Method for producing single crystal silicon and device for producing single crystal silicon

Abstract

Provided is a method for producing a single crystal silicon by heating a rotating crucible using a single crystal silicon production apparatus in a state in which the distribution of heat generated by a heater is not uniform to generate a silicon melt, and starting applying a horizontal magnetic field to the silicon melt to grow a single crystal silicon, the silicon single crystal manufacturing apparatus includes a cylindrical heater surrounding a crucible and first to fourth support electrodes supporting the heater, the heater includes first to fourth heating units, the first support electrode connects the first and second heating units to a positive electrode of a power source, the second support electrode connects the second and third heating units to a negative electrode of the power source, and the third support electrode connects the third and fourth heating units to the positive electrode. The fourth support electrode connects the fourth and first heat generating units to the negative electrode, and at least one of the first to fourth support electrodes is configured from a thin-diameter support electrode having at least a portion thereof thinner than the remaining support electrodes.

Description

Technical Field

[0001] This invention relates to a method and apparatus for manufacturing monocrystalline silicon. Background Technology

[0002] As a method for manufacturing monocrystalline silicon, the MCZ (Magnetic Field Applied Czekowski) method, which applies a horizontal magnetic field to molten silicon, is sometimes used. When applying a horizontal magnetic field to molten silicon using the MCZ method, there are cases where the convection direction in the virtual plane within the molten silicon, orthogonal to the direction of the applied horizontal magnetic field, is clockwise (hereinafter, sometimes referred to as the "right vortex mode") and counterclockwise (hereinafter, sometimes referred to as the "left vortex mode").

[0003] Whether the convection mode becomes a right-hand vortex mode or a left-hand vortex mode is random, causing the oxygen concentration entering the monocrystalline silicon to deviate depending on the convection mode and the furnace environment. In order to obtain monocrystalline silicon with a stable oxygen concentration, controlling the convection mode of the silicon melt during pulling becomes important. Therefore, various methods for controlling the convection mode of the silicon melt in the crucible have been studied (for example, see Patent Document 1).

[0004] Patent Document 1 discloses a method in which the convection mode is fixed to either a right-hand vortex mode or a left-hand vortex mode by making the thermal environment inside the furnace of the manufacturing apparatus non-axisymmetric with respect to the central axis of the crucible, thereby eliminating fluctuations in oxygen concentration caused by the convection mode. Specifically, Patent Document 1 discloses a method using a heating section in which the heat output of a first heating region on one side and a second heating region on the other side of a virtual plane orthogonal to the direction of application of a horizontal magnetic field within the molten silicon are set to different values.

[0005] Patent Document 1 discloses a method for making the heat generation of the first heating region and the second heating region different, which involves making the contact resistance value of the power supply section that supplies power to the heating part of each of the first and second heating regions different.

[0006] Then, as a method to make the contact resistance values ​​different, the following methods are disclosed: a method to make the total number of resistance adjustment components inserted between the terminals and electrodes connected to the heating parts of the first and second heating regions different; a method to make the fastening force of the fastening mechanism for fastening the terminals and electrodes connected to the heating parts of the first and second heating regions different; and a method to make the material or thickness of the adhesive layer for bonding the terminals and electrodes connected to the heating parts of the first and second heating regions different.

[0007] Furthermore, in Patent Document 1, as another method to make the heat generation of the first heating region and the second heating region different, a method is disclosed to make at least one of the lengths and total number of slits provided in the first and second heating regions different.

[0008] Existing technical documents Patent documents Patent document 1: Japanese Patent Application Publication No. 2022-102247. Summary of the Invention

[0009] The technical problem that the invention aims to solve However, in the method for differentiating contact resistance values ​​disclosed in Patent Document 1, when the contact resistance value is set to a desired value, the convection pattern of the molten silicon may change from the desired state due to factors such as operational errors and component deterioration. Furthermore, in the method for differentiating at least one of the length and total number of slits disclosed in Patent Document 1, a heating element with a special shape is required.

[0010] The purpose of this invention is to provide a method and apparatus for manufacturing monocrystalline silicon with stable oxygen concentration, without significantly altering the structure of conventional apparatus.

[0011] Solutions for solving technical problems The method for manufacturing monocrystalline silicon of the present invention uses a monocrystalline silicon manufacturing apparatus to simultaneously pull monocrystalline silicon while applying a horizontal magnetic field to molten silicon. In this method, the monocrystalline silicon manufacturing apparatus includes: a crucible for containing the molten silicon; a heater formed in a cylindrical shape surrounding the crucible and arranged such that the central axis of the cylindrical shape is coaxial with the central axis of the crucible; and a first support electrode, a second support electrode, a third support electrode, and a fourth support electrode, formed in 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 having the same heating characteristics and arranged along the outer periphery of the crucible. The first support electrode connects the first heating portion and the second heating portion to the positive terminal of a power supply, and the second support electrode connects the second heating portion and the third heating portion to the negative terminal of the power supply or ground. The third supporting electrode connects the third and fourth heating parts to the positive electrode, and the fourth supporting electrode connects the fourth heating part and the first heating part to the negative electrode or the ground wire. At least one of the first, second, third, and fourth supporting electrodes is composed of at least a portion of thin-diameter supporting electrodes with a diameter smaller than the other supporting electrodes. The method for manufacturing single-crystal silicon includes: a silicon melt generation step, in which silicon raw material in a rotating crucible is heated to generate the silicon melt under a state of uneven heat distribution in the heater; a magnetic field application step, in which the horizontal magnetic field is applied to the silicon melt; and a cultivation step, in which the convection direction of the silicon melt in a virtual plane orthogonal to the central magnetic field line of the horizontal magnetic field is fixed in one direction, and the single-crystal silicon is cultivated by lifting a seed crystal liquid in the silicon melt.

[0012] In the method for manufacturing monocrystalline silicon according to the present invention, it is preferable that the monocrystalline silicon manufacturing apparatus includes a heat-insulating material, the heat-insulating material being formed in a cylindrical shape surrounding the heater and configured to make the heat dissipation distribution to the heater uneven.

[0013] In the method for manufacturing monocrystalline silicon of the present invention, it is preferable that the heat insulation material is configured to make the overall thermal conductivity uniform and that the central axis of the heat insulation material is not located on the same axis as the central axis of the crucible.

[0014] In the method for manufacturing monocrystalline silicon of the present invention, it is preferable that the heat insulation material is configured such that the thermal conductivity of a portion is different from that of the other portion, and is configured such that the central axis of the heat insulation material is on the same axis as the central axis of the crucible.

[0015] In the method for manufacturing monocrystalline silicon of the present invention, preferably, the first supporting electrode, the second supporting electrode, the third supporting electrode, the fourth supporting electrode and the heat insulation material are configured such that: when the rotational speed of the crucible is R (rpm) when the horizontal magnetic field is applied to the molten silicon, and the time from the start of applying the horizontal magnetic field to the time when the horizontal magnetic field of a magnetic field strength that fixes the convection direction acts on the molten silicon is T (minutes), the position of the highest heating temperature of the crucible when viewed from above is located on the opposite side of the rotation direction of the crucible relative to the first horizontal dashed line that is orthogonal to the central magnetic field line and includes the central axis of the crucible, and the angle θ (°) between the second horizontal dashed line connecting the central axis of the crucible and the position of the highest heating temperature and the first horizontal dashed line satisfies the following formula (1).

[0016] θ = 360 × R × T … (1).

[0017] The monocrystalline silicon manufacturing apparatus of the present invention applies a horizontal magnetic field to molten silicon while simultaneously pulling monocrystalline silicon. The apparatus comprises: a crucible for containing the molten silicon; a heater formed in a cylindrical shape surrounding the crucible and arranged such that the central axis of the cylindrical shape is coaxial with the central axis of the crucible; and a first support electrode, a second support electrode, a third support electrode, and a fourth support electrode, formed in rod shape from a conductive material and supporting the heater. The heater comprises a first heating portion, a second heating portion, a third heating portion, and a fourth heating portion having the same heating characteristics and arranged along the outer periphery of the crucible. The first supporting electrode connects the first heating element and the second heating element to the positive terminal of the power supply. The second supporting electrode connects the second heating element and the third heating element to the negative terminal or ground of the power supply. The third supporting electrode connects the third heating element and the fourth heating element to the positive terminal. The fourth supporting electrode connects the fourth heating element and the first heating element to the negative terminal or ground. At least one of the first, second, third, and fourth supporting electrodes is composed of at least a portion of a thin-diameter supporting electrode that is thinner than the other supporting electrodes.

[0018] In the monocrystalline silicon manufacturing apparatus of the present invention, it is preferable that the apparatus includes a heat-insulating material formed in a cylindrical shape surrounding the heater and configured to make the heat dissipation distribution to the heater uneven.

[0019] In the monocrystalline silicon manufacturing apparatus of the present invention, it is preferable that the heat insulation material is configured to make the overall thermal conductivity uniform and is arranged such that the central axis of the heat insulation material is not on the same axis as the central axis of the crucible.

[0020] In the monocrystalline silicon manufacturing apparatus of the present invention, it is preferable that the heat insulation material is configured such that the thermal conductivity of a portion is different from that of the other portion, and is configured such that the central axis of the heat insulation material is on the same axis as the central axis of the crucible.

[0021] In the single-crystal silicon manufacturing apparatus of the present invention, preferably, the first support electrode, the second support electrode, the third support electrode, the fourth support electrode and the heat insulation material are configured as follows: when the rotational speed of the crucible is R (rpm) when the horizontal magnetic field is applied to the silicon molten liquid, and the time from the start of applying the horizontal magnetic field to the time when the horizontal magnetic field of a magnetic field strength that fixes the convection direction acts on the silicon molten liquid is T (minutes), the position of the highest heating temperature of the crucible when viewed from above is located on the opposite side of the rotational direction of the crucible relative to the first horizontal dashed line that is orthogonal to the central magnetic field line of the horizontal magnetic field and includes the central axis of the crucible, and the angle θ (°) between the second horizontal dashed line connecting the central axis of the crucible and the position of the highest heating temperature and the first horizontal dashed line satisfies the following formula (2).

[0022] θ=360×R×T…(2). Attached Figure Description

[0023] Figure 1 This is a longitudinal sectional view showing the general structure of the monocrystalline silicon manufacturing apparatus involved in the embodiment.

[0024] Figure 2 This is a top view schematic diagram showing the heater, insulation material, and magnetic field application part involved in the embodiment.

[0025] Figure 3 This is a perspective view of the heater involved in the implementation method.

[0026] Figure 4 This is a side view showing the low-resistance support electrode and the high-resistance support electrode involved in the embodiment.

[0027] Figure 5 This is an equivalent circuit diagram of the heater and power supply unit involved in the implementation method.

[0028] Figure 6A This is an explanatory diagram of the preferred structure of the first to fourth support electrodes and the heat insulation material involved in the embodiment, and is a top view showing the position of the highest heating temperature.

[0029] Figure 6B This is an explanatory diagram of the preferred structure of the first to fourth support electrodes and the heat insulation material involved in the embodiment, and a graph showing the relationship between the elapsed time from the start of the application of the horizontal magnetic field and the magnetic field strength.

[0030] Figure 7 This is a block diagram of the main parts of the monocrystalline silicon manufacturing apparatus involved in the implementation method.

[0031] Figure 8 This is a flowchart illustrating a method for manufacturing monocrystalline silicon according to the embodiments.

[0032] Figure 9 This is a top view showing the location of the high-temperature region of the molten liquid involved in the embodiment.

[0033] Figure 10A It is a graph showing the occurrence rate of each convection mode in the comparative examples and examples 1 to 8 involved in the embodiments.

[0034] Figure 10B It is a graph showing the occurrence rate of each convection mode in the comparative examples and examples 9 to 16 involved in the embodiments. Detailed Implementation

[0035] [Implementation Method] [Structure of a single-crystal silicon manufacturing apparatus] First, the structure of the monocrystalline silicon manufacturing apparatus according to the embodiments of the present invention will be described.

[0036] Figure 1 This is a longitudinal sectional view showing the general structure of a single-crystal silicon manufacturing apparatus. Figure 2 This is a top view schematic diagram showing the heater, insulation material, and magnetic field application part. Figure 3 This is a 3D view of the heater. Figure 4 This is a side view showing the low-resistance support electrode and the high-resistance support electrode. Figure 5 This is the equivalent circuit diagram of the heater and power supply unit. Figure 6A This is an explanatory diagram of the preferred structure of the first to fourth supporting electrodes and the insulation material, and a top view showing the position of the highest heating temperature. Figure 6B This is an explanatory diagram of the preferred structure of the first to fourth supporting electrodes and the insulation material, and a graph showing the relationship between the elapsed time from the start of the application of the horizontal magnetic field and the magnetic field strength. Figure 7 This is a block diagram of the main parts of a monocrystalline silicon manufacturing apparatus.

[0037] Figure 1 The single-crystal silicon manufacturing apparatus 1 shown is an apparatus for manufacturing single-crystal silicon SM using the MCZ method. It applies a horizontal magnetic field to a molten silicon M while simultaneously lifting the single-crystal silicon SM, which has a neck SM1, a shoulder SM2, a straight body SM3, and a tail (not shown). The single-crystal silicon manufacturing apparatus 1 includes a chamber 2 forming a shell, a crucible 3 disposed in the center of the chamber 2, a heater 4 disposed around the crucible 3, and a temperature measuring unit 15.

[0038] Crucible 3 is a double-layered structure consisting of an outer graphite crucible 3A and an inner quartz crucible 3B, with the molten silicon M contained within the quartz crucible 3B. Both the graphite crucible 3A and the quartz crucible 3B are bottomed cylindrical containers, appearing circular in a top view taken from above. Crucible 3 is fixed to the upper end of a rotatable and height-adjustable support shaft 5.

[0039] The heater 4 is a graphite heater formed into a generally cylindrical shape and disposed around the crucible 3. A cylindrical insulating material 6 is disposed on the outer side of the heater 4 along the inner surface of the chamber 2. The insulating material 6 is configured to make the overall thermal conductivity uniform.

[0040] Above the crucible 3, a lifting shaft 7 is arranged on the same axis as the support shaft 5. The lifting shaft 7 is formed of wire or the like. The seed crystal SC is installed at the lower end of the lifting shaft 7.

[0041] A cylindrical heat shield 8 is disposed in the chamber 2, surrounding the growing monocrystalline silicon SM above the molten silicon M in the crucible 3.

[0042] The heat shield 8 suppresses the temperature rise of the growing monocrystalline silicon SM by blocking radiant heat from the molten silicon M, the sidewall of the crucible 3 and the heater.

[0043] A gas inlet 2A is provided at the upper part of chamber 2 for introducing inert gases such as argon into chamber 2. An exhaust port 2B is provided at the lower part of chamber 2 for drawing and discharging gases from chamber 2 by driving a vacuum pump (not shown).

[0044] Temperature measurement unit 15 measures the temperatures of 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 planned-grown monocrystalline silicon SM and the inner peripheral surface of the opening of the heat shield 8. As will be described later, the convection pattern of the silicon molten liquid M can be confirmed by measuring the temperatures of the first measurement point P1 and the second measurement point P2. For example, when the convection direction of the silicon molten liquid M is fixed by heating it with heater 4, Figure 1 When the convection mode of the molten silicon M changes to a right-hand vortex mode (clockwise), the measured temperature at the first measuring point P1 becomes higher than the measured temperature at the second measuring point P2. Furthermore, when the convection direction of the molten silicon M is fixed counterclockwise by heating it with heater 4 (i.e., when the convection mode changes to a left-hand vortex mode), the measured temperature at the first measuring point P1 becomes lower than the measured temperature at the second measuring point P2.

[0045] The temperature measuring unit 15 includes a pair of reflectors 15A and a pair of radiation thermometers 15B.

[0046] The reflector 15A is disposed inside the chamber 2. The reflector 15A is preferably disposed such that the angle between the reflector surface 15C and the horizontal plane is 40° or more and 50° or less.

[0047] A radiation thermometer 15B is disposed outside chamber 2. The radiation thermometer 15B receives signals via a quartz window 2C disposed in chamber 2 (reference). Figure 1 The incident radiation L is used to measure the temperature of the first measurement point P1 and the second measurement point P2 in a non-contact manner.

[0048] like Figure 2 As shown, the single-crystal silicon manufacturing apparatus 1 further includes a magnetic field application unit 16.

[0049] The magnetic field applying unit 16 includes a first magnetic body 16A and a second magnetic body 16B, each composed of an electromagnetic coil. The first magnetic body 16A and the second magnetic body 16B are disposed facing each other across the crucible 3 on the outside of the chamber 2. The magnetic field applying unit 16 applies a horizontal magnetic field such that, when viewed from above, the central magnetic field line 16C passing through the central axis of the coil intersects the central axis 3C of the crucible 3 (hereinafter, sometimes referred to as "crucible central axis 3C"), with the direction being from the second magnetic body 16B toward the first magnetic body 16A. Figure 2 The arrow in the diagram indicates the upward direction of the central magnetic field line 16C. Figure 1 (From the front to the back of the paper).

[0050] The heater 4 is configured such that its central axis 4C (hereinafter, sometimes referred to as "heater central axis 4C") is on the same axis as the crucible central axis 3C. On the other hand, the insulating material 6 is configured such that its central axis 6C (hereinafter, sometimes referred to as "insulating material central axis 6C") is not on the same axis as the crucible central axis 3C and the heater central axis 4C. That is, the gap between the heater 4 and the crucible 3 is uniform in the circumferential direction of the crucible 3. Furthermore, the gap between the insulating material 6 and the heater 4 is non-uniform in the circumferential direction of the heater 4. By configuring the heater 4 and the insulating material 6 in this way, the heat dissipation from the heater 4 based on the insulating material 6 becomes non-uniform in the circumferential direction of the crucible 3.

[0051] like Figure 2 and Figure 3 As shown, the heater 4 includes a heating element 40, which is a cylindrical graphite heater. The heating element 40 is formed to have a uniform thickness throughout its circumference. Multiple upper slits 41 extending downwards from the upper end and multiple lower slits 42 extending upwards from the lower end are alternately arranged along the circumference of the heating element 40. The width of each upper slit 41 and each lower slit 42 is equal, and the groove depth along the vertical direction is also equal. Furthermore, the spacing between the upper slits 41 and the lower slits 42 is equal throughout the entire circumference of the heater 4.

[0052] The heating element 40 is divided into four parts by a first vertical virtual plane VF1 and a second vertical virtual plane VF2, which contain the heater's central axis 4C and are orthogonal to each other. Each part comprises a first heating element 40A, a second heating element 40B, a third heating element 40C, and a fourth heating element 40D, all possessing the same heating characteristics. The same heating characteristics mean that when the same amount of electricity is supplied, the same parts heat up at the same temperature.

[0053] The total number of upper slits 41 and lower slits 42 in the first heating section 40A to the fourth heating section 40D is equal. In this embodiment, two upper slits 41 and three lower slits 42 are formed in the first heating section 40A to the fourth heating section 40D, and the total number of upper slits 41 and lower slits 42 is five each.

[0054] In this way, the resistance values ​​of the first heating element 40A to the fourth heating element 40D, which have the same shape, are the same.

[0055] The heater 4 is configured such that the heater's central axis 4C and the crucible's central axis 3C are on the same axis, and that the central magnetic field line 16C overlaps with the first vertical virtual plane VF1 when viewed from above. Alternatively, the heater 4 can be configured such that the central magnetic field line 16C does not overlap with the first vertical virtual plane VF1 when viewed from above.

[0056] The monocrystalline silicon manufacturing apparatus 1 includes a power supply unit 9 that supplies power to the heating element 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 heating element 40.

[0057] Terminals 91A to 91D extend downward from the lower end of the portion divided by the two lower slits 42 in the heating section 40 and are integrally formed with the heating section 40. Furthermore, terminals 91A to 91D have connecting portions 911A to 911D that bend inward at a right angle from the lower end, and through holes 912A to 912D are formed in the connecting portions 911A to 911D.

[0058] That is, the heater 4 is constructed by using a cylindrical heating element 40 as a heater element and a graphite heater integrally formed with the first terminal 91A to the fourth terminal 91D as the bottom of the heater.

[0059] like Figure 3As shown, the first support electrode 92A to the fourth support electrode 92D are conductive carbon rod-shaped electrodes. One or more but no more than three of the first support electrode 92A to the fourth support electrode 92D are... Figure 4 The upper part of the diagram shows a low-resistance support electrode 92L, and the remaining support electrodes are composed of... Figure 4 The high-resistance support electrode 92H shown in the lower part of the figure is configured as a narrow-diameter support electrode.

[0060] The low-resistance support electrode 92L includes an electrode body 921L, a clamping portion 922, an external thread portion 923, and a power connection portion 924. The electrode body 921L is cylindrical. The clamping portion 922 is a cylinder with a larger diameter and lower height than the electrode body 921L, and is located at one axial end of the electrode body 921L. The external thread portion 923 extends from the clamping portion 922 to the side opposite to the electrode body 921L. The power connection portion 924 is located at the other axial end of the electrode body 921L.

[0061] The high-resistance support electrode 92H has a structure in which a narrow-diameter electrode body 921H replaces the electrode body 921L. The narrow-diameter electrode body 921H is formed into a generally cylindrical shape, with at least a portion having a diameter smaller than that of the electrode body 921L, and is configured such that the resistance value of the high-resistance support electrode 92H is higher than that of the low-resistance support electrode 92L. From the viewpoint of supporting the heater 4, the diameter of the thinnest part of the narrow-diameter electrode body 921H is preferably 50 mm or more.

[0062] 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 the desired values ​​by adjusting the diameter or length of the electrode body 921L and the fine-diameter electrode body 921H.

[0063] Regarding the first support electrode 92A to the fourth support electrode 92D, which are composed of a high-resistance support electrode 92H or a low-resistance support electrode 92L, carbon nuts 93A to 93D are screwed into the external threaded portion 923 of the through hole 912A to 912D that is inserted into the terminal 91A to 91D. The terminals 91A to 91D are clamped by the nuts 93A to 93D and the clamping portion 922, thereby electrically connecting to the terminals 91A to 91D and supporting the heater 4.

[0064] like Figure 5 As shown, 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.

[0065] One end of the first and second anode wirings 95A and 95C is connected, for example, via a connector (not shown) to the power connection portion 924 of the first and third support electrodes 92A and 92C, and the other end is connected to the anode of the power supply 94. One end of the first and second cathode wirings 95B and 95D is connected, for example, via a connector (not shown) to the power connection portion 924 of the second and fourth support electrodes 92B and 92D, and the other end is connected to the cathode of the power supply 94. Alternatively, the other end of the first and second cathode wirings 95B and 95D can also be connected to a ground wire.

[0066] exist Figure 5 In the structure of the heater 4 and power supply unit 9 shown, for example, when the fourth support electrode 92D is composed of a high-resistance support electrode 92H and the first support electrode 92A to the third support electrode 92C are composed of low-resistance support electrodes 92L, the current flowing from the power supply 94 to the fourth support electrode 92D becomes less than the current flowing from the power supply 94 to the second support electrode 92B. As a result, the first and second heating parts 40A and 40B heat up at a higher temperature than the third and fourth heating parts 40C and 40D, and the heat distribution becomes uneven in the circumferential direction of the crucible 3.

[0067] In this way, by using one or more but no more than three support electrodes, consisting of a high-resistance support electrode 92H forming one to three support electrodes 92A to 92D, the position where the heating temperature of the crucible 3 is highest when viewed from above (hereinafter sometimes referred to as the "highest heating temperature position") can be set to the desired position.

[0068] Furthermore, as described above, the heat insulation material 6 is configured such that the central axis 6C of the heat insulation material is not on the same axis as the central axis 3C of the crucible and the central axis 4C of the heater, and is configured such that the heat dissipation from the heater 4 is unevenly distributed in the circumferential direction of the crucible 3.

[0069] 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 insulation material 6 and the heater 4 is minimized, the maximum heating temperature and the position of the maximum heating temperature of the crucible 3 can be adjusted more precisely.

[0070] Furthermore, the following state is sometimes referred to as "non-uniform heating state": the crucible 3 is heated to a position with a highest heating temperature by adjusting the heat distribution of the heater 4 and the heat dissipation distribution from the heater 4 based on the insulating material 6. On the other hand, the state in which the crucible 3 is heated in a manner where there is no position with a highest heating temperature, that is, the state in which the heating distribution of the crucible 3 becomes more uniform in the circumferential direction of the crucible 3, is sometimes referred to as "uniform heating state".

[0071] Here, because crucible 3 has high thermal conductivity and uniform thickness, the temperature of crucible 3, which is heated by heater 4 in a non-uniform heating state, changes continuously. Therefore, the region heated to the highest temperature in the silicon molten liquid M (hereinafter, sometimes referred to as the "high temperature region of the molten liquid") and the region heated to the lowest temperature (hereinafter, sometimes referred to as the "low temperature region of the molten liquid") face each other across the center of the silicon molten liquid M.

[0072] The positions of the high-resistance support electrode 92H and the insulating material 6 relative to the crucible 3 are preferably set such that the temperature difference between the high-temperature region and the low-temperature region of the melt is 3°C or more, and more preferably 5°C or more. This is because by setting the melt temperature difference to 3°C or more, it is easier to fix the convection mode into one mode regardless of the timing of the application of the horizontal magnetic field, and by setting it to 5°C or more, it is even easier to fix the convection mode into one mode regardless of the timing of the application of the horizontal magnetic field.

[0073] The first support electrode 92A to the fourth support electrode 92D and the thermal insulation material 6 are preferably configured as follows: Figure 1 and Figure 2 The first part 31A and the second part 31B of the crucible 3, located on opposite sides of the first vertical virtual plane VF1, have different heating amounts. Figure 6A As shown, the first support electrode 92A to the fourth support electrode 92D and the heat insulation material 6 are preferably configured such that, when viewed from above, the highest heating temperature position 3MA of the crucible 3 is located to the right of the crucible central axis 3C and is located on the opposite side of the rotation direction D1 of the crucible 3 relative to the first horizontal dashed line VL1 which is orthogonal to the central magnetic field line 16C and includes the crucible central axis 3C. The angle θ (°) between the second horizontal dashed line VL2 connecting the crucible central axis 3C and the highest heating temperature position 3MA and the first horizontal dashed line VL1 satisfies the following formula (3).

[0074] Alternatively, more preferably, the first support electrode 92A to the fourth support electrode 92D and the heat insulation material 6 are configured such that, when viewed from above, the highest heating temperature position 3MB of the crucible 3 is located to the left of the crucible central axis 3C and is located on the opposite side of the rotation direction D1 relative to the first horizontal dashed line VL1, and the angle θ (°) between the second horizontal dashed line VL3 connecting the crucible central axis 3C and the highest heating temperature position 3MB and the first horizontal dashed line VL1 satisfies the following formula (3).

[0075] θ = 360 × R × T…(3) Additionally, in equation (3), R is the rotational speed (rpm) of crucible 3 when a horizontal magnetic field is applied to the molten silicon M. T is the time (minutes) from the start of applying the horizontal magnetic field until the horizontal magnetic field strength that fixes the convection direction (hereinafter, sometimes referred to as "convection direction fixed magnetic field strength K1") acts on the molten silicon 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.

[0076] Here, the first support electrode 92A to the fourth support electrode 92D and the heat insulation material 6 are configured such that the highest heating temperature positions 3MA and 3MB are located at... Figure 6A The reasons for the indicated location will be explained.

[0077] If crucible 3 is heated under uniform heating conditions, the molten silicon M inside crucible 3 will be uniformly heated along the entire circumference of crucible 3.

[0078] In this scenario, convection occurs in the molten silicon M, rising near the sides of the crucible 3 and descending near the center. Without a horizontal magnetic field applied to the molten silicon M, the position of the descending flow changes erratically and deviates from the center of the crucible 3 due to the instability of the convection.

[0079] When a horizontal magnetic field is applied to the molten silicon M in this state to achieve a specified magnetic field strength K2, such as Figure 6B As shown, the magnitude of the magnetic field acting on the molten silicon M increases proportionally with the elapsed time from the start of application. Then, when a horizontal magnetic field with a fixed magnetic field strength K1 is applied to the molten silicon M in the convection direction, the rotation in the downward flow direction D1 is restricted, and the convection direction in the virtual plane orthogonal to the direction of application of the horizontal magnetic field is finally fixed.

[0080] In this way, when crucible 3 is heated in a uniform heating state, a horizontal magnetic field is applied in a state where the position of the descending flow changes randomly. Therefore, depending on the timing of the application, the convection mode becomes a right vortex mode or a left vortex mode.

[0081] On the other hand, when crucible 3 is heated in a non-uniform heating state, even without applying a horizontal magnetic field to the molten silicon M, an upward flow stably occurs on the right side of crucible 3 and a downward flow stably occurs on the left side of crucible 3, or an upward flow stably occurs on the left side of crucible 3 and a downward flow stably occurs on the right side of crucible 3. The position of the downward flow does not change as randomly as when crucible 3 is heated in a uniform heating state.

[0082] Furthermore, as the crucible 3 rotates at a speed of R (rpm), the high-temperature region of the molten liquid rotates in the direction of rotation D1. That is, the region in the molten silicon M where the upward flow occurs moves from the vicinity of the highest heating temperature positions 3MA and 3MB in the direction of rotation D1 at a speed of R (rpm).

[0083] As described above, the highest heating temperature position 3MA is set to satisfy the above equation (3). Therefore, regardless of the timing of the application of the horizontal magnetic field, when a horizontal magnetic field with a fixed magnetic field strength K1 is applied to the silicon molten liquid M after T minutes from the start of the application of the horizontal magnetic field, the rotation of the upward flow in the rotation direction D1 is restricted when the high-temperature region of the molten liquid overlaps with the first horizontal dashed line VL1 in the view from above. Finally, the convection is fixed in the counterclockwise direction and becomes a left vortex mode. Furthermore, the highest heating temperature position 3MB is also set to satisfy the above equation (3). Therefore, regardless of the timing of the application of the horizontal magnetic field, when a horizontal magnetic field with a fixed magnetic field strength K1 is applied to the silicon molten liquid M after T minutes from the start of the application of the horizontal magnetic field, the rotation of the upward flow in the rotation direction D1 is restricted when the high-temperature region of the molten liquid overlaps with the first horizontal dashed line VL1 in the view from above. Finally, the convection is fixed in the clockwise direction and becomes a right vortex mode.

[0084] In this way, by applying a horizontal magnetic field with a fixed magnetic field strength K1 in the convection direction to the molten silicon M when the high-temperature region of the molten liquid overlaps with the first horizontal dashed line VL1, the left vortex mode or the right vortex mode can be generated more stably than when the horizontal magnetic field with a fixed magnetic field strength K1 in the convection direction is applied to the molten silicon M when the high-temperature region of the molten liquid does not overlap with the first horizontal dashed line VL1.

[0085] like Figure 7 As shown, the monocrystalline silicon manufacturing apparatus 1 further includes a raw material supply unit 18, a crucible rotation drive unit 19, a pull drive unit 20, an input unit 21, a storage unit 22, and a control unit 23. The control unit 23 is connected to the power supply 94, the radiation thermometer 15B, the magnetic field application unit 16, the raw material supply unit 18, the crucible rotation drive unit 19, the pull drive unit 20, the input unit 21, and the storage unit 22 in a manner that enables the transmission and reception of various information.

[0086] The power supply 94 supplies power to the heating element 40 under the control of the control unit 23 and via the power supply unit 9.

[0087] The radiation thermometer 15B outputs a signal corresponding to the measurement result to the control unit 23.

[0088] The magnetic field applying unit 16 applies a horizontal magnetic field of a specified intensity to the molten silicon M under the control of the control unit 23.

[0089] The raw material supply unit 18 feeds silicon raw materials into the crucible 3 under the control of the control unit 23.

[0090] 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.

[0091] The lifting drive unit 20 raises and lowers the lifting shaft 7 under the control of the control unit 23. Furthermore, the lifting drive unit 20, under the control of the control unit 23, rotates the lifting shaft 7 at a predetermined speed in the opposite or the same direction as the rotation direction of the support shaft 5.

[0092] The input unit 21 may be composed of a touch panel or a physical button, for example. The input unit 21 is used for various preset input operations and outputs signals corresponding to the input operations to the control unit 23.

[0093] The storage unit 22 is composed of a known storage device such as an HDD (Hard Disk Drive). The storage unit 22 stores various information required for the pull control of the single-crystal silicon SM.

[0094] The control unit 23 is equipped with a CPU (Central Processing Unit). The control unit 23 controls the pulling of the single-crystal silicon SM by having the CPU execute the program stored in the storage unit 22.

[0095] [Manufacturing method of monocrystalline silicon] Next, the manufacturing method of monocrystalline silicon SM using monocrystalline silicon manufacturing apparatus 1 will be described. Figure 8 This is a flowchart illustrating a method for manufacturing monocrystalline silicon. Furthermore, in this embodiment, the first support electrode 92A to the fourth support electrode 92D and the heat insulation material 6 are configured such that the position of the highest heating temperature is... Figure 6A The case of the highest heating temperature position 3MA shown will be explained.

[0096] First, the operator inputs the pulling conditions of the monocrystalline silicon SM to be manufactured through the operation input unit 21.

[0097] like Figure 8 As shown, the control unit 23 acquires the input lifting conditions (step S1).

[0098] Then, the control unit 23 performs the manufacturing process of single crystal silicon SM according to the acquired pulling conditions.

[0099] Specifically, the control unit 23 maintains an inert gas environment in the chamber 2 under reduced pressure. With the heater 4 turned off (no power is supplied to the heater 4) and no horizontal magnetic field is applied, after the silicon raw material is fed into the crucible 3 by controlling the raw material supply unit 18, the crucible rotation drive unit 19 is controlled to make the crucible 3 rotate at a speed R along the rotation direction D1 (step S2).

[0100] Next, the control unit 23 controls the power supply 94 to heat the crucible 3 under uneven heating conditions through the heating part 40 of the heater 4, so that the silicon raw material melts and generates silicon molten liquid M (step S3: silicon molten liquid generation process). In step S3, if all the silicon raw material melts, the region in the silicon molten liquid M where the upward flow occurs moves from a position near the highest heating temperature position 3MA to the rotational direction D1 at a rotational speed R (rpm).

[0101] Then, the control unit 23 controls the magnetic field application unit 16 to begin applying a horizontal magnetic field to the molten silicon 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). Through the processing of step S4, when a horizontal magnetic field with a fixed convection direction and magnetic field strength K1 (e.g., 0.1 Tesla) acts on the molten silicon M, the convection of the molten silicon M is fixed in a counterclockwise direction and becomes a left vortex mode.

[0102] Next, the control unit 23 determines whether the convection mode of the silicon molten liquid M is fixed as a left vortex mode based on the signal corresponding to the measurement result from the radiation thermometer 15B (step S5: convection direction confirmation process).

[0103] When the control unit 23 determines that the convection mode is not fixed as the left vortex mode (step S5: No), after a specified time, the processing of step S5 is performed again.

[0104] On the other hand, when the control unit 23 determines that the convection mode is fixed as the left vortex mode (step S6: Yes), it continues to apply the horizontal magnetic field while controlling the pull drive unit 20 to grow monocrystalline silicon SM (step S6: growth process). In step S6, the pull drive unit 20 moves the pull shaft 7 up and down according to the control of the control unit 23, so that the seed crystal SC is immersed in the silicon melt M and then the seed crystal SC is pulled up, thereby growing monocrystalline silicon SM.

[0105] [Effects of the Implementation Method] In the monocrystalline silicon manufacturing apparatus 1, the first heating part 40A to the fourth heating part 40D of the heater 4 are electrically connected to the power supply 94, and at least one of the first support electrodes 92A to the fourth support electrode 92D supporting the heater 4 is composed of a high-resistance support electrode 92H.

[0106] By configuring the first support electrode 92A to the fourth support electrode 92D in this manner, the current flowing through the high-resistance support electrode 92H can be made less than the current flowing through the low-resistance support electrode 92L, and the heating temperature of the first heating section 40A to the fourth heating section 40D can be made non-uniform. Therefore, the crucible 3 can be heated under non-uniform heating conditions, and the downward flow of the silicon molten liquid M can occur at a stable position. Therefore, by applying a horizontal magnetic field to the silicon molten liquid M which is flowing downward at a stable position, the convection mode of the silicon molten liquid M can be fixed in a desired state, and a single crystal silicon SM with stable oxygen concentration can be manufactured. Furthermore, since a single crystal silicon SM with stable oxygen concentration can be manufactured, the yield of single crystal silicon SM can be improved, and energy efficiency, production efficiency, and waste reduction can be achieved.

[0107] Furthermore, since a non-uniform heating state can be achieved by using only one of the support electrodes 92A to 92D (the first support electrode 92A to the fourth support electrode 92D) with a high-resistance support electrode 92H, the conventional heater 4 can be used without significantly changing the conventional device structure.

[0108] In addition, the resistance value of the high-resistance support electrode 92H can be significantly adjusted by simply adjusting the diameter of the thin-diameter electrode body 921H, making it easy to achieve the desired non-uniform heating state.

[0109] [Variation Example] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the specific structure is not limited to these embodiments. Various modifications and design changes that do not depart from the spirit of the present invention are also included in the present invention.

[0110] When multiple support electrodes among the first support electrode 92A to the fourth support electrode 92D are formed by high-resistance support electrodes 92H, the resistance value of at least one high-resistance support electrode 92H can also be higher than the resistance value of the other high-resistance support electrodes 92H.

[0111] The heat insulation material 6 can also be configured such that the central axis 6C of the heat insulation material is on the same axis as the central axis 3C of the crucible and the central axis 4C of the heater, and is configured to make the heat dissipation distribution of the crucible 3 more uniform.

[0112] Although a structure using an insulating material 6 with uniform overall thermal conductivity is illustrated, a cylindrical insulating material with a thermal conductivity that is different from that of other parts can also be configured such that the central axis of the insulating material is on the same axis as the crucible central axis 3C and the heater central axis 4C, and the insulating material is configured such that the heat dissipation distribution to the crucible 3 becomes uneven. In this case, the thermal conductivity of the insulating material can be set to satisfy the above equation (3), or it can be set not to satisfy the above equation (3). Example

[0113] Next, embodiments of the present invention will be described. However, the present invention is not limited to these embodiments.

[0114] [Experimental Conditions] [Definition of the location of the high-temperature region of the molten liquid] like Figure 9 As shown, positions A to H, representing the locations of the high-temperature regions of the molten silicon when viewed from above, are defined. Position A is defined as follows: the angle between the reference line extending forward from the center of the molten silicon M in the direction of application of the central magnetic field line 16C and the horizontal line extending from the center of the molten silicon M to position A is 0°. Positions B, C, D, E, F, G, and H are positions rotated clockwise from position A by only 45°, 90°, 135°, 180°, 225°, 270°, and 315°, respectively.

[0115] [Comparative Example] First, prepare the monocrystalline silicon manufacturing apparatus 1 according to the above-described embodiment.

[0116] Then, all the first support electrodes 92A to the fourth support electrodes 92D are made to have the same thickness, and the heat insulation material 6 is configured such that the central axis 6C of the heat insulation material is on the same axis as the central axis 3C of the crucible and the central axis 4C of the heater.

[0117] In the comparative example, since crucible 3 is heated under uniform heating conditions, no high-temperature region or low-temperature region of the molten silicon M is generated. That is, under the conditions of the comparative example, the temperature difference of the molten silicon is 0°C.

[0118] Then, by performing steps S1 to S6 in the above-described method for manufacturing single-crystal silicon SM, a single-crystal silicon SM with a straight body SM3 having a diameter of 300 mm and a length of 2000 mm is grown. Furthermore, the rotation direction D1 of the crucible 3 is... Figure 9 The counterclockwise direction.

[0119] [Examples 1-16] In Examples 1-8, the heat insulation material 6 was configured such that the central axis 6C of the heat insulation material was on the same axis as the central axis 3C of the crucible and the central axis 4C of the heater. Then, the thickness of the first support electrode 92A to the fourth support electrode 92D was adjusted such that the high-temperature region of the molten liquid was located at positions A, B, C, D, E, F, G, and H, respectively, and the temperature difference of the molten liquid was 3°C, thereby growing single-crystal silicon SM under the same conditions as in the comparative example.

[0120] In Examples 9 to 16, except that the position of the insulating material 6 relative to the crucible 3 and the heater 4 was adjusted so that the high temperature region of the molten liquid was located at position A, position B, position C, position D, position E, position F, position G, and position H respectively, and the temperature difference of the molten liquid was 5°C respectively, the single crystal silicon SM was grown under the same conditions as in Examples 1 to 8.

[0121] [evaluate] Before the cultivation of monocrystalline silicon SM in Comparative Examples and Examples 1-16 began, a horizontal magnetic field was applied at any time after the formation of silicon molten liquid M, and convection patterns were observed. The occurrence rate of each convection pattern and the stability of the generated eddies were evaluated.

[0122] The occurrence rates of each convection mode are shown in Table 1 below. Figure 10A and Figure 10B The evaluation results of the stability of the eddy current are shown in Table 1.

[0123] [Table 1] ◎: No eddy current reversal occurred. 〇: Occasionally, eddy current reversal may occur (the probability of reversal is less than 10%). △: Vortex reversal occurs (the probability of reversal is over 10%).

[0124] In the comparative examples, as shown in Table 1, Figure 10A and Figure 10B As shown, the occurrence rates of the right-hand vortex mode and the left-hand vortex mode are almost the same. Furthermore, in the comparative examples, the fixed vortex direction reverses with a probability of more than 10%.

[0125] The reason for this result is that crucible 3 is heated under uniform heating conditions, and the position of the descending flow changes randomly, thus becoming a right vortex mode or a left vortex mode depending on the timing of the application of the horizontal magnetic field.

[0126] On the other hand, in Examples 1 to 8, as shown in Table 1 and Figure 10AAs shown, the difference in the occurrence rate of the right vortex mode compared to the left vortex mode is more than 10%. Compared to the comparative example, it can be confirmed that regardless of the timing of the application of the horizontal magnetic field, the convection mode is easily fixed as one mode.

[0127] The reason for this result is that crucible 3 is heated in a non-uniform heating state, and the position of the downward flow is fixed. Therefore, regardless of the timing of the application of the horizontal magnetic field, the probability of fixing the convection mode into a single mode is increased.

[0128] In particular, in Examples 3, 4, 6, and 7, the difference between the occurrence rate of the right vortex mode and the occurrence rate of the left vortex mode was more than 30%. Compared with Examples 1, 2, 5, and 8, it can be confirmed that it is easier to fix the convection mode into one type regardless of the timing of the application of the horizontal magnetic field. Furthermore, in Examples 1, 2, and 5, the fixed vortex direction reversed with a probability of more than 10%, but in Examples 3, 4, 6-8, the probability of the fixed vortex direction reversing was less than 10%.

[0129] By comparing the comparative examples with Examples 1 to 8, it can be confirmed that by adjusting the thickness of the first support electrode 92A to the fourth support electrode 92D and the arrangement position of the heat insulation material 6, at least the thickness of the first support electrode 92A to the fourth support electrode 92D can be easily fixed into one mode, and single crystal silicon with stable oxygen concentration can be manufactured without significantly changing the conventional device structure.

[0130] Furthermore, in Examples 9 to 16, as shown in Table 1 and Figure 10B As shown, the difference between the occurrence rate of the right vortex mode and the occurrence rate of the left vortex mode is more than 40%. Compared with the comparative examples and Examples 1-8, it can be confirmed that it is easier to fix the convection direction in one direction regardless of the timing of the application of the horizontal magnetic field. In addition, in Examples 9-16, the probability of the fixed vortex direction reversing is less than 10%.

[0131] The reason for this result is that the temperature difference of the melt is greater than that of Examples 1-8, resulting in a stronger downward flow than in Examples 1-8. The location of this downward flow is fixed, thus further increasing the probability of fixing the convection direction to one direction regardless of the timing of the application of the horizontal magnetic field.

[0132] In particular, in Examples 10-12 and 14-16, the difference between the occurrence rate of the right vortex mode and the occurrence rate of the left vortex mode is more than 70%. Compared with Examples 9 and 13, it can be confirmed that it is easier to fix the convection direction in one direction regardless of the timing of the application of the horizontal magnetic field.

[0133] The reason for this result is that in Examples 9 and 13, the high-temperature region of the molten liquid is located on the central magnetic field line 16C when viewed from above. Therefore, the downward flow that occurs on the opposite side of the cooling region of the molten liquid relative to the center of the silicon molten liquid M occurs near the central magnetic field line 16C. In contrast, in Examples 10-12 and 14-16, the high-temperature region of the molten liquid is located to the right or left of the central magnetic field line 16C when viewed from above. The downward flow occurs in the region far from the central magnetic field line 16C. Therefore, compared to Examples 9 and 13, the probability of fixing the convection direction to one direction is further increased regardless of the timing of the application of the horizontal magnetic field.

[0134] 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%. Compared with Examples 10 and 14, it can be confirmed that regardless of the timing of the application of the horizontal magnetic field, it is easier to fix the convection direction in one direction.

[0135] The reasons for this result are as follows. As mentioned above, the high-temperature region of the molten liquid rotates in the rotation direction D1 as the crucible 3 rotates. Furthermore, the high-temperature melting point region of Example 10 is located ahead of the high-temperature melting point region of Examples 11 and 12 in the rotation direction D1, and the high-temperature melting point region of Example 14 is located ahead of the high-temperature melting point region of Examples 15 and 16 in the rotation direction D1. Therefore, it is believed that this is because, in Examples 11, 12, 15, and 16, the position of the high-temperature melting point region when a horizontal magnetic field of 0.1 Tesla with a fixed magnetic field strength K1 for the convection direction is applied is closer to the first horizontal dashed line VL1 than in Examples 10 and 14, further increasing the probability of fixing the convection direction to one direction regardless of the timing of the application of the horizontal magnetic field.

[0136] Furthermore, in Examples 12 and 16, the fixed vortex direction does not reverse. Compared to Examples 11 and 15, it can be confirmed that the right vortex mode or the left vortex mode can be easily and stably generated regardless of the timing of the application of the horizontal magnetic field.

[0137] The reason for this result is that the high-temperature melting point region of Example 11 is located in front of the high-temperature melting point region of Example 12 in the direction of rotation D1, and the high-temperature melting point region of Example 15 is located in front of the high-temperature melting point region of Example 16 in the direction of rotation D1. Therefore, in Examples 12 and 16, the position of the high-temperature melting point region when the 0.1 Tesla horizontal magnetic field is applied is closer to the first horizontal dashed line VL1 than in Examples 11 and 15. Regardless of the timing of the application of the horizontal magnetic field, the right vortex mode or the left vortex mode can be easily and stably generated.

[0138] By comparing Examples 1 to 8 with Examples 9 to 16, it can be confirmed that by adjusting the thickness of the first support electrode 92A to the fourth support electrode 92D and the arrangement of the heat insulation material 6 in such a way that the temperature difference of the melt is more than 5°C, it is easier to fix the convection mode into one mode, and it is possible to manufacture monocrystalline silicon with more stable oxygen concentration without significantly changing the conventional device structure.

[0139] Furthermore, it is believed that even if a cylindrical insulating material with a thermal conductivity that is different from that of other parts is used instead of the insulating material 6 with a uniform overall thermal conductivity, the same result as in this embodiment can be obtained.

[0140] Industrial availability The monocrystalline silicon manufacturing method and apparatus of the present invention can manufacture monocrystalline silicon with stable oxygen concentration without significantly changing the conventional apparatus structure. Therefore, it can improve the yield of monocrystalline silicon and achieve improvements in energy efficiency, production efficiency and waste reduction.

[0141] Explanation of reference numerals in the attached figures 1-Single crystal silicon manufacturing apparatus, 3-Crucible, 3C-Central axis of crucible, 3MA, 3MB-Positions with the highest heating temperature, 4-Heater, 40A-First heating element, 40B-Second heating element, 40C-Third heating element, 40D-Fourth heating element, 4C-Central axis of heater, 6-Insulation material, 6C-Central axis of insulation material, 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 supply, M-Molten silicon, SM-Single crystal silicon, VL1-First horizontal dashed line, VL2, VL3-Second horizontal dashed lines.

Claims

1. A method of producing single crystal silicon, which uses a single crystal silicon production apparatus to pull single crystal silicon while applying a horizontal magnetic field to a silicon melt, in the method of producing single crystal silicon, the single crystal silicon production apparatus has: a crucible that contains the silicon melt; a heater that is formed in a cylindrical shape around the crucible and is arranged so that the center axis of the cylindrical shape and the center axis of the crucible are on the same axis; and a first support electrode, a second support electrode, a third support electrode, and a fourth support electrode that are formed in a rod shape from a material having electrical conductivity and support the heater, the heater has a first heating portion, a second heating portion, a third heating portion, and a fourth heating portion that have the same heating characteristics as each other and are arranged along the peripheral direction of the crucible, the first support electrode connects the first heating portion and the second heating portion to the positive electrode of a power supply, the second support electrode connects the second heating portion and the third heating portion to the negative electrode of the power supply or a ground wire, the third support electrode connects the third heating portion and the fourth heating portion to the positive electrode, the fourth support electrode connects the fourth heating portion and the first heating portion to the negative electrode or the ground wire, at least one of the first support electrode, the second support electrode, the third support electrode, and the fourth support electrode is composed of a thin-diameter support electrode that is thinner than the remaining support electrodes in at least a portion, the method of producing single crystal silicon has: a silicon melt generation step of heating a silicon raw material in the crucible that is rotating in a state in which the heating distribution of the heater is uneven to generate the silicon melt; a magnetic field application step of starting to apply the horizontal magnetic field to the silicon melt; and a cultivation step of cultivating the single crystal silicon by pulling a seed crystal in the silicon melt after fixing the convection direction of the silicon melt in a virtual plane that is orthogonal to the central magnetic line of the horizontal magnetic field to one direction.

2. The method of producing single crystal silicon according to claim 1, wherein the single crystal silicon production apparatus has a heat insulating material that is formed in a cylindrical shape around the heater and is configured so that the heat dissipation distribution to the heater becomes uneven.

3. The method of producing single crystal silicon according to claim 2, wherein the heat insulating material is configured so that the overall thermal conductivity becomes uniform and is arranged so that the center axis of the heat insulating material and the center axis of the crucible are not on the same axis.

4. The method of producing single crystal silicon according to claim 2, wherein the heat insulating material is configured so that the thermal conductivity of a portion and the thermal conductivity of another portion are different and is arranged so that the center axis of the heat insulating material and the center axis of the crucible are on the same axis.

5. The method of producing single crystal silicon according to any one of claims 2 to 4, wherein the first support electrode, the second support electrode, the third support electrode, the fourth support electrode, and the heat insulating material are configured so that the rotation speed of the crucible when the horizontal magnetic field is applied to the silicon melt is R, When a time from when the horizontal magnetic field starts to act on the silicon melt to when the horizontal magnetic field having a magnetic field strength that fixes the convection direction acts on the silicon melt is T, a highest heating temperature position of the crucible, at which a heating temperature is highest in plan view, is located on an opposite side of the crucible in a rotation direction with respect to a first horizontal dotted line that is orthogonal to the central magnetic force line and that includes the central axis of the crucible, and a second horizontal dotted line that connects the central axis of the crucible and the highest heating temperature position makes an angle θ with the first horizontal dotted line, the angle θ satisfying the following formula (1), the R being in rpm, the T being in minutes, and the θ being in °, θ = 360 × R × T … (1).

6. A single crystal silicon manufacturing apparatus that pulls up a single crystal silicon while applying a horizontal magnetic field to a silicon melt, the single crystal silicon manufacturing apparatus comprising: a crucible that houses the silicon melt; a heater that is formed in a cylindrical shape around the crucible and that is arranged such that a central axis of the cylindrical shape and a central axis of the crucible are on the same axis; and a first support electrode, a second support electrode, a third support electrode, and a fourth support electrode that are formed in a rod shape from a material having electrical conductivity and that support the heater, wherein the heater includes a first heating portion, a second heating portion, a third heating portion, and a fourth heating portion that have the same heating characteristics and that are arranged along an outer peripheral direction of the crucible, the first support electrode connects the first heating portion and the second heating portion to a positive electrode of a power supply, the second support electrode connects the second heating portion and the third heating portion to a negative electrode of the power supply or a ground wire, the third support electrode connects the third heating portion and the fourth heating portion to the positive electrode, the fourth support electrode connects the fourth heating portion and the first heating portion to the negative electrode or the ground wire, and at least one of the first support electrode, the second support electrode, the third support electrode, and the fourth support electrode is composed of a thin diameter support electrode that is thinner than the remaining support electrodes in at least a part.

7. The single crystal silicon manufacturing apparatus according to claim 6, comprising: a heat insulating material that is formed in a cylindrical shape around the heater and that is configured to make a heat dissipation distribution to the heater uneven.

8. The single crystal silicon manufacturing apparatus according to claim 7, wherein the heat insulating material is configured to make a thermal conductivity of the entire heat insulating material uniform and is arranged such that a central axis of the heat insulating material and the central axis of the crucible are not on the same axis.

9. The single crystal silicon manufacturing apparatus according to claim 7, wherein the heat insulating material is configured to make a thermal conductivity of a part of the heat insulating material different from a thermal conductivity of the other part and is arranged such that the central axis of the heat insulating material and the central axis of the crucible are on the same axis.

10. The single crystal silicon manufacturing apparatus according to any one of claims 7 to 9, wherein 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 horizontal magnetic field is applied to the silicon melt, a rotation speed of the crucible is R, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ When T is the time from when the horizontal magnetic field is applied to when the horizontal magnetic field having a magnetic field strength that fixes the convection direction acts on the silicon melt, a highest heating temperature position at which the heating temperature of the crucible is highest in a plan view is located on the opposite side of the crucible in the rotation direction with respect to a first horizontal dotted line that is orthogonal to the central magnetic line of the horizontal magnetic field and that includes the central axis of the crucible, and a second horizontal dotted line that connects the central axis of the crucible and the highest heating temperature position forms an angle θ with the first horizontal dotted line, the angle θ satisfies the following equation (2), the unit of R is rpm, the unit of T is minute, and the unit of θ is °, θ = 360 x R x T … (2).

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