figures 2 and 3, the heater 4 has a heat generating portion 40, which is a cylindrical graphite heater. The heat generating portion 40 is formed with a uniform thickness around the entire circumference. The heat generating portion 40 has multiple upper slits 41 extending downward from the upper end and multiple lower slits 42 extending upward from the lower end, which are formed alternately in the circumferential direction. Each upper slit 41 and each lower slit 42 has the same width and the same cutting depth in the vertical direction. The spacing between the upper slits 41 and the lower slits 42 is also uniform around the entire circumference of the heater 4.

The heating section 40 is divided into four parts by a first vertical imaginary plane VF1 and a second vertical imaginary plane VF2 that are orthogonal to each other and include the heater central axis 4C, and includes a first heating section 40A, a second heating section 40B, a third heating section 40C, and a fourth heating section 40D that have the same heating characteristics. The same heating characteristics mean that the same parts generate heat at the same temperature when the same amount of power is supplied.
The first to fourth heat generating sections 40A to 40D have the same total number of upper slits 41 and lower slits 42. In this embodiment, two upper slits 41 and three lower slits 42 are formed in each of the first to fourth heat generating sections 40A to 40D, and the total number of upper slits 41 and lower slits 42 is five for each section.
In this way, the resistance values of the first to fourth heat generating portions 40A to 40D, which have the same shape, are the same.
The heater 4 is disposed so that the heater central axis 4C is coaxial with the crucible central axis 3C and so that the central magnetic field line 16C overlaps the first vertical imaginary plane VF1 in plan view. Note that the heater 4 may be disposed so that the central magnetic field line 16C does not overlap the first vertical imaginary plane VF1 in plan view.

The silicon single crystal manufacturing apparatus 1 includes a power supply unit 9 that supplies power to the heat generating unit 40. The power supply unit 9 includes a first terminal 91A, a second terminal 91B, a third terminal 91C, and a fourth terminal 91D, a first support electrode 92A, a second support electrode 92B, a third support electrode 92C, and a fourth support electrode 92D, and four nuts 93A, 93B, 93C, and 93D. The first terminal 91A to the fourth terminal 91D are arranged at 90° intervals along the circumferential direction of the heat generating unit 40.
The first terminal 91A to the fourth terminal 91D extend downward from the lower end of the portion of the heat generating portion 40 that is partitioned by the two lower slits 42, and are formed integrally with the heat generating portion 40. The first terminal 91A to the fourth terminal 91D also include connection portions 911A to 911D that are bent inward at a right angle from the lower end, and through holes 912A to 912D are formed in the connection portions 911A to 911D.
That is, the heater 4 is constructed using a graphite heater in which the cylindrical heat generating portion 40, which is a heater element, and the first to fourth terminals 91A to 91D, which are heater legs, are integrally molded.

As shown in Fig. 3, the first to fourth support electrodes 92A to 92D are rod-shaped electrodes made of conductive carbon. Of the first to fourth support electrodes 92A to 92D, one to three are low-resistance support electrodes 92L shown in the upper diagram of Fig. 4, and the remaining support electrodes are high-resistance support electrodes 92H as small-diameter support electrodes shown in the lower diagram of Fig. 4.
The low-resistance support electrode 92L includes an electrode body 921L, a clamping portion 922, a male threaded portion 923, and a power supply connection portion 924. The electrode body 921L is formed in a cylindrical shape. The clamping portion 922 is formed in a cylindrical shape with a larger diameter and a shorter height than the electrode body 921L, and is provided at one axial end of the electrode body 921L. The male threaded portion 923 is provided so as to extend from the clamping portion 922 to the opposite side of the electrode body 921L. The power supply connection portion 924 is provided at the other axial end of the electrode body 921L.
The high-resistance support electrode 92H has a configuration including a small-diameter electrode body 921H instead of the electrode body 921L. The small-diameter electrode body 921H is formed in a generally cylindrical shape with at least a portion of the diameter smaller than the diameter of the electrode body 921L, and is configured so that the resistance value of the high-resistance support electrode 92H is higher than the resistance value of the low-resistance support electrode 92L. From the viewpoint of supporting the heater 4, the diameter of the smallest portion of the small-diameter electrode body 921H is preferably 50 mm or more.
As is well known, the resistance values of the low resistance support electrode 92L and the high resistance support electrode 92H can be set to desired values by adjusting the diameter or length of the electrode body 921L and the small diameter electrode body 921H.
The first to fourth support electrodes 92A to 92D, each formed of a high-resistance support electrode 92H or a low-resistance support electrode 92L, have carbon nuts 93A to 93D screwed onto male threaded portions 923 inserted into through holes 912A to 912D of the terminals 91A to 91D, and the terminals 91A to 91D are clamped between the nuts 93A to 93D and the clamping portions 922, thereby electrically connecting the terminals 91A to 91D and supporting the heater 4.

As shown in FIG. 5, the power supply unit 9 further includes a power supply 94, a first anode wiring 95A, a first cathode wiring 95B, a second anode wiring 95C, and a second cathode wiring 95D.
One ends of the first and second anode wires 95A and 95C are connected to the power supply connectors 924 of the first and third support electrodes 92A and 92C, for example, via connectors not shown, and the other ends are connected to the anodes of the power supply 94. One ends of the first and second cathode wires 95B and 95D are connected to the power supply connectors 924 of the second and fourth support electrodes 92B and 92D, for example, via connectors not shown, and the other ends are connected to the cathodes of the power supply 94. The other ends of the first and second cathode wires 95B and 95D may be connected to earth.

5 , if the fourth support electrode 92D is configured as a high-resistance support electrode 92H and the first to third support electrodes 92A to 92C are configured as low-resistance support electrodes 92L, the current flowing from the power source 94 to the fourth support electrode 92D will be smaller than the current flowing from the power source 94 to the second support electrode 92B. As a result, the first and second heating portions 40A and 40B will generate heat at a higher temperature than the third and fourth heating portions 40C and 40D, and the heat distribution will be non-uniform in the circumferential direction of the crucible 3.
In this way, by configuring one to three of the first support electrode 92A to the fourth support electrode 92D as high-resistance support electrodes 92H, the position where the heating temperature for the crucible 3 is highest in a planar view (hereinafter sometimes referred to as the "highest heating temperature position") can be set to the desired position.
Furthermore, as described above, the insulating material 6 is arranged so that the insulating material central axis 6C is not positioned on the same axis as the crucible central axis 3C and the heater central axis 4C, and is configured so that the heat extraction distribution from the heater 4 is uneven in the circumferential direction of the crucible 3.
Therefore, by adjusting the position of the high resistance support electrode 92H relative to the crucible 3 and the position where the gap between the insulating material 6 and the heater 4 is smallest, the maximum heating temperature of the crucible 3 and the maximum heating temperature position can be adjusted more precisely.
In the following, the state in which the crucible 3 is heated so that a maximum heating temperature position exists by adjusting the heat generation distribution of the heater 4 and the heat removal distribution from the heater 4 by the heat insulating material 6 may be referred to as a "non-uniform heating state." On the other hand, the state in which the crucible 3 is heated so that a maximum heating temperature position does not exist, that is, the state in which the crucible 3 is heated so that the heating distribution of the crucible 3 is uniform in the circumferential direction of the crucible 3, may be referred to as a "uniform heating state."

Here, because the thermal conductivity of the crucible 3 is high and the thickness of the entire crucible 3 is uniform, the temperature of the crucible 3 heated in a non-uniform heating state by the heater 4 changes continuously. Therefore, the region heated to the highest temperature at the maximum heating temperature position in the silicon melt M (hereinafter may be referred to as the "high-temperature melt region") and the region heated to the lowest temperature (hereinafter may be referred to as the "low-temperature melt region") face each other across the center of the silicon melt M.
The positions of the high-resistance support electrode 92H and the heat insulator 6 relative to the crucible 3 are preferably set so that the melt temperature difference, obtained by subtracting the temperature of the melt low-temperature region from the temperature of the melt high-temperature region, is 3° C. or more, and more preferably 5° C. or more. This is because setting the melt temperature difference to 3° C. or more makes it easier to fix the convection mode to one mode regardless of the timing of application of the horizontal magnetic field, and setting it to 5° C. or more makes it easier to fix the convection mode to one mode regardless of the timing of application of the horizontal magnetic field.

It is preferable that the first support electrode 92A to the fourth support electrode 92D and the heat insulating material 6 are configured so that the heating amounts of the first part 31A and the second part 31B of the crucible 3, which are located on both sides of the first vertical imaginary plane VF1 shown in Figures 1 and 2, are different from each other. As shown in Figure 6 (A), the first support electrode 92A to the fourth support electrode 92D and the heat insulating material 6 are more preferably configured so that the maximum heating temperature position 3MA, where the heating temperature for the crucible 3 is the highest in a planar view, is located on the right side of the crucible central axis 3C, and is located in the opposite direction of the rotation direction D1 of the crucible 3 with respect to a first horizontal imaginary line VL1 that is perpendicular to the central magnetic field line 16C and includes the crucible central axis 3C, and so that the angle θ (°) formed between the first horizontal imaginary line VL1 and a second horizontal imaginary line VL2 connecting the crucible central axis 3C and the maximum heating temperature position 3MA satisfies the following formula (3).
Alternatively, it is more preferable that the first support electrode 92A to the fourth support electrode 92D and the heat insulating material 6 are configured so that the maximum heating temperature position 3MB, where the heating temperature for the crucible 3 is the highest in a planar view, is located on the left side of the crucible central axis 3C and is located in the opposite direction of the rotation direction D1 with respect to the first horizontal imaginary line VL1, and that the angle θ (°) formed between the first horizontal imaginary line VL1 and a second horizontal imaginary line VL3 connecting the crucible central axis 3C and the maximum heating temperature position 3MB satisfies the following formula (3):
θ=360×R×T… (3)
In equation (3), R is the rotation speed (rpm) of the crucible 3 when the horizontal magnetic field is applied to the silicon melt M. T is the time (minutes) from the start of application of the horizontal magnetic field until the horizontal magnetic field with a magnetic field strength that fixes the direction of convection (hereinafter, may be referred to as "convection direction fixed magnetic field strength K1") acts on the silicon melt M. The convection direction fixed magnetic field strength K1 is 0.05 tesla (500 gauss) or more and 0.15 tesla (1500 gauss) or less.

Here, the reason why the first to fourth support electrodes 92A to 92D and the heat insulating material 6 are configured so that the highest heating temperature positions 3MA and 3MB are located at the positions shown in FIG. 6(A) will be described.
If the crucible 3 is heated in a uniform heating state, the silicon melt M in the crucible 3 is heated uniformly over the entire area in the circumferential direction of the crucible 3 .
In this case, convection occurs in the silicon melt M, rising near the side of the crucible 3 and descending near the center. In a state where no horizontal magnetic field is applied to the silicon melt M, the position of the downward flow changes randomly and may deviate from the center of the crucible 3 due to instability of the convection.
When application of a horizontal magnetic field to the silicon melt M in this state is started so that the magnetic field strength reaches a predetermined magnetic field strength K2, the magnitude of the magnetic field acting on the silicon melt M increases in proportion to the elapsed time from the start of application, as shown in Fig. 6(B) . Then, when a horizontal magnetic field with a convection direction fixing magnetic field strength K1 acts on the silicon melt M, the rotation of the downward flow in the rotation direction D1 is restricted, and eventually the direction of convection in an imaginary plane perpendicular to the application direction of the horizontal magnetic field is fixed.
When the crucible 3 is heated in this uniform heating state, a horizontal magnetic field is applied while the position of the downward flow is changing randomly, and therefore the convection mode changes to either a right vortex mode or a left vortex mode depending on the timing of application.

On the other hand, when the crucible 3 is heated in a non-uniform heating state, even when no horizontal magnetic field is applied to the silicon melt M, an upward flow of the silicon melt M occurs stably on the right side of the crucible 3, and a downward flow occurs stably on the left side of the crucible 3, or an upward flow occurs stably on the left side of the crucible 3, and a downward flow occurs stably on the right side of the crucible 3, and the position of the downward flow does not change randomly as in the case where the crucible 3 is heated in a uniform heating state.
Furthermore, the high-temperature melt region rotates in a rotation direction D1 in accordance with the rotation of the crucible 3 at a rotation speed R (rpm). That is, the region in which an upward flow is generated in the silicon melt M moves from the vicinity of the maximum heating temperature positions 3MA and 3MB in the rotation direction D1 at the rotation speed R (rpm).
As described above, since the maximum heating temperature position 3MA is set to satisfy the above formula (3), when a horizontal magnetic field with a convection-direction fixed magnetic field intensity K1 acts on the silicon melt M after T minutes from the start of application of the horizontal magnetic field, regardless of the timing of application of the horizontal magnetic field, the rotation of the upward flow in the rotation direction D1 is constrained with the melt high-temperature region overlapping the first horizontal virtual line VL1 in a plan view, and eventually the convection is fixed to the counterclockwise direction, resulting in a left-handed vortex mode. Furthermore, since the maximum heating temperature position 3MB is also set to satisfy the above formula (3), when a horizontal magnetic field with a convection-direction fixed magnetic field intensity K1 acts on the silicon melt M after T minutes from the start of application of the horizontal magnetic field, regardless of the timing of application of the horizontal magnetic field, when a horizontal magnetic field with a convection-direction fixed magnetic field intensity K1 acts on the silicon melt M after T minutes from the start of application of the horizontal magnetic field, the rotation of the upward flow in the rotation direction D1 is constrained with the melt high-temperature region overlapping the first horizontal virtual line VL1 in a plan view, and eventually the convection is fixed to the clockwise direction, resulting in a right-handed vortex mode.
In this way, by applying a horizontal magnetic field with a fixed magnetic field strength K1 in the convection direction to the silicon melt M when the high-temperature melt region overlaps the first horizontal virtual line VL1, a left vortex mode or a right vortex mode can be generated more stably than when applying a horizontal magnetic field with a fixed magnetic field strength K1 in the convection direction to the silicon melt M when the high-temperature melt region does not overlap the first horizontal virtual line VL1.

As shown in FIG. 7, the silicon single crystal manufacturing apparatus 1 further includes a raw material supply unit 18, a crucible rotation drive unit 19, a pull-up drive unit 20, an input unit 21, a memory unit 22, and a control unit 23. The control unit 23 is connected to a power supply 94, a radiation thermometer 15B, a magnetic field application unit 16, the raw material supply unit 18, the crucible rotation drive unit 19, the pull-up drive unit 20, the input unit 21, and the memory unit 22 so that various information can be transmitted and received.

The power supply 94 supplies power to the heat generating unit 40 via the power supply unit 9 under the control of the control unit 23 .
The radiation thermometer 15B outputs a signal corresponding to the measurement result to the control unit 23.
The magnetic field applying unit 16 applies a horizontal magnetic field of a predetermined strength to the silicon melt M based on the control of the control unit 23 .
The raw material supply unit 18 charges the silicon raw material into the crucible 3 under the control of the control unit 23 .
The crucible rotation drive unit 19 rotates the crucible 3 at a predetermined speed in a predetermined direction under the control of the control unit 23 .
The lifting drive unit 20 raises and lowers the lifting shaft 7 under the control of the control unit 23. Also, the lifting drive unit 20 rotates the lifting shaft 7 at a predetermined speed in the opposite direction to or the same direction as the rotation direction of the support shaft 5 under the control of the control unit 23.

The input unit 21 is configured, for example, with a touch panel or physical buttons. The input unit 21 is used to input various settings and outputs signals corresponding to the input operations to the control unit 23.

The memory unit 22 is composed of a well-known storage device, such as a hard disk drive (HDD). The memory unit 22 stores various information necessary for controlling the pulling of silicon single crystal SM.

The control unit 23 includes a CPU (Central Processing Unit). The control unit 23 controls the pulling of the silicon single crystal SM by the CPU executing a program stored in the memory unit 22.

[Method for producing silicon single crystal]
Next, a method for manufacturing a silicon single crystal SM using the silicon single crystal manufacturing apparatus 1 will be described. Fig. 8 is a flowchart showing the method for manufacturing a silicon single crystal. In this embodiment, the first to fourth support electrodes 92A to 92D and the heat insulating material 6 are configured so that the maximum heating temperature position is the maximum heating temperature position 3MA shown in Fig. 6(A).

First, the operator operates the input unit 21 to input the pulling conditions for the silicon single crystal SM to be produced.
As shown in FIG. 8, the control unit 23 acquires the inputted pulling condition (step S1).
Thereafter, the control unit 23 performs the manufacturing process of the silicon single crystal SM based on the acquired pulling conditions.
Specifically, the control unit 23 maintains an inert gas atmosphere under reduced pressure inside the chamber 2, turns off the heater 4 (no power is supplied to the heater 4), and controls the raw material supply unit 18 to charge the silicon raw material into the crucible 3 while not applying a horizontal magnetic field, and then controls the crucible rotation drive unit 19 to rotate the crucible 3 in the rotation direction D1 at a rotation speed R (step S2).

Next, the control unit 23 controls the power supply 94 to heat the crucible 3 in a non-uniform heating state using the heat generating element 40 of the heater 4, melting the silicon raw material and generating silicon melt M (step S3: silicon melt generation process). In step S3, when all of the silicon raw material has melted, the region in which an upward flow is occurring in the silicon melt M moves in the rotation direction D1 at a rotation speed R (rpm) from a position near the maximum heating temperature position 3MA.

Then, the control unit 23 controls the magnetic field application unit 16 to start applying a horizontal magnetic field to the silicon melt M so that the magnetic field strength becomes a predetermined magnetic field strength K2 (e.g., 0.3 Tesla) (step S4: magnetic field application process). When a horizontal magnetic field with a convection direction fixed magnetic field strength K1 (e.g., 0.1 Tesla) acts on the silicon melt M through the processing of step S4, the convection of the silicon melt M is fixed counterclockwise, resulting in a left-handed vortex mode.

Next, the control unit 23 determines whether the convection mode of the silicon melt M has been fixed to the left vortex mode based on a signal corresponding to the measurement result from the radiation thermometer 15B (step S5: convection direction confirmation step).
When the control unit 23 determines that the convection mode is not fixed to the left vortex mode (step S5: NO), the control unit 23 performs the process of step S5 again after a predetermined time has elapsed.
On the other hand, when the control unit 23 determines that the convection mode has been fixed to the left-vortex mode (step S6: YES), the control unit 23 controls the pull-up drive unit 20 to grow a silicon single crystal SM while continuing to apply the horizontal magnetic field (step S6: growth process). In step S6, the pull-up drive unit 20, under the control of the control unit 23, raises and lowers the pull-up shaft 7 so as to immerse the seed crystal SC in the silicon melt M and then pull up the seed crystal SC, thereby growing the silicon single crystal SM.

[Effects of the embodiment]
In the silicon single crystal manufacturing apparatus 1, the first heating portion 40A to the fourth heating portion 40D of the heater 4 are electrically connected to a power source 94, and at least one of the first supporting electrode 92A to the fourth supporting electrode 92D that support the heater 4 is composed of a high-resistance supporting electrode 92H.
By configuring the first to fourth support electrodes 92A to 92D in this manner, the current flowing through the high-resistance support electrode 92H can be made smaller than the current flowing through the low-resistance support electrode 92L, thereby making the heating temperatures of the first to fourth heating elements 40A to 40D non-uniform. This allows the crucible 3 to be heated in a non-uniform heating state, and a downward flow of the silicon melt M can be generated in a stable position. Therefore, by applying a horizontal magnetic field to the silicon melt M in which a stable downward flow is generated, the convection mode of the silicon melt M can be fixed in a desired state, and a silicon single crystal SM with a stable oxygen concentration can be produced. Furthermore, since a silicon single crystal SM with a stable oxygen concentration can be produced, the yield of the silicon single crystal SM can be improved, and improved energy efficiency, improved production efficiency, and reduced waste can be achieved.
Furthermore, since a non-uniform heating state can be achieved simply by using the high resistance support electrode 92H as at least one of the first support electrode 92A to the fourth support electrode 92D, a conventional heater 4 can be used and there is no need to significantly modify the conventional device configuration.
Furthermore, the resistance value of the high resistance support electrode 92H can be adjusted to a large value by simply adjusting the diameter of the small diameter electrode body 921H, and the desired non-uniform heating state can be easily achieved.

[Modification]
Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and various improvements and design changes that do not deviate from the gist of the present invention are also included in the present invention.

If multiple of the first support electrode 92A to fourth support electrode 92D are high-resistance support electrodes 92H, the resistance value of at least one high-resistance support electrode 92H may be higher than the resistance values of the other high-resistance support electrodes 92H.

The heat insulating material 6 may be arranged so that the central axis 6C of the heat insulating material is positioned on the same axis as the central axis 3C of the crucible and the central axis 4C of the heater, thereby making the heat extraction distribution for the crucible 3 uniform.
Although an example has been given of a configuration using an insulating material 6 with a uniform thermal conductivity throughout, a cylindrical insulating material configured so that the thermal conductivity of one portion is different from that of the other portions may be arranged so that the central axis of the insulating material is positioned on the same axis as the crucible central axis 3C and the heater central axis 4C, thereby configuring the heat extraction distribution for the crucible 3 to be non-uniform.In this case, the thermal conductivity of the insulating material may be set to satisfy the above formula (3), or may not be set to satisfy it.

Next, we will explain examples of the present invention. Note that the present invention is not limited to these examples.

[Experimental conditions]
[Definition of the position of the high-temperature melt region]
Positions A to H, which represent the positions of the melt high-temperature region in a plan view, are defined as shown in Fig. 9. Position A is a position where the angle between a reference line extending forward in the application direction of the central magnetic field line 16C from the center of the silicon melt M in a plan view and a level line extending from the center of the silicon melt M to position A is 0°. Positions B, C, D, E, F, G, and H are positions rotated by 45°, 90°, 135°, 180°, 225°, 270°, and 315° clockwise from position A.

Comparative Example
First, the silicon single crystal manufacturing apparatus 1 of the above embodiment was prepared.
The first to fourth support electrodes 92A to 92D were all made to have the same thickness, and the heat insulator 6 was arranged so that the heat insulator central axis 6C was positioned on the same axis as the crucible central axis 3C and the heater central axis 4C.
In the comparative example, the crucible 3 is heated in a uniform heating state, so that no high-temperature melt region or low-temperature melt region occurs in the silicon melt M. In other words, under the conditions of the comparative example, the melt temperature difference is 0°C.
Then, by performing the processes of steps S1 to S6 in the manufacturing method of the silicon single crystal SM, a silicon single crystal SM having a straight body portion SM3 with a diameter of 300 mm and a length of 2000 mm was grown. The rotation direction D1 of the crucible 3 is the counterclockwise direction in FIG. 9.

Examples 1 to 16
In Examples 1 to 8, the insulator 6 was positioned so that the insulator central axis 6C was aligned on the same axis as the crucible central axis 3C and the heater central axis 4C. The thicknesses of the first to fourth support electrodes 92A to 92D were adjusted so that the high-temperature melt regions were located at positions A, B, C, D, E, F, G, and H, respectively, and the melt temperature difference was 3°C, and a silicon single crystal SM was grown under the same conditions as in the comparative example.
In Examples 9 to 16, silicon single crystals SM were grown under the same conditions as in Examples 1 to 8, except that the positions of the heat insulator 6 relative to the crucible 3 and heater 4 were adjusted so that the high-temperature melt regions were located at positions A, B, C, D, E, F, G, and H, respectively, and the melt temperature difference was 5°C.

[evaluation]
Before starting the growth of silicon single crystals SM in the comparative example and examples 1 to 16, a horizontal magnetic field was applied at random timing after the generation of silicon melt M, and the convection modes were observed, and the occurrence rate of each convection mode and the stability of the generated vortices were evaluated.
The occurrence rate of each convection mode is shown in Table 1 below and in FIGS. 10(A) and (B), and the evaluation results of the vortex stability are also shown in Table 1.

In the comparative example, the occurrence rates of the right vortex mode and the left vortex mode were almost the same, as shown in Table 1 and Figures 10 (A) and 10(B). In addition, in the comparative example, the direction of the vortex once fixed reversed with a probability of 10% or more.
The reason for this result is thought to be that the crucible 3 was heated in a uniform state, and the position of the downward flow changed randomly, resulting in either a right-wing vortex mode or a left-wing vortex mode depending on the timing of application of the horizontal magnetic field.

On the other hand, in Examples 1 to 8, as shown in Table 1 and Figure 10 (A), the difference between the occurrence rate of the right vortex mode and the occurrence rate of the left vortex mode was 10% or more, and it was confirmed that, compared to the comparative example, it was easier to fix the convection mode to one mode regardless of the timing of application of the horizontal magnetic field.
The reason for this result is thought to be that the crucible 3 was heated in an uneven heating state, which fixed the position of the downward flow, increasing the probability that the convection mode would be fixed to one mode regardless of the timing of application of the horizontal magnetic field.

In particular, in Examples 3, 4, 6, and 7, the difference between the occurrence rate of right-handed vortex modes and the occurrence rate of left-handed vortex modes was 30% or more, confirming that, compared to Examples 1, 2, 5, and 8, it was easier to fix a single convection mode regardless of the timing of application of the horizontal magnetic field. Furthermore, in Examples 1, 2, and 5, the direction of a vortex once fixed reversed with a probability of 10% or more, whereas in Examples 3, 4, 6 to 8, the probability of a vortex direction once fixed reversing was less than 10%.

A comparison of the comparative example with Examples 1 to 8 confirmed that by adjusting the thickness of at least the first to fourth support electrodes 92A to 92D, among the thicknesses of the first to fourth support electrodes 92A to 92D and the position of the heat insulator 6, so that the melt temperature difference is 3°C or more, it is possible to easily fix the convection mode to one mode, and to produce silicon single crystals with a stable oxygen concentration without making major changes to the conventional device configuration.

10 (B), in Examples 9 to 16, the difference between the occurrence rate of the right vortex mode and the occurrence rate of the left vortex mode was 40% or more, and it was confirmed that the direction of convection was more easily fixed in one direction regardless of the timing of application of the horizontal magnetic field compared to the comparative example and Examples 1 to 8. Furthermore, in Examples 9 to 16, the probability that the direction of the vortex once fixed would reverse was less than 10%.
The reason for these results is thought to be that the melt temperature difference was larger than in Examples 1 to 8, which resulted in a stronger downward flow than in Examples 1 to 8, and the position of the downward flow was fixed, thereby increasing the probability that the direction of the convection would be fixed in one direction regardless of the timing of application of the horizontal magnetic field.

In particular, in Examples 10 to 12 and 14 to 16, the difference between the occurrence rate of the right vortex mode and the occurrence rate of the left vortex mode was 70% or more, and it was confirmed that, compared to Examples 9 and 13, it was easier to fix the direction of convection in one direction regardless of the timing of application of the horizontal magnetic field.
The reason for these results is thought to be that in Examples 9 and 13, the melt high-temperature region is located on the central magnetic field line 16C in a planar view, and therefore the downward flow that occurs on the opposite side of the melt high-temperature region from the center of the silicon melt M occurs in the vicinity of the central magnetic field line 16C, whereas in Examples 10 to 12 and 14 to 16, the melt high-temperature region is located to the right or left of the central magnetic field line 16C in a planar view, and therefore the downward flow occurs in a region away from the central magnetic field line 16C, and therefore, compared to Examples 9 and 13, the probability that the direction of convection will be fixed in one direction is further increased.

Furthermore, in Examples 11, 12, 15, and 16, the difference between the occurrence rate of the right vortex mode and the occurrence rate of the left vortex mode was 100%, and it was confirmed that, compared to Examples 10 and 14, it was even easier to fix the direction of convection in one direction regardless of the timing of application of the horizontal magnetic field.
The reason for these results is believed to be as follows: As described above, the melt high-temperature region rotates in the rotation direction D1 as the crucible 3 rotates. Furthermore, the melt high-temperature region in Example 10 is located forward in the rotation direction D1 relative to the melt high-temperature regions in Examples 11 and 12, while the melt high-temperature region in Example 14 is located forward in the rotation direction D1 relative to the melt high -temperature regions in Examples 15 and 16. Therefore, when a horizontal magnetic field of 0.1 Tesla, which is the convection-direction fixing magnetic field strength K1, is applied in Examples 11, 12, 15, and 16, the position of the melt high-temperature region is closer to the first horizontal virtual line VL1 than in Examples 10 and 14, which is believed to further increase the probability that the convection direction is fixed in one direction regardless of the timing of application of the horizontal magnetic field.

Furthermore, in Examples 12 and 16, the direction of the vortex once fixed does not reverse, and it was confirmed that, compared to Examples 11 and 15, it is easier to stably generate a right vortex mode or a left vortex mode regardless of the timing of application of the horizontal magnetic field.
The reason for these results is thought to be that the high-temperature melt region in Example 11 is located forward in the direction of rotation D1 relative to the high-temperature melt region in Example 12, and the high-temperature melt region in Example 15 is located forward in the direction of rotation D1 relative to the high-temperature melt region in Example 16.Therefore, the position of the high-temperature melt region when a horizontal magnetic field of 0.1 Tesla is applied in Examples 12 and 16 is closer to the first horizontal virtual line VL1 than in Examples 11 and 15, making it easier to stably generate a right-vortex mode or a left-vortex mode regardless of the timing of application of the horizontal magnetic field.

From a comparison between Examples 1 to 8 and Examples 9 to 16, it was confirmed that by adjusting the thicknesses of the first support electrode 92A to the fourth support electrode 92D and the positions of the heat insulating material 6 so that the melt temperature difference is 5°C or more, it is possible to more easily fix the convection mode to one mode, and that it is possible to produce silicon single crystals with a more stable oxygen concentration without making major changes to the conventional device configuration.
It is believed that similar results to those of this embodiment can be obtained by using a cylindrical insulating material in which the thermal conductivity of one part is different from that of the other part instead of the insulating material 6 having a uniform thermal conductivity overall.

The silicon single crystal manufacturing method and silicon single crystal manufacturing apparatus of the present invention can produce silicon single crystals with a stable oxygen concentration without making major changes to the configuration of conventional equipment, thereby improving the yield of silicon single crystals, improving energy efficiency, increasing production efficiency, and reducing waste.

1...silicon single crystal manufacturing apparatus, 3...crucible, 3C...crucible central axis, 3MA, 3MB...maximum heating temperature position, 4...heater, 40A...first heating element, 40B...second heating element, 40C...third heating element, 40D...fourth heating element, 4C...heater central axis, 6...insulating material, 6C...insulating material central axis, 92A...first supporting electrode, 92B...second supporting electrode, 92C...third supporting electrode, 92D...fourth supporting electrode, 92H...high-resistance supporting electrode (narrow-diameter supporting electrode), 94...power source, M...silicon melt, SM...silicon single crystal, VL1...first horizontal imaginary line, VL2, VL3...second horizontal imaginary lines.

Claims (10)

A method for producing a silicon single crystal, which uses a silicon single crystal production apparatus to pull up a silicon single crystal while applying a horizontal magnetic field to a silicon melt,
The silicon single crystal manufacturing apparatus comprises:
a crucible for containing the silicon melt;
a heater formed in a cylindrical shape surrounding the crucible, the central axis of the cylindrical heater being positioned coaxially with the central axis of the crucible;
a first support electrode, a second support electrode, a third support electrode, and a fourth support electrode each formed in a rod shape from a conductive material and supporting the heater;
the heater includes a first heating portion, a second heating portion, a third heating portion, and a fourth heating portion, which have the same heating characteristics and are arranged in a circumferential direction of the crucible;
the first support electrode connects the first heat generating portion and the second heat generating portion to a positive electrode of a power source;
the second support electrode connects the second heat generating portion and the third heat generating portion to the negative electrode of the power source or to a ground;
the third support electrode connects the third heat generating portion and the fourth heat generating portion to the positive electrode;
the fourth support electrode connects the fourth heat generating portion and the first heat generating portion to the negative electrode or the ground;
at least one of the first support electrode, the second support electrode, the third support electrode, and the fourth support electrode is configured as a small-diameter support electrode having at least a portion thinner than the remaining support electrodes;
The method for producing a silicon single crystal comprises:
a silicon melt generating step of heating the silicon raw material in the rotating crucible with the heater generating heat in a non-uniform state to generate the silicon melt;
a magnetic field application step of starting to apply the horizontal magnetic field to the silicon melt;
a growing step of growing the silicon single crystal by pulling up a seed crystal immersed in the silicon melt once the direction of convection of the silicon melt in an imaginary plane perpendicular to the central magnetic field line of the horizontal magnetic field has been fixed in one direction. 2. The method for producing a silicon single crystal according to claim 1,
The silicon single crystal manufacturing apparatus is provided with a cylindrical heat insulating material that surrounds the heater and is configured to provide a non-uniform heat dissipation distribution to the heater. 3. The method for producing a silicon single crystal according to claim 2,
A method for producing a silicon single crystal, wherein the insulating material is configured to have a uniform thermal conductivity throughout and is arranged so that the central axis of the insulating material is not coaxial with the central axis of the crucible. 3. The method for producing a silicon single crystal according to claim 2,
A method for producing a silicon single crystal, wherein the insulating material is configured so that the thermal conductivity of one portion is different from the thermal conductivity of another portion, and the central axis of the insulating material is positioned on the same axis as the central axis of the crucible. The method for producing a silicon single crystal according to any one of claims 2 to 4,
The first support electrode, the second support electrode, the third support electrode, the fourth support electrode, and the heat insulating material are
The rotation speed of the crucible when the horizontal magnetic field is applied to the silicon melt is R (rpm),
When the time from when the application of the horizontal magnetic field is started until the horizontal magnetic field having a magnetic field strength at which the direction of the convection is fixed acts on the silicon melt is T (minutes),
a maximum heating temperature position where the heating temperature for the crucible is the highest in a planar view is located on the opposite side of the rotation direction of the crucible with respect to a first horizontal imaginary line that is perpendicular to the central magnetic field line and includes the central axis of the crucible, and an angle θ (°) formed between a second horizontal imaginary line connecting the central axis of the crucible and the maximum heating temperature position and the first horizontal imaginary line satisfies the following formula (1):
θ=360×R×T… (1) A silicon single crystal manufacturing apparatus that pulls up a silicon single crystal while applying a horizontal magnetic field to a silicon melt,
a crucible for containing the silicon melt;
a heater formed in a cylindrical shape surrounding the crucible, the central axis of the cylindrical heater being positioned coaxially with the central axis of the crucible;
a first support electrode, a second support electrode, a third support electrode, and a fourth support electrode each formed in a rod shape from a conductive material and supporting the heater;
the heater includes a first heating portion, a second heating portion, a third heating portion, and a fourth heating portion, which have the same heating characteristics and are arranged in a circumferential direction of the crucible;
the first support electrode connects the first heat generating portion and the second heat generating portion to a positive electrode of a power source;
the second support electrode connects the second heat generating portion and the third heat generating portion to the negative electrode of the power source or to a ground;
the third support electrode connects the third heat generating portion and the fourth heat generating portion to the positive electrode;
the fourth support electrode connects the fourth heat generating portion and the first heat generating portion to the negative electrode or the ground;
At least one of the first support electrode, the second support electrode, the third support electrode, and the fourth support electrode is configured as a thin-diameter support electrode, at least a portion of which is thinner than the remaining support electrodes. 7. The silicon single crystal manufacturing apparatus according to claim 6,
The silicon single crystal manufacturing apparatus includes a cylindrical heat insulating material that surrounds the heater and is configured to provide a non-uniform heat dissipation distribution to the heater. The silicon single crystal manufacturing apparatus according to claim 7,
A silicon single crystal manufacturing apparatus, wherein the heat insulating material is configured to have a uniform thermal conductivity throughout, and is positioned so that the central axis of the heat insulating material is not coaxial with the central axis of the crucible. The silicon single crystal manufacturing apparatus according to claim 7,
A silicon single crystal manufacturing apparatus in which the insulating material is configured so that the thermal conductivity of one portion is different from the thermal conductivity of another portion, and the central axis of the insulating material is positioned coaxially with the central axis of the crucible. The silicon single crystal manufacturing apparatus according to any one of claims 7 to 9,
The first support electrode, the second support electrode, the third support electrode, the fourth support electrode, and the heat insulating material are
The rotation speed of the crucible when the horizontal magnetic field is applied to the silicon melt is R (rpm),
When the time from when the application of the horizontal magnetic field is started until the horizontal magnetic field acts on the silicon melt, the horizontal magnetic field having a magnetic field strength at which the direction of convection of the silicon melt is fixed in an imaginary plane perpendicular to the central magnetic field line of the horizontal magnetic field, is T (minutes),
a maximum heating temperature position where the heating temperature for the crucible is the highest in a planar view is located on the opposite side of the rotation direction of the crucible with respect to a first horizontal imaginary line that is perpendicular to the central magnetic field line of the horizontal magnetic field and includes the central axis of the crucible, and an angle θ (°) formed between a second horizontal imaginary line connecting the central axis of the crucible and the maximum heating temperature position and the first horizontal imaginary line satisfies the following formula (2):
θ=360×R×T… (2)