Single crystal lifting device and single crystal lifting method

Abstract

The present invention provides a single crystal pulling device comprising a pulling furnace having a central axis and a magnetic field generating device having a coil, for applying a horizontal magnetic field to a molten semiconductor raw material, wherein the coil is saddle-shaped and two sets of pairs of oppositely arranged saddle-shaped coils are provided, and the two coil axes in the two sets of coil pairs are contained within the same horizontal plane, and within the horizontal plane, when the direction of the magnetic field lines of the central axis of the pulling furnace is the X-axis and the direction perpendicular to the X-axis is the Y-axis, the central angle α between the two coil axes with the X-axis between them is 90 degrees or less, and the angle β between adjacent coils with the Y-axis between them is 20 degrees or less. By doing so, the coil height can be reduced by increasing the magnetic field generation efficiency, the center of the magnetic field can be raised to near the molten surface of the semiconductor raw material, and a single crystal with a lower oxygen concentration than conventional methods can be obtained, and defect-free crystals can be pulled at a higher speed. The invention also provides a single crystal pulling device and a single crystal pulling method.

Description

Technology Field

[0001] The present invention relates to a single crystal pulling apparatus and a single crystal pulling method using the same. Background Technology

[0002] Semiconductors such as silicon and gallium arsenide are composed of single crystals and are used in computer memory ranging from small to large sizes, and there is a demand for increased capacity, lower costs, and higher quality of memory devices.

[0003] Conventionally, as one of the single crystal pulling methods for manufacturing single crystals that satisfy the requirements of these semiconductors, a method is known in which a magnetic field is applied to a molten semiconductor raw material contained in a crucible to suppress heat convection occurring in the molten liquid, thereby manufacturing a large-diameter, high-quality semiconductor (generally referred to as the magnetic field application Czochralski (MCZ) method).

[0004] Figure 8 explains an example of a single crystal pulling apparatus using the conventional CZ method.

[0005] This single crystal lifting device (100) is configured to have a lifting furnace (101) with an open top surface and a crucible (102) embedded within the lifting furnace (101). In addition, a heater (103) for heating and melting the semiconductor raw material (106) inside the crucible (102) is provided around the crucible (102) on the inside of the lifting furnace (101), and on the outside of the lifting furnace (101), a superconducting magnet (130) is arranged in a refrigerant container (hereinafter also referred to as a cylindrical refrigerant container) (105) containing a pair (2) of superconducting coils (104 (104a, 104b)).

[0006] In the manufacture of a single crystal, a semiconductor raw material (106) is placed in a crucible (102) and heated by a heater (103) to melt the semiconductor raw material (106). A seed crystal, not shown, is lowered and contacted in the molten liquid, for example, from above the central part of the crucible (102), and the seed crystal is pulled up in the direction of the pulling direction (108) at a predetermined speed by a pulling mechanism not shown. As a result, a crystal grows in the solid-liquid boundary layer, and a single crystal is produced. At this time, if fluid movement of the molten liquid induced by the heating of the heater (103), i.e., thermal convection, occurs, the single crystal being pulled up is prone to becoming dielectric, and the yield of single crystal production decreases.

[0007] Accordingly, as a countermeasure, a superconducting coil (104) of a superconducting magnet (130) is used. That is, the semiconductor raw material (106) in the molten liquid is subjected to an operating restraining force by magnetic field lines (107) generated by current flow to the superconducting coil (104), so that it does not convect within the crucible (102) and is slowly raised upward along with the raising of the seed crystal, and is manufactured as a solid single crystal (109). Meanwhile, above the raising furnace (101), although not shown, a raising mechanism is provided to raise the single crystal (109) along the center line of the crucible (the center axis (110) of the raising furnace (101)).

[0008] Next, according to FIG. 9, an example of a superconducting magnet (130) used in the single crystal lifting device (100) shown in FIG. 8 will be described.

[0009] This superconducting magnet (130) is configured such that a superconducting coil (104 (104a, 104b)) is housed in a cylindrical vacuum container (119) with a cylindrical refrigerant container interposed therein. In this superconducting magnet (130), a pair of superconducting coils (104a, 104b) facing each other through the center of the cylindrical vacuum container (119) are housed. These pair of superconducting coils (104a, 104b) are Helmholtz-type magnetic field coils that generate a magnetic field following the same direction in the transverse direction, and as shown in FIG. 8, they generate magnetic field lines (107) that are symmetrical with respect to the central axis (110) of the lifting furnace (101) and the cylindrical vacuum container (119) (the position of this central axis (110) is referred to as the magnetic field center).

[0010] Meanwhile, this superconducting magnet (130) is equipped with a current lead (111) for introducing current into two superconducting coils (104a, 104b) as shown in FIGS. 8 and 9, a small helium refrigerator (112) for cooling a first radiation shield (117) and a second radiation shield (118) housed inside a cylindrical vacuum container (119), a gas discharge pipe (113) for discharging helium gas inside a cylindrical refrigerant container (105), and a service port (114) having a supply port for supplying liquid helium. An elevating furnace (101) as shown in FIG. 8 is disposed inside the bore (115) of this superconducting magnet (130) (the inner diameter of the bore is indicated by D).

[0011] FIG. 10 shows the magnetic field distribution of the conventional superconducting magnet (130) described above.

[0012] As shown in FIG. 10, in a conventional superconducting magnet (130), a pair of superconducting coils (104a, 104b) facing each other are arranged, so the magnetic field gradually increases in both directions in the direction of each coil arrangement (X direction in FIG. 10), and the magnetic field gradually decreases in the direction perpendicular to this (Y direction in FIG. 10). In this conventional configuration, as shown in FIG. 9 and 10, the magnetic field gradient within the bore (115) is excessively large, so the suppression of heat convection occurring in the molten liquid is unbalanced, and the magnetic field efficiency is poor. That is, as shown by the diagonal line in FIG. 10, in the region near the center of the magnetic field, the magnetic field uniformity is poor (i.e., in FIG. 10, it is in a thin, long cross shape in the up-down and left-right directions), so there was a problem that the precision of suppressing heat convection was poor and high-quality single crystals could not be pulled.

[0013] A technology for solving the above-mentioned problem is disclosed in Patent Document 1. The technology disclosed in Patent Document 1 will be explained with reference to FIGS. 11a and 11b.

[0014] This shows another example of a superconducting magnet, where FIG. 11a is a perspective view and FIG. 11b shows the AA cross-section of FIG. 11a. In Patent Document 1, to solve the above problem, as shown in FIG. 11a and FIG. 11b, the number of superconducting coils (104) is set to 4 or more (for example, 4, such as 104a, 104b, 104c, and 104d), and the center of each superconducting coil (104) is arranged on a plane inside a cylindrical vacuum vessel (119) coaxially around the rim of the furnace, and each arranged superconducting coil (104) is set in an opposing direction with the axis of the cylindrical vacuum vessel (119) interposed therebetween, and the angle of placement θ (see FIG. 11b) of each pair of adjacent superconducting coils facing the inside of the cylindrical vacuum vessel (119) is in the range of 100° to 130° (i.e., the center angle α (see FIG. 11b) between adjacent coil axes with the X-axis in between is It is disclosed that the setting is set to 50°~80°.

[0015] According to this, a transverse magnetic field with a small magnetic field gradient and good uniformity can be generated inside the bore (115), and a magnetic field distribution in the shape of concentric circles or squares can be generated on a plane, and unbalanced electromagnetic force can be significantly suppressed. Furthermore, as a result, the uniform magnetic field region in the pulling direction is improved, and the magnetic field in the transverse magnetic field direction becomes nearly horizontal, and by suppressing unbalanced electromagnetic force, the manufacturing of a high-quality single crystal can be realized, and furthermore, it is disclosed that a high-quality single crystal can be pulled with a high yield according to this single crystal pulling method. Meanwhile, in FIG. 11b, the symbol d represents the diameter (inner diameter) of the superconducting coil, and the symbol l represents the distance between a pair of coils.

[0016] According to this method, the magnetic field distribution applied to the molten semiconductor raw material is uniformized and unbalanced electromagnetic force is suppressed, so thermal convection is suppressed even at a lower magnetic flux density compared to the conventional technology using two coils.

[0017] However, even with such a uniform magnetic field distribution, it was made clear by a comprehensive heat transfer analysis including three-dimensional molten convection that in a transverse magnetic field where the magnetic field lines are directed in the X-axis direction, there is a difference in thermal convection within a cross-section parallel to the X-axis and within a cross-section parallel to the Y-axis (see Patent Document 2).

[0018] When a conductive fluid moves in a magnetic field, an induced current is generated in a direction orthogonal to the magnetic field lines and the velocity component perpendicular to the magnetic field lines. However, when using an electrically insulating quartz crucible, the walls of the crucible and the free surface of the molten semiconductor material act as insulating walls, so an induced current does not flow in a direction orthogonal to them. For this reason, the convection suppression force due to electromagnetic force is weakened in the upper part of the molten semiconductor material. Also, when comparing a cross-section parallel to the X-axis (a cross-section parallel to the magnetic field lines) and a cross-section perpendicular to the X-axis (a cross-section perpendicular to the magnetic field lines), convection is stronger in the cross-section perpendicular to the X-axis (a cross-section perpendicular to the magnetic field lines).

[0019] As such, even with the uniform magnetic field distribution achieved by the four coils mentioned above, the difference in convection velocity is somewhat reduced, but the flow velocity distribution remains non-uniform in the circumferential direction. In particular, because a flow field connecting the crucible wall to the growth interface persists within the cross-section perpendicular to the magnetic field lines, oxygen leached from the quartz crucible reaches the crystal, so there is a limit to the effect of reducing oxygen concentration by applying a magnetic field, and it is difficult to meet the requirements for ultra-low oxygen concentrations, such as those for semiconductor crystals for power devices or image sensors, which have recently been in high demand. Furthermore, the presence of a non-uniform flow field in the circumferential direction causes growth streaks in crystals that are pulled while rotating, and when evaluating the cross-section parallel to the growth direction, variations in resistivity and oxygen concentration with the crystal rotation cycle are observed, resulting in a ring-shaped distribution within the wafer surface sliced ​​perpendicular to the growth direction.

[0020] In Patent Document 2, a single crystal pulling apparatus as shown in FIGS. 12a and 12b is disclosed to solve this problem. FIG. 12a is a schematic diagram of the apparatus, and FIG. 12b shows a cross-section representing an example of a superconducting magnet.

[0021] In a horizontal plane (120) comprising two coil axes (121) passing through the centers of pairs (104a and 104c, 104b and 104d) of superconducting coils (104), when the direction of the magnetic field lines (107) in the central axis (110) of the lifting furnace is the X-axis, the magnetic flux density distribution on the X-axis is an upwardly convex distribution, and when the magnetic flux density in the central axis (110) within the horizontal plane (120) is set as the magnetic flux density setting value, the magnetic flux density on the X-axis becomes 80% or less of the magnetic flux density setting value at the crucible wall, and at the same time, the magnetic flux density distribution on the Y-axis passing through the central axis (110) perpendicular to the X-axis within the horizontal plane (120) is a downwardly convex distribution, and the magnetic flux density on the Y-axis becomes 140% or more of the magnetic flux density setting value at the crucible wall, so that the magnetic field distribution In a magnetic field generating device, two pairs of opposing superconducting coils (104) (104a and 104c, 104b and 104d) are provided such that each coil axis (121) is contained within the same horizontal plane (120), and the center angle α between the two coil axes (121) is set to be between 100 degrees and 120 degrees.

[0022] Accordingly, the technology disclosed in Patent Document 2 can achieve the following effects. That is, even in a cross-section perpendicular to the X-axis where the convection suppression force by electromagnetic force was insufficient, the flow rate of the molten semiconductor raw material can be reduced, and the flow rate in a cross-section parallel to the X-axis of the molten semiconductor raw material can be balanced with the flow rate in a cross-section perpendicular to the X-axis of the molten semiconductor raw material.

[0023] In addition, by reducing the flow rate of the molten semiconductor material within the cross-section perpendicular to the X-axis, the time until oxygen leached from the crucible wall reaches the single crystal is extended, and the amount of oxygen evaporated from the free surface of the molten semiconductor material is increased, thereby allowing the single crystal pulling device to significantly reduce the oxygen concentration entering the single crystal. Furthermore, it was stated that by balancing the flow rate in the cross-section parallel to the X-axis of the molten semiconductor material with the flow rate in the cross-section perpendicular to the X-axis of the molten semiconductor material, the single crystal pulling device can suppress growth streaks in the single crystal being grown. Prior art literature

[0024] Japanese Patent Publication No. 2004-51475 Japanese Patent Publication No. 2017-57127 Japanese Patent Publication No. H10-291892 Japanese Patent Publication No. 2003-63891 The problem to be solved

[0025] However, as a result of the inventors analyzing the magnetic field distribution in various coil arrangements, it was found that a magnetic field distribution producing the same effect as in Patent Document 2 can be realized in coil arrangements other than those described in Patent Document 2.

[0026] In addition, to increase magnetic field efficiency in the above coil arrangement, it is necessary to maximize the coil diameter, but this also requires a corresponding increase in the height of the container containing the coil. In the case of a magnetic device (also referred to as a magnetic field generator or a superconducting magnet) in a cylindrical container, disassembly and reassembly are required at the stage where crystal lifting is completed; however, since the magnetic device needs to be lowered and raised at that time, the magnetic device must be installed on a lifting device.

[0027] Furthermore, regarding the magnet described in Patent Document 2, there was a problem in that the magnetic field generation efficiency was reduced compared to the coil arrangement of Patent Document 1, which is described as a comparative example of Patent Document 2, resulting in a smaller magnetic flux density at the center. In order to grow a defect-free region crystal by the CZ method, it is necessary for the vertical temperature gradient to be uniform across the entire crystal growth interface (hereinafter also simply referred to as the growth interface); however, for CZ crystals, where the outer periphery of the crystal cools easily, an upwardly convex growth interface is required. However, there was a problem in that if the magnetic flux density at the center is small, the temperature boundary layer immediately below the rotating crystal becomes thicker, which reduces heat input from the melt and makes it difficult for the growth interface to become upwardly convex.

[0028] Regarding the positional relationship between the magnet and the molten raw material, as described in Patent Document 3, it is known that raising the height of the center of the transverse magnetic field to near the molten surface of the molten raw material lowers the oxygen concentration in the crystal, while lowering it to a deeper position in the molten material increases the oxygen concentration. The upper limit position of this magnetic device is determined by the stroke of the lifting device and interference with the lifting furnace side, but generally, the chamber of the lifting furnace is connected to a hydraulic cylinder and arm located on the outside of the magnetic device to enable lifting and rotating. FIG. 13 shows an example of the lifting device (122) of the lifting furnace and the lifting device (123) of the superconducting magnet. Therefore, this determines the upper limit position of the magnetic device. As the overall height of the magnetic device increases, it becomes impossible to raise the center of the magnetic field position, which is the middle of the coil's height direction, upward, making it disadvantageous to obtain crystals with low oxygen concentration.

[0029] The present invention is made in consideration of the above problems and aims to provide a single crystal pulling apparatus and a single crystal pulling method that can reduce the coil height by increasing the magnetic field generation efficiency, raise the center of the magnetic field to near the molten surface of the semiconductor raw material, obtain a single crystal with a lower oxygen concentration than conventional methods, and enable the growth interface to be convex upward by enabling excitation with a higher magnetic flux density than conventional methods, and also enable the pulling of a defect-free crystal at a higher speed. means of solving the problem

[0030] To achieve the above objective, the present invention provides a single crystal pulling device comprising a pulling furnace having a central axis in which a heating heater and a crucible receiving a molten semiconductor raw material are arranged, and a magnetic field generating device having a superconducting coil provided around the pulling furnace, wherein a horizontal magnetic field is applied to the molten semiconductor raw material by energizing the superconducting coil to suppress convection of the molten semiconductor raw material within the crucible.

[0031] The superconducting coil of the magnetic field generating device is saddle-shaped, curved along the outer shape of the lifting furnace, and two pairs of saddle-shaped superconducting coils are provided facing each other around the lifting furnace.

[0032] When the axis passing through the centers of this pair of opposing superconducting coils is taken as the coil axis,

[0033] In the above two pairs of superconducting coil pairs, the two coil axes are contained within the same horizontal plane, and

[0034] A single crystal pulling apparatus is provided, characterized in that, when the direction of the magnetic field lines at the central axis of the pulling furnace within this horizontal plane is set as the X-axis and the direction perpendicular to the X-axis within the horizontal plane is set as the Y-axis, the central angle α between the two coil axes with the X-axis between them is 90 degrees or less, and the angle β between adjacent superconducting coils with the Y-axis between them is 20 degrees or less.

[0035] Since the central angle α between the two coil axes with the X-axis between them is 90 degrees or less, and the angle between the adjacent superconducting coils with the Y-axis between them is 20 degrees or less, convection suppression force is generated near the cross-section perpendicular to the X-axis, and the magnetic flux density perpendicular to the crucible in the angular region in the circumferential direction corresponding to the coil center position is not excessively high, the diffusion boundary layer near the crucible wall in that part is not thinned, and melting from the crucible (quartz crucible) is further suppressed. That is, by suppressing convection, the time for oxygen leached from the crucible wall to reach the single crystal is extended, thereby increasing the amount of oxygen evaporation from the free surface of the molten semiconductor raw material. Furthermore, since the leaching of oxygen can be suppressed by suppressing melting from the crucible, the oxygen concentration introduced into the single crystal can be significantly reduced, and it is possible to produce a single crystal with an ultra-low oxygen concentration.

[0036] In addition, since the center angle α and the angle between the coils β are within the above range, the total length of the coil can be increased further than that of the superconducting coil of Patent Document 2, for example, and thus the magnetic flux density of the center axis can be increased compared to Patent Document 2. As the magnetic flux density near the growth interface increases, the temperature boundary layer immediately below the rotating single crystal becomes thinner, so heat flow from the melt to the single crystal proceeds, and as a result, the growth interface becomes convex upward. In this state, if the single crystal is cooled from the side, it can be pulled up with a large, uniform temperature gradient within the plane, so it becomes possible to pull a defect-free region crystal at a higher speed.

[0037] Meanwhile, if the angle between coils β becomes greater than 20 degrees, the component of magnetic field lines perpendicular to the crucible near the cross-section perpendicular to the magnetic field lines (X-axis) becomes smaller, so the convection suppression force in this region cannot be obtained. In addition, if the center angle α becomes greater than 90 degrees, the overall length of the superconducting coil is shortened due to the positional relationship with neighboring coils (other pairs of coils), so the magnetic field generation efficiency decreases, and thus the above-mentioned effect of increasing the magnetic flux density of the center axis cannot be obtained.

[0038] Furthermore, since the center angle α and the angle between coils β are within the above range, the flow rate in the cross-section parallel to the X-axis of the molten semiconductor raw material and the flow rate in the cross-section perpendicular to the X-axis of the molten semiconductor raw material can be balanced, and thereby, the single crystal pulling device can be made capable of suppressing growth streaks in the single crystal being grown.

[0039] In addition, since the superconducting coil is saddle-shaped rather than a conventional circular coil, the circumference of the coil can be increased, allowing for the generation of a magnetic field with a higher magnetic flux density even at the same current value. In other words, the efficiency of magnetic field generation can be increased.

[0040] Furthermore, since the overall height of the coil is reduced compared to a circular shape due to its saddle shape, the position of the coil center height within the magnetic field generator can be raised. Therefore, when raised to the upper limit by the lifting device, the magnetic field center can be set at a higher position relative to the molten liquid, and it becomes possible to obtain a single crystal with a lower oxygen concentration than, for example, a conventional single crystal lifting device such as Patent Document 2.

[0041] At this time, the magnetic field generating device may be equipped with a lifting device capable of moving up and down in the vertical direction.

[0042] Accordingly, when dismantling and setting after the end of operation, the magnetic field generator can be lowered, allowing the operator to easily dismantle and clean the hot zone inside the furnace. In addition, when lifting a single crystal, it becomes possible to more easily adjust the height of the magnetic field generator so that the oxygen concentration in the single crystal becomes a desired value.

[0043] In addition, the saddle-shaped superconducting coil described above may have a vertical width that is shorter than its horizontal width.

[0044] With this, the overall height of the coil can be reduced more reliably, the position of the coil center height can be raised to set the magnetic field center at a higher position, and a single crystal with low oxygen concentration can be obtained more easily.

[0045] In addition, the present invention provides a single crystal pulling method characterized by pulling a semiconductor single crystal using the single crystal pulling device.

[0046] With this single-crystal pulling method, it is possible to grow semiconductor single crystals with suppressed growth fringes and a significantly reduced influx of oxygen. Furthermore, single crystals with desired defect regions can be pulled. In particular, defect-free crystals can be pulled at a higher speed.

[0047] At this time, when lifting the semiconductor single crystal, the height position of the magnetic field generating device can be adjusted according to the target value of the oxygen concentration included in the semiconductor single crystal.

[0048] By doing this, fine oxygen concentration control is possible, and semiconductor single crystals with low oxygen concentration can be grown more reliably.

[0049] In addition, when lifting the semiconductor single crystal, the magnetic field strength can be adjusted according to the target defect region of the semiconductor single crystal.

[0050] In this way, for example, by increasing the magnetic field strength (or magnetic flux density) of the central axis as described above, the growth interface can be made convex upward, and by cooling from the side of the crystal, a uniform temperature gradient within the plane can be obtained, allowing for the growth of a defect-free region crystal at a higher speed. Conversely, by lowering the magnetic field strength (or magnetic flux density) of the central axis, the temperature gradient, particularly in the center of the crystal, can be reduced, allowing for the growth of a single crystal rich in vacancies. In this manner, a single crystal of the target defect region can be grown. Effects of the invention

[0051] As described above, the single crystal pulling device of the present invention can significantly reduce the oxygen concentration introduced into the single crystal and suppress growth streaks in the single crystal being grown. Furthermore, it can be a single crystal pulling device capable of pulling a single crystal with a desired defect region (especially a defect-free region crystal) at a higher speed than conventional devices.

[0052] Furthermore, according to the single crystal pulling method of the present invention, it is possible to grow a semiconductor single crystal with suppressed growth fringes and a significantly reduced influx of oxygen concentration. In addition, the desired defect region can be adjusted by controlling the magnetic field strength (magnetic flux density) of the central axis. Brief explanation of the drawing

[0053] FIG. 1 is a schematic diagram showing an example of a single crystal pulling apparatus of the present invention. FIG. 2a is a perspective view showing an example of the shape of a superconducting coil of the present invention. FIG. 2b is a cross-sectional view showing an example of the arrangement of a superconducting coil of the present invention. Figure 3 is an analysis diagram showing the magnetic flux density distribution in Example 1. Figure 4 is an analysis diagram showing the velocity vector and oxygen concentration distribution within the melt in Example 1. Figure 5 is an analysis diagram showing the velocity vector and oxygen concentration distribution within the melt in Example 2. Figure 6 is an analysis diagram showing the magnetic flux density distribution in Comparative Example 1. Figure 7 is an analysis diagram showing the velocity vector and oxygen concentration distribution within the melt in Comparative Example 1. FIG. 8 is a schematic diagram showing an example of a conventional single-crystal pulling apparatus. Figure 9 is a schematic diagram showing an example of a conventional superconducting magnet. Figure 10 is an explanatory diagram showing an example of the magnetic field distribution of a conventional superconducting magnet. FIG. 11a is a perspective view showing an example of another conventional superconducting magnet. FIG. 11b is a cross-sectional view showing an example of another conventional superconducting magnet. FIG. 12a is a schematic diagram showing an example of another conventional single-crystal pulling apparatus. FIG. 12b is a cross-sectional view showing an example of another conventional superconducting magnet. FIG. 13 is a schematic diagram showing an example of a lifting device for a lifting furnace and a lifting device for a superconducting magnet. Figure 14 is a graph showing the relationship between the magnetic flux density component (B⊥) orthogonal to the inner wall of the crucible and the perimeter angle. Figure 15 is an analysis diagram showing the magnetic flux density distribution in Comparative Example 2. Figure 16 is an analysis diagram showing the velocity vector and oxygen concentration distribution within the melt in Comparative Example 2. Figure 17 is an interpretation diagram showing the velocity vector and oxygen concentration distribution within the melt in Comparative Example 3. Specific details for implementing the invention

[0054] When a conductive fluid moves in a magnetic field, an induced current is generated in a direction orthogonal to the magnetic field lines and the velocity component perpendicular to the magnetic field lines. However, when using an electrically insulating quartz crucible, the crucible walls and the free surface of the molten semiconductor material act as insulating walls, so an induced current does not flow in a direction orthogonal to them. For this reason, the convection suppression force becomes insufficient in the vicinity of the cross-section perpendicular to the X-axis within the molten semiconductor material.

[0055] However, if two pairs of opposing superconducting coils are provided around the pulling furnace, and the axis passing through the centers of the opposing pairs of superconducting coils is taken as the coil axis, and the two coil axes of the two sets of superconducting coil pairs are contained within the same horizontal plane, and the center angle α between the two coil axes (direction of magnetic field lines in the center axis of the pulling furnace within the horizontal plane) is 90 degrees or less, and the coil angle β between adjacent superconducting coils (direction perpendicular to the X-axis within the horizontal plane) is 20 degrees or less, then the flow rate of the molten semiconductor raw material can be reduced even in the cross-section perpendicular to the X-axis where the convection suppression force by electromagnetic force was insufficient, and the flow rate in the cross-section parallel to the X-axis of the molten semiconductor raw material and the flow rate in the cross-section perpendicular to the X-axis of the molten semiconductor raw material can be balanced. And, as a result, as described above, the oxygen concentration introduced into the single crystal can be significantly reduced, and it is possible to suppress growth fringes in the grown single crystal. Furthermore, for example, the overall length of the coil can be increased further than that of the superconducting coil of Patent Document 2, and the magnetic flux density of the central axis can be increased further. As a result, in particular, the upward convexity of the growth interface becomes possible, making it possible to pull up a defect-free region crystal at a higher speed.

[0056] Furthermore, if a saddle-shaped coil is used as a superconducting coil, the magnetic field generation efficiency can be increased, and the overall height of the coil can be made smaller than that of a circular coil, the height of the coil center can be raised, the magnetic field center position can be set to a higher position, and a single crystal with an even lower oxygen concentration can be obtained.

[0057] The inventors discovered this and completed the present invention.

[0058] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

[0059] Figure 1 shows an example of a single crystal pulling device of the present invention.

[0060] The single crystal lifting device (11) of FIG. 1 is based on the CZ method and is configured to have a heating heater (3), a quartz crucible (2) in which molten semiconductor raw material (hereinafter also referred to as molten liquid or melt) (6) is contained, a lifting furnace (1) having a central axis (10), and a superconducting magnet (magnetic field generating device (30)) having a superconducting coil provided around the lifting furnace (1), and to apply a horizontal magnetic field to the molten liquid (6) by passing current through the superconducting coil, thereby suppressing convection of the molten liquid (6) within the crucible (2) and lifting the single crystal (9) in the lifting direction (8).

[0061] Here, with reference to FIGS. 2a and 2b, the shape and arrangement of the superconducting coil in the magnetic field generating device (30) will be described in detail. FIG. 2a is a perspective view showing an example of the shape of the superconducting coil, and FIG. 2b is a cross-sectional view showing an example of its arrangement.

[0062] There are a total of four superconducting coils (also simply called coils) (4) (4a-4d), each having a saddle-shaped curved along the outer shape of the tubular lifting furnace (1). Two sets of pairs are provided facing each other around the lifting furnace (1). Here, they are combinations of 4a and 4c, and 4b and 4d.

[0063] Since the coil (4) is saddle-shaped rather than circular like conventional coils, the circumference of the coil can be increased, and a magnetic field with a greater magnetic flux density can be generated, and the efficiency of magnetic field generation can be high.

[0064] In addition, since it is easier to make the overall height of the coil smaller compared to a circular one, the center height position of the coil can be raised to a higher position compared to a circular one. That is, the center of the magnetic field can be set at a higher position relative to the molten liquid (6), and the production of a single crystal (9) with a lower oxygen concentration can be achieved.

[0065] Meanwhile, the coil (4) may have a vertical width shorter than its horizontal width. In this case, the overall height of the coil can be reduced more effectively, and furthermore, a single crystal (9) with a low oxygen concentration can be obtained even more easily.

[0066] Additionally, when the axis passing through the centers of the oppositely arranged pair of coils (4) is taken as the coil axis, the two coil axes (13, 14) of the two sets of coils (4) (pairs of 4a and 4c, and pairs of 4b and 4d) are contained within the same horizontal plane (12) (see FIG. 1). Furthermore, regarding the magnetic field lines (7), when the direction of the magnetic field lines in the center axis (10) of the lifting furnace (1) is taken as the X-axis within the horizontal plane (12), the angle formed by the two coil axes (13, 14) with the X-axis in between (center angle α) is 90 degrees or less.

[0067] In addition, the angle between adjacent coils with respect to the Y-axis (a direction perpendicular to the X-axis within the horizontal plane (12)) is 20 degrees or less. In the case of FIG. 2a and 2b, the angle between the end of coil (4d) in coil (4a) and the end of coil (4a) in coil (4d), or the angle between the end of coil (4b) in coil (4c) and the end of coil (4c) in coil (4b), is the angle between coils.

[0068] Meanwhile, the range that the angle between coils β can take is 0 to 20 degrees. When the angle between coils β is at its minimum value of 0 degrees, the center angle α can take its maximum value of 90 degrees. Meanwhile, when the angle between coils β is at its maximum value of 20 degrees, the range that the center angle α can take is 80 to 90 degrees.

[0069] Regarding this saddle-shaped coil (4), the effect when the center angle α and the angle between the coils β are within the above range is explained below.

[0070] First, as described above, the convection suppression force is insufficient in the vicinity of the cross-section perpendicular to the X-axis among the molten semiconductor raw materials; however, by having a center angle of 90 degrees or less and a coil-to-coil angle β of 20 degrees or less, it is possible to generate a convection suppression force in the vicinity of the cross-section perpendicular to the X-axis. In addition, since the magnetic flux density orthogonal to the crucible in the peripheral angle region corresponding to the coil center position in the planar view is not excessively high, the diffusion boundary layer near the crucible wall in that part does not become thin, and melting from the quartz crucible is further suppressed. By these, a single crystal with significantly reduced oxygen concentration can be obtained.

[0071] Here, the point of inhibition of melting from the above-mentioned quartz crucible is explained more specifically with an example.

[0072] FIG. 14 plots the magnetic flux density component B⊥ perpendicular to the crucible wall of a 32-inch (800 mm) crucible against the circumferential angle with the X-axis set to 90 degrees. Meanwhile, this circumferential angle is, in this case, the counterclockwise angle θ with the Y-axis between the coils (4a, 4d) as the reference (0 degrees), as shown in FIG. 2b. It is plotted for four types of patterns (two circular coil patterns and two saddle-shaped coil patterns). The circular coil pattern in FIG. 14 is a coil described in Patent Document 2. Two sets of coils with a width of 900 mm are prepared in a horizontal plane containing the coil axis, with the direction of the magnetic field lines at the center axis of the lifting device as the X-axis, and each of the coil axes of these two sets of coils is arranged to be included within the same horizontal plane. Additionally, the coils are arranged in a cylindrical container with the center angle α between the X-axis set to 120 degrees and 60 degrees. In the circular coil with α=60 degrees, B⊥ decreases near 0 degrees, which corresponds to the cross-section perpendicular to the magnetic field lines (X-axis), whereas in the circular coil with α=120 degrees, the near 90 degrees becomes weak, while the near 0 degrees becomes very strong. Therefore, it can be seen that a strong convection suppression force is obtained even near the cross-section perpendicular to the magnetic field lines (X-axis).

[0073] Meanwhile, even with a saddle-shaped coil, if α=120 degrees and β=6 degrees, it can be seen that, just like a circular coil with α=120 degrees, B⊥ is large near 0 degrees and decreases near 90 degrees, resulting in the same distribution.

[0074] In contrast, in the saddle-shaped coil of α=90 degrees and β=20 degrees, which is an example of the present invention, the peak observed around 35 degrees in the saddle-shaped coil of α=120 degrees is shifted to around 45 degrees, and the maximum value is also reduced. However, compared to the circular coil of α=60 degrees, B⊥ around 0 degrees remains strong, and since B⊥ increases around 90 degrees corresponding to the X-axis, it can be seen that the convection suppression force acts evenly not only near the cross-section perpendicular to the magnetic field line (X-axis) but also throughout the entire circumferential direction. As the extremely large B⊥ disappears, the thinning of the diffusion boundary layer near the crucible wall in that part is eliminated, and melting from the quartz crucible is further suppressed.

[0075] In addition, it is possible to balance the flow rate in the cross-section parallel to the X-axis of the molten liquid (6) with the flow rate in the cross-section perpendicular to the X-axis, and by realizing the balance, growth streaks in the single crystal (9) can be suppressed.

[0076] In addition, for example, the total length of the coil (4) can be increased compared to the coil of Patent Document 2, and in particular, an additional increase in magnetic flux density at the central axis (10) and upward convexity of the growth interface of the single crystal (9) being grown can be achieved, and high-speed lifting of the defect-free region crystal becomes possible.

[0077] Here, for example, Patent Document 4 discloses an electromagnet in which a plurality of saddle-shaped coils are arranged around a crucible, but the magnetic field generated by said electromagnet is a rotating magnetic field synchronized with the rotation of the crucible in a direction orthogonal to the axis of lifting the single crystal, and is completely different from a static magnetic field like that of the present invention. In this Patent Document 4, by controlling the de-energization time of the plurality of coils to generate a rotating magnetic field synchronized with the rotation of the crucible, a driving force in the circumferential direction is applied to the melt, the relative speed between the crucible and the melt is made zero, and by reducing the melting from the crucible, a crystal that does not contain impurities is obtained. However, the single crystal lifting device (11) of the present invention does not require a magnetic field generating device that requires complex control like that of this Patent Document 4, and can obtain a crystal with an ultra-low oxygen concentration by reducing the melting from the crucible as described above, and also makes it possible to lift a single crystal of a desired defect region, for example, a defect-free region crystal containing about 10 ppma-JEIDA of oxygen, at a higher speed.

[0078] In addition, the single crystal lifting device (11) has a lifting device (22) for the lifting path (1), and is capable of vertical lifting or turning of the lifting path (1).

[0079] Furthermore, there is a lifting device (23) for the magnetic field generator (30), and the magnetic field generator (30) installed on the lifting device (23) can be raised (moved up and down) in the vertical direction. By doing so, after the operation is finished, the hot zone dismantling and cleaning in the lifting furnace (1) can be easily performed, and the oxygen concentration of the single crystal (9) being grown can be easily adjusted by adjusting the height of the magnetic field generator (30).

[0080] Next, a single crystal pulling method of the present invention using the single crystal pulling device (11) of the present invention as described above will be explained. Here, a method for pulling a silicon single crystal, which is a semiconductor single crystal, will be explained.

[0081] First, in a single crystal pulling device (11), semiconductor raw material (polycrystalline silicon) is placed in a crucible (2) and heated by a heating heater (3), and the semiconductor raw material is melted (melted liquid (6)).

[0082] Next, by energizing the superconducting coil (4), a horizontal magnetic field generated by the magnetic field generator (30) is applied to the molten liquid (6), thereby suppressing convection within the crucible (2) of the molten liquid (6).

[0083] Next, a seed crystal (not shown) is lowered and brought into contact with the molten liquid (6) from, for example, the upper part of the center of the crucible (2), and the seed crystal is lifted by a lifting mechanism (not shown) while rotating it in the direction of the lifting direction (8) at a predetermined speed. As a result, a crystal grows in the solid-liquid boundary layer, and a semiconductor single crystal (silicon single crystal) (9) is produced.

[0084] With this single crystal pulling method, it is possible to grow a semiconductor single crystal with suppressed growth streaks and a significantly reduced oxygen concentration. Although the oxygen concentration in the single crystal being pulled is not particularly limited, it is possible to produce one with an oxygen concentration of 5 ppma-JEIDA or less, preferably 3 ppma-JEIDA or less, and furthermore, 1 ppma-JEIDA or less.

[0085] Meanwhile, when raising this semiconductor single crystal, the height position of the magnetic field generating device (30) can be adjusted using the lifting device (23) according to the target value of the oxygen concentration contained in this semiconductor single crystal.

[0086] Specifically, the relationship between the height position of the magnetic field generator (30) and the oxygen concentration in the single crystal (9) is determined in advance through experiments, etc., and before the lifting begins, the height position of the magnetic field generator (30) is set to a desired height position. During the lifting of the single crystal (9), the oxygen concentration in the single crystal can be controlled using other parameters without changing the magnetic field height. Representative parameters may include crucible rotation or heater position.

[0087] In addition, fine oxygen concentration control is possible by pattern controlling the height position of the magnetic field generator (30) during the lifting of one single crystal (9).

[0088] In addition, by adjusting the magnetic field strength (magnetic flux density), the defect region of the single crystal being grown can be adjusted to a target defect region. As described above, since the overall length of the coil can be increased even further than that of Patent Document 2, the magnetic flux density along the central axis can be increased, for example, and as a result, a defect-free crystal can be pulled up at a higher speed. Conversely, if the central magnetic flux density is lowered, the temperature gradient in the central region becomes smaller, so a single crystal rich in vacancies can be obtained.

[0089] Examples

[0090] The present invention will be explained more specifically below by presenting embodiments and comparative examples, but the present invention is not limited thereto.

[0091] (Example 1)

[0092] A single crystal was pulled using the single crystal pulling device (11) of the present invention shown in FIGS. 1, 2a, and 2b.

[0093] The story of the first of the three of the four two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the two of the

[0094] The calculation conditions for the analysis are calculated as follows: charge amount 400 kg, 32-inch (800 mm) crucible, silicon single crystal with a diameter of 306 mm, crystal rotation 9 rpm, crucible rotation 0.4 rpm, and pulling speed 0.4 mm / min.

[0095] Figure 3 shows the results of magnetic field analysis by ANSYS-Maxwell3D, and displays the distribution of magnetic flux density after analyzing by adjusting the current × number of turns of the coil so that the magnetic flux density at the central axis becomes 1000 Gauss.

[0096] From the results of the above magnetic field analysis, the magnetic flux density of the space including the crystal and melt regions was extracted, and a 3D melt convection analysis considering the magnetic field distribution was performed using CGSim 3D Flow. The center height position of the coil (also referred to as the height position of the coil axis) was set on the surface of the melt, as in Comparative Example 3 described later. The left side of Fig. 4 shows the velocity vector within the melt obtained from the results, and the right side shows the oxygen concentration distribution within the melt. ⊥B represents a cross-section perpendicular to the magnetic field lines, and / / B represents a cross-section parallel to the magnetic field lines.

[0097] Even in the magnetic field of Example 1, and similar to Comparative Example 3 described later, the oxygen concentration in the melt is lowered to the extent that the convection suppression force is strong even in the cross-section perpendicular to the magnetic field lines, and relatively active flow is observed only below the crystal stage.

[0098] Even with the coil shape and arrangement in the present invention, crystals with an ultra-low oxygen concentration that are lower than 1 ppma-JEIDA on the entire wafer surface and have excellent in-plane distribution were obtained.

[0099] (Example 2)

[0100] As the coil lengthens in Example 1, the magnetic field generation efficiency also increases, allowing for energization up to 4000 Gauss at the central axis. Accordingly, in Example 2, the magnetic flux density at the central axis was set to 4000 Gauss, and the height position of the coil axis was set to the molten surface to perform 3D melt convection analysis, after which the silicon single crystal was pulled using this device.

[0101] Figure 5 shows the velocity vectors within the melt and the oxygen concentration distribution within the melt obtained by numerical analysis. Compared to Example 1, the oxygen concentration within the melt is higher (3-5 ppma-JEIDA near the growth interface), but it can be seen that the growth interface is significantly convex upward. With this shape of the growth interface, the vertical temperature gradient (G) within the plane becomes equal, making it possible to form a defect-free region.

[0102] (Comparative Example 1)

[0103] A single crystal was pulled using a single crystal pulling device of a conventional superconducting magnet (magnetic field generator) shown in FIGS. 12a and 12b.

[0104] For a magnetic field generating device placed in a cylindrical vacuum vessel with two sets of oppositely positioned circular coils of diameter 900 mm arranged so that each coil axis is included within the same horizontal plane, with the direction of the magnetic field lines at the center axis of the pulling device being the X-axis, and the center angle α between the coil axes with the X-axis between them being 120 degrees, magnetic field analysis and 3D melt convection analysis were performed, and then a silicon single crystal was pulled using this device.

[0105] The calculation conditions for the analysis are calculated as follows: charge amount 400 kg, 32-inch (800 mm) crucible, silicon single crystal with a diameter of 306 mm, crystal rotation 9 rpm, crucible rotation 0.4 rpm, and pulling speed 0.4 mm / min.

[0106] Figure 6 shows the results of magnetic field analysis by ANSYS-Maxwell3D, and displays the distribution of magnetic flux density after analyzing by adjusting the current × number of turns of the coil so that the magnetic flux density at the central axis becomes 1000 Gauss.

[0107] From the results of the above magnetic field analysis, the magnetic flux density of the space including the crystal and melt regions was extracted, and a 3D melt convection analysis considering the magnetic field distribution was performed. The height position of the coil axis was set to a position 140 mm below the surface of the melt, which is the upper limit position in Comparative Example 1. Figure 7 shows the velocity vector within the melt obtained from the results, and the right side shows the oxygen concentration distribution within the melt.

[0108] In the magnetic field of Comparative Example 1, the convection suppression force is strong even in the cross-section perpendicular to the magnetic field lines, and relatively active flow is observed only below the crystal stage, and the oxygen concentration in the melt is also low.

[0109] With this coil arrangement, crystals with an excellent in-plane distribution of approximately 3 to 5 ppma-JEIDA can be obtained across the entire wafer surface, but to increase the magnetic field generation efficiency, it is necessary to increase the coil diameter, and furthermore, if the center height of the coil is increased to lower the oxygen concentration, interference with the pulling device is likely to occur. Therefore, in the device of Comparative Example 1, it is difficult to further lower the oxygen concentration.

[0110] (Comparative Example 2)

[0111] For a magnetic field generating device in which four superconducting coils are arranged in the same horizontal plane (two sets of pairs of opposing coils), with the coils having a vertical width of 620 mm and a horizontal width (length of the outermost circumference along the curve) of 855 mm (887 mm), and the direction of the magnetic field lines at the central axis is the X-axis, the central angle α between the coil axes is 120 degrees with the X-axis between them, and the angle β between the coils is 6 degrees with the Y-axis perpendicular to the X-axis between them, magnetic field analysis and 3D melt convection analysis were performed, and then a silicon single crystal was pulled using this device.

[0112] Figure 15 is the result of magnetic field analysis by ANSYS-Maxwell3D, and shows the distribution of magnetic flux density after analyzing by adjusting the current × number of turns of the coil so that the magnetic flux density at the central axis becomes 1000 Gauss.

[0113] From the results of the above magnetic field analysis, the magnetic flux density of the space including the crystal and melt regions was extracted, and a 3D melt convection analysis considering the magnetic field distribution was performed. The center height position of the coil was set 140 mm below the molten surface, the same as in Comparative Example 1. The left side of Fig. 16 shows the velocity vector within the melt obtained from the results, and the right side shows the oxygen concentration distribution within the melt.

[0114] In the magnetic field of Comparative Example 2, just like in Comparative Example 1, the convection suppression force is strong even in the cross-section perpendicular to the magnetic field lines, and relatively active flow is observed only below the crystal stage, and the oxygen concentration in the melt is also reduced.

[0115] Even with such coil shape and arrangement, crystals with an excellent in-plane distribution of about 3~5 ppma-JEIDA can be obtained across the entire wafer surface.

[0116] In addition, since the vertical width of the coil is smaller compared to Comparative Example 1, there is room to raise the center height of the coil to further lower the oxygen concentration. This will be described later as Comparative Example 3.

[0117] (Comparative Example 3)

[0118] By using the saddle-shaped coil of Comparative Example 2, the coil height (vertical width of the coil) could be reduced by 280 mm compared to Comparative Example 1 (total coil height: 900 mm). Accordingly, in Comparative Example 3, the height position of the coil axis was set on the surface of the molten liquid to perform 3D melt convection analysis, and then the silicon single crystal was pulled using this device.

[0119] Figure 17 shows the velocity vectors within the melt and the oxygen concentration distribution within the melt obtained from numerical analysis. It can be seen that the oxygen concentration within the melt is lower compared to Comparative Example 2.

[0120] In fact, with this coil arrangement, the center height position of the coil can be set to the molten surface, and crystals with an ultra-low oxygen concentration and excellent in-plane distribution can be obtained, with the concentration falling below 1 ppma-JEIDA across the entire wafer surface.

[0121] However, as shown in Comparative Examples 2 and 3, in coil arrangements where the center angle α is greater than 90 degrees, the coil length is shortened and the arrangement is such that magnetic field lines repel each other, resulting in low magnetic field generation efficiency; consequently, it is difficult to increase the magnetic flux density at the center. The upper limit of the magnetic flux density is determined by ensuring that the force applied to the coil is within a range that can be supported by the structural material, and by designing with a margin so that the empirical magnetic field inside the coil does not reach the saturation magnetic flux density of the superconducting wire; however, for this coil, the upper limit at the center was approximately 2000 Gauss. At this level of magnetic flux density, the temperature boundary layer immediately beneath the rotating crystal does not become sufficiently thin, which makes it difficult to convex the crystal growth interface upward, and has the drawback of making it difficult to obtain a defect-free region crystal where the temperature gradient across the entire growth interface needs to be uniform. In other words, it is not a pulling device like the present invention suitable for pulling not only single crystals with low oxygen concentration but also for pulling defect-free region crystals.

[0122] (Comparative Example 4)

[0123] For a magnetic field generating device that is a saddle-shaped coil along a circle with a radius of 900 mm centered on the central axis of the pulling furnace, and has four superconducting coils arranged in the same horizontal plane with a vertical width of 620 mm and a horizontal width (length of the outermost circumference along the curve) of 942 mm (986 mm) (two sets of pairs of opposing coils), with a central angle α of 90 degrees and an angle between coils β of 30 degrees, magnetic field analysis and 3D melt convection analysis were performed, and then a silicon single crystal was pulled using this device.

[0124] Similar to Comparative Example 3, the center height position of the coil could be set on the molten surface, but the oxygen concentration was about 2-3 ppma-JEIDA across the entire wafer surface, which is higher than that of Comparative Example 3. It is thought that the oxygen concentration increased because the angle β between the coils became greater than 20 degrees, the magnetic component orthogonal to the crucible near the cross-section perpendicular to the X-axis became smaller, and the suppression of convection there weakened.

[0125] Furthermore, in coil arrangements where the angle β between coils is greater than 20 degrees, the coil length is shortened, and since the arrangement results in magnetic field lines repelling each other, the magnetic field generation efficiency is low, making it difficult to increase the magnetic flux density at the center. The upper limit of the magnetic flux density is determined by ensuring that the force applied to the coil is within a range that can be supported by the structural material, and by designing with a margin so that the empirical magnetic field inside the coil does not reach the saturation magnetic flux density of the superconducting wire; however, since the empirical magnetic field inside this coil tends to increase, the upper limit at the center was approximately 3,000 Gauss. At this level of magnetic flux density, the temperature boundary layer immediately below the rotating crystal is not yet sufficiently thin, so there is a drawback in that it is difficult to pull a defect-free region crystal at high speed, where the upward convexity of the growth interface is small and the temperature gradient across the entire growth interface needs to be uniform. In other words, it is not a pulling device like the present invention suitable for pulling not only single crystals with low oxygen concentration but also defect-free region crystals.

[0126] (Example 3)

[0127] Four superconducting coils with a vertical width of 620 mm and a horizontal width (length of the outermost circumference along the curve) of 1185 mm (1282 mm) were arranged in the same horizontal plane (two sets of pairs of opposing coils), and the arrangement was the same as in Example 1 except that the center angle α was set to 86 degrees and the angle between coils β was set to 16 degrees, and after performing magnetic field analysis and 3D melt convection analysis, the silicon single crystal was pulled using this device.

[0128] Even with the coil shape and arrangement in the present invention as described above, crystals with an ultra-low oxygen concentration that are lower than 1 ppma-JEIDA on the entire wafer surface and have excellent in-plane distribution, almost identical to Example 1, were obtained.

[0129] Meanwhile, the present invention is not limited to the above embodiments. The above embodiments are examples, and any configuration that is substantially identical to the technical concept described in the claims of the present invention and exhibits the same functional effect is included within the technical scope of the present invention.

Claims

Claim 1 A single crystal pulling device comprising a pulling furnace having a central axis in which a heating element and a crucible containing a molten semiconductor raw material are arranged, and a magnetic field generating device having a superconducting coil provided around the pulling furnace, wherein a horizontal magnetic field is applied to the molten semiconductor raw material by energizing the superconducting coil to suppress convection of the molten semiconductor raw material within the crucible, wherein the superconducting coil of the magnetic field generating device has a saddle-shaped form curved along the outer shape of the pulling furnace and has a vertical width shorter than its horizontal width, and two sets of pairs of the saddle-shaped superconducting coils are provided facing each other around the pulling furnace, and when the axis passing through the centers of the pairs of superconducting coils facing each other is taken as the coil axis, the two coil axes of the two sets of superconducting coils are contained within the same horizontal plane, and within this horizontal plane, the direction of the magnetic field lines at the central axis of the pulling furnace is taken as the X-axis, and within the horizontal plane, a magnetic field perpendicular to the X-axis A single crystal pulling apparatus characterized by the fact that, when the direction is the Y-axis, the center angle α between the two coil axes with the X-axis between them is 90 degrees or less, and the coil-to-coil angle β between adjacent superconducting coils with the Y-axis between them is 20 degrees or less. Claim 2 A single crystal lifting device according to claim 1, wherein the magnetic field generating device is characterized by having a lifting device capable of moving up and down in the vertical direction. Claim 3 A single crystal lifting method characterized by lifting a semiconductor single crystal using a single crystal lifting device described in claim 1 or 2. Claim 4 A single crystal lifting method according to claim 3, characterized by adjusting the height position of the magnetic field generating device according to the target value of the oxygen concentration contained in the semiconductor single crystal when lifting the semiconductor single crystal. Claim 5 A single crystal lifting method according to claim 3, characterized by adjusting the magnetic field strength according to the target defect region of the semiconductor single crystal when lifting the semiconductor single crystal. Claim 6 A single crystal lifting method according to claim 4, characterized by adjusting the magnetic field strength according to the target defect region of the semiconductor single crystal when lifting the semiconductor single crystal. Claim 7 delete Claim 8 delete

Images