Method for manufacturing single crystal silicon

Abstract

Provided is a method for producing a single crystal silicon, which is a single crystal for a 200-mm-diameter wafer, has a straight tube diameter of 201 mm or more and 230 mm or less, has a resistivity of 0.8 mΩcm or more and 1.2 mΩcm or less in the straight tube start portion, and is produced by pulling a single crystal silicon (10) from a silicon melt (9) containing red phosphorus as a dopant by a pulling method and growing the single crystal silicon (10), wherein the crystal rotation speed of the single crystal silicon (10) is controlled to be 17 rpm or more and 40 rpm or less for at least a part of a shoulder forming process of the single crystal silicon (10).

Description

Technical Field

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

[0002] In recent years, mobile devices such as mobile phones have become widely used. There is a strong demand for these devices to be portable and usable for extended periods, leading to research into increasing the capacity of batteries built into these devices or reducing their power consumption.

[0003] To reduce the power consumption of mobile devices themselves, it is necessary to reduce the power consumption of the semiconductor devices installed inside the mobile devices.

[0004] For example, a low-voltage power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) used as a power device in mobile devices consumes power in accordance with the current flowing through it when it is energized, because it has a constant internal resistance.

[0005] Therefore, reducing the internal resistance of low-voltage power MOSFETs when they are energized can reduce the power consumption of mobile devices. This background strongly demands a low-resistivity N-type single-crystal silicon to reduce the resistance of low-voltage power MOSFETs when they are energized.

[0006] However, in the pulling of such low resistivity N-type monocrystalline silicon, dislocations sometimes occur when the crown (shoulder) is grown from the neck of the monocrystalline silicon and a straight section is cultivated.

[0007] Regarding this, Patent Document 1 discloses the following technology: by controlling the crystal rotation speed and crucible rotation speed in the crown, the in-plane uniformity of the dopant concentration in the crown is improved, and dislocation is prevented.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2012-250859 Summary of the Invention

[0011] The technical problem that the invention aims to solve

[0012] However, dislocation in the cylindrical start of monocrystalline silicon is not only caused by the non-uniformity of dopant concentration, but sometimes also by impurities floating on the silicon melt mixing into the monocrystalline silicon near the cylindrical start. Therefore, the technology described in Patent Document 1 is insufficient to prevent dislocation.

[0013] The purpose of this invention is to provide a method for manufacturing monocrystalline silicon that can prevent dislocation from the shoulder to the cylinder of the monocrystalline silicon.

[0014] Solutions for solving technical problems

[0015] The present invention was made with regard to the following aspect: from the shoulder of the monocrystalline silicon, the distance between the heat shield plate and the outer peripheral surface of the monocrystalline silicon is excessively separated within a constant range, which reduces the purging ability of gases such as Ar gas and makes it impossible to disperse impurities on the surface of the silicon melt, thus causing dislocation. Specifically, the present invention takes the following as its main purpose.

[0016] The present invention discloses a method for manufacturing single-crystal silicon, wherein single-crystal silicon is grown by pulling from a silicon melt containing red phosphorus as a dopant using a Czochralski method. The single-crystal silicon is characterized in that the single-crystal silicon is a wafer with a diameter of 200 mm, the diameter of the cylindrical shell is 201 mm or more and 230 mm or less, the resistivity of the beginning portion of the cylindrical shell is 0.8 mΩcm or more and 1.2 mΩcm or less, and the crystal rotation speed of at least a portion of the single-crystal silicon in the shoulder formation process is controlled to be 17 rpm or more and 40 rpm or less.

[0017] The present invention discloses a method for manufacturing monocrystalline silicon, wherein monocrystalline silicon is grown from a silicon melt containing arsenic as a dopant by a Czochralski method. The method is characterized in that the monocrystalline silicon is a wafer with a diameter of 200 mm, the diameter of the cylindrical shell is 201 mm or more and 230 mm or less, the resistivity of the beginning portion of the cylindrical shell is 1.8 mΩcm or more and 3.0 mΩcm or less, and the crystal rotation speed of at least a portion of the monocrystalline silicon in the shoulder formation process is controlled to be 17 rpm or more and 40 rpm or less.

[0018] According to the present invention, the crystal rotation speed of at least a portion of the monocrystalline silicon in the shoulder formation process is controlled to be 17 rpm or more and 40 rpm or less. As the monocrystalline silicon rotates, eddies (forced convection) are generated on the surface of the molten silicon in a direction away from the monocrystalline silicon. Thus, impurities floating on the surface of the molten silicon can be driven outward by the eddies, thereby preventing impurities from being incorporated into the monocrystalline silicon and preventing dislocation.

[0019] In this invention, it is preferable to control the crystal rotation speed of the single crystal silicon in the shoulder forming process, which is in the range of 20 mm or more and 190 mm or less, to be 17 rpm or more and 40 rpm or less.

[0020] According to the present invention, since dislocation is prone to occur in the range of 20 mm or more and 190 mm or less in diameter of single crystal silicon during the shoulder forming process, dislocation can be appropriately prevented by setting the crystal rotation speed of single crystal silicon in this range to 17 rpm or more and 40 rpm or less.

[0021] In this invention, it is preferable to control the crystal rotation speed of the single crystal silicon in the shoulder forming process, which is in the range of 100 mm or more and 190 mm or less, to be 17 rpm or more and 40 rpm or less.

[0022] In the shoulder formation process, even when the crystal rotation speed is set to less than 17 rpm, single-crystal silicon can be grown in a dislocation-free state up to a crystal diameter of 100 mm. However, in the range where the crystal diameter is 100 mm or more, dislocation occurs if the crystal rotation speed is set to less than 17 rpm. Therefore, especially in the case where the single-crystal silicon crystal diameter is 100 mm or more but less than 190 mm, setting the crystal rotation speed to 17 rpm or more effectively suppresses dislocation.

[0023] In this invention, it is preferable to set the crystal rotation speed of the single crystal silicon to 3 rpm or more and 20 rpm or less at a position more than 80 mm from the beginning of the straight cylinder of the single crystal silicon.

[0024] Within this range, when the crystal rotation speed is below 3 rpm, the oxygen distribution within the crystal plane may deteriorate, leading to quality issues. On the other hand, when the crystal rotation speed exceeds 20 rpm, crystal deformation may occur.

[0025] Since the temperature gradient around the molten silicon at a position more than 80 mm from the beginning of the cylinder becomes lower than the temperature gradient around the molten silicon with a diameter of 20 mm or more and less than 190 mm in the single crystal silicon shoulder formation process, it becomes more susceptible to the influence of the crystal rotation speed and becomes more prone to crystal deformation.

[0026] Here, crystal deformation refers to an abnormal shape, such as a decrease in the roundness of the horizontal cross-section of a crystal. If crystal deformation occurs, the following adverse effects may result: in the case of a silicon wafer, the quality of the outer periphery of the wafer may deteriorate, or the wafer may become a wafer with a diameter that does not meet the desired specifications in certain areas.

[0027] Furthermore, as mentioned above, crystal deformation is affected by the crystal rotation speed. If the crystal rotation speed is too high, crystal deformation will occur. In this case, crystal deformation can be avoided by reducing the crystal rotation speed to a constant speed or below.

[0028] According to the present invention, at a position exceeding 80 mm from the beginning of the cylindrical portion of the monocrystalline silicon, crystal deformation can be prevented by setting the crystal rotation speed of the monocrystalline silicon to 20 rpm or less.

[0029] In this invention, it is preferred that the pulling device for pulling the monocrystalline silicon is a wire pulling device, and the crystal rotation speed of the monocrystalline silicon is set to a crystal rotation speed that avoids the resonant rotation speed of the wire of the pulling device. It is particularly preferred that the crystal rotation speed of the monocrystalline silicon in the necking process is set to less than 14 rpm.

[0030] When pulling monocrystalline silicon using a wire-type pulling device, at crystal speeds of 14 rpm to 16 rpm during the necking process, wobbling can easily occur in the wire due to resonance. Therefore, a crystal speed that avoids the resonance speed of the wire is preferred.

[0031] Furthermore, even when setting the speed to over 16 rpm to avoid resonance, there is a tendency for the wire to wobble more as the speed increases. Therefore, the crystal speed of the monocrystalline silicon in the necking process is set to less than 14 rpm, thereby preventing wobble in the wire and enabling stable necking formation. Attached Figure Description

[0032] Figure 1 This is a schematic diagram illustrating the structure of the lifting device involved in the embodiments of the present invention.

[0033] Figure 2 This is a schematic diagram used to illustrate the function of the described implementation method.

[0034] Figure 3 This is a schematic diagram used to illustrate the function of the described implementation method.

[0035] Figure 4 This is a schematic diagram used to illustrate the function of the described implementation method.

[0036] Figure 5 This is a schematic diagram showing the crystal rotation speed corresponding to the position of the single-crystal silicon in the described embodiment. Detailed Implementation

[0037] [1] Structure of the single-crystal silicon pulling device 1

[0038] Figure 1 The diagram shows a schematic representation of the structure of a single-crystal silicon pulling device 1, which is capable of being used in the manufacturing method of single-crystal silicon according to the embodiments of the present invention. The pulling device 1 is a device for pulling single-crystal silicon 10 by the pulling method, and is a wire-type pulling device having a chamber 2 forming the periphery and a crucible 3 disposed in the center of the chamber 2.

[0039] The crucible 3 is a dual structure consisting of an inner quartz crucible 3A and an outer graphite crucible 3B, and is fixed to the upper end of a support shaft 4 that can rotate and move up and down.

[0040] A resistance heater 5 is provided on the outside of the crucible 3, surrounding the crucible 3, and a heat insulation material 6 is provided on the outside of the crucible 3 along the inner surface of the chamber 2.

[0041] Above the crucible 3, a wire 7 is arranged on the same or opposite axis as the support shaft 4 and rotates at a predetermined speed. A seed crystal 8 is installed at the lower end of the wire 7.

[0042] A water-cooled body 11 is arranged in the chamber 2 as a cylindrical cooling device for growing single crystal silicon 10 above the silicon melt 9 surrounding the crucible 3.

[0043] The water-cooled body 11 is made of a metal with good thermal conductivity, such as copper, and is forcibly cooled by cooling water flowing inside. The water-cooled body 11 functions to promote the cooling of the growing single-crystal silicon 10 and to control the temperature gradient along the wire 7 in the center and outer periphery of the single crystal.

[0044] Furthermore, a cylindrical heat shield plate 12 is arranged to surround the outer peripheral surface and lower end surface of the water-cooled body 11.

[0045] The heat shield plate 12 serves the following functions: it blocks the high-temperature radiant heat from the silicon melt 9 in the crucible 3, the heater 5, or the sidewall of the crucible 3 to the growing single crystal silicon 10; and it suppresses the thermal diffusion to the low-temperature water cooler 11 near the solid-liquid interface, which is the crystal growth interface, and together with the water cooler 11, it controls the temperature gradient in the pulling axis direction of the center and the outer periphery of the single crystal.

[0046] A gas inlet 13 is provided at the upper part of chamber 2 to introduce inert gases such as Ar into chamber 2. An exhaust port 14 is provided at the lower part of chamber 2 to draw in and discharge gases from chamber 2 by a vacuum pump (not shown).

[0047] The inert gas introduced into the chamber 2 from the gas inlet 13 descends between the growing monocrystalline silicon 10 and the water cooler 11. After passing through the gap (liquid surface gap) between the lower end of the heat shield plate 12 and the liquid surface of the molten silicon 9, it flows toward the outside of the heat shield plate 12, and then toward the outside of the crucible 3. It then descends on the outside of the crucible 3 and is discharged from the exhaust port 14.

[0048] When this cultivation apparatus is used to cultivate monocrystalline silicon 10, the interior of chamber 2 is maintained in a depressurized, inert gas atmosphere. The solid raw materials, such as polycrystalline silicon, filled in crucible 3 are melted by heating with heater 5, forming molten silicon 9. Once molten silicon 9 forms in crucible 3, wire 7 is lowered to immerse seed crystal 8 in the molten silicon 9. While rotating crucible 3 and wire 7 in a predetermined direction, wire 7 is slowly pulled up, thereby cultivating monocrystalline silicon 10 connected to seed crystal 8.

[0049] [2] Dislocation mechanism and avoidance scheme in monocrystalline silicon 10

[0050] In the initial stage of pulling monocrystalline silicon 10 with a straight cylinder diameter of 201mm or more and 230mm or less, such as Figure 2 As shown, the gap between the heat shield plate 12 and the shoulder of the monocrystalline silicon 10 is large. In this state, even if gases such as Ar are blown out from above, the flow rate of the gas flowing between the heat shield plate 12 and the monocrystalline silicon 10 will decrease. Therefore, impurities that are floating on the surface of the molten silicon 9 can easily approach the monocrystalline silicon 10. If the impurities adhere to the monocrystalline silicon 10, dislocations will occur in that area.

[0051] On the other hand, if the monocrystalline silicon 10 is pulled into the straight section, then as Figure 3 As shown, the gap between the heat shield plate 12 and the single crystal silicon 10 is reduced, which allows impurities floating on the surface of the silicon melt 9 to be moved away from the single crystal silicon 10 towards the inner circumferential surface of the quartz crucible 3A by the flow rate of the blown gas, thus reducing the possibility of dislocation in the single crystal silicon 10.

[0052] Regarding impurities on the surface of the silicon melt 9, it is assumed that when pulling single-crystal silicon 10 with low resistivity, red phosphorus or arsenic added as dopants evaporates during the pulling process, and impurities recrystallized on the furnace wall or other surfaces fall to the surface of the silicon melt 9 and float. The evaporation rate of red phosphorus or arsenic is positively correlated with the concentration of these dopants in the silicon melt 9; the higher the concentration, the greater the evaporation rate.

[0053] Therefore, in cases where the dopant concentration in the silicon melt 9 is very high, such as when red phosphorus is used as a dopant and the resistivity in the straight cylindrical beginning of the single crystal silicon 10 is less than 1.2 mΩcm, or when arsenic is used as a dopant and the resistivity in the straight cylindrical beginning of the single crystal silicon 10 is less than 3.0 mΩcm, the dopant evaporation becomes more intense compared to the usual low concentration case. As a result, the amount of impurities that fall onto the surface of the silicon melt 9 and float therein increases, and consequently, the possibility of dislocation in the single crystal silicon 10 becomes higher.

[0054] Therefore, in this embodiment, in Figure 2 The initial pulling stage of the single-crystal silicon 10 shown is as follows: Figure 4As shown, the crystal rotation speed of the monocrystalline silicon 10 is increased, so that forced convection eddies are generated on the surface of the silicon melt 9, thereby causing impurities floating on the surface of the silicon melt 9 to move away from the monocrystalline silicon 10 and preventing impurities from adhering to the surface of the monocrystalline silicon 10.

[0055] Specifically, such as Figure 5 As shown, in the shoulder forming process, the crystal rotation speed is set to 17 rpm or more for the section of the single-crystal silicon 10 with a diameter of 20 mm or more and 190 mm or less; for the section exceeding 80 mm from the beginning of the straight cylinder, the crystal rotation speed is set to 20 rpm or less; and the crystal rotation speed in the neck process is set to less than 14 rpm. Furthermore, as mentioned above, it is particularly preferable to set the crystal rotation speed to 17 rpm or more for the section of the single-crystal silicon 10 with a diameter of 100 mm or more and 190 mm or less.

[0056] In the lifting device 1 based on wire 7, the seed crystal chuck and the single crystal silicon 10 located on wire 7 can be regarded as oscillators of a hammer. If the acceleration due to gravity is set as g (9.8 m / s²), 2 Let L (m) be the distance from the fulcrum of the oscillator to the center of gravity. Then the resonant speed n (rpm) of the wire 7 can be obtained by the following formula (1).

[0057] n=(1 / 2π)×√(g / L)×60……(1).

[0058] If the resonance speed n is calculated in a typical lifting device 1 for a single crystal silicon 10 with a straight cylinder diameter of 210 mm, it becomes 14 rpm to 16 rpm. If the crystal speed of the single crystal silicon 10 is set to this range, resonance will occur in the single crystal silicon 10. Therefore, in the neck process, shoulder process, and straight cylinder process, the crystal speed is always set to a range that avoids the resonance speed. It should be set to at least less than 14 rpm or more than 16 rpm. In this embodiment, it is set to 13 rpm, which does not produce resonance in the early stage of lifting.

[0059] On the other hand, the reason for returning the crystal rotation speed of the monocrystalline silicon 10 to 13 rpm in the range where the diameter of the monocrystalline silicon 10 exceeds 190 mm is that, in the lifting of the straight section of the monocrystalline silicon 10, compared with the range where the diameter of the monocrystalline silicon is more than 20 mm and less than 190 mm in the shoulder forming process of the monocrystalline silicon 10, the temperature gradient of the silicon melt 9 around the crystal becomes smaller. Therefore, if the crystal rotation speed is kept too fast, crystal deformation will occur.

[0060] Therefore, in this embodiment, the crystal rotation speed in the range exceeding 190 mm is restored to 13 rpm. Furthermore, to minimize the time required to transition from 14 rpm to 16 rpm, it is preferable to vary the crystal rotation speed between 13 rpm and 17 rpm within 10 seconds.

[0061] Example

[0062] Next, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments.

[0063] [1] Case where red phosphorus is used as a dopant

[0064] First, red phosphorus was used as a dopant, and the resistivity of the beginning of the straight cylinder was set to 0.8 mΩcm. When pulling a 210 mm diameter single crystal silicon 10 wafer with a diameter of 200 mm, the pulling was performed at 7 levels as the crystal rotation speed, and the results are shown in Table 1 below.

[0065] Among the seven crystal rotation speed levels, if set to less than 17 rpm, it becomes difficult to achieve dislocation-free lifting during the shoulder formation process. It is understood that to achieve a dislocation-free success rate of over 50% in the shoulder formation process, the crystal rotation speed needs to be set to 17 rpm or higher.

[0066] In the shoulder formation process, even at a crystal rotation speed of 15 rpm (below 17 rpm), single-crystal silicon 10 can be grown in a dislocation-free state up to a crystal diameter of 100 mm. However, dislocation occurs in the region with a crystal diameter of 100 mm or more. Therefore, especially in the region with a crystal diameter of 100 mm or more, the dislocation is suppressed by setting the crystal rotation speed to 17 rpm or more.

[0067] [Table 1]

[0068]

[0069] While the shoulder can be formed without problems at a crystal rotation speed of 40 rpm, the typical critical value for the lifting device 1 is 40 rpm. Setting it to a high-speed rotation speed exceeding 40 rpm would require a more robust drive system, such as a motor, increasing equipment costs. Therefore, it is preferable to set the upper limit of the crystal rotation speed for the shoulder to 40 rpm.

[0070] The lower limit of the crystal rotation speed in the straight section is 3 rpm, and the upper limit is 20 rpm. If it is below 3 rpm, the intraplane distribution of oxygen concentration deteriorates. If it exceeds 20 rpm, crystal deformation occurs in the straight section.

[0071] In addition, the diameter of the monocrystalline silicon 10 is usually increased in the shoulder forming process, but if the diameter of the monocrystalline silicon 10 becomes 190 mm or more, it is set to be transferred to the straight section forming process.

[0072] Next, when pulling single-crystal silicon 10 using red phosphorus as a dopant, the crystal rotation speed was changed to perform the pulling process. The results are shown in Table 2. Furthermore, the dislocation-free success rate refers to the ratio of the number of single-crystal silicon 10 that can be pulled without dislocations to the total number of single-crystal silicon 10 pulled.

[0073] [Table 2]

[0074]

[0075] Comparing Example 1 and Comparative Example 1, in the single crystal silicon 10 with a resistivity of 0.8 mΩcm in the starting part of the straight cylinder, compared with Comparative Example 1 which maintains 13 rpm, the dislocation-free success rate of Example 1, which sets the crystal rotation speed from 20 mm shoulder diameter to 80 mm below the starting part of the straight cylinder, is significantly increased from 0% to 50%.

[0076] Similarly, even when comparing Example 2 and Comparative Example 2, the success rate of dislocation elimination increased from 60% to 90%, confirming the advantage of changing the crystal rotation speed to 17 rpm.

[0077] On the other hand, as in Comparative Example 3, in the example where the crystal rotation speed is set to 22 rpm, it can be formed without problems at the shoulder, but crystal deformation occurs when it enters the straight section, resulting in dislocation at a position 100 mm below the beginning of the straight section.

[0078] Furthermore, in Comparative Example 4, the crystal rotation speed was set to 17 rpm and the crystal was pulled from the neck formation stage. However, due to the oscillation of the wire 7, it was difficult to stabilize the diameter and the process could not proceed to the shoulder formation stage.

[0079] As described above, when using red phosphorus as a dopant to pull a 210 mm diameter monocrystalline silicon 10 with a resistivity of 0.8 mΩcm or more and 1.2 mΩcm or less in the starting part of a straight cylinder, if the crystal rotation speed is set to 17 rpm or more in the range where the diameter of the monocrystalline silicon 10 in the shoulder formation process is 20 mm or more and 190 mm or less, it is confirmed that the dislocation elimination success rate is improved.

[0080] [2] Cases where arsenic is used as a dopant

[0081] Furthermore, using arsenic as a dopant, similar to the case with red phosphorus, the crystal rotation speed was changed during the shoulder formation process to a range where the diameter of the single-crystal silicon 10 was between 20 mm and 190 mm. The results are shown in Table 3.

[0082] [Table 3]

[0083]

[0084] When arsenic is used as a dopant, the stability of the neck process depends on the oscillation of wire 7, and the type of dopant is independent of the oscillation of wire 7.

[0085] Regarding the dislocation in the shoulder formation process, it is believed that dislocation occurs through the same mechanism as in the case of red phosphorus. As shown in Table 3, similar to red phosphorus, an increase in the dislocation-free rate is confirmed.

[0086] The deformation in the straight section is a matter of temperature gradient and is unrelated to the type of dopant. However, the upper and lower ranges of crystal rotation speed in each process are the same as those of red phosphorus.

[0087] Similar to the case of red phosphorus, if we compare Example 3 and Comparative Example 5, where the resistivity in the beginning of the straight cylinder is also 1.8 mΩcm, it can be seen that the success rate of dislocation elimination increases from 50% to 60%.

[0088] Furthermore, even when comparing Example 4 and Comparative Example 6, where the resistivity in the beginning of the straight cylinder is also 3.0 mΩcm, it can be seen that the success rate of dislocation elimination is increased from 70% to 90%.

[0089] Thus, it was confirmed that even when arsenic is used as a dopant, the dislocation-free success rate is improved by setting the crystal rotation speed of the single-crystal silicon 10 with a diameter of 20 mm or more and 190 mm or less in the shoulder formation process to 17 rpm or more.

[0090] Explanation of reference numerals in the attached figures

[0091] 1-Lifting device, 2-Cavity, 3-Crucible, 3A-Quartz crucible, 3B-Graphite crucible, 4-Support shaft, 5-Heater, 6-Insulation material, 7-Wire, 8-Seed crystal, 9-Silicon melt, 10-Single crystal silicon, 11-Water cooler, 12-Heat shielding plate, 13-Gas inlet, 14-Exhaust port.

Claims

1. A method for manufacturing monocrystalline silicon, comprising growing monocrystalline silicon by pulling it from a silicon melt containing red phosphorus as a dopant using a Czochralski method, while simultaneously allowing gas to descend between the monocrystalline silicon and a heat shield plate, characterized in that... The pulling device for the monocrystalline silicon is a wire pulling device. The single-crystal silicon is a wafer with a diameter of 200 mm, and the diameter of the straight cylinder is 201 mm or more and 230 mm or less. The resistivity of the beginning portion of the straight cylinder is 0.8 mΩcm or more and 1.2 mΩcm or less. In the shoulder formation process, the crystal rotation speed of the single-crystal silicon in the section with a diameter of 20 mm or more is controlled to be 17 rpm or more and 40 rpm or less. This generates eddies on the surface of the molten silicon away from the single-crystal silicon. The eddies drive away impurities floating on the surface of the molten silicon. These impurities are those that have settled on the surface of the molten silicon due to the evaporation and recrystallization of red phosphorus during the pulling process of the single-crystal silicon. The crystal rotation speed of the monocrystalline silicon in the necking process is set to 13 rpm or less. At a position exceeding 80 mm from the beginning of the monocrystalline silicon cylinder, the crystal rotation speed is controlled to be between 3 rpm and 13 rpm. The crystal rotation speed is set to avoid the resonant rotation speed of the wire in the pulling device. When the crystal rotation speed of the monocrystalline silicon is increased, and when the crystal rotation speed is reduced back, the speed changes between 13 rpm and 17 rpm within 10 seconds.

2. A method for manufacturing monocrystalline silicon, comprising growing monocrystalline silicon by pulling it from a silicon melt containing arsenic as a dopant using a Czochralski method, while simultaneously allowing gas to descend between the monocrystalline silicon and a heat shield plate, characterized in that... The pulling device for the monocrystalline silicon is a wire pulling device. The single-crystal silicon is a wafer with a diameter of 200 mm, and the diameter of the cylindrical section is 201 mm or more and 230 mm or less. The resistivity of the beginning portion of the cylindrical section is 1.8 mΩcm or more and 3.0 mΩcm or less. During the shoulder formation process, the crystal rotation speed of the single-crystal silicon in the section with a diameter of 20 mm or more is controlled to 17 rpm or more and 40 rpm or less. This generates eddies on the surface of the molten silicon in a direction away from the single-crystal silicon. These eddies drive away impurities floating on the surface of the molten silicon. These impurities are arsenic that has evaporated and recrystallized during the pulling process of the single-crystal silicon and settled onto the surface of the molten silicon. The crystal rotation speed of the monocrystalline silicon in the necking process is set to 13 rpm or less. At a position exceeding 80 mm from the beginning of the monocrystalline silicon cylinder, the crystal rotation speed is controlled to be between 3 rpm and 13 rpm. The crystal rotation speed is set to avoid the resonant rotation speed of the wire in the pulling device. When the crystal rotation speed of the monocrystalline silicon is increased, and when the crystal rotation speed is reduced back, the speed changes between 13 rpm and 17 rpm within 10 seconds.

Images