Single crystal pulling apparatus

Abstract

To suppress dispersion of oxygen concentration of each single crystal without fixing a conventional mode.SOLUTION: A single crystal pulling-up apparatus includes a chamber, a crucible installed in the chamber for storing a silicon melt, a pulling-up shaft to which a seed crystal is attached at one end, and a pulling-up drive unit for moving up and down and rotating the pulling-up shaft. The single crystal pulling-up apparatus further includes a pulling-up unit for pulling up a silicon single crystal, a thermal shield arranged so as to surround the silicon single crystal above the crucible, and a magnetic field applying unit for applying a horizontal magnetic field to the silicon melt in the crucible. A plurality of notches are formed and arranged at the bottom edge of the thermal shield two-times symmetrically to the pulling-up shaft as the center.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a single crystal pulling apparatus for growing a silicon single crystal.

Background Art

[0002] As a method for manufacturing a silicon single crystal, the Czochralski method is known. In recent years, the so-called MCZ method, in which a silicon single crystal is grown while applying a horizontal magnetic field to a silicon melt, has been increasingly used. By the way, in the growth of a silicon single crystal by the MCZ method, even when a silicon single crystal is grown under the same process conditions using the same single crystal pulling apparatus, the quality of the grown silicon single crystal, particularly the oxygen concentration in the silicon single crystal, may vary.

[0003] As factors for the variation in oxygen concentration in the growth of a silicon single crystal by the MCZ method, the following two factors can be considered. The first factor is the rotation direction of the convection generated in the silicon melt by the application of the horizontal magnetic field (hereinafter referred to as the convection mode). The inventors have found that, in the process of melting a solid polysilicon raw material in a crucible and then applying a horizontal magnetic field to pull up a silicon single crystal, convection rotating from the bottom of the crucible toward the surface of the silicon melt occurs.

[0004] FIG. 1 is a schematic diagram for explaining the convection mode and is a view of the crucible 3 seen from the direction of application of the horizontal magnetic field. The convection mode is divided into two cases: when the clockwise convection C1 is dominant in the crucible 3 as shown in FIG. 1(a) (hereinafter referred to as the right vortex mode), and when the counterclockwise convection C2 is dominant in the crucible 3 as shown in FIG. 1(b) (hereinafter referred to as the left vortex mode). In FIG. 1, the symbol MD is the direction of application of the magnetic field center of the horizontal magnetic field.

[0005] The second factor is the symmetry of the structures constituting the single crystal pulling apparatus. Generally, single crystal pulling apparatuses are designed with an axisymmetric structure with respect to the pulling axis. This is because, in a system where a silicon single crystal and a crucible rotate, having the same axis of rotation and an axisymmetric structure makes the system more thermally stable. However, in reality, there are structures that cannot be axially symmetric, such as the electrodes of the heater that heats the crucible and the observation window, so it is not a perfectly axially symmetric structure.

[0006] During the pulling of silicon single crystals, oxygen is released from the crucible, but this oxygen is transported to the solid-liquid interface during growth by the convection described above and incorporated into the crystal. If the single crystal pulling apparatus has a perfectly axially symmetric structure and the process conditions are the same, the amount of oxygen incorporated into the crystal will be the same regardless of the convection mode.

[0007] However, in reality, due to the non-uniformity of the thermal environment caused by the single crystal pulling apparatus not having a perfectly axially symmetric structure, the amount of oxygen flux transported differs between the right-handed and left-handed vortex modes. As a result, silicon single crystals with different oxygen concentrations are grown depending on the convection mode. Even when silicon single crystals are grown using the same single crystal pulling apparatus and under the same process conditions, differences in convection modes result in crystals with different oxygen concentrations, leading to a decrease in the yield of the manufactured silicon single crystals.

[0008] Patent Document 1 discloses a method for eliminating variations in oxygen concentration caused by the convection mode by stably selecting one of two convection modes (right-handed vortex mode or left-handed vortex mode). Specifically, the method involves actively biasing the heating capacity of the heater to fix the convection mode to one side, thereby suppressing variations in oxygen concentration for each silicon single crystal.

[0009] Furthermore, Patent Document 2 discloses a method for fixing the convection mode to one side by biasing the flow of inert gas between the heat shield and the surface of the silicon melt. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2019-151502 [Patent Document 2] Japanese Patent Publication No. 2019-151503 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] However, the method described in the above-mentioned patent document has the problem that, by forcibly fixing the convection mode, the surrounding thermal environment affecting the pulled silicon single crystal becomes non-uniform, making stable pulling difficult.

[0012] The present invention aims to provide a single crystal pulling apparatus that can suppress variations in oxygen concentration for each silicon single crystal without fixing the convection mode. [Means for solving the problem]

[0013] The single crystal pulling apparatus of the present invention comprises a chamber, a crucible disposed within the chamber for storing silicon molten metal, a pulling shaft to which a seed crystal is attached at one end, a pulling drive unit for raising and lowering and rotating the pulling shaft, a pulling unit for pulling up a silicon single crystal, a heat shield provided above the crucible so as to surround the silicon single crystal, a magnetic field application unit for applying a horizontal magnetic field to the silicon molten metal in the crucible, and a plurality of notches formed at the lower end of the heat shield so as to be twice symmetrical with respect to the pulling shaft.

[0014] In the single crystal pulling apparatus described above, it is preferable that the chamber is provided with a plurality of observation windows arranged so as to be twice symmetrical with respect to the pulling axis.

[0015] The single crystal pulling apparatus of the present invention includes a chamber, a crucible disposed in the chamber for storing a silicon melt, a pulling shaft having a seed crystal attached to one end, and a pulling drive unit for raising and lowering and rotating the pulling shaft, and has a pulling unit for pulling a silicon single crystal, a heat shield provided above the crucible so as to surround the silicon single crystal, a magnetic field applying unit for applying a horizontal magnetic field to the silicon melt in the crucible, and a plurality of observation windows formed in the chamber, and the plurality of observation windows are arranged to be bilaterally symmetric about the pulling shaft.

[0016] In the above single crystal pulling apparatus, it is preferable to include a plurality of dopant supply devices, and the chamber is provided with a plurality of dopant inlets arranged to be bilaterally symmetric about the pulling shaft.

[0017] In the above single crystal pulling apparatus, it is preferable to have a cylindrical heat insulating material provided along the inner surface of the chamber, and a plurality of holes are formed in the heat insulating material so as to be bilaterally symmetric about the pulling shaft.

[0018] In the above single crystal pulling apparatus, it is preferable that the pair of notch portions are arranged to be aligned along the application direction of the magnetic field center of the horizontal magnetic field.

Brief Description of the Drawings

[0019] [Figure 1] It is a schematic diagram for explaining the convection mode. [Figure 2] It is a schematic cross-sectional view of the single crystal pulling apparatus according to an embodiment of the present invention. [Figure 3] It is a schematic plan view for explaining the arrangement of the magnetic field applying unit, the observation window, and the notch portion of the single crystal pulling apparatus according to an embodiment of the present invention. [Figure 4] It is a schematic diagram for explaining the relationship between the flow of the inert gas and the flow of the convection. [Figure 5] It is a schematic cross-sectional view of the single crystal pulling apparatus according to a modified example of the present invention. [Figure 6] It is a schematic plan view for explaining the arrangement of a magnetic field application section, an observation window, and a notch section of a single crystal pulling apparatus according to a modified example of the present invention. [Figure 7] It is a schematic plan view for explaining the arrangement of an observation window and a notch section of a single crystal pulling apparatus in an example and a comparative example.

Embodiments for Carrying Out the Invention

[0020] 〔Background Leading to the Present Invention〕 As described above, if the single crystal pulling apparatus has a completely axially symmetric structure, the amount of oxygen incorporated into the silicon single crystal is equal regardless of the convection mode. However, due to the presence of a structure that cannot be axially symmetric, a completely axially symmetric structure cannot be realized.

[0021] In examining the structure of a single crystal pulling apparatus for suppressing the quality difference of silicon single crystals due to the convection mode, the present inventors verified the influence of a static magnetic field on a silicon melt.

[0022] The influence that a static magnetic field exerts on a silicon melt, that is, the Lorentz force, is the same regardless of the positive or negative direction of the magnetic field. Assuming that the magnetic field is B, the induced current is j, and the Lorentz force is F (where B, j, and F are all vectors), F = j × B (cross product). Here, when a magnetic field B’ = -B is applied, the induced current flowing j ’ becomes j’ = -j. The Lorentz force F’ is F’ = j’ × B’ = -j × -B = j × B = F, and F and F’ are the same. Therefore, the entire system including the magnetic field is two-fold symmetric (180-degree rotational symmetry).

[0023] From the above, it can be seen that if the structure of the single crystal pulling apparatus is made two-fold symmetric about the pulling axis, the influence that the silicon melt receives from the apparatus and the magnetic field is the same whether the convection mode is a right vortex mode or a left vortex mode. That is, it is considered that by making the structure of the single crystal pulling apparatus two-fold symmetric, the variation in oxygen concentration can be suppressed.

[0024] [Configuration of the single crystal pulling apparatus] The configuration of a single crystal pulling apparatus according to an embodiment of the present invention will be described. As shown in Figure 2, the single crystal pulling apparatus 1 is a device for pulling silicon single crystals SM by the MCZ method, and comprises a chamber 2, a crucible 3 placed inside the chamber 2 to store silicon molten M, a heater 4, a pulling unit 5 for pulling up the silicon single crystal SM, a heat shield 6 provided above the crucible 3 so as to surround the silicon single crystal SM, a heat insulating material 7 provided along the inner surface of the chamber 2, a crucible drive unit 8, and a magnetic field application unit 9 for applying a horizontal magnetic field to the silicon molten M.

[0025] Crucible 3 has a double-layered structure consisting of a quartz crucible 3A and a graphite crucible 3B that houses the quartz crucible 3A. The crucible drive unit 8 includes a support shaft 11 that supports the crucible 3 from below, and rotates and raises the crucible 3 at a predetermined speed.

[0026] Chamber 2 comprises a main chamber 12 and a pull chamber 13 connected to the upper part of the main chamber 12. The main chamber 12 and the pull chamber 13 are connected via a gate valve 14.

[0027] The main chamber 12 comprises a main body 12A on which a crucible 3, heater 4, heat shield 6, etc. are arranged, and a lid 12B that closes the top surface of the main body 12A. The lid 12B is provided with an opening 15 for introducing an inert gas such as argon gas into the main chamber 12, and a pair of quartz observation windows 16 for observing the inside of the chamber 2 using optical observation means or the like. A support portion 17 extending inward is provided between the main body 12A and the lid 12B.

[0028] The pull chamber 13 is provided with a gas inlet 20 for introducing an inert gas into the main chamber 12. A gas exhaust port 21 is provided at the bottom of the main body 12A of the main chamber 12 for sucking out and discharging gas from inside the main chamber 12 by driving a vacuum pump (not shown). The inert gas introduced into the chamber 2 from the gas inlet 20 descends between the growing silicon single crystal SM and the heat shield 6. The inert gas then flows through the gap between the lower end of the heat shield 6 and the surface of the silicon molten M, and then outwards from the outside of the heat shield 6 and further outwards from the crucible 3. After that, the inert gas descends outside the crucible 3 and is discharged from the gas exhaust port 21.

[0029] The heater 4 is of the resistance heating type and is positioned around the crucible 3. The insulation material 7 is cylindrical and is located on the outside of the heater 4, along the inner surface of the chamber 2. The lifting unit 5 includes a lifting shaft A to which a seed crystal SC is attached at one end, and a lifting drive unit 23 that raises, lowers, and rotates the lifting shaft A.

[0030] The thermal shield 6 blocks high-temperature radiant heat from the silicon molten M in the crucible 3, the heater 4, and the side walls of the crucible 3 from reaching the silicon single crystal SM being grown. Furthermore, the thermal shield 6 suppresses the diffusion of heat to the outside near the solid-liquid interface, which is the crystal growth interface, thereby controlling the vertical temperature gradient between the center and outer periphery of the silicon single crystal SM. Furthermore, the heat shield 6 functions as a flow straightening tube that exhausts the evaporated material from the silicon molten liquid M to the outside of the furnace using an inert gas introduced from above the furnace.

[0031] The heat shield 6 is supported at its upper end by the support portion 17 of the chamber 2. The heat shield 6 is formed in a frustoconical shape, with its diameter decreasing towards the lower end. A pair of notches 6A are formed at the lower end of the heat shield 6. By forming the notches 6A, a distribution can be intentionally created in the flow of inert gas flowing over the silicon molten M. In other words, by forming the notches 6A, the flow rate and velocity of the inert gas flowing between the silicon single crystal SM and the heat shield 6 can be made to differ in the circumferential direction. The position of the notches 6A will be described later. The shape of the heat shield 6 is not limited to the shape described above. For example, it may have a cylindrical main body and a flange-like projection extending inward from the entire circumference of the lower end of the main body, with the projection being formed into a frustoconical shape whose diameter decreases as it extends downward.

[0032] Figure 3 is a schematic plan view illustrating the arrangement of the magnetic field application section 9, the pair of observation windows 16, and the pair of notches 6A. Note that Figure 3 simplifies the arrangement by showing only the external shape of, for example, the chamber 2. As shown in Figure 3, the magnetic field application unit 9 comprises a first magnetic body 9A and a second magnetic body 9B, both composed of electromagnetic coils. The magnetic bodies 9A and 9B are positioned on the outside of the chamber 2, facing each other across the crucible 3 (see Figure 2). With the magnetic field application unit 9 arranged in this manner, the direction MD of the magnetic field center is positioned so that it passes through the central axis C of the crucible 3 and is horizontal. That is, the magnetic field center is horizontal, passing through the central axis C of the crucible 3.

[0033] The pair of notches 6A are formed in positions that are twice symmetrical with respect to the pulling axis A. The pair of notches 6A are arranged so that the two notches 6A are aligned along the direction MD in which the magnetic field is applied. In other words, one notch 6A is located upstream of the direction MD in which the magnetic field is applied, and the other notch 6A is located downstream of the direction MD in which the magnetic field is applied, and they are positioned at the furthest distance from each other.

[0034] The pair of observation windows 16 are also formed in positions that are twice as symmetrical with respect to the lifting axis A, similar to the notch 6A. The pair of observation windows 16 are arranged so that the two observation windows 16 are aligned along the direction MD in which the magnetic field is applied.

[0035] Note that twofold symmetry does not need to be exactly 180° rotational symmetry; rotational symmetry of 180±2° is sufficient.

[0036] Furthermore, the central axis C of the heat shield 6 (see Figure 2) does not need to perfectly coincide with the central axis of the lifting axis A, and may be offset by up to 2.5 mm in either horizontal direction. Similarly, the heater 4, the insulation material 7, and the main body 12A of the chamber 2 may be offset by up to 2.5 mm in either horizontal direction.

[0037] When manufacturing a silicon single crystal SM using such a single crystal pulling apparatus 1, all the silicon raw material is melted in a magnetic field-free state. Once all the silicon raw material has melted, a horizontal magnetic field is applied to restrain the convective motion and pull up the silicon single crystal SM. The inert gas supplied from the gas inlet 20 (see Figure 2) is supplied to the surface of the silicon molten M and flows along the surface of the silicon molten M toward the outside of the crucible 3. At this time, the flow velocity of the inert gas flowing through the notch 6A increases because the gap is enlarged by the notch 6A. Once the silicon single crystal SM has reached its tail, the application of the horizontal magnetic field is stopped, and the pulling process is terminated. Furthermore, the application of the horizontal magnetic field may be started before the silicon raw material melts. In other words, the application of the horizontal magnetic field may be started before the silicon raw material melts, or it may be started after the silicon raw material melts.

[0038] According to the above embodiment, the structure of the single crystal pulling apparatus 1 is twice symmetrical because the pair of observation windows 16 and the pair of notches 6A are positioned in positions that are twice symmetrical with respect to the pulling axis A. As described above, if the structure of the single crystal pulling apparatus 1 is twice symmetrical with respect to the pulling axis A, the influence that the silicon molten M receives from the apparatus and magnetic field will be the same regardless of the convection mode, and therefore variations in oxygen concentration can be suppressed. Furthermore, even when manufacturing multiple single-crystal pulling devices and pulling silicon single crystals with each device, variations in oxygen concentration between devices can be suppressed.

[0039] Furthermore, as described above, the flow velocity of the inert gas flowing through the notch 6A increases. Therefore, as shown in Figure 4(a), if the pair of notches 6A are arranged along a horizontal direction D1 perpendicular to the direction MD of application of the center of the horizontal magnetic field, the inert gas GD with increased flow velocity collides with the convection flow C1 flowing on the surface of the silicon molten M, affecting the flow of convection C1. The notches 6A of the present invention are arranged such that a pair of notches 6A are aligned along the application direction MD of the center of the horizontal magnetic field, so that the convection flow C1 does not collide with the inert gas GD, which has a high flow velocity, as shown in Figure 4(b). This reduces the effect that the formation of the notches 6A has on the flow on the surface of the silicon molten M.

[0040] In the above embodiment, the notches 6A were arranged along the direction MD of application of the center of the horizontal magnetic field, but this is not the only arrangement. If it does not affect the flow on the surface of the silicon molten M, the notches 6A may be arranged, for example, along a direction perpendicular to the direction MD of application of the center of the horizontal magnetic field. Similarly, the observation windows 16 do not need to be arranged along the direction MD of application of the horizontal magnetic field.

[0041] Furthermore, although the single crystal pulling apparatus 1 of the above embodiment is provided with a pair of observation windows 16 and a pair of notches 6A to give the apparatus a doubly symmetrical structure, the apparatus may also be given a doubly symmetrical structure with only a pair of observation windows 16 without providing the notches 6A. When providing notches 6A to such an apparatus, it is preferable to arrange them in a doubly symmetrical manner. Similarly, the device may have a doubly symmetrical structure using only a pair of notches 6A, without providing an observation window 16.

[0042] Furthermore, although a pair of notches 6A and a pair of observation windows 16 are arranged in the above embodiment, if the structure is symmetrical twice, it is not limited to one pair, but multiple notches 6A and observation windows 16, such as four, may be arranged.

[0043] [Variation] Next, we will describe a modified example of a single crystal pulling apparatus. As shown in Figures 5 and 6, the modified single crystal pulling apparatus 1B can be further supplied with dopants using a dopant supply device 25. The dopant supply device 25 comprises a dopant holding container 25A and a dopant discharge tube 25B, and is a device that enables dopant filling and discharge even during operation. The dopant discharge tube 25B is inserted into the chamber 2 via a dopant inlet 26. In this modified single crystal pulling apparatus 1B, a pair of dopant inlet ports 26 are arranged in positions that are twice as symmetrical with respect to the pulling axis A. In this modified example, although two dopant supply devices 25 are provided, it is not necessary to supply dopants using both dopant supply devices 25; dopants may be supplied using only one dopant supply device 25.

[0044] Furthermore, the modified single crystal pulling apparatus 1B is equipped with a temperature measuring device 27. The temperature measuring device 27 measures the temperature inside the chamber 2 through holes 28 formed in the chamber 2 and the insulating material 7. In this modified single crystal pulling apparatus 1B, a pair of holes 28 are formed in positions that are twice as symmetrical with respect to the pulling axis A.

[0045] As mentioned above, structures that are thought to affect the uniformity of the thermal environment should be designed with a twofold symmetry.

[0046] [Examples and Comparative Examples] Next, examples and comparative examples of the present invention will be described. In the examples and comparative examples, multiple silicon single crystals were pulled using a single crystal pulling apparatus as described with reference to Figure 2, etc. Specifically, 400 kg of polysilicon raw material was placed in a 32-inch diameter crucible and melted, and then a silicon single crystal with a diameter of 300 mm was pulled under the same process conditions. At that time, the convection mode was determined using the temperature measurement unit 30 (see Figure 2). The temperature measuring unit 30 comprises a pair of reflectors 30A and a pair of radiation thermometers 30B, and measures the surface temperature of the silicon molten liquid M.

[0047] [Comparative Example 1] Figure 7 is a schematic plan view illustrating the arrangement of the observation window and notch in the single crystal pulling apparatus of the examples and comparative examples. As shown in Figure 7, the single crystal pulling apparatus of Comparative Example 1 is provided with one observation window 16, and the heat shield 6 has one notch 6A. In other words, the observation window 16 and notch 6A of Comparative Example 1 do not have a doubly symmetric structure. Specifically, the observation window 16 in Comparative Example 1 is located only on the upstream side of the magnetic field application direction MD, passing through the lifting axis A when viewed from above. The notch 6A in Comparative Example 1 is located only on the downstream side of the magnetic field application direction MD.

[0048] [Example 1] As shown in Figure 7, the single crystal pulling apparatus of Example 1 is provided with one observation window 16. In addition, the heat shield 6 of the single crystal pulling apparatus of Example 1 has two notches 6A positioned symmetrically twice around the pulling axis A. Specifically, the observation window 16 in Example 1 is located only on the upstream side of the magnetic field application direction MD. The notch 6A in Example 1 is located on both the upstream and downstream sides of the magnetic field application direction MD.

[0049] [Example 2] As shown in Figure 7, the single crystal pulling apparatus of Example 2 has two observation windows 16 positioned symmetrically twice around the pulling axis A. In addition, the heat shield 6 of the single crystal pulling apparatus of Example 2 has a notch 6A formed therein. Specifically, the observation window 16 in Example 2 is located on both the upstream and downstream sides of the magnetic field application direction MD. The notch 6A in Example 2 is located only on the downstream side of the magnetic field application direction MD.

[0050] [Example 3] As shown in Figure 7, the single crystal pulling apparatus of Example 3 has two observation windows 16 positioned in a way that is twice symmetrical with respect to the pulling axis A. 3The heat shield 6 of the single crystal pulling apparatus has two notches 6A positioned so as to be twice symmetrical with respect to the pulling axis A. Specifically, the observation window 16 in Example 3 is located on the upstream and downstream sides of the magnetic field application direction MD. The notch 6A in Example 3 is located on the upstream and downstream sides of the magnetic field application direction MD.

[0051] 〔evaluation〕 In the comparative examples and examples described above, the oxygen concentration of wafers cut from silicon single crystals pulled in a right-handed vortex mode was evaluated based on the difference between the oxygen concentration of wafers cut from silicon single crystals pulled in a left-handed vortex mode. Five silicon single crystals were pulled up in both right-handed and left-handed vortex modes, and wafers were cut out from a position 500 mm below the top of each silicon single crystal to measure the oxygen concentration.

[0052] Specifically, the difference between the average oxygen concentration of five wafers in right-handed vortex mode and the average oxygen concentration of five wafers in left-handed vortex mode was evaluated as a percentage of the average oxygen concentration of all (10) wafers. In other words, the evaluation index α can be expressed by the following formula (1).

[0053]

number

[0054] The evaluation index α represents the difference in oxygen concentration between the right-handed and left-handed vortex modes. A larger α indicates a greater difference in oxygen concentration, meaning there is greater variation in oxygen concentration between batches.

[0055] [Table 1]

[0056] As shown in Table 1, by making the observation window 16 or the notch 6A a doubly symmetrical structure, the difference in oxygen concentration between the right vortex mode and the left vortex mode was reduced. In particular, in Example 3, by making the observation window 16 and the notch 6A a doubly symmetrical structure, the difference in oxygen concentration between the right vortex mode and the left vortex mode was eliminated, and silicon single crystals of the same quality were obtained. Furthermore, even when only the notched portion had a doubly symmetrical structure in Example 1, the difference in oxygen concentration between the right-hand vortex mode and the left-hand vortex mode was reduced compared to Comparative Example 1, which had a conventional structure. Furthermore, in Example 2, when only the observation window had a doubly symmetrical structure, it was found that the difference in oxygen concentration between the right-handed and left-handed vortex modes was smaller than in Example 1. In other words, it was found that making the observation window a doubly symmetrical structure is more effective than making the notch a doubly symmetrical structure. The above demonstrates that batch-to-batch variations in oxygen concentration can be reduced by making the observation window or notch of the single crystal pulling apparatus a doubly symmetrical structure. [Explanation of Symbols]

[0057] 1...Single crystal pulling device, 2...Chamber, 3...Crucible, 5...Pulling section, 6...Heat shield, 6A...Notch, 7...Insulation material, 9...Magnetic field application section, 16...Observation window, 23...Pulling drive section, 25...Dopant supply device, 26...Dopant inlet, 28...Hole, A...Pulling shaft, M...Silicon melt, SC...Seed crystal, SM...Silicon single crystal.

Claims

1. A chamber comprising a main chamber and a pull chamber connected to the upper part of the main chamber, A crucible for storing molten silicon is placed inside the main chamber, A lifting unit for lifting a silicon single crystal has a lifting shaft to which a seed crystal is attached at one end, and a lifting drive unit for raising, lowering and rotating the lifting shaft, A heat shield is provided above the crucible so as to surround the silicon single crystal, A magnetic field application unit for applying a horizontal magnetic field to the silicon melt in the crucible, The main chamber is provided with a plurality of observation windows formed in the upper part of the main chamber, which allow observation of the inside of the main chamber. At the lower end of the heat shield, a plurality of notches are formed, arranged in a manner that is twice symmetrical with respect to the lifting axis. The aforementioned plurality of observation windows are arranged so as to be twice symmetrical with respect to the lifting axis, A single crystal pulling apparatus in which the plurality of notches and the plurality of observation windows are arranged to be aligned along the direction in which the magnetic field center of the horizontal magnetic field is applied.

2. In the single crystal pulling apparatus according to claim 1, Equipped with multiple dopant supply devices, The chamber is arranged in a manner that is twice as symmetrical with respect to the lifting axis. A single crystal pulling apparatus equipped with multiple dopant input ports.

3. In the single crystal pulling apparatus according to claim 1, The chamber has a cylindrical insulating material provided along its inner surface, A single crystal pulling apparatus having a plurality of holes formed in the thermal insulation material, arranged in a way that is twofold symmetrical with respect to the pulling axis.

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