Method for manufacturing silicon single crystals, and apparatus for manufacturing silicon single crystals

Abstract

To provide a silicon single crystal manufacturing method capable of restraining the occurrence of malfunction and a variation of an oxygen concentration per silicon single crystal during manufacture.SOLUTION: A silicon single crystal manufacturing method for pulling a silicon single crystal while applying a horizontal magnetic field to a silicon melt includes: a first heat manufacturing step for heating first and second heat evolution parts at the same heat evolution amount using a silicon single crystal manufacturing device comprising a crucible and a cylindrical heater surrounding the crucible, the heater comprising the first and second semi-cylindrical heat evolution parts having the same heat evolution characteristics, and being arranged so that heating amounts of first and second portions of the crucible respectively positioned on both sides to a vertical virtual plane including a central axis of the crucible and a central magnetic force line of the horizontal magnetic field are different from each other, when the first and second heat evolution parts generate heat at heat evolution amounts different from each other; and a second heat manufacturing step for heating the first and second heat evolution parts at the heat evolution amounts different from each other.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for producing a silicon single crystal and an apparatus for producing a silicon single crystal. [Background Art]

[0002] As a method for producing a silicon single crystal, the MCZ (Magnetic-field-applied Czochralski) method, in which a horizontal magnetic field is applied to a silicon melt, is sometimes used. When a horizontal magnetic field is applied to a silicon melt using the MCZ method, the convection direction in a virtual plane orthogonal to the application direction of the horizontal magnetic field in the silicon melt may be clockwise (hereinafter sometimes referred to as "right vortex mode") or counterclockwise (hereinafter sometimes referred to as "left vortex mode").

[0003] Whether the convection mode becomes the right vortex mode or the left vortex mode is random, and the convection mode and the in-furnace environment cause variation in the concentration of oxygen taken into the silicon single crystal. In order to obtain a silicon single crystal having a stable oxygen concentration, it is important to control the convection mode of the silicon melt during pulling. For this reason, various studies have been conducted on techniques for controlling the convection mode of the silicon melt in a crucible (see, for example, Patent Document 1).

[0004] Patent Document 1 discloses a method in which the thermal environment in the furnace of the production apparatus is made axially asymmetric with respect to the central axis of the crucible, thereby fixing the convection mode to one of the right vortex mode and the left vortex mode, and eliminating variation in oxygen concentration caused by the convection mode. As a specific method, Patent Document 1 discloses a method of making the resistance value of a heater along the circumferential direction of the crucible and the thickness of a heat insulating material different from each other. [Prior Art Literature] [Patent Literature]

[0005] [Patent Document 1] Japanese Unexamined Patent Publication No. 2019-151502 [Summary of the Invention] [Problems that the invention aims to solve]

[0006] However, in the method disclosed in Patent Document 1, a non-axisymmetric thermal environment is achieved by the furnace structure, so the degree of non-axissymmetry cannot be changed during the manufacturing of silicon single crystals. Therefore, for example, in the raw material melting process, there is a risk that the silicon raw material will melt unevenly in the circumferential direction of the crucible. In this case, the solid silicon raw material floating in the molten silicon may overturn and come into strong contact with the quartz crucible, potentially damaging the quartz crucible.

[0007] The present invention aims to provide a method for manufacturing silicon single crystals and a silicon single crystal manufacturing apparatus that can suppress the occurrence of defects during manufacturing and variations in oxygen concentration among silicon single crystals. [Means for solving the problem]

[0008] The present invention provides a method for manufacturing a silicon single crystal, comprising: pulling up a silicon single crystal while applying a horizontal magnetic field to a silicon molten liquid using a silicon single crystal manufacturing apparatus, wherein the silicon single crystal manufacturing apparatus comprises: a crucible containing the silicon molten liquid; and a cylindrical heater surrounding the crucible, wherein the heater comprises a semi-cylindrical first heating section and a second heating section, each having the same heating characteristics, and when the first heating section and the second heating section generate heat at different rates, the heating amounts of the first and second parts of the crucible, located on opposite sides of a vertical virtual plane including the central axis of the crucible and the central magnetic field lines of the horizontal magnetic field, are different, and the method for manufacturing the silicon single crystal comprises: a first heating manufacturing step performed while the first heating section and the second heating section generate heat at the same rate; and a second heating manufacturing step performed while the first heating section and the second heating section generate heat at different rates.

[0009] In the silicon single crystal manufacturing method of the present invention, the silicon single crystal manufacturing apparatus comprises a first power supply and a second power supply, a first power supply path for supplying power from the first power supply to the first heating section, and a second power supply path for supplying power from the second power supply to the second heating section. Preferably, the first heating manufacturing step is performed while controlling the first power supply and the second power supply so that the first heating section and the second heating section generate the same amount of heat, and the second heating manufacturing step is performed while controlling the first power supply and the second power supply so that the first heating section and the second heating section generate different amounts of heat from each other.

[0010] In the silicon single crystal manufacturing method of the present invention, the silicon single crystal manufacturing apparatus comprises a bypass supply path connecting the first power supply path and the second power supply path, and a rectifier provided in the bypass supply path that supplies power only in the direction from the first power supply path to the second power supply path. Preferably, the first heating manufacturing step is performed while controlling the first power supply and the second power supply so that power is supplied from the first power supply and power is not supplied from the second power supply, and the second heating manufacturing step is performed while controlling the first power supply and the second power supply so that power is supplied from both the first power supply and the second power supply.

[0011] In the method for manufacturing a silicon single crystal of the present invention, the method comprises: a silicon melt generation step of melting a silicon raw material in the crucible to generate a silicon melt; a magnetic field application step of starting to apply the horizontal magnetic field to the silicon melt; a convection direction confirmation step of confirming that the direction of convection of the silicon melt in a virtual plane perpendicular to the central magnetic field line is fixed in one direction; a first growth step of growing a neck portion and a shoulder portion by pulling up a seed crystal deposited in the silicon melt; and a second growth step of growing a straight body portion and a tail portion by pulling up the seed crystal, wherein the silicon melt generation step and the second growth step are performed as the first heating manufacturing step, and the magnetic field application step, the convection direction confirmation step and the first growth step are performed as the second heating manufacturing step.

[0012] The present invention provides a method for manufacturing a silicon single crystal, comprising: a silicon melt generation step of melting silicon raw material in the crucible to generate the silicon melt; a magnetic field application step of starting to apply the horizontal magnetic field to the silicon melt; a convection direction confirmation step of confirming that the direction of convection of the silicon melt in a virtual plane perpendicular to the central magnetic field line is fixed in one direction; a first growth step of growing the neck and shoulder portions by pulling up a seed crystal deposited in the silicon melt; an inversion determination step; and a second growth step of growing the straight body and tail portions by pulling up the seed crystal. Preferably, the silicon melt generation step is performed as the first heating and manufacturing step, the magnetic field application step, the convection direction confirmation step, and the first growth step are performed as the second heating and manufacturing step, and in the reversal determination step, if it is determined that there is a possibility of the direction of convection reversing when the second growth step is performed as the first heating and manufacturing step based on the silicon single crystal pulling conditions, the second growth step is performed as the second heating and manufacturing step, and if it is determined that there is no possibility of the direction of convection reversing, the second growth step is performed as the first heating and manufacturing step.

[0013] In the method for manufacturing a silicon single crystal of the present invention, the first heating element and the second heating element are, in plan view, And, It is preferable that the high-temperature region is positioned so as to be perpendicular to the vertical virtual plane and coincide with a horizontal virtual line that includes the central axis of the crucible.

[0014] The silicon single crystal manufacturing apparatus of the present invention comprises a crucible for containing the silicon melt, a cylindrical heater surrounding the crucible, and a power supply unit for supplying power to the heater, wherein the heater comprises a semi-cylindrical first heating element and a second heating element, each having the same heating characteristics, and the power supply unit comprises a first power supply and a second power supply, a first power supply path for supplying power from the first power supply to the first heating element, and a second power supply path for supplying power from the second power supply to the second heating element.

[0015] In the silicon single crystal manufacturing apparatus of the present invention, it is preferable that the power supply unit comprises a bypass supply path connecting the first power supply path and the second power supply path, and a rectifier unit provided in the bypass supply path that supplies power only in the direction from the first power supply path to the second power supply path.

[0016] Preferably, the silicon single crystal manufacturing apparatus of the present invention includes a control unit for controlling the manufacturing process of pulling up the silicon single crystal, and the manufacturing process comprises a first heating manufacturing process performed while controlling the first power supply and the second power supply so that the first heating unit and the second heating unit generate the same amount of heat, and a second heating manufacturing process performed while controlling the first power supply and the second power supply so that the first heating unit and the second heating unit generate different amounts of heat from each other.

[0017] Preferably, the silicon single crystal manufacturing apparatus of the present invention includes a control unit for controlling the manufacturing process of pulling up the silicon single crystal, and the manufacturing process comprises a first heating manufacturing process performed while controlling the first power supply and the second power supply so that power is supplied from the first power supply and power is not supplied from the second power supply, and a second heating manufacturing process performed while controlling the first power supply and the second power supply so that power is supplied from the first power supply and the second power supply.

[0018] In the silicon single crystal manufacturing apparatus of the present invention, the manufacturing process comprises: a silicon melt generation step of melting silicon raw material in the crucible to generate the silicon melt; a magnetic field application step of starting to apply the horizontal magnetic field to the silicon melt; a convection direction confirmation step of confirming that the direction of convection of the silicon melt in a virtual plane perpendicular to the central magnetic field lines of the horizontal magnetic field has been fixed in one direction; a first growth step of growing a neck portion and a shoulder portion by pulling up a seed crystal deposited in the silicon melt; and a second growth step of growing a straight body portion and a tail portion by pulling up the seed crystal. Preferably, the control unit performs the silicon melt generation step and the second growth step as the first heating manufacturing step, and the magnetic field application step, the convection direction confirmation step and the first growth step as the second heating manufacturing step.

[0019] In the silicon single crystal manufacturing apparatus of the present invention, the manufacturing process comprises: a silicon melt generation step of melting silicon raw material in the crucible to generate the silicon melt; a magnetic field application step of starting to apply the horizontal magnetic field to the silicon melt; a convection direction confirmation step of confirming that the direction of convection of the silicon melt in a virtual plane perpendicular to the central magnetic field line of the horizontal magnetic field is fixed in one direction; a first growth step of growing the neck and shoulder portions by pulling up a seed crystal deposited in the silicon melt; an inversion determination step; and a second growth step of growing the straight body and tail portions by pulling up the seed crystal. Preferably, the control unit comprises the steps of: performing the silicon melt generation step as the first heating and manufacturing step; performing the magnetic field application step, the convection direction confirmation step, and the first growth step as the second heating and manufacturing step; and in the reversal determination step, if it is determined that there is a possibility of the direction of convection reversing when the second growth step is performed as the first heating and manufacturing step based on the silicon single crystal pulling conditions, the second growth step is performed as the second heating and manufacturing step; and if it is determined that there is no possibility of the direction of convection reversing, the second growth step is performed as the first heating and manufacturing step.

[0020] In the silicon single crystal production apparatus of the present invention, it is preferable that the first heat generating part and the second heat generating part are arranged such that, in a plan view, the maximum temperature region overlaps a horizontal imaginary line that is orthogonal to a vertical imaginary plane including the central axis of the crucible and the central magnetic force line of the horizontal magnetic field and includes the central axis of the crucible. [Brief Description of the Drawings]

[0021] [Figure 1] It is a longitudinal sectional view showing a schematic configuration of the silicon single crystal production apparatus according to the first and second embodiments. [Figure 2] It is a schematic plan view showing the heater and the magnetic field applying unit according to the first and second embodiments. [Figure 3] It is a perspective view of the heater according to the first and second embodiments. [Figure 4] It is an equivalent circuit diagram of the heater and the power supply unit according to the first embodiment. [Figure 5] It is a block diagram of a main part of the silicon single crystal production apparatus according to the first and second embodiments. [Figure 6] It is a flowchart showing a method for producing a silicon single crystal according to the first and second embodiments. [Figure 7] It is an equivalent circuit diagram of the heater and the power supply unit according to the second embodiment. [Mode for Carrying Out the Invention]

[0022] [First Embodiment] [Configuration of Silicon Single Crystal Production Apparatus] First, the configuration of the silicon single crystal production apparatus according to the first embodiment of the present invention will be described. FIG. 1 is a longitudinal sectional view showing a schematic configuration of the silicon single crystal production apparatus. FIG. 2 is a schematic plan view showing the heater and the magnetic field applying unit. FIG. 3 is a perspective view of the heater. FIG. 4 is an equivalent circuit diagram of the heater and the power supply unit. FIG. 5 is a block diagram of a main part of the silicon single crystal production apparatus.

[0023] The silicon single crystal manufacturing apparatus 1 shown in Figure 1 is an apparatus for manufacturing silicon single crystals SM by the MCZ method, and while applying a horizontal magnetic field to the silicon molten M, it pulls up the silicon single crystal SM which has a neck portion SM1, a shoulder portion SM2, a straight body portion SM3 and a tail portion (not shown). The silicon single crystal manufacturing apparatus 1 consists of a chamber 2 which forms the outer shell, a crucible 3 which is located in the center of the chamber 2, and the crucible 3 It includes a heater 4 positioned around it and a temperature measuring unit 15.

[0024] Crucible 3 has a double-walled 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 cylindrical containers with closed bottoms and are circular in shape when viewed from above. Crucible 3 is fixed to the upper end of a support shaft 5 that can rotate and move up and down.

[0025] The heater 4 is a graphite heater formed in a roughly cylindrical shape and positioned around the crucible 3. A cylindrical insulating material 6 is provided on the outside of the heater 4, along the inner surface of the chamber 2.

[0026] Above the crucible 3, a lifting shaft 7 is positioned coaxially with the support shaft 5. The lifting shaft 7 is made of wire or the like. A seed crystal SC is attached to the lower end of the lifting shaft 7.

[0027] Inside chamber 2, a cylindrical heat shield 8 is positioned to surround the silicon single crystal SM being grown above the silicon molten liquid M in crucible 3. The heat shield 8 suppresses the temperature rise of the silicon single crystal SM during growth by blocking radiant heat from the silicon molten liquid M, the side walls of the crucible 3, and the heater.

[0028] The upper part of the chamber 2 is provided with a gas inlet 2A for introducing an inert gas such as argon gas into the chamber 2. The lower part of the chamber 2 is provided with an exhaust port 2B for drawing out and discharging gas from the chamber 2 by driving a vacuum pump (not shown).

[0029] The 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 surface of the silicon single crystal SM to be grown and the inner surface of the opening of the heat shield 8. As will be described later, the convection mode of the silicon melt M can be confirmed by measuring the temperatures of the first measurement point P1 and the second measurement point P2. For example, heating the silicon melt M by the heater 4 causes the direction of convection of the silicon melt M to be clockwise in Figure 1. to When fixed, that is, when the convection mode of the silicon molten 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. Also, heating of the silicon molten M by the heater 4 causes the direction of convection of the silicon molten M to become counterclockwise. the law of nature When fixed in this state, that is, when 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.

[0030] The temperature measuring unit 15 comprises a pair of reflectors 15A and a pair of radiation thermometers 15B. The reflector 15A is installed inside the chamber 2. Preferably, the reflector 15A is installed such 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 the radiation light L incident on the chamber 2 through the quartz window 2C (see Figure 1) and measures the temperatures of the first measurement point P1 and the second measurement point P2 in a non-contact manner.

[0031] As shown in Figure 2, the silicon single crystal manufacturing apparatus 1 further includes a magnetic field application unit 16. The magnetic field application unit 16 comprises 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 positioned opposite each other on the outside of the chamber 2, with the crucible 3 in between. The magnetic field application unit 16 applies a horizontal magnetic field such that, in a plan view, the central magnetic field line 16C passing through the central axis of the coil intersects with the central axis 3C of the crucible 3 (hereinafter sometimes referred to as the "crucible central axis 3C"), and is in the direction from the second magnetic body 16B toward the first magnetic body 16A (the upward direction indicated by the arrow showing the central magnetic field line 16C in Figure 2, and the direction from the front to the back of the paper in Figure 1).

[0032] The heater 4 is positioned such that its central axis 4C (hereinafter sometimes referred to as "heater central axis 4C") lies on the same axis as the crucible central axis 3C. Similarly, the insulating material 6 is positioned such that its central axis lies on the same axis as the crucible central axis 3C. In other words, the crucible 3, heater 4, and insulating material 6 are positioned so that the gap between the crucible 3 and the heater 4, and the gap between the heater 4 and the insulating material 6, are uniform in the circumferential direction of the crucible 3. With this arrangement of the crucible 3, heater 4, and insulating material 6, when the heater 4 generates heat uniformly in the circumferential direction, the heating distribution by the heater 4 and the heat removal distribution by the insulating material 6 become uniform in the circumferential direction of the crucible 3.

[0033] As shown in Figures 2 and 3, the heater 4 includes a heating element 40 which is a cylindrical graphite heater. The heating element 40 is formed with a uniform thickness throughout its circumference. The heating element 40 has a plurality of upper slits 41 extending downward from the upper end and a plurality of lower slits 42 extending upward from the lower end in the circumferential direction. ni naru It is formed in such a way. Each upper slit 41 and each lower slit 42 has the same width dimension and the same cutting depth along the vertical direction. In addition, the distance between the upper slit 41 and the lower slit 42 is also equal around the entire circumference of the heater 4.

[0034] The heating element 40 comprises a semi-cylindrical first heating element 40A located on one side of the first vertical virtual plane VF1 containing the heater central axis 4C, and a semi-cylindrical second heating element 40B located on the other side and having the same heating characteristics as the first heating element 40A. The same heating characteristics mean that when the same amount of power is supplied, the same part generates the same amount of heat. The first heating element 40A and the second heating element 40B have the same total number of upper slits 41 and lower slits 42. In this embodiment, the first and second heating elements 40A and 40B each have four upper slits 41 and six lower slits 42, so the total number of upper slits 41 and lower slits 42 is 10 each.

[0035] The silicon single crystal manufacturing apparatus 1 includes a power supply unit 9 that supplies power to the heating 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 to fourth terminals 91A to 91D are arranged at 90° intervals along the circumferential direction of the heating unit 40. The first terminal 91A to the fourth terminal 91D extend downward from the lower end of the portion of the heating element 40 that is partitioned by the two lower slits 42, and are formed integrally with the heating element 40. Furthermore, the first terminal 91A to the fourth terminal 91D are provided with connecting portions 911A to 911D that are bent inward at a right angle from their lower ends, and through holes 912A to 912D are formed in the connecting portions 911A to 911D. In other words, the heater 4 is constructed using a graphite heater in which a cylindrical heating element 40 and the first terminal 91A to the fourth terminal 91D, which are heater legs, are integrally molded.

[0036] The heating element 40 is divided into a zigzag first meandering section 43A, a second meandering section 43B, a third meandering section 43C, and a fourth meandering section 43D by the formation of an upper slit 41 and a lower slit 42, and these first to fourth meandering sections 43A to 43D constitute four heater elements. Specifically, between the first terminal 91A and the second terminal 91B, two upper slits 41 and three lower slits 42 are alternately formed to form the first meandering section 43A. Similarly, between the second terminal 91B and the third terminal 91C, two upper slits 41 and three lower slits 42 are alternately formed to form the second meandering section 43B. Between the third terminal 91C and the fourth terminal 91D, two upper slits 41 and three lower slits 42 are alternately formed to form the third meandering section 43C. Between the fourth terminal 91D and the first terminal 91A, two upper slits 41 and three lower slits 42 are alternately formed to form the fourth meandering section 43D. Thus, the resistance values ​​of the first meandering section 43A to the fourth meandering section 43D, which have the same shape as each other, are the same. Therefore, when the magnitude of the current flowing through the first meandering section 43A to the fourth meandering section 43D is the same, the first meandering section 43A to the fourth meandering section 43D generate the same amount of heat. The first heating element 40A is formed by the first meandering section 43A and the second meandering section 43B, and the second heating element 40B is formed by the third meandering section 43C and the fourth meandering section 43D.

[0037] As shown in Figure 2, the heater 4 is positioned such that its central axis 4C lies on the same axis as the crucible central axis 3C, and the first heating element 40A and the second heating element 40B are arranged symmetrically with respect to the second vertical virtual plane VF2 which includes the crucible central axis 3C and the central magnetic field line 16C. In other words, the heater 4 is positioned such that the second vertical virtual plane VF2 overlaps with the first vertical virtual plane VF1 shown in Figure 3. It can also be said that the heater 4 is arranged such that the first heating element 40A and the second heating element 40B are arranged symmetrically twice with respect to the crucible central axis 3C. Furthermore, when the first heating element 40A and the second heating element 40B generate heat at different rates, the heater 4 generates heat from the first portion 31 of the crucible 3 located on both sides of the second vertical virtual plane VF2 which includes the crucible central axis 3C and the central magnetic field line 16C. A and Part 2 31B It can also be said that the heating amounts are arranged to be different from each other. Furthermore, in a plan view, the central regions of the first and second heat-generating sections 40A and 40B, respectively, become the highest temperature regions 401A and 401B. It can also be said that, in a plan view, the heater 4 is positioned such that the highest temperature regions 401A and 401B of the first and second heat-generating sections 40A and 40B, respectively, are perpendicular to the second vertical virtual plane VF2 and coincide with the horizontal virtual line VL that includes the crucible central axis 3C. The reason why the central regions of the first and second heat-generating sections 40A and 40B become the highest temperature regions 401A and 401B is that although the amount of heat generated in the regions through which current flows in the first and second heat-generating sections 40A and 40B is the same, heat transfer causes the regions furthest from both ends of the first and second heat-generating sections 40A and 40B to reach the highest temperature.

[0038] As shown in Figure 3, the first support electrode 92A to the fourth support electrode 92D are conductive carbon rod-shaped electrodes. The first support electrode 92A to the fourth support electrode 92D are inserted through holes 912A to 912D in terminals 91A to 91D at one end, and carbon nuts 93A to 93D are screwed onto male threads formed on one end, thereby electrically connecting them to terminals 91A to 91D and supporting the heater 4.

[0039] As shown in Figure 4, the power supply unit 9 further comprises a first power supply 94A and a second power supply 94B, a first power supply path 95A that supplies power from the first power supply 94A to the first heat-generating unit 40A, and a second power supply path 95B that supplies power from the second power supply 94B to the second heat-generating unit 40B.

[0040] At least one of the first power supply 94A and the second power supply 94B is configured to allow the amount of power supplied to be changed. The first power supply line 95A is composed of a second support electrode 92B and a first anode wiring 951A that connects the other end 921B of the second support electrode 92B to the anode of the first power supply 94A. The second power supply line 95B consists of a fourth support electrode 92D and a second anode wiring 951B that connects the other end 921D of the fourth support electrode 92D to the anode of the second power supply 94B. The cathodes of the first power supply 94A and the second power supply 94B are grounded by grounding wires 952A and 952B, respectively. The other end 921A of the first support electrode 92A and the other end 921C of the third support electrode 92C are grounded by grounding wires 953A and 953B, respectively.

[0041] As shown in Figure 4, with the configuration of the heater 4 and power supply unit 9, when a current of value Ix flows from the first power supply 94A and the second power supply 94B, a current of value 0.5Ix flows through the first meandering section 43A to the fourth meandering section 43D. As described above, since the resistance values ​​of the first meandering section 43A to the fourth meandering section 43D are the same, when the same current of value Ix flows from the first power supply 94A and the second power supply 94B, that is, when the same amount of power is supplied, the first heating section 40A and the second heating section 40B generate the same amount of heat. On the other hand, if a current of value Iy flows from the first power supply 94A and a current of value Iz, which is different from Iy, flows from the second power supply 94B, that is, if power of different magnitudes is supplied from the first power supply 94A and the second power supply 94B, a current of value 0.5Iy flows through the first and second meandering sections 43A and 43B, and a current of value 0.5Iz flows through the third and fourth meandering sections 43C and 43D. As a result, the first heating section 40A and the second heating section 40B generate heat with different amounts of heat from each other. In the following, the mode in which the first and second heating elements 40A and 40B generate the same amount of heat is referred to as the "uniform heating mode," and the mode in which the first and second heating elements 40A and 40B generate different amounts of heat is referred to as the "non-uniform heating mode." Also, in Figure 4, among the symbols attached to the arrows indicating current, the symbols outside the parentheses indicate the current value in the uniform heating mode, and the symbols inside the parentheses indicate the current value in the non-uniform heating mode. Furthermore, in the non-uniform heating mode, the current value of the current flowing from either the first power supply 94A or the second power supply 94B may be the same as the current value in the uniform heating mode, and the current values ​​of the current flowing from the first power supply 94A and the second power supply 94B may be different from the current values ​​in the uniform heating mode.

[0042] When the crucible 3 is heated in uniform heating mode, the silicon molten M inside the crucible 3 is heated uniformly over the entire circumference of the crucible 3. In this case, convection occurs in the silicon molten M, rising near the sides of the crucible 3 and descending near the center. In this state, due to the instability of the convection, the position of the descending flow changes disorderly and may shift away from the center of the crucible 3. When a horizontal magnetic field is applied to the silicon molten M, the rotation of the descending flow in the circumferential direction of the crucible 3 is gradually constrained, and eventually the direction of convection in a virtual plane perpendicular to the direction of application of the horizontal magnetic field is fixed. Thus, when crucible 3 is heated in uniform heating mode, a horizontal magnetic field is applied while the position of the downflow changes disorderly. Therefore, depending on the timing of the application, the convection mode can become either a right-handed vortex mode or a left-handed vortex mode.

[0043] On the other hand, when the crucible 3 is heated in non-uniform heating mode, the silicon molten M inside the crucible 3 is heated such that the temperature of the part located on the side of the first heating element 40A is different from the temperature of the part located on the side of the second heating element 40B. For example, if the second heating element 40B located on the left side of the crucible 3 generates more heat than the first heating element 40A located on the right side, an upward flow will stably occur on the left side of the crucible 3 and a downward flow will stably occur on the right side of the crucible 3, and the position of the downward flow will not change disorderly as it would when the first and second heating elements 40A and 40B generate the same amount of heat. If a horizontal magnetic field is applied to the silicon molten M in this state, the convection will be fixed clockwise and become a right-handed vortex mode, regardless of the timing of the application. In particular, 2 Heat-generating part 40 B The maximum temperature range is 401 B Because it coincides with the horizontal imaginary line VL in a plan view, the imaginary line connecting the position where the updraft is strongest and the position where the downdraft is strongest is almost perpendicular to the generation position of the central magnetic field line 16C, and a horizontal magnetic field is applied. Therefore, a right-hand vortex mode can be generated stably. In order to generate right-hand vortex modes with a high probability regardless of the timing of the application of the horizontal magnetic field, the output power bias Δ calculated by the following equation (1) is preferably 4.0% or more, and more preferably 5.0% or more. Δ(%)=(Q 2 / Q 1 -1) × 100 … (1) Q1: Output power of the first heating element 40A Q2: Output power of the second heating element 40B

[0044] In order to suppress variations in oxygen concentration among silicon single crystals SM, it is necessary to fix the direction of convection of the silicon melt M in one direction, and therefore it is preferable to heat the crucible 3 in a non-uniform heating mode. However, when growing a straight body SM3 of a silicon single crystal SM in a non-uniform heating mode, the thermal environment inside the chamber 2 is asymmetric with respect to the crucible central axis 3C, and the diameter of the straight body SM3 fluctuates greatly. If the pulling speed is controlled to suppress this diameter fluctuation, the pulling speed may also fluctuate greatly. Therefore, it is thought that by heating the crucible 3 in a non-uniform heating mode before pulling up the straight body SM3 to fix the convection of the molten silicon M in one direction, and then transitioning to heating the crucible 3 in a uniform heating mode before pulling up the straight body SM3, fluctuations in the diameter of the straight body SM3 and fluctuations in the pulling speed can be suppressed.

[0045] However, when heating crucible 3 in uniform heating mode, as mentioned above, the position of the descending flow changes disorderly, and there is a risk that the direction of convection may reverse during the pulling of the straight body SM3. If such a reversal of the direction of convection occurs, there is a risk that the concentration of oxygen taken into the straight body SM3 will vary. Furthermore, it is thought that whether or not a reversal of the direction of convection occurs depends on the pulling conditions of the silicon single crystal SM. Therefore, it is preferable to first confirm whether the direction of convection may reverse when switching from the non-uniform heating mode to the uniform heating mode after fixing the direction of convection in the non-uniform heating mode, and then decide whether or not to switch to the uniform heating mode after fixing the convection mode based on the results of this confirmation.

[0046] As shown in Figure 5, the silicon single crystal manufacturing apparatus 1 further comprises a raw material supply unit 18, a crucible rotation drive unit 19, a pulling drive unit 20, an input unit 21, a storage unit 22, and a control unit 23. The control unit 23 is connected to a first power supply 94A, a second power supply 94B, a radiation thermometer 15B, a magnetic field application unit 16, a raw material supply unit 18, a crucible rotation drive unit 19, a pulling drive unit 20, an input unit 21, and a storage unit 22, enabling them to send and receive various types of information.

[0047] The first power supply 94A and the second power supply 94B supply the same or different amounts of power to the first heating element 40A and the second heating element 40B, respectively, based on 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 application unit 16 applies a horizontal magnetic field of a predetermined strength to the silicon molten liquid M based on the control of the control unit 23. The raw material supply unit 18 feeds silicon raw material into the crucible 3 based on the control of the control unit 23. Alternatively, the silicon single crystal manufacturing apparatus 1 may not have a raw material supply unit 18, and an operator may feed the silicon raw material into the crucible 3. The crucible rotation drive unit 19 rotates the crucible 3 at a predetermined speed in a predetermined direction based on the control of the control unit 23. The lifting drive unit 20 raises and lowers the lifting shaft 7 based on the control of the control unit 23. The lifting drive unit 20 also rotates the lifting shaft 7 at a predetermined speed in the opposite or the same direction as the rotation of the support shaft 5, based on the control of the control unit 23.

[0048] The input unit 21 is configured, for example, as a touch panel or physical buttons. The input unit 21 is used for inputting various settings and outputs signals corresponding to the input operations to the control unit 23.

[0049] The memory unit 22 is composed of a well-known storage device, such as an HDD (Hard Disk Drive). The memory unit 22 stores various information necessary for controlling the pulling of the silicon single crystal SM, as well as information for determining convection reversal. The convection reversal determination information includes, for each silicon single crystal (SM) pulling condition and for each silicon single crystal manufacturing apparatus 1, whether or not the direction of convection may reverse when the convection mode of the silicon molten M is fixed in a non-uniform heating mode and then transitioned to a uniform heating mode. The possibility of convection reversal for each pulling condition may be confirmed by experiments using the silicon single crystal manufacturing apparatus 1 or by manufacturing silicon single crystals (SM), or by simulation.

[0050] The control unit 23 includes a CPU (Central Processing Unit). The control unit 23 controls the pulling of silicon single crystal SMs by having the CPU execute a program stored in the memory unit 22.

[0051] [Method for manufacturing silicon single crystals] Next, we will describe the method for manufacturing silicon single crystals SM using the silicon single crystal manufacturing apparatus 1. Figure 6 is a flowchart showing the method for manufacturing silicon single crystals. In the first embodiment, an example is given in the non-uniform heating mode in which the second heating element 40B generates a greater amount of heat than the first heating element 40A. Furthermore, the amount of heat generated by the first and second heating elements 40A and 40B in the uniform heating mode may be the same as or different from the amount of heat generated by the first heating element 40A or the second heating element 40B in the non-uniform heating mode.

[0052] First, the operator operates the input unit 21 to input the pulling conditions for the silicon single crystal SM to be manufactured. The control unit 23 acquires the input lifting condition, as shown in Figure 6 (step S1). After this, the control unit 23 performs the silicon single crystal SM manufacturing process based on the acquired pulling conditions. Specifically, the control unit 23 maintains the chamber 2 in a reduced-pressure inert gas atmosphere, turns off the heater 4 (does not supply power to the heater 4), and does not apply a horizontal magnetic field. It then controls the raw material supply unit 18 to feed silicon raw material into the crucible 3, and then controls the crucible rotation drive unit 19 to rotate the crucible 3 in one direction (step S2). If the silicon single crystal manufacturing apparatus 1 is not equipped with a raw material supply unit 18, the operator will feed the silicon raw material into the crucible 3.

[0053] Next, the control unit 23 controls the first and second power supplies 94A and 94B to heat the crucible 3 in a uniform heating mode using the first and second heating elements 40A and 40B of the heater 4, melting the silicon raw material and generating a silicon melt M (Step S3: Silicon Melt Generation Process). In Step S3, the crucible 3 is heated uniformly over its entire circumference. As a result, the silicon raw material can be uniformly melted in the circumferential direction of the crucible 3, and solid silicon raw material floating in the silicon melt M can be prevented from overturning and coming into contact with the quartz crucible 3B. Consequently, damage to the quartz crucible 3B can be suppressed. Then, once all the silicon raw materials have melted, the position of the downward flow generated in the silicon molten liquid M changes in a disordered manner.

[0054] The control unit 23 controls the first and second power supplies 94A and 94B at the timing when all the silicon raw material has melted, switching from uniform heating mode to non-uniform heating mode (step S4). After a predetermined time has elapsed since the processing in step S4, the temperature of the left portion of the silicon molten liquid M heated by the second heating unit 40B becomes higher than the temperature of the right portion heated by the first heating unit 40A, causing a stable upward flow to occur on the left side of the crucible 3 and a stable downward flow to occur on the right side of the crucible 3. After this, the control unit 23 controls the magnetic field application unit 16 to start applying a horizontal magnetic field to the silicon melt M (Step S5: Magnetic field application step). The silicon melt M is given a predetermined strength by the process in Step S5. of When a horizontal magnetic field acts, the convection of the molten silicon M is fixed in a clockwise direction, resulting in a right-handed vortex mode.

[0055] Next, the control unit 23 determines whether the convection mode of the silicon molten M is fixed to a right-handed vortex mode based on the signal corresponding to the measurement result from the radiation thermometer 15B (Step S6: Convection direction confirmation step). If the control unit 23 determines that the convection mode is not fixed to the right vortex mode (step S6: NO), it repeats the process of step S6 after a predetermined time has elapsed. Meanwhile, if the control unit 23 determines that the convection mode is fixed to the right vortex mode (step S6: YES), it controls the lifting drive unit 20 to grow the neck portion SM1 and shoulder portion SM2 while continuing heating in the non-uniform heating mode and applying a horizontal magnetic field (step S7: first growth step). In step S7, the lifting drive unit 20 raises and lowers the lifting shaft 7 based on the control of the control unit 23 so as to deposit the seed crystal SC into the silicon melt M and then lift the seed crystal SC.

[0056] During or after growing the shoulder portion SM2, the control unit 23, based on the pulling conditions for the silicon single crystal SM and the convection reversal determination information stored in the memory unit 22, determines that the convection mode is fixed to the right vortex mode and changes from a non-uniform heating mode to a uniform heating mode. heating When switching modes, it is determined whether or not the direction of convection may reverse (Step S8: Reversal Determination Step).

[0057] The control unit 23 switches from the non-uniform heating mode to the uniform heating mode. heating If it is determined that there is no possibility of the direction of convection reversing when switching to a different mode (Step S8: NO), then during the growth of the shoulder section SM2, or after the growth of the shoulder section SM2 and before the growth of the straight section SM3, the first and second power supplies 94A and 94B are controlled to switch from the uneven heating mode to a uniform heating mode. heating The system switches to mode (step S9). Then, the control unit 23 controls the lifting drive unit 20 to grow the straight section SM3 and the tail section (step S10: second growth process). In this case, the thermal environment inside the chamber 2 is axially symmetric with respect to the crucible's central axis 3C, which suppresses variations in the diameter of the straight body SM3 and the pulling speed. Furthermore, even with heating in uniform heating mode, the direction of convection of the molten silicon M does not reverse, which suppresses variations in oxygen concentration in the straight body SM3.

[0058] Meanwhile, the control unit 23 switches from the non-uniform heating mode to the uniform heating mode. heating If it is determined that switching modes may reverse the direction of convection (Step S8: YES), the straight section SM3 and the tail section are grown while maintaining the non-uniform heating mode (Step S10: Second growth process). In this case, the continuation of the non-uniform heating mode maintains a non-axially symmetric thermal environment within the chamber 2 with respect to the crucible central axis 3C, which may cause fluctuations in the diameter of the straight body SM3 and fluctuations in the pulling speed. However, the continuation of heating in the non-uniform heating mode does not reverse the direction of convection of the silicon molten liquid M, thus suppressing variations in oxygen concentration in the straight body SM3.

[0059] In the above silicon single crystal SM manufacturing process, step S3, the silicon melt generation step, is performed as a first heating manufacturing step in which the first and second heating units 40A and 40B are heated at the same rate in a uniform heating mode. Furthermore, step S5, the magnetic field application step, step S6, the convection direction confirmation step, and step S7, the first growth step, are performed as second heating manufacturing steps in which the first and second heating units 40A and 40B are heated at different rates in a non-uniform heating mode. In addition, step S10, the second growth step, is performed as a first heating manufacturing step if it is determined in step S8, the reversal determination step, that there is no possibility of the convection direction reversing, and as a second heating manufacturing step if it is determined that there is a possibility of the convection direction reversing.

[0060] [Effects of the First Embodiment] The silicon single crystal manufacturing apparatus 1 includes a cylindrical heater 4 surrounding the crucible 3 as a configuration for heating the crucible 3. The heater 4 comprises a semi-cylindrical first heating element 40A and a second heating element 40B, and when the first heating element 40A and the second heating element 40B generate heat at different rates, the first portion 31 of the crucible 3 located on both sides with respect to the second vertical virtual plane VF2 A and Part 2 31B The heating amounts of the heating elements are arranged to be different from each other. The control unit 23 of the silicon single crystal manufacturing apparatus 1 performs a first heating manufacturing process in which the first and second heating elements 40A and 40B are heated at the same amount, and a second heating manufacturing process in which the first and second heating elements 40A and 40B are heated at different amounts from each other. Therefore, for example, by generating a silicon melt M in a uniform heating mode, it is possible to suppress the inversion of silicon raw materials floating in the silicon melt M, thereby suppressing damage to the quartz crucible 3B. Furthermore, by applying a horizontal magnetic field to the silicon melt M in a non-uniform heating mode, the convection mode can be fixed to a right-handed vortex mode regardless of the timing of the application of the horizontal magnetic field, thereby suppressing variations in oxygen concentration among silicon single crystals SM. In addition, since variations in oxygen concentration among silicon single crystals SM can be suppressed, the yield of silicon single crystals SM can be improved, leading to improved energy efficiency, increased production efficiency, and reduced waste.

[0061] The silicon single crystal manufacturing apparatus 1 includes first and second power supplies 94A and 94B, a first power supply path 95A that supplies power from the first power supply 94A only to the first heat-generating section 40A, and a second power supply path 95B that supplies power from the second power supply 94B only to the second heat-generating section 40B. Therefore, by simply controlling the amount of power supplied from the first power supply 94A and the second power supply 94B, it is possible to switch between uniform heating mode and non-uniform heating mode.

[0062] [Second Embodiment] Next, the configuration of the silicon single crystal manufacturing apparatus according to the second embodiment of the present invention will be described. Figure 7 is an equivalent circuit diagram of the heater and power supply unit.

[0063] The silicon single crystal manufacturing apparatus 1A of the second embodiment differs from the silicon single crystal manufacturing apparatus 1 of the first embodiment in that the control unit 23A shown in Figure 5 performs different control than the control unit 23 of the first embodiment, and the power supply unit 9A shown in Figure 7 has a different configuration than the power supply unit 9 of the first embodiment. Other configurations are the same as those of the silicon single crystal manufacturing apparatus 1 of the first embodiment.

[0064] As shown in Figure 7, the power supply unit 9A has the same configuration as the power supply unit 9 of the first embodiment, plus a bypass supply path 96A connecting the first power supply path 95A and the second power supply path 95B, and a rectifier unit 96B provided in the bypass supply path 96A that supplies power only in the direction from the first power supply path 95A to the second power supply path 95B. The bypass supply path 96A is composed of wiring connecting the first anode wiring 951A and the second anode wiring 951B. The rectifier section 96B is Bypass supply line 96A It is composed of diodes placed in the middle of the circuit.

[0065] With the configuration of the heater 4 and power supply unit 9A as shown in Figure 7, if a current of Ip flows from the first power supply 94A and no current flows from the second power supply 94B, that is, if power is supplied from the first power supply 94A and no power is supplied from the second power supply 94B, a current of 0.25Ip flows through the first meandering section 43A to the fourth meandering section 43D, and the first heating element 40A and the second heating element 40B generate the same amount of heat. On the other hand, when a current of Ip flows from the first power supply 94A and a current of Iq flows from the second power supply 94B, that is, when power is supplied from both the first power supply 94A and the second power supply 94B, a current of 0.25Ip flows through the first and second meandering sections 43A and 43B, and a current of 0.25Ip + 0.5 flows through the third and fourth meandering sections 43C and 43D. I Because a current of q flows, the second heating element 40B generates a greater amount of heat than the first heating element 40A. In Figure 7, among the symbols attached to the arrows indicating current, the symbols outside the parentheses indicate the current value in the uniform heating mode, and the symbols inside the parentheses indicate the current value in the non-uniform heating mode.

[0066] When manufacturing a silicon single crystal SM, the control unit 23A performs the same control as the control unit 23 in the first embodiment shown in Figure 6, but the control when heating the crucible 3 in uniform heating mode and non-uniform heating mode differs from that of the control unit 23. When heating the crucible 3 in uniform heating mode, the control unit 23A controls the first and second power supplies 94A and 94B so that power is supplied from the first power supply 94A and not from the second power supply 94B. When heating the crucible 3 in non-uniform heating mode, the control unit 23A controls the first and second power supplies 94A and 94B so that power is supplied from both the first power supply 94A and the second power supply 94B.

[0067] [Effects of the second embodiment] The first heating element 40A and the second heating element 40B have the same heating characteristics. The silicon single crystal manufacturing apparatus 1A includes first and second power supplies 94A and 94B, first and second power supply lines 95A and 95B, a bypass supply line 96A connecting the first power supply line 95A and the second power supply line 95B, and a rectifier 96B provided in the bypass supply line 96A that supplies power only in the direction from the first power supply line 95A to the second power supply line 95B. Therefore, while a predetermined amount of power is being supplied from the first power supply 94A, the uniform heating mode and the non-uniform heating mode can be switched simply by controlling whether or not to supply power from the second power supply 94B. Furthermore, since it is sufficient to supply power from the second power supply 94B to the difference in heating temperatures between the first heating element 40A and the second heating element 40B, a power supply with a small capacity can be used as the second power supply 94B. Furthermore, power supplies whose power supply amount cannot be changed can be applied as the first and second power supplies 94A and 94B. Furthermore, because variations in oxygen concentration between silicon single crystal SMs can be suppressed, the yield of silicon single crystal SMs can be improved, leading to improved energy efficiency, increased production efficiency, and reduced waste.

[0068] [Differentiation] Although embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and various improvements and design changes, etc., that do not depart from the spirit of the present invention are also included.

[0069] In the first and second embodiments, the processes in steps S8 and S9 may be omitted, and the straight section SM3 and the tail section may be grown in the non-uniform heating mode.

[0070] In the first and second embodiments, the operator may perform at least one of the following processes: the heating mode switching process in step S3, S4, and S9; the horizontal magnetic field application start process in step S5; the convection mode determination process in step S6; and the convection reversal possibility determination process in step S8. In the first and second embodiments, the second heating manufacturing step was exemplified as a step to fix the convection mode to a right-handed vortex mode by heating the silicon melt M so that the temperature of the left portion becomes higher than the temperature of the right portion. However, a step to fix the convection mode to a left-handed vortex mode may also be performed by heating the silicon melt M so that the temperature of the right portion becomes higher than the temperature of the left portion.

[0071] In the first and second embodiments, when the first heating element 40A and the second heating element 40B generate heat at different rates, the heater 4 generates heat in the first part 31 of the crucible 3. A and Part 2 31BThe heaters should be arranged so that they provide different amounts of heat to each other. They may be arranged rotated by an angle of less than 45° clockwise or counterclockwise from the state shown in Figure 2, or they may be arranged rotated by an angle greater than 45° but less than 90° clockwise or counterclockwise. In other words, the heaters 4 may be arranged so that the second vertical virtual plane VF2 does not overlap with the first vertical virtual plane VF1 shown in Figure 3. [Examples]

[0072] Next, embodiments of the present invention will be described. However, the present invention is not limited to these embodiments.

[0073] [Experimental conditions] [Comparative Example] First, a silicon single crystal manufacturing apparatus 1 according to the first embodiment was prepared. Then, by controlling the first and second power supplies 94A and 94B, a silicon melt M was generated by heating the crucible 3 in a uniform heating mode. Next, while maintaining the uniform heating mode, a horizontal magnetic field was applied to the silicon melt M to confirm that the convection mode was fixed, and then a silicon single crystal SM having a straight body SM3 with a diameter of 300 mm and a total length of 2000 mm was grown. In this case, the output power bias Δ calculated using equation (1) above will be 0%.

[0074] [Examples 1-8] In Example 1, after generating a silicon melt M by heating the crucible 3 in uniform heating mode, the first and second power supplies 94A and 94B were controlled so that the output power bias Δ was 3.0%, switching from uniform heating mode to non-uniform heating mode. After the temperature of the silicon melt M stabilized, a horizontal magnetic field was applied to the silicon melt M to confirm that the convection mode was fixed, and then a comparison was made. Examples and We grew silicon single crystals (SM) of the same size. In Examples 2, 3, 4, 5, 6, 7, and 8, the first and second power supplies 94A and 94B were controlled so that the output power bias Δ was 4.0%, 5.0%, 6.0%, -3.0%, -4.0%, -5.0%, and -6.0%, respectively, after generating the silicon melt M by heating the crucible 3 in uniform heating mode. The conditions were the same as in Example 1, but for comparison. Examples and We grew silicon single crystals (SM) of the same size.

[0075] [evaluation] Ten silicon single crystal SMs were grown for each of the comparative example and Examples 1-8, and the occurrence rate of convection modes, oxygen concentration, and oxygen concentration variability were evaluated. The oxygen concentration was evaluated as follows. First, wafers were obtained from a position 1000 mm below the top end of the straight body SM3 of each silicon single crystal SM in the comparative example and Examples 1-8, and the oxygen concentration of the wafers was measured using FTIR (Fourier Transform Infrared Spectrophotometer). Then, the average value of the oxygen concentration in the wafers obtained from the 10 silicon single crystal SMs of the comparative example was used for normalization, and the upper and lower limits of the oxygen concentration were calculated for each of the comparative example and Examples 1-8. The difference between the upper and lower limits of the oxygen concentration was calculated as the variation in oxygen concentration.

[0076] [Table 1]

[0077] [Occurrence rate of convection mode] In the comparative example, the occurrence rate of the left vortex mode was 50%, meaning that the right vortex mode and the left vortex mode occurred virtually randomly. On the other hand, in Examples 1-4, the occurrence rate of the right-handed vortex mode exceeded 50%, and the occurrence rate of the right-handed vortex mode increased as the output power bias Δ increased. In particular, in Examples 2-4, where the output power bias Δ was 4.0% or more, the occurrence rate of the right-handed vortex mode was 90% or more, and in Examples 3 and 4, where the output power bias Δ was 5.0% or more, the occurrence rate of the right-handed vortex mode was 100%. Furthermore, a similar trend to Examples 1-4 was observed in Examples 5-8, where the occurrence rate of the left-handed vortex mode was 90% or more in Examples 6-8, where the output power bias Δ was -4.0% or less, and in Examples 7 and 8, where the output power bias Δ was -5.0% or less, the occurrence rate of the left-handed vortex mode was 100%.

[0078] From the above, it was confirmed that by controlling the first and second power supplies 94A and 94B so that the absolute value of the output power bias Δ is 4.0% or more, it is possible to easily fix the convection mode to one mode regardless of the timing of the horizontal magnetic field application. In particular, it was confirmed that by controlling the first and second power supplies 94A and 94B so that the absolute value of the output power bias Δ is 5.0% or more, it is possible to fix the convection mode to one mode regardless of the timing of the horizontal magnetic field application.

[0079] [Variation in oxygen concentration] The variation in oxygen concentration in the comparative example was 0.40. On the other hand, the oxygen concentration of Examples 1 to 8 of The variation is less than 0.30, and the greater the absolute value of the output power bias Δ, the greater the oxygen concentration. of The variation was small. In particular, in Examples 2-4, 6-8, where the absolute value of the output power bias Δ was 4.0% or more, the oxygen concentration of The variation was 0.25 or less, nearly half the size of the comparative example, and in Examples 3, 4, 7, and 8, where the absolute value of the output power bias Δ was 5.0% or more, the oxygen concentration of The variability was 0.05, which is extremely small compared to the comparative example.

[0080] From the above, it was confirmed that by controlling the first and second power supplies 94A and 94B so that the absolute value of the output power bias Δ is 4.0% or more, the variation in oxygen concentration in the straight drum section SM3 can be reduced, and in particular, by controlling the first and second power supplies 94A and 94B so that the absolute value of the output power bias Δ is 5.0% or more, the variation in oxygen concentration in the straight drum section SM3 can be reduced to an extremely small extent. [Industrial applicability]

[0081] The silicon single crystal manufacturing method and silicon single crystal manufacturing apparatus of the present invention can suppress the occurrence of defects during manufacturing and variations in oxygen concentration from one silicon single crystal to another, thereby improving the yield of silicon single crystals, improving energy efficiency, increasing production efficiency, and reducing waste. [Explanation of symbols]

[0082] 1,1A...Silicon single crystal manufacturing apparatus, 3...Crucible, 3C...Crucible central axis, 4...Heater, 9,9A...Power supply unit, 16C...Central magnetic field lines, 23,23A...Control unit, 31 A …first part, 31B ...Second part, 40A...First heating element, 40B...Second heating element, 94A...First power supply, 94B...Second power supply, 95A...First power supply path, 95B...Second power supply path, 96A...Bypass supply path, 96B...Rectifier section, 401A, 401B...Maximum temperature region, M...Silicon melt, SM...Silicon single crystal, SM1...Neck section, SM2...Shoulder section, SM3...Straight body section, VF1...First vertical virtual plane, VF2...Second vertical virtual plane.

Claims

1. A method for manufacturing silicon single crystals, comprising using a silicon single crystal manufacturing apparatus to pull up a silicon single crystal while applying a horizontal magnetic field to a silicon molten state, The silicon single crystal manufacturing apparatus is A crucible for containing the aforementioned silicon melt, A cylindrical heater surrounding the crucible, The system includes a power supply unit that supplies power to the heater, The heater comprises a semi-cylindrical first heating element and a second heating element, each having the same heating characteristics, and when the first heating element and the second heating element generate different amounts of heat, the heating amounts of the first and second parts of the crucible, which are located on opposite sides of a vertical virtual plane including the central axis of the crucible and the central magnetic field lines of the horizontal magnetic field, are arranged to be different. The aforementioned power supply unit is First power supply and second power supply, A first power supply path that supplies power from the first power source to the first heating element, A second power supply path that supplies power from the second power source to the second heat-generating section, A bypass supply path connecting the first power supply path and the second power supply path, The bypass supply path includes a rectifier that supplies power only in the direction from the first power supply path to the second power supply path, The method for manufacturing the silicon single crystal is as follows: A first heating manufacturing process is performed while the first heating element and the second heating element generate heat at the same amount, The process includes a second heating manufacturing step in which the first heating element and the second heating element are heated at different heat levels, The first heating manufacturing process is carried out while controlling the first and second power supplies so that power is supplied from the first power supply and not from the second power supply. A method for manufacturing a silicon single crystal, wherein the second heating manufacturing step is performed while controlling the first power supply and the second power supply so that power is supplied from the first power supply and the second power supply.

2. A method for manufacturing a silicon single crystal, comprising using a silicon single crystal manufacturing apparatus to pull up a silicon single crystal while applying a horizontal magnetic field to a silicon molten material, The silicon single crystal manufacturing apparatus is A crucible for containing the aforementioned silicon melt, The crucible is surrounded by a cylindrical heater, The heater comprises a semi-cylindrical first heating element and a second heating element, each having the same heating characteristics, and when the first heating element and the second heating element generate different amounts of heat, the heating amounts of the first and second parts of the crucible, which are located on opposite sides of a vertical virtual plane including the central axis of the crucible and the central magnetic field lines of the horizontal magnetic field, are arranged to be different. The method for manufacturing the silicon single crystal is as follows: A silicon melt generation step, which involves melting the silicon raw material in the crucible to generate the silicon melt, A magnetic field application step in which the application of the horizontal magnetic field to the silicon melt is initiated, A convection direction confirmation step confirms that the direction of convection of the silicon melt in a virtual plane perpendicular to the central magnetic field line is fixed in one direction, The first growth step involves growing the neck and shoulder portions by pulling up a seed crystal that has been deposited in the aforementioned silicon melt, The process includes a second growth step of growing a straight body and a tail by pulling up the aforementioned seed crystal, The silicon melt generation step and the second growth step are performed as a first heating manufacturing step while the first heating section and the second heating section generate heat at the same amount. A method for manufacturing a silicon single crystal, wherein the magnetic field application step, the convection direction confirmation step, and the first growth step are performed as a second heating manufacturing step in which the first heating section and the second heating section generate heat at different amounts from each other.

3. A method for manufacturing a silicon single crystal, comprising using a silicon single crystal manufacturing apparatus to pull up a silicon single crystal while applying a horizontal magnetic field to a silicon molten material, The silicon single crystal manufacturing apparatus is A crucible for containing the aforementioned silicon melt, The crucible is surrounded by a cylindrical heater, The heater comprises a semi-cylindrical first heating element and a second heating element, each having the same heating characteristics, and when the first heating element and the second heating element generate different amounts of heat, the heating amounts of the first and second parts of the crucible, which are located on opposite sides of a vertical virtual plane including the central axis of the crucible and the central magnetic field lines of the horizontal magnetic field, are arranged to be different. The method for manufacturing the silicon single crystal is as follows: A silicon melt generation step, which involves melting the silicon raw material in the crucible to generate the silicon melt, A magnetic field application step in which the application of the horizontal magnetic field to the silicon melt is initiated, A convection direction confirmation step confirms that the direction of convection of the silicon melt in a virtual plane perpendicular to the central magnetic field line is fixed in one direction, The first growth step involves growing the neck and shoulder portions by pulling up a seed crystal that has been deposited in the aforementioned silicon melt, Inversion determination process, The process includes a second growth step of growing a straight body and a tail by pulling up the aforementioned seed crystal, The silicon melt generation process is carried out as a first heating manufacturing process in which the first heating unit and the second heating unit are heated at the same amount of heat. The magnetic field application step, the convection direction confirmation step, and the first growth step are performed as a second heating manufacturing step in which the first heating section and the second heating section generate heat at different amounts from each other. A method for manufacturing a silicon single crystal, wherein, in the reversal determination step, if it is determined that there is a possibility of the direction of convection reversing when the second growth step is performed as the first heating and manufacturing step based on the pulling conditions for the silicon single crystal, the second growth step is performed as the second heating and manufacturing step, and if it is determined that there is no possibility of the direction of convection reversing, the second growth step is performed as the first heating and manufacturing step.

4. In the method for manufacturing a silicon single crystal according to any one of claims 1 to 3, A method for manufacturing a silicon single crystal, wherein the first heating element and the second heating element are arranged such that, in a plan view, their highest temperature regions are perpendicular to the vertical virtual plane and coincide with a horizontal virtual line that includes the central axis of the crucible.

5. A silicon single crystal manufacturing apparatus for pulling up a silicon single crystal while applying a horizontal magnetic field to a silicon molten state, A crucible for containing the aforementioned silicon melt, A cylindrical heater surrounding the crucible, The system includes a power supply unit that supplies power to the heater, The heater comprises a first semi-cylindrical heating element and a second heating element, each having the same heating characteristics. The aforementioned power supply unit is First power supply and second power supply, A first power supply path that supplies power from the first power source to the first heating element, A second power supply path that supplies power from the second power source to the second heat-generating section, A bypass supply path connecting the first power supply path and the second power supply path, A silicon single crystal manufacturing apparatus comprising a rectifier unit provided in the bypass supply path and supplying power only in the direction from the first power supply path to the second power supply path.

6. In the silicon single crystal manufacturing apparatus according to claim 5, The system includes a control unit that controls the manufacturing process for pulling up the aforementioned silicon single crystal, The aforementioned manufacturing process is, A first heating manufacturing process is carried out while controlling the first power supply and the second power supply so that power is supplied from the first power supply and power is not supplied from the second power supply, A silicon single crystal manufacturing apparatus comprising: a second heating manufacturing step performed while controlling the first power supply and the second power supply so as to supply power from the first power supply and the second power supply.

7. A silicon single crystal manufacturing apparatus for pulling up a silicon single crystal while applying a horizontal magnetic field to a silicon molten liquid, A crucible for containing the aforementioned silicon melt, A cylindrical heater surrounding the crucible, A power supply unit that supplies power to the heater, The system includes a control unit that controls the manufacturing process for pulling up the silicon single crystal, The heater comprises a first semi-cylindrical heating element and a second heating element, each having the same heating characteristics. The aforementioned power supply unit is First power supply and second power supply, A first power supply path that supplies power from the first power source to the first heating element, The system comprises a second power supply path that supplies power from the second power source to the second heat-generating section, The aforementioned manufacturing process is, A silicon melt generation step, which involves melting the silicon raw material in the crucible to generate the silicon melt, A magnetic field application step in which the application of the horizontal magnetic field to the silicon melt is initiated, A convection direction confirmation step confirms that the direction of convection of the silicon melt in a virtual plane perpendicular to the central magnetic field lines of the horizontal magnetic field is fixed in one direction, The first growth step involves growing the neck and shoulder portions by pulling up a seed crystal that has been deposited in the aforementioned silicon melt, The process includes a second growth step of growing a straight body and a tail by pulling up the aforementioned seed crystal, The control unit, The silicon melt generation step and the second growth step are performed as a first heating manufacturing step, while controlling the first power supply and the second power supply so that the first heating unit and the second heating unit generate the same amount of heat. A silicon single crystal manufacturing apparatus, wherein the magnetic field application step, the convection direction confirmation step, and the first growth step are performed as a second heating manufacturing step, while controlling the first power supply and the second power supply so that the first heating section and the second heating section generate heat at different amounts from each other.

8. A silicon single crystal manufacturing apparatus for pulling up a silicon single crystal while applying a horizontal magnetic field to a silicon molten state, A crucible for containing the aforementioned silicon melt, A cylindrical heater surrounding the crucible, A power supply unit that supplies power to the heater, The system includes a control unit that controls the manufacturing process for pulling up the silicon single crystal, The heater comprises a first semi-cylindrical heating element and a second heating element, each having the same heating characteristics. The aforementioned power supply unit is First power supply and second power supply, A first power supply path that supplies power from the first power source to the first heating element, The system comprises a second power supply path that supplies power from the second power source to the second heat-generating section, The aforementioned manufacturing process is, A silicon melt generation step, which involves melting the silicon raw material in the crucible to generate the silicon melt, A magnetic field application step in which the application of the horizontal magnetic field to the silicon melt is initiated, A convection direction confirmation step confirms that the direction of convection of the silicon melt in a virtual plane perpendicular to the central magnetic field lines of the horizontal magnetic field is fixed in one direction, The first growth step involves growing the neck and shoulder portions by pulling up a seed crystal that has been deposited in the aforementioned silicon melt, Inversion determination process, The process includes a second growth step of growing a straight body and a tail by pulling up the aforementioned seed crystal, The control unit, The silicon melt generation process is carried out as a first heating manufacturing process, in which the first heating unit and the second heating unit are controlled to generate the same amount of heat, while controlling the first power supply and the second power supply. The magnetic field application step, the convection direction confirmation step, and the first growth step are performed as a second heating manufacturing step, while controlling the first power supply and the second power supply so that the first heating section and the second heating section generate heat at different amounts from each other. A silicon single crystal manufacturing apparatus, wherein, in the reversal determination step, if it is determined that there is a possibility of the direction of convection reversing when the second growth step is performed as the first heating and manufacturing step based on the silicon single crystal pulling conditions, the second growth step is performed as the second heating and manufacturing step, and if it is determined that there is no possibility of the direction of convection reversing, the second growth step is performed as the first heating and manufacturing step.

9. In the silicon single crystal manufacturing apparatus according to any one of claims 5 to 8, A silicon single crystal manufacturing apparatus in which the first heating element and the second heating element are arranged in a plan view such that the highest temperature region is perpendicular to a vertical virtual plane containing the central axis of the crucible and the central magnetic field line of the horizontal magnetic field, and overlaps with a horizontal virtual line containing the central axis of the crucible.

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