METHOD FOR PRODUCE A SILICON CRYSTAL AND DEVICE FOR PRODUCEING A SILICON CRYSTAL

Abstract

A method for manufacturing monocrystalline silicon for growing monocrystalline silicon while a horizontal magnetic field is applied to a silicon melt, using a monocrystalline silicon manufacturing apparatus comprising a crucible and a heating device having a hollow cylindrical shape surrounding the crucible. The heating device comprises a first and a second heat-generating section, both having a hollow semi-cylindrical shape and the same heat-generating characteristics. The heating device is arranged such that when the heat-generating sections produce heat with different heat-generating quantities, the heating quantities of the first and second sections of the crucible are different. The first and second sections are arranged on either side across a vertical virtual plane that includes a central axis of the crucible and a central magnetic field line of the horizontal magnetic field.The process involves performing a first heating and generation cycle while the heat generation sections produce heat with the same heat generation quantity, and a second heating and generation cycle while the heat generation sections produce heat with different heat generation quantities.

Description

TECHNICAL AREA

[0001] The present invention relates to a method for producing monocrystalline silicon and a production apparatus for producing monocrystalline silicon. BACKGROUND OF THE TECHNOLOGY

[0002] The MCZ process (Magnetic Field Applied Czochralski process), in which a horizontal magnetic field is applied to a silicon melt, is occasionally used as a manufacturing method for monocrystalline silicon. When a horizontal magnetic field is applied to the silicon melt using the MCZ process, a direction of convection in a virtual plane orthogonal to the direction of application of the horizontal magnetic field in the silicon melt is sometimes clockwise (hereinafter referred to as "clockwise vortex mode") and sometimes counterclockwise (hereinafter referred to as "counterclockwise vortex mode").

[0003] The resulting convection mode is randomly either clockwise or counterclockwise. Consequently, the oxygen concentration incorporated into monocrystalline silicon varies depending on the convection mode and the furnace environment. To obtain monocrystalline silicon ingots with a stable oxygen concentration, it is important to control the convection mode of the silicon melt during the drawing of the ingots. For this reason, various studies have been conducted on methods for controlling the convection mode of the silicon melt in a crucible (see, for example, patent literature 1).

[0004] Patent literature 1 discloses a method for eliminating a variation in oxygen concentration caused by the convection mode by providing a thermal environment inside the furnace of a production device that is not axially symmetric with respect to a central axis of the crucible, thereby fixing the convection mode to one of the vortex mode clockwise and the vortex mode counterclockwise.

[0005] Patent literature 1 discloses as a specific method the variation of the resistance value of a heating device and the thickness of a thermal insulation material along a circumferential direction of the crucible. QUOTE LIST PATENT LITERATURE(S)

[0006] Patent Literature 1: JP 2019-151502 A SUMMARY OF THE INVENTIONAL TASK(S) THAT THE INVENTION IS INTENDED TO SOLVE

[0007] However, in the process disclosed in patent literature 1, the non-axially symmetric thermal environment is achieved through the furnace structure, and therefore the degree of non-axial symmetry cannot be changed during the production of monocrystalline silicon.

[0008] Thus, for example, in a raw material melting step, the silicon material may be melted unevenly around the circumference of the crucible. This can cause the solid silicon material floating in the molten silicon to tip over and come into strong contact with a quartz crucible, leading to damage to the quartz crucible.

[0009] One object of the invention is to provide a method for producing monocrystalline silicon and a production apparatus for monocrystalline silicon that are capable of preventing the occurrence of defects during production and the variation in oxygen concentration between monocrystalline silicon ingots. MEANS OF SOLVING THE TASK(S)

[0010] A manufacturing process for monocrystalline silicon according to one aspect of the invention is a manufacturing process for monocrystalline silicon for growing the monocrystalline silicon while a horizontal magnetic field is applied to a silicon melt, using a manufacturing apparatus for monocrystalline silicon, wherein the manufacturing apparatus for monocrystalline silicon comprises a crucible configured to hold the silicon melt and a heating device having a hollow cylindrical shape surrounding the crucible, wherein the heating device comprises a first heat-generating section and a second heat-generating section, each having a hollow semi-cylindrical shape, wherein the first and second heat-generating sections have identical heat-generating properties, and wherein the heating device is arranged such that,where the first and second heat-generating sections produce heat with different heat-generating quantities, the heating quantity of a first section of the crucible and the heating quantity of a second section of the crucible are different, the first section and the second section being arranged on either side with respect to a vertical virtual plane comprising a central axis of the crucible and a central magnetic field line of the horizontal magnetic field, the manufacturing process comprising: performing a first heating and producing phase while the first heat-generating section and the second heat-generating section are producing heat with identical heat-generating quantities; and performing a second heating and producing phase while the first heat-generating section and the second heat-generating section are producing heat with different heat-generating quantities.

[0011] In the manufacturing process for monocrystalline silicon according to the aspect of the invention, the manufacturing apparatus for monocrystalline silicon preferably further comprises a first power source and a second power source, a first power supply path through which electric current from the first power source is supplied to the first heat generation section, and a second power supply path through which electric current from the second power source is supplied to the second heat generation section, wherein the first heating and generation is carried out while the first power source and the second power source are controlled to cause the first heat generation section and the second heat generation section to generate heat with an identical heat generation quantity, and the second heating and generation is carried out while the first power source and the second power source are controlled to causethat the first heat generation section and the second heat generation section generate heat with different amounts of heat generation.

[0012] In the manufacturing process for monocrystalline silicon according to the aspect of the invention, the manufacturing apparatus for monocrystalline silicon preferably further comprises a bypass supply path connecting the first power supply path to the second power supply path, and a flow controller provided in the bypass supply path and configured to supply electrical current only in one direction from the first power supply path to the second power supply path, wherein the first heating and generation is carried out while the first power source and the second power source are controlled to supply electrical current from the first power source and not from the second power source, and the second heating and generation is carried out while the first power source and the second power source are controlled to supply electrical current from the first power source and the second power source.

[0013] Preferably, the manufacturing process for monocrystalline silicon according to the aspect of the invention further comprises: generating the silicon melt by melting a silicon material in the crucible; beginning to apply the horizontal magnetic field to the silicon melt; verifying that a convection direction of the silicon melt is fixed in a virtual plane, wherein the virtual plane is orthogonal to the central magnetic field line; performing a first growth in which a neck and shoulder are allowed to grow by bringing a seed crystal into contact with the silicon melt and then pulling the seed crystal upwards;and performing a second growth in which a straight body and a tail are grown by pulling up the seed crystal, with the generation of the silicon melt and the second growth being carried out as the first heating and generation, and the commencement of the application of the horizontal magnetic field, the testing, and the first growth being carried out as the second heating and generation.

[0014] Preferably, the manufacturing process for monocrystalline silicon according to this aspect of the invention further comprises: generating the silicon melt by melting a silicon material in the crucible; beginning to apply the horizontal magnetic field to the silicon melt; verifying that a convection direction of the silicon melt is fixed in a virtual plane, wherein the virtual plane is orthogonal to the central magnetic field line; performing a first growth in which a neck and shoulder are allowed to grow by bringing a seed crystal into contact with the silicon melt and then pulling the seed crystal upwards; performing a reversal determination;and performing a second growth in which a straight body and a tail are grown by pulling up the seed crystal, wherein the generation of the silicon melt is performed as the first heating and generation, the commencement of the application of the horizontal magnetic field, the testing and the first growth are performed as the second heating and generation, and in the reversal determination with respect to the second growth to be performed as the first heating and generation based on a pull-up condition of the monocrystalline silicon, the second growth is performed as the second heating and generation if it is determined that the convection direction is likely to be reversed, and the second growth is performed as the first heating and generation if it is determined that the convection direction is likely not to be reversed.

[0015] In the manufacturing process for monocrystalline silicon according to the aspect of the invention, it is preferred that the first heat generation section and the second heat generation section are arranged such that the first and the second heat generation section each have maximum temperature ranges which overlap a horizontal virtual line in planar view, wherein the horizontal virtual line is orthogonal to the vertical virtual plane and includes the central axis of the crucible.

[0016] A manufacturing apparatus for monocrystalline silicon according to another aspect of the invention comprises: a crucible configured to hold the silicon melt; a heating device having a hollow cylindrical shape and surrounding the crucible;and a power supply section configured to supply electric current to the heating device, the heating device comprising a first heat-generating section and a second heat-generating section, each having a hollow semi-cylindrical shape, the first and second heat-generating sections having identical heat-generating characteristics, and the power supply section comprising a first power source and a second power source, a first power supply path through which electric current from the first power source is supplied to the first heat-generating section, and a second power supply path through which electric current from the second power source is supplied to the second heat-generating section.

[0017] In the manufacturing apparatus for monocrystalline silicon according to the other aspect of the invention, the power supply section preferably further comprises a bypass supply path connecting the first power supply path to the second power supply path, and a flow controller provided in the bypass supply path and configured to supply electrical current only in one direction from the first power supply path to the second power supply path.

[0018] The manufacturing apparatus for monocrystalline silicon according to the other aspect of the invention preferably further comprises: a control unit configured to control the manufacturing process, wherein the monocrystalline silicon is raised during the manufacturing process, the manufacturing process comprising performing a first heating and generating stage while the first power source and the second power source are controlled to cause the first heat-generating section and the second heat-generating section to generate heat with an identical heat-generating quantity, and performing a second heating and generating stage while the first power source and the second power source are controlled to cause the first heat-generating section and the second heat-generating section to generate heat with different heat-generating quantities.

[0019] The manufacturing apparatus for monocrystalline silicon according to the other aspect of the invention preferably further comprises: a control configured to control the manufacturing process, wherein the monocrystalline silicon is raised during the manufacturing process, the manufacturing process comprising performing a first heating and generation step while the first power source and the second power source are controlled to supply electric current from the first power source and not from the second power source, and performing a second heating and generation step while the first power source and the second power source are controlled to supply electric current from both the first and second power sources.

[0020] In the manufacturing apparatus for monocrystalline silicon according to the other aspect of the invention, the manufacturing process preferably further comprises generating the silicon melt by melting a silicon material in the crucible, beginning the application of the horizontal magnetic field to the silicon melt, verifying that a convection direction of the silicon melt is fixed in a virtual plane, wherein the virtual plane is orthogonal to a central magnetic field line of the horizontal magnetic field, performing a first growth in which a neck and shoulder are grown by bringing a seed crystal into contact with the silicon melt and then pulling up the seed crystal, and performing a second growth in which a straight body and tail are grown by pulling up the seed crystal, and the control is configured.to carry out the generation of the silicon melt and the second growth as the first heating and generation, and to begin applying the horizontal magnetic field, testing, and the first growth as the second heating and generation.

[0021] In the manufacturing apparatus for monocrystalline silicon according to the other aspect of the invention, the manufacturing process preferably further comprises generating the silicon melt by melting a silicon material in the crucible, beginning the application of the horizontal magnetic field to the silicon melt, verifying that a convection direction of the silicon melt is fixed in a virtual plane, wherein the virtual plane is orthogonal to a central magnetic field line of the horizontal magnetic field, performing a first growth in which a neck and shoulder are grown by bringing a seed crystal into contact with the silicon melt and then pulling up the seed crystal, performing a reversal determination and performing a second growth in which a straight body and tail are grown by pulling up the seed crystal, and the control is configured.to perform the generation of the silicon melt as the first heating and generation, the initiation of the application of the horizontal magnetic field, the testing and the first growth as the second heating and generation, and in the reversal determination regarding the second growth, which is to be performed as the first heating and generation, based on a pull-up condition of the monocrystalline silicon, to perform the second growth as the second heating and generation if it is determined that the convection direction is likely to be reversed, and to perform the second growth as the first heating and generation if it is determined that the convection direction is unlikely to be reversed.

[0022] In the manufacturing apparatus for monocrystalline silicon according to the other aspect of the invention, it is preferred that the first heat generation section and the second heat generation section are arranged such that the first and the second heat generation section each have maximum temperature ranges that overlap a horizontal virtual line in planar view, wherein the horizontal virtual line is orthogonal to a vertical virtual plane and includes a central axis of the crucible, wherein the vertical virtual plane includes the central axis of the crucible and a central magnetic field line of the horizontal magnetic field. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a vertical cross-sectional view of a schematic configuration of a manufacturing device for monocrystalline silicon according to a first embodiment and a second embodiment. Fig.Figure 2 is a schematic top view of a heating device and a magnetic field application section according to the first and second embodiments. Fig. Figure 3 is a perspective view of the heating device according to the first and second embodiments. Fig. Figure 4 is an equivalent circuit diagram of the heating device and a power supply section according to the first embodiment. Fig. Figure 5 is a block diagram of relevant parts of the manufacturing apparatus for monocrystalline silicon according to the first and second embodiments. Fig. Figure 6 is a flowchart of a manufacturing process for monocrystalline silicon according to the first and second embodiments. Fig. Figure 7 is an equivalent circuit diagram of the heating device and a power supply section according to the second embodiment. DESCRIPTION OF THE EXECUTION FORM(S) First embodiment Configuration of the manufacturing device for monocrystalline silicon

[0023] First, the configuration of a manufacturing device for monocrystalline silicon according to a first embodiment of the invention is described.

[0024] Fig. Figure 1 is a vertical cross-sectional view of a schematic configuration of the manufacturing apparatus for monocrystalline silicon. Fig. Figure 2 is a schematic top view of a heating device and a magnetic field application section. Fig. Figure 3 is a perspective view of the heating device. Fig. Figure 4 is an equivalent circuit diagram of the heating device and a power supply section. Fig. Figure 5 is a block diagram of relevant parts of the manufacturing apparatus for monocrystalline silicon 1.

[0025] One in Fig.The monocrystalline silicon 1 manufacturing apparatus shown in Figure 1 is a device for producing monocrystalline silicon SM by the MCZ process, in which the monocrystalline silicon SM, comprising a neck SM1, a shoulder SM2, a straight body SM3, and a tail (not shown), is drawn up while a horizontal magnetic field is applied to a silicon melt M. The monocrystalline silicon 1 manufacturing apparatus comprises a chamber 2 forming an outer shell, a crucible 3 arranged in a central section of the chamber 2, a heating device 4 arranged around the crucible 3, and a temperature measuring section 15.

[0026] The crucible 3 has a double-layered structure comprising a graphite crucible 3A on an outer surface and a quartz crucible 3B on an inner surface, with the silicon melt M contained within the quartz crucible 3B. Both the graphite crucible 3A and the quartz crucible 3B are hollow cylindrical containers with a bottom and each has a circular shape in planar view when viewed from a vertical top. The crucible 3 is attached to the upper end of a support shaft 5, which is rotatable and movable up and down.

[0027] The heating device 4 is a graphite heating device having a substantially hollow cylindrical shape and is arranged around the crucible 3. A thermal insulation material 6, also having a hollow cylindrical shape, is provided on an outer surface of the heating device 4 along an inner surface of the chamber 2.

[0028] Above the crucible 3, a draw-up shaft 7 is arranged coaxially with the support shaft 5. The draw-up shaft 7 is formed, for example, from a wire. A seed crystal SC is attached to one lower end of the draw-up shaft 7.

[0029] Inside chamber 2, a heat shield 8, which has a hollow cylindrical shape, is arranged above the silicon melt M in the crucible 3 to surround the growing monocrystalline silicon SM.

[0030] The heat shield 8 protects the growing monocrystalline silicon SM from radiant heat from the silicon melt M, a side wall of the crucible 3 and the heating device, thus preventing a temperature increase of the monocrystalline silicon SM.

[0031] A gas inlet 2A, through which an inert gas, such as argon gas, is introduced into chamber 2, is provided at an upper part of chamber 2. An exhaust outlet 2B, through which the gas is drawn into and discharged from chamber 2 when a vacuum pump (not shown) is driven, is provided at a lower part of chamber 2.

[0032] The temperature measuring section 15 measures temperatures at a first measuring point P1 and a second measuring point P2. The position of each of the first measuring point P1 and the second measuring point P2 in a radial direction is defined between an outer circumferential surface of the monocrystalline silicon SM to be grown and an inner circumferential surface of an opening in the heat shield 8. As will be described later, the convection mode of the silicon melt M can be verified by measuring the temperatures at the first measuring point P1 and the second measuring point P2. For example, if the convection direction of the silicon melt M is determined by the heating device 4, which heats the silicon melt M, to be clockwise, then the convection mode of the silicon melt M can be determined. Fig.If the convection direction of the silicon melt M is set to clockwise (i.e., the convection mode of the silicon melt M is clockwise), the temperature measured at the first measuring point P1 is higher than that at the second measuring point P2. If the convection direction of the silicon melt M is set to counterclockwise by the heating device 4, which heats the silicon melt M (i.e., the convection mode is counterclockwise), the temperature measured at the first measuring point P1 is lower than that at the second measuring point P2.

[0033] The temperature measuring section 15 comprises a pair of reflectors 15A and a pair of radiation thermometers 15B.

[0034] The reflectors 15A are provided within chamber 2. The reflectors 15A are preferably provided with an angle between a reflective surface 15C of each of the reflectors 15A and a horizontal plane that lies in a range of 40 degrees to 50 degrees.

[0035] The radiation thermometers 15B are provided outside chamber 2. The radiation thermometers 15B receive radiant light L, which passes through quartz window 2C (see Fig. 1) are inserted into the chamber 2 and measure the temperatures at the first measuring point P1 and the second measuring point P2 in a non-contact manner.

[0036] As in Fig. As shown in Figure 2, the manufacturing device for monocrystalline silicon 1 further comprises a magnetic field application section 16.

[0037] The magnetic field application section 16 comprises a first magnetic body 16A and a second magnetic body 16B, each in the form of an electromagnetic coil. The first magnetic body 16A and the second magnetic body 16B are positioned outside the chamber 2, facing each other with the crucible 3 between them. The magnetic field application section 16 applies a horizontal magnetic field such that, in planar view, a central magnetic field line 16C, passing through a coil center axis, intersects a center axis 3C of the crucible 3 (hereafter occasionally referred to as the "crucible center axis 3C") and is directed from the second magnetic body 16B to the first magnetic body 16A (i.e., in an upward direction, indicated by an arrow pointing the central magnetic field line 16C inwards). Fig. 2 represents a direction from the front to the back of the plate. Fig. 1 corresponds to).

[0038] The heating device 4 is arranged such that a central axis 4C thereof (hereinafter referred to as the "heating element central axis 4C") is arranged coaxially with the crucible central axis 3C. The thermal insulation material 6 is also arranged such that a central axis thereof is arranged coaxially with the crucible central axis 3C. In other words, the crucible 3, the heating device 4, and the thermal insulation material 6 are arranged such that the gap between the crucible 3 and the heating device 4, and the gap between the heating device 4 and the thermal insulation material 6, are each uniform along a circumferential direction of the crucible 3. With this arrangement of the crucible 3, the heating element 4, and the thermal insulation material 6, when the heating device 4 generates heat uniformly along the circumferential direction, the heat distribution through the heating device 4 and the heat extraction distribution through the thermal insulation material 6 are each uniform along the circumferential direction of the crucible 3.

[0039] As in Fig. 2 and Fig. As shown in Figure 3, the heating device 4 comprises a heat-generating section 40 in the form of a graphite heating element having a hollow cylindrical shape. The heat-generating section 40 has a uniform thickness in one circumferential direction. The heat-generating section 40 has a plurality of upper slots 41 extending downwards from an upper end of the heat-generating section 40 and a plurality of lower slots 42 extending upwards from a lower end. The upper slots 41 and the lower slots 42 are arranged alternately in the circumferential direction. The upper slots 41 and the lower slots 42 are equal to each other in width and depth in a vertical direction. Furthermore, the upper slot 41 and the lower slot 42 are spaced uniformly around the entire circumference of the heating device 4.

[0040] The heat generation section 40 comprises a first heat generation section 40A and a second heat generation section 40B. The first heat generation section 40A, which has a hollow semi-cylindrical shape, is arranged on one side of a first vertical virtual plane VF1 that includes the heating device center axis 4C. The second heat generation section 40B, which also has a hollow semi-cylindrical shape, is arranged on the other side and has the same heat generation characteristic as the first heat generation section 40A. The same heat generation characteristic means that when an equal amount of electric current is supplied, an equal amount generates the same amount of heat.

[0041] The first heat generation section 40A and the second heat generation section 40B have the same total number of upper slots 41 and lower slots 42. In the exemplary embodiment, the first and second heat generation sections 40A and 40B each have four upper slots 41 and six lower slots 42, and thus the total number of upper slots 41 and lower slots 42 is ten.

[0042] The manufacturing apparatus for monocrystalline silicon 1 comprises a power supply section 9 for supplying electric current to the heat generation section 40. The power supply section 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-degree intervals along the circumferential direction of the heat generation section 40.

[0043] The first to fourth connections 91A to 91D each extend downwards from a lower end of a section divided by two lower slots 42 and are each integrally formed with the heat-generating section 40. Furthermore, the first to fourth connections 91A to 91D each comprise connecting sections 911A to 911D, each bent inwards at a right angle from a lower end of each connection. The connecting sections 911A to 911D each have through-holes 912A to 912D.

[0044] In other words, the heating device 4 comprises a graphite heating device formed by one-piece forming of the heat-generating section 40, which has a hollow cylindrical shape that is a heating element, and the first to fourth terminals 91A to 91D, which are heating feet.

[0045] The heat generation section 40 is divided into a first curved section 43A, a second curved section 43B, a third curved section 43C, and a fourth curved section 43D, each having a zigzag shape, with upper slots 41 and lower slots 42 provided therein. The first to fourth curved sections 43A to 43D configure four heating elements.

[0046] Specifically, two upper slots 41 and three lower slots 42 are provided alternately between the first terminal 91A and the second terminal 91B to provide the first curve section 43A. Likewise, two upper slots 41 and three lower slots 42 are provided alternately between the second terminal 91B and the third terminal 91C to provide the second curve section 43B.

[0047] Two upper slots 41 and three lower slots 42 are provided alternately between the third terminal 91C and the fourth terminal 91D to provide the third cam section 43C. Two upper slots 41 and three lower slots 42 are provided alternately between the fourth terminal 91D and the first terminal 91A to provide the fourth cam section 43D.

[0048] Therefore, the first to fourth curve sections 43A to 43D, which have the same shape, exhibit the same resistance value. Consequently, if the magnitude of the current flowing through the first to fourth curve sections 43A to 43D is the same, then the first to fourth curve sections 43A to 43D generate the same amount of heat.

[0049] The first heat generation section 40A includes the first curve section 43A and the second curve section 43B, and the second heat generation section 40B includes the third curve section 43C and the fourth curve section 43D.

[0050] As in Fig. As shown in Figure 2, the heating device 4 is arranged such that the heating device central axis 4C is coaxial with the crucible central axis 3C, and the first heat-generating section 40A and the second heat-generating section 40B are surface-symmetric with respect to a second vertical virtual plane VF2, which includes the crucible central axis 3C and the central magnetic field line 16C. In other words, the heating device 4 is arranged such that the second vertical virtual plane VF2 is coaxial with the crucible central axis 3C shown in Figure 2. Fig. 3 shown first vertical virtual plane VF1 coincides.

[0051] It can also be said that the heating device 4 is arranged such that the first heat generation section 40A and the second heat generation section 40B are doubly symmetrical with respect to the crucible central axis 3C.

[0052] Furthermore, it can also be said that the heating device 4 is arranged such that, when the first heat-generating section 40A and the second heat-generating section 40B generate heat with different heat-generating quantities, the heating quantities for a first section 31A and a second section 31B of the crucible 3 are different from each other, wherein the first section 31A and the second section 31B are arranged on both sides with respect to the second vertical virtual plane VF2, which includes the crucible central axis 3C and the central magnetic field line 16C.

[0053] Furthermore, in planar view, central areas of the first and second heat generation sections 40A and 40B are each maximum temperature ranges 401A and 401B. It can also be said that the heating device 4 is arranged such that the maximum temperature ranges 401A and 401B of the first and second heat generation sections 40A and 40B overlap a horizontal virtual line VL in planar view, which is orthogonal to the second vertical virtual plane VF2 and includes the crucible center axis 3C.The reason why the central areas of the first and second heat generation sections 40A and 40B are the highest temperature areas 401A and 401B is that the areas where the current flows in the first and second heat generation sections 40A and 40B have the same amount of heat generation, but heat transfer causes areas furthest from both ends of each of the first and second heat generation sections 40A and 40B to have the highest temperature.

[0054] As in Fig.As shown in Figure 3, the first to fourth support electrodes 92A to 92D are rod-shaped electrodes made of conductive carbon. Each of the first to fourth support electrodes 92A to 92D has one end that is inserted through the corresponding through-hole 912A to 912D of the respective terminals 91A to 91D, and each of the carbon nuts 93A to 93D is screwed onto an external thread formed at the corresponding end. Thus, the first to fourth support electrodes 92A to 92D are each electrically connected to the terminals 91A to 91D and support the heating device 4.

[0055] As in Fig.As shown in Figure 4, the power supply section 9 comprises a first power source 94A and a second power source 94B, a first power supply path 95A through which electric current from the first power source 94A is supplied to the first heat generation section 40A, and a second power supply path 95B through which electric current from the second power source 94B is supplied to the second heat generation section 40B.

[0056] At least one of the first power source 94A or the second power source 94B is capable of changing the amount of electric current supplied.

[0057] The first power supply path 95A includes the second support electrode 92B and a first anode wiring 951A, which connects the other end 921B of the second support electrode 92B to an anode of the first power source 94A.

[0058] The second power supply path 95B includes the fourth support electrode 92D and a second anode wiring 951B, which connects the other end 921D of the fourth support electrode 92D to an anode of the second power source 94B.

[0059] The cathodes of the first power source 94A and the second power source 94B are grounded by a grounding wire 952A and a grounding wire 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 a grounding wire 953A and a grounding wire 953B, respectively.

[0060] With the configuration of the heating device 4 and the power supply section 9, as shown in Fig.As shown in Figure 4, when a current with a current value Ix flows from the first power source 94A and the second power source 94B, a current with a current value of 0.5 Ix flows through the first to fourth curve sections 43A to 43D. As described above, the first to fourth curve sections 43A to 43D have the same resistance value. Therefore, when the current with the same current value Ix flows from the first power source 94A and the second power source 94B, that is, when the electric current of the same magnitude is supplied, the first heat-generating section 40A and the second heat-generating section 40B produce heat with the same amount of heat generation.

[0061] If, in contrast, a current with a value ly flows from the first power source 94A, and a current with a value Iz, which differs from the value ly, flows from the second power source 94B—that is, if the electric current supplied by the first power source 94A has a value that differs from that supplied by the second power source 94B—then a current with a value of 0.5 ly flows through the first and second curve sections 43A and 43B, and a current with a value of 0.5 Iz flows through the third and fourth curve sections 43C and 43D. Thus, the first and second heat-generating sections 40A and 40B produce heat with different amounts of heat generation.

[0062] Hereinafter, a mode to cause the first and second heat-generating sections 40A and 40B to produce heat with the same heat output is occasionally referred to as the "uniform heating mode," and a mode to cause the first and second heat-generating sections 40A and 40B to produce heat with different heat outputs is referred to as the "non-uniform heating mode." In the non-uniform heating mode, the current value flowing from either the first power source 94A or the second power source 94B may be the same as the current value in the uniform heating mode, and the current value flowing from either the first power source 94A or the second power source 94B may differ from the current value in the uniform heating mode.

[0063] When the crucible 3 is heated in the uniform heating mode, the silicon melt M in the crucible 3 is heated uniformly over the entire circumference of the crucible 3.

[0064] In this case, convection occurs in the silicon melt M, rising near the side face of the crucible 3 and sinking near the center. Under these conditions, the position of a downward flow changes randomly and, for example, deviates from the center of the crucible 3 due to unstable convection. Then, when a horizontal magnetic field is applied to the silicon melt M, the rotation of the downward flow around the circumference of the crucible 3 is gradually restricted, and finally, the direction of convection is fixed in a virtual plane orthogonal to the applied direction of the horizontal magnetic field.

[0065] As described above, when crucible 3 is heated in the uniform heating mode, the horizontal magnetic field is applied while the position of the downward flow changes randomly. The convection mode thus becomes either the clockwise vortex mode or the counterclockwise vortex mode, depending on when the field is applied.

[0066] On the other hand, when the crucible 3 is heated in the non-uniform heating mode, the silicon melt M in the crucible 3 is heated in such a way that the temperature of a part of the silicon melt M, which is located near the first heat generation section 40A, differs from that of another part, which is located near the second heat generation section 40B.

[0067] For example, if the second heat-generating section 40B, located on the left side of the crucible 3, generates a greater amount of heat than the first heat-generating section 40A, located on the right side, an upward current is stably generated in the silicon melt M on the left side of the crucible 3, and a downward current is stably generated in the silicon melt M on the right side of the crucible 3, and the position of the downward current does not change randomly, unlike in a case where the first and second heat-generating sections 40A and 40B generate the same amount of heat. If, in this state, a horizontal magnetic field is applied to the silicon melt M, regardless of when the field is applied, the convection will be fixed in a clockwise direction, such that it is in a clockwise vortex mode.Since the maximum temperature range 401A of the first heat generation section 40A overlaps the horizontal virtual line VL in planar view, a horizontal magnetic field is applied, while a virtual line connecting a position where the upward flow is strongest with a position where the downward flow is strongest is almost orthogonal to a generation position of the central magnetic field line 16C. The clockwise vortex mode can thus be generated stably.

[0068] In order to generate the vortex mode clockwise with a high probability independent of the time of application of a horizontal magnetic field, the output power deviation Δ, calculated by a formula (1) below, is preferably 4.0% or more, more preferably 5.0% or more. Δ(%)=(Q1 / Q2−1)×100 Q1: Output power of the first heat generation stage 40A Q2: Output power of the second heat generation section 40B

[0069] To prevent a variation in oxygen concentration between ingots of monocrystalline silicon SM, it is necessary here to fix the convection direction of the silicon melt M to one direction, and therefore the crucible 3 is preferably heated in the non-uniform heating mode.

[0070] However, if the straight body SM3 of monocrystalline silicon SM is grown in a thermal environment in chamber 2 that is not axially symmetric with respect to the crucible's central axis 3C in the non-uniform heating mode, the diameter variation of the straight body SM3 can be greater. If a growth rate is controlled to prevent the diameter variation, the growth rate variation can be greater.

[0071] Thus, it is assumed that the diameter variation of the straight body SM3 and the draw-up speed variation can be prevented by heating the crucible 3 in the non-uniform heating mode before the straight body SM3 is drawn up, in order to fix the convection of the silicon melt M in one direction, and then switching the heating mode of the crucible 3 to the uniform heating mode and drawing up the straight body SM3.

[0072] However, if, as described above, crucible 3 is heated in the uniform heating mode, the position of the downward flow changes randomly, which can cause a reversal of the convection direction during the pull-up of the straight body SM3. If such a reversal of the convection direction occurs, the concentration of oxygen absorbed into the straight body SM3 can vary. Additionally, it is assumed that whether or not the reversal of the convection direction occurs depends on the pull-up conditions of the monocrystalline silicon SM.

[0073] Thus, it is preferably checked in advance whether the convection direction is likely to be reversed or not when the non-uniform heating mode is moved to the uniform heating mode after the convection direction has been set in the non-uniform heating mode, and based on the results of the check, it is determined whether the non-uniform heating mode should be moved to the uniform heating mode or not after the convection mode has been set.

[0074] As in Fig.As shown in Figure 5, the manufacturing device for monocrystalline silicon 1 further comprises a material feeder 18, a crucible rotation driver 19, a pull-up driver 20, an input section 21, a memory 22 and a control unit 23. The first power source 94A, the second power source 94B, the radiation thermometers 15B, the magnetic field application section 16, the material feeder 18, the crucible rotation driver 19, the pull-up driver 20, the input section 21 and the memory 22 are connected to the control unit 23 so that various information can be sent to and received from the control unit 23.

[0075] The first power source 94A and the second power source 94B supply electric current of the same or different magnitudes to the first heat generation section 40A and the second heat generation section 40B respectively, under the control of the controller 23.

[0076] The radiation thermometers 15B each output signals corresponding to measurement results to the control unit 23.

[0077] The magnetic field application section 16 applies a horizontal magnetic field of predetermined intensity to the silicon melt M under the control of the control unit 23.

[0078] The material feeder 18 supplies a silicon material to the crucible 3 under the control of the control unit 23. An operator can supply the silicon material to the crucible 3 without having to connect the material feeder 18 to the monocrystalline silicon 1 manufacturing device.

[0079] The crucible rotation driver 19 rotates the crucible 3 at a predetermined speed in a predetermined direction under the control of the controller 23.

[0080] The lifting driver 20 raises and lowers the lifting shaft 7 under the control of the control unit 23. In addition, the lifting driver 20 rotates the lifting shaft 7 at a predetermined speed in a direction opposite to or equal to the direction of rotation of the support shaft 5 under the control unit 23.

[0081] The input section 21 is, for example, provided in the form of a touch panel or a physical button. The input section 21, which is used for input operations of various settings, outputs signals corresponding to the input operations to the controller 23.

[0082] Memory 22 is provided in the form of a known storage device, such as a hard disk drive (HDD). Memory 22 stores various pieces of information necessary for the pull-up control of the monocrystalline silicon SM and information for determining the convection reversal.

[0083] The information for determining convection reversal includes, for each monocrystalline silicon SM pull-up condition and for each monocrystalline silicon 1 fabrication device, details indicating whether the convection direction is likely to reverse when the silicon melt M is set to the non-uniform heating mode and then switched to the uniform heating mode. The presence or absence of the convection reversal probability for each pull-up condition can be verified experimentally using the monocrystalline silicon 1 fabrication device or by fabricating monocrystalline silicon SM, or alternatively, by simulation.

[0084] The controller 23 includes a CPU (central processing unit). The controller 23 controls the growth of the monocrystalline silicon SM by the CPU, which executes a program stored in memory 22. Manufacturing process for monocrystalline silicon

[0085] The following describes a manufacturing process for monocrystalline silicon SM using the manufacturing apparatus for the production of monocrystalline silicon 1. Fig. Figure 6 is a flowchart of the manufacturing process for monocrystalline silicon.

[0086] The first embodiment illustrates that the second heat generation section 40B generates heat with a greater heat output than the first heat generation section 40A in the non-uniform heating mode. The heat outputs of the first and second heat generation sections 40A and 40B in the uniform heating mode can be the same as, or different from, the heat output of the first heat generation section 40A or the second heat generation section 40B in the non-uniform heating mode.

[0087] First, an operator uses input section 21 to enter the pull-up conditions for the monocrystalline silicon SM to be produced.

[0088] The controller 23 records the entered pull-up conditions (step S1), as shown in Fig. 6 shown.

[0089] Subsequently, the control unit 23 carries out a manufacturing process for the monocrystalline silicon SM based on the recorded draw-up conditions.

[0090] Specifically, while an inert atmosphere at reduced pressure is maintained within chamber 2, the heating device 4 is switched off (i.e., no electrical power is supplied to the heating device 4), and no horizontal magnetic field is applied, the controller 23 controls the material feeder 18 to feed the silicon material into the crucible 3 and then controls the crucible rotation driver 19 to rotate the crucible 3 in one direction (step S2). If the material feeder 18 is not provided on the monocrystalline silicon 1 fabrication device, the operator feeds the silicon material into the crucible 3.

[0091] The controller 23 then controls the first and second power sources 94A and 94B to heat the crucible 3 in uniform heating mode using the first and second heat generation sections 40A and 40B of the heating device 4, thereby melting the silicon material to produce the silicon melt M (step S3: silicon melt generation step). In step S3, the crucible 3 is heated uniformly across its entire circumference. Therefore, the silicon material melts uniformly along the circumference of the crucible 3, and the solid silicon material suspended in the silicon melt M is prevented from tipping over and coming into contact with the quartz crucible 3B. As a result, damage to the quartz crucible 3B is prevented.

[0092] When all the silicon material is melted, the position of the downward flow generated in the silicon melt M changes randomly.

[0093] At the point when all the silicon material is melted, the controller 23 controls the first and second power sources 94A and 94B to switch from the uniform heating mode to the non-uniform heating mode (step S4). After a predetermined time has elapsed since step S4, the temperature of a left portion of the silicon melt M, heated by the second heat-generating section 40B, becomes higher than the temperature of a right portion, heated by the first heat-generating section 40A, and an upward flow is stably generated on the left side in the crucible 3, and a downward flow is also stably generated on the right side in the crucible 3.

[0094] The controller 23 then controls the magnetic field application section 16 to begin applying a horizontal magnetic field to the silicon melt M (step S5: magnetic field application step). When the horizontal magnetic field of a predetermined intensity is applied to the silicon melt M by step S5, the convection is set to a clockwise direction, such that it is in clockwise vortex mode.

[0095] The controller 23 then checks whether the convection mode of the silicon melt M is set to the vortex mode in a clockwise direction or not, based on the signals corresponding to the measurement results from the radiation thermometers 15B (step S6: convection direction check step).

[0096] If it is determined that the convection mode is not set to the clockwise vortex mode (step S6: NO), the controller 23 performs step S6 again after a predetermined time has elapsed.

[0097] If, on the other hand, the convection mode is set to the clockwise vortex mode (step S6: YES), the controller 23 controls the pull-up driver 20 to grow the neck SM1 and shoulder SM2 while heating continues in the uneven heating mode and a horizontal magnetic field is applied (step S7: first growth step). In step S7, the pull-up driver 20 raises and lowers the pull-up shaft 7 under the control of the controller 23 to bring the seed crystal SC into contact with the silicon melt M and then pull the seed crystal SC upwards.

[0098] During or after the growth of the SM2 shoulder, the controller 23 determines whether the convection direction is likely to be reversed or not when the non-uniform heating mode is switched to the uniform mode, while the convection mode is set to the clockwise vortex mode, based on the pull-up conditions of the monocrystalline silicon SM and the information for determining the convection reversal stored in the memory 22 (step S8: reversal determination step).

[0099] If it is determined that the convection direction is unlikely to be reversed by switching from uneven heating mode to even mode (Step S8: NO), the controller 23 controls the first and second power sources 94A and 94B to switch from uneven heating mode to even mode during shoulder SM2 growth or after shoulder SM2 growth and before straight body SM3 growth (Step S9). Then, the controller 23 controls the pull-up driver 20 to allow straight body SM3 and tail to grow (Step S10: second growth step).

[0100] In this case, the thermal environment in chamber 2 is axially symmetric with respect to the crucible's central axis 3C, thus preventing both diameter variation of the straight body SM3 and variation in its drawing speed. Furthermore, since the convection direction of the silicon melt M does not reverse even during heating in the uniform heating mode, variation in the oxygen concentration within the straight body SM3 is also prevented.

[0101] On the other hand, if it is determined that the convection direction is likely to be reversed by switching the uneven heating mode to the even mode (step S8: YES), the controller 23 allows the straight body SM3 and the tail to grow while maintaining the uneven heating mode (step S10: second growth step).

[0102] Since, in this case, the thermal environment in chamber 2 is not kept axially symmetric with respect to the crucible's central axis 3C due to the continuation of the uneven heating mode, diameter variation of the straight body SM3 and / or variation in the drawing speed can occur. However, since the convection direction of the silicon melt M does not reverse due to the continuation of heating in the uneven heating mode, variation in the oxygen concentration in the straight body SM3 can be prevented.

[0103] In the monocrystalline silicon (SM) manufacturing process described above, the silicon melt generation step of step S3 is performed as a first heating and generation process, carried out while the first and second heat generation sections, 40A and 40B, generate heat with the same amount of heat in the uniform heating mode. The magnetic field application step of step S5, the convection direction check step of step S6, and the first growth step of step S7 are performed as a second heating and generation process, carried out while the first and second heat generation sections, 40A and 40B, generate heat with different amounts of heat in the non-uniform heating mode.Furthermore, the second growth step of step S10 is carried out as the first heating and generation process if, in the reversal determination step of step S8, it is determined that the convection direction is unlikely to be reversed, and is carried out as the second heating and generation process if it is determined that the convection direction is likely to be reversed. Advantage(s) of the first embodiment

[0104] The manufacturing apparatus for monocrystalline silicon 1 comprises the heating device 4, which has a hollow cylindrical shape and surrounds the crucible 3 as a structure for heating the crucible 3. The heating device 4 comprises the first heat-generating section 40A and the second heat-generating section 40B, each having a hollow semi-cylindrical shape. The heating device 4 is arranged such that when the first heat-generating section 40A and the second heat-generating section 40B generate heat with different heat-generating quantities, the heating quantities of the first section 31A and the second section 31B of the crucible 3, which are arranged on both sides with respect to the second vertical virtual plane VF2, are different from each other.In the manufacturing process for monocrystalline silicon SM, the control unit 23 of the manufacturing device for monocrystalline silicon 1 performs the first heating and generation process, which is carried out while the first and second heat generation sections 40A and 40B generate heat with the same amount of heat generation, and the second heating and generation process, which is carried out while the first and second heat generation sections 40A and 40B generate heat with different amounts of heat generation.

[0105] Therefore, for example, by generating the silicon melt M in the uniform heating mode, it is possible to prevent the silicon material floating in the silicon melt M from tipping over, thus preventing damage to the quartz crucible 3B. Additionally, by applying a horizontal magnetic field to the silicon melt M in the non-uniform heating mode, the convection mode can be set to the clockwise vortex mode, regardless of when the horizontal magnetic field is applied, thereby preventing variations in oxygen concentration between monocrystalline silicon SM ingots. Furthermore, since variations in oxygen concentration between monocrystalline silicon SM ingots can be prevented, the yield of monocrystalline silicon SM can be improved, leading to improved energy efficiency, increased production efficiency, and reduced waste.

[0106] The manufacturing apparatus for monocrystalline silicon 1 comprises the first and second power sources 94A and 94B, the first power supply path 95A, through which electric current from the first power source 94A is supplied only to the first heat generation section 40A, and the second power supply path 95B, through which electric current from the second power source 94B is supplied only to the second heat generation section 40B.

[0107] With this arrangement, switching between the uniform heating mode and the non-uniform heating mode can be carried out by simply controlling the supply amounts of electrical current from the first power source 94A and the second power source 94B. Second embodiment

[0108] Next, a configuration of a manufacturing device for monocrystalline silicon according to a second embodiment of the invention is described.

[0109] Fig.Figure 7 is an equivalent circuit diagram of a heating device and a power supply section.

[0110] A manufacturing device for monocrystalline silicon 1A of the second embodiment differs from the manufacturing device 1 for monocrystalline silicon of the first embodiment in that a Fig. Control unit 23A, as shown in section 5, performs a different control operation than the control unit 23 of the first embodiment, and by the fact that a Fig. The power supply section 9A shown in Figure 7 has a different configuration than the power supply section 9 of the first embodiment. The other configurations of the monocrystalline silicon manufacturing device 1A are the same as those of the monocrystalline silicon manufacturing device 1 of the first embodiment.

[0111] As in Fig.As shown in Figure 7, the power supply section 9A, in addition to having the same configuration as the power supply section 9 of the first embodiment, includes a bypass supply path 96A connecting the first power supply path 95A to the second power supply path 95B, and a flow regulator 96B provided in the bypass supply path 96A which supplies electrical current in only one direction from the first power supply path 95A to the second power supply path 95B.

[0112] The bypass supply path 96A is provided in the form of a wiring connection that links the first anode wiring 951A to the second anode wiring 951B. The flow regulator 96B is provided in the form of a diode located in the middle of the second power supply path 951B.

[0113] With the configuration of the heating device 4 and the power supply section 9A, as shown in Fig.As shown in Figure 7, when a current with a current value Ip flows from the first power source 94A and no current flows from the second power source 94B, that is, when the electric current is supplied from the first power source 94A and no electric current is supplied from the second power source 94B, a current with a current value 0.25 Ip flows through the first to fourth curve section 43A to 43D, and the first heat generation section 40A and the second heat generation section 40B generate heat with the same amount of heat generation.

[0114] If, on the other hand, a current with a current value Ip flows from the first power source 94A and a current with a current value Iq flows from the second power source 94B, that is, if the electric current is supplied from the first power source 94A and the second power source 94B, a current with a current value of 0.25 Ip flows through the first and second curve sections 43A and 43B, and a current with a current value of 0.25 Ip + 0.5 Iq flows through the third and fourth curve sections 43C and 43D. Thus, the second heat generation section 40B generates heat with a greater heat generation quantity than the first heat generation section 40A.

[0115] In Fig. 7. Among the codes attached to the arrows indicating the current, the codes outside the brackets represent the current values ​​in the uniform heating mode, while the codes inside the brackets represent the current values ​​in the non-uniform heating mode.

[0116] The 23A controller performs the control similarly to the 23 controller of the in Fig. 6 of the first embodiment shown, when the monocrystalline silicon SM is produced, but the control for heating the crucible 3 in the uniform heating mode and the non-uniform heating mode differs from that of the control 23.

[0117] When crucible 3 is heated in uniform heating mode, controller 23A controls the first and second power sources 94A and 94B, respectively, so that electrical current is supplied from the first power source 94A and not from the second power source 94B. When crucible 3 is heated in non-uniform heating mode, controller 23A controls the first and second power sources 94A and 94B, respectively, so that electrical current is supplied from both the first power source 94A and the second power source 94B. Advantage(s) of the second embodiment

[0118] The first heat generation section 40A and the second heat generation section 40B have the same heat generation characteristics. The monocrystalline silicon manufacturing apparatus 1A comprises the first and second power sources 94A and 94B, the first and second power supply paths 95A and 95B, the bypass power supply path 96A, which connects the first power supply path 95A and the second power supply path 95B, and the flow regulator 96B, which is provided in the bypass power supply path 96A and supplies electrical current only in the direction from the first power supply path 95A to the second power supply path 95B.

[0119] Therefore, switching between the uniform heating mode and the non-uniform heating mode can be carried out by simply controlling whether or not electrical current is supplied from the second power source 94B, while a predetermined amount of electrical current is supplied from the first power source 94A.

[0120] Since the second power source 94B only needs to supply electrical current sufficient to create a difference in the heat generation temperature between the first heat generation section 40A and the second heat generation section 40B, an additional power source with a small capacity can be used as the second power source 94B.

[0121] Furthermore, a power source that is not able to change the amount of electric current supplied can be used as the first and second power sources 94A and 94B.

[0122] Since the variation in oxygen concentration between monocrystalline silicon SM ingots can be prevented, the yield of monocrystalline silicon SM can be improved, which allows for an improvement in energy efficiency, an increase in production efficiency and a reduction in waste. Modifications

[0123] Although the exemplary embodiments of the invention have been described above with reference to the accompanying drawings, specific configurations are not limited to those in the exemplary embodiments, and various improvements and modifications of the designs, which do not deviate from the core of the invention, are included in the invention.

[0124] In the first and second embodiments, the straight body SM3 and the tail can be allowed to grow in the uneven heating mode without performing steps S8 and S9.

[0125] In the first and second embodiments, an operator can perform at least one of the following processes: a switching process of the heating modes in steps S3, S4 and S9, a starting process of applying a horizontal magnetic field in step S5, a testing process of the convection mode in step S6, or a determination process of the probability of convection reversal in step S8.

[0126] In the first and second embodiments, the second heating and manufacturing process is illustrated as a process in which the convection mode is set by heating the silicon melt M to the vortex mode in a clockwise direction, in order to make the temperature of the left part of the silicon melt M higher than the temperature of the right part. However, another process can be carried out in which the convection mode is set by heating the silicon melt M to the vortex mode counterclockwise, in order to make the temperature of the right part higher than the temperature of the left part.

[0127] In the first and second embodiments, the heating device 4 only needs to be arranged such that the heating quantities applied to the first section 31A and the second section 31B of the crucible 3 are different from each other when the first heat-generating section 40A and the second heat-generating section 40B generate heat with different heat-generating quantities. The heating device 4 can be arranged in a state that is angled at less than 45 degrees from the one shown in Fig. 2. The heating device 4 can be arranged such that the second vertical virtual plane VF2 is not aligned with the one shown in Figure 2. The heating device can be rotated clockwise or counterclockwise, or in a state rotated by an angle greater than 45 degrees and less than 90 degrees clockwise or counterclockwise. In other words, the heating device 4 can be arranged such that the second vertical virtual plane VF2 is not aligned with the one shown in Figure 2. Fig. 3 shown first vertical virtual plane VF1 coincides. Example(s)

[0128] Examples of the invention are described below. It should be noted that the invention is not limited to examples. Test conditions: Comparison example

[0129] First, the manufacturing device for monocrystalline silicon 1 was manufactured according to the first embodiment.

[0130] Next, the first and second power sources 94A and 94B were controlled to heat crucible 3 in uniform heating mode to produce the silicon melt M. Subsequently, a horizontal magnetic field was applied to the silicon melt M while maintaining the uniform heating mode, and it was verified that the convection mode was set. Then, an ingot of monocrystalline silicon SM with a straight body SM3, measuring 300 mm in diameter and 2000 mm in total length, was grown.

[0131] In this case, the output power deviation Δ, calculated by the above formula (1), is 0%. Examples 1 to 8

[0132] In Example 1, crucible 3 was heated in uniform heating mode to produce the silicon melt M. Then, the first and second power sources 94A and 94B were controlled so that the output power deviation Δ 3.0%, and the uniform heating mode was switched to the non-uniform heating mode. After the temperature of the silicon melt M was stabilized, a horizontal magnetic field was applied to the silicon melt M, and it was verified that the convection mode was established. Then, an ingot of monocrystalline silicon SM of the same size as in Comparative Example 1 was allowed to grow.

[0133] In Examples 2, 3, 4, 5, 6, 7 and 8, the crucible 3 was heated in the uniform heating mode to produce the silicon melt M, and then ingots of monocrystalline silicon SM of the same size as in Comparative Example 1 were grown under the same conditions as in Example 1, except that the first and second power sources 94A and 94B were controlled such that the output power deviation Δ was 4.0%, 5.0%, 6.0%, -3.0%, -4.0%, -5.0% and -6.0%, respectively. Evaluation

[0134] Ten ingots of monocrystalline silicon SM were grown in each of the comparison examples and examples 1 to 8, and the occurrence rate of the convection mode, the oxygen concentration, and the variation of the oxygen concentration were evaluated.

[0135] The oxygen concentration was evaluated as follows. First, a wafer of straight body SM3 was obtained from each ingot of monocrystalline silicon SM in the comparison examples and examples 1 to 8 at a position 1,000 mm below the top end, and the oxygen concentration of the wafer was measured using FTIR (Fourier-transform infrared spectrophotometer). Then, normalization was performed using the mean oxygen concentration in the wafers obtained from the ten ingots of monocrystalline silicon SM in the comparison example, and the upper and lower limits of the oxygen concentration in each of the comparison examples and examples 1 to 8 were calculated. Furthermore, the difference between the upper and lower limits of the oxygen concentration was calculated as the variation of the oxygen concentration. Table 1 Output power deviation Δ (%) Occurrence rate of the convection mode (%) Oxygen concentration (normalized value) Variation of oxygen concentration Vortex mode counterclockwise Clockwise vortex mode comparative example 0 50 50 0.80 to 1.20 0,40 Example 1 3,0 30 70 0.90 to 1.20 0,30 Example 2 4,0 10 90 1.15 to 1.20 0,25 Example 3 5,0 0 100 1.15 to 1.20 0,05 Example 4 6,0 0 100 1.15 to 1.20 0,05 Example 5 -3,0 70 30 0.80 to 1.10 0,30 Example 6 -4,0 90 10 0.80 to 1.15 0,25 Example 7 -5,0 100 0 0.80 to 0.85 0,05 Example 8 -6,0 100 0 0.80 to 0.85 0,05 Occurrence rate of the convection mode

[0136] In the comparative example, the occurrence rate of the counterclockwise vortex mode was 50%, and the clockwise and counterclockwise vortex modes occurred essentially randomly.

[0137] In contrast, in Examples 1 to 4, the occurrence rate of the clockwise vortex mode exceeded 50%, and the greater the output power deviation Δ, the higher the occurrence rate of the clockwise vortex mode. Specifically, in Examples 2 to 4, where the output power deviation Δ was 4.0% or greater, the occurrence rate of the clockwise vortex mode was 90% or greater, and in Examples 3 and 4, where the output power deviation Δ was 5.0% or greater, the occurrence rate of the clockwise vortex mode was 100%. Additionally, a similar trend to that observed in Examples 1 to 4 was also seen in Examples 5 to 8.In examples 6 to 8, where the output power deviation Δ was -4.0% or less, the occurrence rate of the counterclockwise vortex mode was 90% or more, and in examples 7 and 8, where the output power deviation Δ was -5.0% or less, the occurrence rate of the counterclockwise vortex mode was 100%.

[0138] The foregoing results could confirm that controlling the first and second power sources 94A and 94B such that the absolute value of the output power deviation Δ was 4.0% or more made it easier to set the convection mode to a specific mode, independent of when a horizontal magnetic field was applied. In particular, it could be confirmed that controlling the first and second power sources 94A and 94B such that the absolute value of the output power deviation Δ was 5.0% or more made it possible to set the convection mode to a specific mode, independent of when a horizontal magnetic field was applied. Variation of oxygen concentration

[0139] The variation in oxygen concentration in the comparison example was 0.40.

[0140] In contrast, the variation in oxygen concentration in each of Examples 1 to 8 was 0.30 or less, and the larger the absolute value of the output power deviation Δ, the smaller the variation in oxygen concentration. Specifically, in Examples 2 to 4 and 6 to 8, where the absolute value of the output power deviation Δ was 4.0% or more, the variation in oxygen concentration was 0.25 or less, which was almost half that of the comparison example. In Examples 3, 4, 7, and 8, where the absolute value of the output power deviation Δ was 5.0% or more, the variation in oxygen concentration was 0.05, which was extremely small compared to the comparison example.

[0141] The foregoing results could confirm that the variation of oxygen concentration in the straight body SM3 can be made smaller by controlling the first and second power sources 94A and 94B such that the absolute value of the output power deviation Δ was 4.0% or more, and that in particular the variation of oxygen concentration in the straight body SM3 can be made extremely small by controlling the first and second power sources 94A and 94B such that the absolute value of the output power deviation Δ was 5.0% or more. COMMERCIAL APPLICABILITY

[0142] Since the manufacturing process for monocrystalline silicon and the apparatus for producing monocrystalline silicon of the invention can prevent the occurrence of defects during production and the variation in oxygen concentration between ingots of monocrystalline silicon, the yield of monocrystalline silicon can be improved, which enables an improvement in energy efficiency, an increase in production efficiency and a reduction in waste. EXPLANATION OF REFERENCE SYMBOLS

[0143] 1, 1A... Monocrystalline silicon manufacturing device, 3... Crucible, 3C... Crucible center axis, 4... Heating device, 9, 9A... Power supply section, 16C... Central magnetic field line, 23, 23A... Control, 31A... First section, 31B... Second section, 40A... First heat generation section, 40B... Second heat generation section, 94A... First power source, 94B... Second power source, 95A... First power supply path, 95B... Second power supply path, 96A... Bypass power supply path, 96B... Flow regulator, 401A, 401B... Maximum temperature range, M... Silicon melt, SM... Monocrystalline silicon, SM1... Neck, SM2... Shoulder, SM3... Straight body, VF1... First vertical virtual plane, VF2...second vertical virtual plane. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2019-151502 A

[0006]

Claims

[1] Manufacturing process for monocrystalline silicon for growing monocrystalline silicon while a horizontal magnetic field is applied to a silicon melt, using a monocrystalline silicon manufacturing apparatus, the manufacturing apparatus for monocrystalline silicon comprises: a crucible configured to hold the silicon molten metal, and a heating device that has a hollow cylindrical shape and surrounds the crucible, wherein the heating device comprises a first heat-generating section and a second heat-generating section, each having a hollow semi-cylindrical shape, wherein the first and the second heat-generating sections have identical heat-generating properties, wherein the heating device is arranged such that, when the first and the second heat-generating sections generate heat with different heat-generating quantities, the heating quantity of a first section of the crucible and the heating quantity of a second section of the crucible are different from each other, wherein the first section and the second section are arranged on both sides with respect to a vertical virtual plane comprising a central axis of the crucible and a central magnetic field line of the horizontal magnetic field, the manufacturing process includes: Performing an initial heating and generation phase, during which the first heat generation stage and the second heat generation stage generate heat with an identical heat generation quantity; and Performing a second heating and generation cycle while the first heat generation stage and the second heat generation stage produce heat with different heat generation quantities. [2] Manufacturing process for monocrystalline silicon according to claim 1, wherein The manufacturing device for monocrystalline silicon further comprises: a first power source and a second power source, a first power supply path through which electrical current from the first power source is supplied to the first heat generation section, and a second power supply path through which electrical current from the second power source is supplied to the second heat generation section, The first heating and generation is carried out while the first power source and the second power source are controlled to ensure that the first heat generation section and the second heat generation section produce heat with an identical heat generation quantity, and The second heating and generation process is carried out while the first power source and the second power source are controlled to cause the first heat generation section and the second heat generation section to produce heat with different heat generation amounts from each other. [3] Manufacturing process for monocrystalline silicon according to claim 2, wherein The manufacturing device for monocrystalline silicon further comprises: a bypass supply path that connects the first supply path with the second supply path, and a flow regulator that is provided in the bypass supply path and configured to supply electrical current in only one direction, from the first supply path to the second supply path, the first heating and generation is carried out while the first power source and the second power source are controlled to supply electrical current from the first power source and not from the second power source, and The second heating and generation process is carried out while the first power source and the second power source are controlled to supply electrical current from the first power source and the second power source. [4] Manufacturing process for monocrystalline silicon according to claim 1, further comprising: Generating the silicon melt by melting a silicon material in the crucible; Starting the application of the horizontal magnetic field to the silicon melt; Verify that a convection direction of the silicon melt in a virtual plane is fixed to a direction, wherein the virtual plane is orthogonal to the central magnetic field line; Performing an initial growth in which a neck and shoulder are grown by bringing a seed crystal into contact with the silicon melt and then drawing up the seed crystal; and Performing a second growth in which a straight body and tail are allowed to grow by pulling up the seed crystal, whereby the production of the silicon melt and the second growth are carried out as the first heating and production, and The process begins with the application of the horizontal magnetic field, the testing and the first growth, followed by the second heating and generation. [5] Manufacturing process for monocrystalline silicon according to claim 1, further comprising: Generating the silicon melt by melting a silicon material in the crucible; Starting the application of the horizontal magnetic field to the silicon melt; Verify that a convection direction of the silicon melt in a virtual plane is fixed to a direction, wherein the virtual plane is orthogonal to the central magnetic field line; Performing an initial growth in which a neck and shoulder are grown by bringing a seed crystal into contact with the silicon melt and then pulling up the seed crystal; Performing a reversal determination; and Performing a second growth in which a straight body and tail are allowed to grow by pulling up the seed crystal, whereby the production of the silicon melt is carried out as the first heating and production process, the application of the horizontal magnetic field, the testing and the first growth are carried out as the second heating and generation, and in the inverse determination regarding the second growth, which is to be carried out as the first heating and production, based on a pull-up condition of monocrystalline silicon, The second growth, the second heating and generation, is carried out when it is determined that the convection direction is likely to be reversed, and The second growth is carried out as the first heating and generation, if it is determined that the direction of convection is unlikely to be reversed. [6] Manufacturing process for monocrystalline silicon according to any one of claims 1 to 5, wherein the first heat generation section and the second heat generation section are arranged such that the first and the second heat generation section each have maximum temperature ranges which overlap a horizontal virtual line in planar view, wherein the horizontal virtual line is orthogonal to the vertical virtual plane and includes the central axis of the crucible. [7] A manufacturing apparatus for monocrystalline silicon, configured to pull up a monocrystalline silicon while a horizontal magnetic field is applied to a silicon melt, the apparatus comprising: a crucible configured to hold the silicon molten metal; a heating device having a hollow cylindrical shape and surrounding the crucible; and a power supply section configured to supply electrical current to the heating device, wherein the heating device comprises a first heat-generating section and a second heat-generating section, each having a hollow semi-cylindrical shape, wherein the first and second heat-generating sections have identical heat-generating characteristics, and The power supply section includes: a first power source and a second power source, a first power supply path through which electrical current from the first power source is supplied to the first heat generation section, and a second power supply path through which electrical current from the second power source is supplied to the second heat generation section. [8] Manufacturing apparatus for monocrystalline silicon according to claim 7, wherein the power supply section further comprises: a bypass supply path that connects the first supply path with the second supply path, and a flow regulator that is provided in the bypass supply path and configured to supply electrical current in only one direction, from the first supply path to the second supply path. [9] Manufacturing apparatus for monocrystalline silicon according to claim 7, further comprising: a controller configured to control the manufacturing process, whereby the monocrystalline silicon is raised during the manufacturing process, wherein The manufacturing process includes: Performing an initial heating and generation phase while controlling the first power source and the second power source to cause the first heat generation section and the second heat generation section to produce heat with an identical heat generation output, and Performing a second heating and generation cycle while controlling the first and second power sources to cause the first and second heat generation sections to produce heat with different heat generation quantities. [10] Manufacturing apparatus for monocrystalline silicon according to claim 8, further comprising: a controller configured to control the manufacturing process, whereby the monocrystalline silicon is raised during the manufacturing process, wherein The manufacturing process includes: Performing an initial heating and generation phase while controlling the first and second power sources to supply electrical current from the first power source and not from the second power source, and Performing a second heating and generation process while controlling the first and second power sources to supply electrical current from the first and second power sources. [11] Manufacturing apparatus for monocrystalline silicon according to claim 9 or 10, wherein The production also includes: Generating the silicon melt by melting a silicon material in the crucible, Starting the application of the horizontal magnetic field to the silicon melt, Verify that a convection direction of the silicon melt in a virtual plane is fixed to a direction, wherein the virtual plane is orthogonal to a central magnetic field line of the horizontal magnetic field, Performing an initial growth in which a neck and shoulder are grown by bringing a seed crystal into contact with the silicon melt and then drawing up the seed crystal, and Performing a second growth, in which a straight body and tail are allowed to grow by pulling up the seed crystal, and the controller is configured to to carry out the production of the silicon melt and the second growth as the first heating and production, and the process of applying the horizontal magnetic field, testing, and performing the first growth as well as the second heating and generation. [12] Manufacturing apparatus for monocrystalline silicon according to claim 9 or 10, wherein The production also includes: Generating the silicon melt by melting a silicon material in the crucible, Starting the application of the horizontal magnetic field to the silicon melt, Verify that a convection direction of the silicon melt in a virtual plane is fixed to a direction, wherein the virtual plane is orthogonal to a central magnetic field line of the horizontal magnetic field, Performing an initial growth in which a neck and shoulder are grown by bringing a seed crystal into contact with the silicon melt and then pulling the seed crystal upwards, Performing a reversal determination, and Performing a second growth, in which a straight body and tail are allowed to grow by pulling up the seed crystal, and the controller is configured to to carry out the production of the silicon melt as the first heating and production process, the beginning of the application of the horizontal magnetic field, the testing and the first growth as the second heating and generation, and in the inverse determination regarding the second growth, which is to be carried out as the first heating and production, based on a pull-up condition of monocrystalline silicon, to carry out the second growth as the second heating and generation when it is determined that the convection direction is likely to be reversed, and to carry out the second growth as the first heating and generation, if it is determined that the direction of convection is unlikely to be reversed. [13] Manufacturing apparatus for monocrystalline silicon according to any one of claims 7 to 10, wherein the first heat generation section and the second heat generation section are arranged such that the first and the second heat generation section each have maximum temperature ranges which overlap a horizontal virtual line in planar view, wherein the horizontal virtual line is orthogonal to a vertical virtual plane and includes a central axis of the crucible, wherein the vertical virtual plane includes the central axis of the crucible and a central magnetic field line of the horizontal magnetic field.

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