JP6318938B2 - Single crystal manufacturing method and manufacturing apparatus - Google Patents

Description

  The present invention relates to a manufacturing method and a manufacturing apparatus for a single crystal, and more particularly to a single crystal drawing control in a floating zone melting method (floating zone method, FZ method).

  The FZ method is known as one of methods for growing a single crystal such as silicon. In the FZ method, a part of a polycrystalline raw material rod is heated to form a melting zone, and the raw material rod and the single crystal located above and below the melting zone are slowly pulled down to gradually grow the single crystal. . In particular, in the initial stage of single crystal growth, after melting the tip of the raw material rod and fusing this melted part to the seed crystal, the single crystal is grown to a certain length while narrowing the diameter for no dislocation. A squeezing step is performed. Thereafter, the diameter of the single crystal is gradually expanded to form a cone portion, and the single crystal is further grown while the diameter is kept constant to form a straight body portion.

  The single crystal squeezing process is often performed manually by skilled workers. Workers rely on their experience and intuition, but because the diameter of the diaphragm is directly observed visually, the judgment of the appropriate state and the amount of operation differ among workers, and even the same worker can make judgments for each batch. Different. Therefore, the squeezing process cannot be performed stably in every batch, and the occurrence frequency of the dislocation of the single crystal after shifting to the growing process of the corn part cannot be reduced.

  In order to improve such a situation, in Patent Document 1, by monitoring the melting zone using four television cameras, it is possible to accurately detect the zone length of the melting zone and to automate the drawing process. A method has been proposed. In this method, the zone length of the melting zone is controlled by manipulating the power supplied to the induction heating coil, and the drawn diameter (crystallization diameter) is controlled by manipulating the descending speed of the raw material rod (elution side material rod). Is done.

Japanese Patent No. 4016363

  However, in the conventional method, the amount of melt is adjusted by manipulating the descending speed of the raw material rod, and the diameter of the restrictor is controlled by adjusting the amount of melt. There is a problem that the control responsiveness is not good. In the conventional method, the zone length of the melting zone is controlled to stabilize the in-plane resistance distribution of the single crystal wafer, but stabilization of the in-plane resistance distribution is not important in the drawing process. Rather, the suppression of single crystal dislocations important in the drawing process is not sufficient, and further improvements are desired.

  Accordingly, an object of the present invention is to provide a method for producing a single crystal that can automate the drawing process and reduce the frequency of occurrence of dislocations of the single crystal after the transition to the cone growing process.

 In order to solve the above problems, a method for producing a single crystal according to the present invention comprises a raw material feed mechanism for lowering a raw material rod, and a single crystal grown using a molten raw material disposed coaxially with the raw material feed mechanism. A method for producing a single crystal by a floating zone melting method using a single crystal production apparatus comprising a crystal feeding mechanism for lowering and an induction heating coil for heating and melting a lower end portion of the raw material rod, the raw material rod After the tip of the substrate is heated and melted, a fusion process for fusing to the seed crystal attached to the crystal feed mechanism, a drawing process for reducing the diameter of the single crystal so as to eliminate dislocations, and expanding the diameter A cone portion forming step for growing the single crystal while the straight crystal portion forming step for growing the single crystal while keeping the diameter constant, and the drawing step includes a high frequency to be supplied to the induction heating coil. Electric A throttle diameter control step of controlling the throttle diameter of the single crystal by PID, and a throttle position control step of controlling the single crystal drop speed to PID control the throttle position of the single crystal. And

  Further, the single crystal manufacturing apparatus according to the present invention includes a raw material feed mechanism for lowering a raw material rod, a crystal feed mechanism for lowering a single crystal grown using a raw material disposed coaxially with the raw material rod, and An induction heating coil for heating and melting the lower end portion of the raw material rod, a CCD camera for photographing a melting zone between the raw material rod and the single crystal, and image processing for processing image data photographed by the CCD camera And a control unit that controls a high-frequency current to the raw material feeding mechanism, the crystal feeding mechanism, and the induction heating coil based on the image data, and the control unit is a single crystal so as to be dislocation-free. In the drawing step for reducing the diameter of the single crystal, a high-frequency current supplied to the induction heating coil is manipulated to perform PID control on the drawing diameter of the single crystal, and in the drawing step, Te, characterized in that it comprises a stop position control unit that PID controls the aperture position by operating the lowering speed of the single crystal of the single crystal.

  According to the present invention, the high-frequency current supplied to the induction heating coil is operated to control the drawing diameter to an appropriate diameter, and the single crystal descent speed is manipulated to make the drawing position of the single crystal appropriate. By controlling to be in the position, the dislocation of the single crystal can be reliably performed in the drawing step, and the frequency of dislocation of the single crystal that occurs after the transition to the cone growing step can be reduced.

 In the present invention, in the initial stage of the drawing step in which the single crystal grows to a predetermined length, the gain of each operation item for PID control of the drawing diameter and the drawing position is relatively reduced, After the initial stage, it is preferable that each gain of each operation item for performing PID control of the aperture diameter and the aperture position is made larger than that in the initial stage. According to this, it is possible to reduce the control amount of the aperture diameter and aperture position in the initial stage, and it is possible to prevent a situation where the aperture diameter becomes excessively small or the aperture position changes excessively. Further, the control amount of the diaphragm diameter and the diaphragm position can be increased after the initial stage, and the diaphragm diameter and the diaphragm position can be maintained at appropriate values.

 In the present invention, the predetermined length is preferably at least 10 mm. If excessive changes in the diaphragm diameter and the diaphragm position are suppressed in the range from the diaphragm start position to at least 10 mm, it is possible to sufficiently suppress the occurrence of problems at the start of the diaphragm.

  ADVANTAGE OF THE INVENTION According to this invention, the drawing process can be automated and the manufacturing method of the single crystal which can reduce the frequency with which dislocation-izing of a single crystal generate | occur | produces after transfer to a cone part growth process can be provided.

FIG. 1 is a schematic diagram showing a configuration of a single crystal manufacturing apparatus 10 by FZ method according to a preferred embodiment of the present invention. FIG. 2 is a flowchart schematically showing a manufacturing process of a single crystal by the FZ method. FIG. 3 is a schematic side view showing the shape of a single crystal ingot manufactured by the single crystal manufacturing apparatus 10. FIG. 4 is a schematic side view showing a state in which the raw material rod 1 and the seed crystal 2 before the single crystal is grown are set in the raw material feeding mechanism 12 and the crystal feeding mechanism 14, respectively. FIG. 5 is a control block diagram of the drawing process. FIG. 6 is a schematic diagram for explaining the control of the aperture diameter. FIG. 7 is a flowchart showing steps for setting each gain of PID control. FIG. 8 is a graph showing the control result of the drawing process, where (a) shows the result of automatic control for three samples, and (b) shows the result of manual control for two samples. Show.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing a configuration of a single crystal manufacturing apparatus 10 by FZ method according to a preferred embodiment of the present invention.

  As shown in FIG. 1, the single crystal production apparatus 10 includes a raw material feed mechanism 12 that moves the raw material rod 1 attached to the lower end of the upper shaft 11 while rotating it, and a seed crystal 2 attached to the upper end of the lower shaft 13. A crystal feed mechanism 14 for lowering the single crystal 3 crystallized at the top of the wire, an induction heating coil 15 (work coil) for heating the raw material rod 1, and an oscillator 16 connected to the induction heating coil 15; The CCD camera 17 that captures the melting zone between the raw material rod 1 and the single crystal 3, the image processing unit 18 that processes the image data captured by the CCD camera 17, the raw material feed mechanism 12, the crystal And a control unit 19 that controls the feed mechanism 14 and the induction heating coil 15.

  The raw material feed mechanism 12 includes a feed control unit 12 a that controls the descending speed Vp of the raw material rod 1 and a rotation control unit 12 b that controls the rotational speed Rp of the raw material rod 1. The crystal feed mechanism 14 includes a feed control unit 14 a that controls the descent speed Vs of the single crystal 3 and a rotation control unit 14 b that controls the rotation speed Rs of the single crystal 3. The control unit 19 includes an aperture diameter calculation unit 19a that calculates the aperture diameter from the image data, and an aperture position calculation unit 19b that calculates the aperture position from the image data.

  The induction heating coil 15 is a loop conductor surrounding the periphery of the raw material rod 1, and the oscillator 16 supplies a high frequency current to the induction heating coil 15. In the present embodiment, a plurality of CCD cameras 17 may be provided. When the multi-camera system is employed, it is possible to more accurately measure the diameter of the single crystal, the position of the diaphragm, and the zone length of the melting zone.

  FIG. 2 is a flowchart schematically showing a manufacturing process of a single crystal by the FZ method.

  As shown in FIG. 2, in the growth of a single crystal by the FZ method, a fusion step S1 in which the tip portion of the raw material rod 1 is melted and fused to the seed crystal 2, and a drawing step in which the single crystal is narrowed down to eliminate dislocations. S2, a cone part growing step S3 for gradually increasing the diameter of the single crystal to a target diameter to grow a cone part, a straight body part growing step S4 for growing the straight body part while maintaining the diameter of the single crystal constant, A bottom portion growing step S5 for growing a bottom portion with a reduced diameter of the single crystal, and a cooling step S6 for cooling after finishing the growth of the single crystal are performed.

  FIG. 3 is a schematic side view showing the shape of a single crystal ingot manufactured by the single crystal manufacturing apparatus 10.

  As shown in FIG. 3, the single crystal ingot 3 has a narrowed portion 3a whose diameter is narrowed to eliminate dislocation, a cone portion 3b whose diameter gradually increases from the upper end of the narrowed portion 3a, and a constant diameter. It has a straight body portion 3c and a bottom portion 3d whose diameter is reduced. In the FZ method, the single crystal ingot 3 is grown in the order of the narrowed portion 3a, the cone portion 3b, the straight body portion 3c, and the bottom portion 3d, and the straight body portion 3c is a portion that is actually provided as a product. In addition, the single crystal 3 of FIG. 1 is the state by which the straight body part 3c was grown to the middle. The length of the single crystal ingot 3 depends on the amount of the raw material rod 1.

  FIG. 4 is a schematic side view showing the raw material rod 1 and the seed crystal 2 before starting the growth of the single crystal, which are set in the raw material feeding mechanism 12 and the crystal feeding mechanism 14, respectively.

  As shown in FIG. 4, the raw material rod 1 has a cone part 1b whose diameter gradually increases from the tip part 1a and a straight body part 1c having a constant diameter. For example, in the case of silicon single crystal, the raw material rod 1 is purified from high-purity polycrystalline silicon using monosilane or the like as a raw material. The seed crystal 2 is made of a columnar or prismatic single crystal having a predetermined crystal orientation.

  In the fusing process, the raw material rod 1 attached to the lower end of the upper shaft 11 is lowered and placed inside the induction heating coil 15, the tip portion 1 a of the raw material rod 1 is heated to a molten state, and the lower shaft 13 The melt portion is fused to the seed crystal 2 attached to the upper end. Thereafter, the seed crystal 2 is slowly lowered and moved away from the induction heating coil 15, whereby a single crystal is crystallized at the solid-liquid interface between the seed crystal 2 and the melt, and the single crystal grows gradually. Further, by appropriately controlling the descending speed of the raw material rod 1 and the descending speed of the single crystal 3, the throttle part 3a, the cone part 3b, the straight body part 3c and the bottom part 3d are formed, and the single crystal shown in FIG. Ingot 3 is completed.

  In the squeezing process, the upper shaft 11 and the lower shaft 13 are each lowered at a desired speed while rotating in a certain direction at a constant rotational speed, and a single crystal whose diameter is narrowed to about several millimeters is reduced to a predetermined length ( For example, about 60 mm). By reducing the diameter of the single crystal before starting the growth of the cone part 3b, the dislocation of the single crystal can be eliminated.

  FIG. 5 is a control block diagram of the drawing process.

  As shown in FIG. 5, in the drawing step, the drawing diameter D and the drawing position H of the single crystal 3 are PID controlled. The “squeezed diameter” is the diameter near the solid-liquid interface between the single crystal 3 and the melting zone 4, and the “squeezed position” is the vertical position near the solid-liquid interface. In particular, the throttle position H is determined as a relative position with respect to the induction heating coil 15 or other fixing member.

  The aperture diameter D and the aperture position H can be obtained from the image data of the CCD camera 17. The image data photographed by the CCD camera 17 is processed by the image processing unit 18 and then supplied to the aperture diameter calculating unit 19a and the aperture position calculating unit 19b, and the aperture diameter D and the aperture position H are calculated respectively. In the drawing step, the raw material feed speed, the raw material rotation speed, and the crystal rotation speed are set to predetermined values in advance, and feedback control is not performed.

  The aperture diameter Do calculated by the aperture diameter calculating unit 19a is subjected to a moving average process in the moving average processing unit 20, and the moving average value Dma of the aperture diameter is compared with the aperture diameter profile (target diameter) Dp by the subtractor 21 to obtain PID. It is supplied to the correction unit 22. The aperture diameter profile Dp is provided from the aperture diameter profile recording unit 25. The PID correction unit 22 determines the correction amount of the diaphragm diameter based on a preset proportional gain, integral gain, and differential gain.

  The correction amount of the aperture diameter is converted into a voltage value ΔE by the converter 23, added to the oscillation voltage profile Ep by the adder 24, and then supplied to the oscillator 16. The oscillation voltage profile Ep is provided from the oscillation voltage profile recording unit 26. The oscillator 16 generates a high-frequency current I proportional to the input voltage, and the high-frequency current I is supplied to the induction heating coil 15. For example, when the measured aperture diameter Do is larger than the target diameter Dp, the high-frequency current I is increased so that the aperture diameter D becomes smaller, and conversely, the measured aperture diameter Do is smaller than the target diameter Dp. First, the high-frequency current I is reduced so that the aperture diameter D is reduced.

  FIG. 6 is a schematic diagram for explaining the control of the aperture diameter.

As shown in FIG. 6, the magnetic flux φ generated by the high-frequency current I flowing through the induction heating coil 15 penetrates the melting zone 4, and an eddy current _IE is generated in the melting zone 4 by this magnetic flux φ. The melt in which the eddy current _IE is generated receives the Lorentz force F, and the direction of the Lorentz force F is the direction toward the center O in the plane direction of the melting zone 4. Even if the direction of the high-frequency current I is reversed, the direction of the Lorentz force F is always toward the center O. Therefore, the melting zone 4 receives a force in the direction of reducing the diameter toward the center O. The Lorentz force F increases as the high-frequency current I increases, and the Lorentz force F decreases as the high-frequency current I decreases. Therefore, the aperture diameter can be controlled by manipulating the output of the oscillator 16.

  In the conventional method of controlling the throttle diameter by manipulating the descending speed of the raw material rod, the control responsiveness is not good because the throttle diameter is indirectly controlled by controlling the amount of melt. However, in this embodiment, since the diameter of the throttle is controlled by operating the current supplied to the induction heating coil 15, the diameter of the throttle can be directly controlled, and the control response of the throttle diameter is improved. Can do.

  The aperture position Ho calculated by the aperture position calculation unit 19b is subjected to a moving average process in the moving average processing unit 30, and the moving average value Hma of the aperture position is compared with the aperture position profile (target position) Hp by the subtractor 31 to obtain the PID. It is supplied to the correction unit 32. The aperture position profile Hp is provided from the aperture position profile recording unit 35. The PID correction unit 32 determines the aperture position correction amount based on a preset proportional gain, integral gain, and differential gain. Further, if necessary, the correction amount of the diaphragm diameter is added to the correction amount of the diaphragm position by the adder 38, and the influence of the control of the diaphragm diameter D (operation of the high frequency current I) on the control of the diaphragm position H is corrected. .

  The correction amount of the aperture position is converted into a descending speed ΔVs by the conversion unit 33, added to the descending speed profile Vsp by the adder 34, and then supplied to the drive circuit 28. The descending speed Vs is adjusted. The descending speed profile Vsp is provided from the descending speed profile recording unit 36. For example, when the measured aperture position Ho is higher than the target position Hp, the descent speed Vs of the single crystal is increased so that the aperture position H moves downward from the current position. When the aperture position Ho is lower than the target position Hp, the descent speed Vs of the single crystal is decreased so that the aperture position H moves upward from the current position.

  When the squeezing position H is not appropriate in the squeezing step, even if the zone length L is an appropriate length, the frequency of occurrence of dislocations in the single crystal cannot be reduced. However, in the present embodiment, since the throttle position H is controlled to be an appropriate position in the throttle process, the frequency of occurrence of dislocation can be reduced.

  Each gain of the PID control of the aperture diameter D and the aperture position H is adjusted according to the length of the single crystal from the start position of the aperture process. The gain setting unit 27 sets and switches each gain of the PID control of the aperture diameter, and the gain setting unit 37 sets and switches each gain of the PID control of the aperture position.

  FIG. 7 is a flowchart showing steps for setting each gain of PID control.

  As shown in FIG. 7, at the initial stage of the drawing process until the single crystal grows to a predetermined length (for example, 10 mm), each gain of PID control with respect to the drawing diameter D and the drawing position H is relatively reduced. The control amount is decreased (step S7, step S8N). By doing in this way, generation | occurrence | production of the dislocation by the division | segmentation of the melting zone by the excessive change of the aperture diameter D and the excessive change of the aperture position H can be suppressed.

  In addition, after the initial stage (for example, 10 to 60 mm), each gain of PID control for the diaphragm diameter D and the diaphragm position H is made relatively larger than that in the initial stage to increase the control amount (steps S8Y and S9). ). By doing in this way, the aperture diameter D and the aperture position H can be maintained at appropriate values, and the aperture process can be stabilized.

  As described above, in the method for manufacturing a single crystal according to the present embodiment, in the automatic control of the drawing process, the control target is the drawing diameter D and the drawing position H, and the operation items for PID control of the drawing diameter D are induction heating. Since the high frequency current I supplied to the coil 15 and the operation item for PID control of the diaphragm position H are the single crystal descending speed Vs, the diaphragm diameter D and the diaphragm position H can be controlled directly and stably. . Therefore, it is possible to reduce the frequency of occurrence of dislocations of the single crystal after the transition to the corn part growing process.

  In addition, the method for producing a single crystal according to the present embodiment is stable over the entire section of the drawing process because the gains of PID control of the drawing diameter D and the drawing position H are changed between the initial stage of the drawing process and the subsequent stages. Control is possible.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

  For example, in the above-described embodiment, silicon is used as the single crystal. However, the present invention is not limited to silicon, and may be germanium, gallium arsenide, gallium phosphide, indium phosphide, or other materials.

  The single crystal manufacturing apparatus shown in FIG. 1 was used, and the silicon single crystal drawing step was performed by automatic control according to the control block shown in FIG. In the automatic control of the aperture process, the aperture diameter and aperture position are calculated from the image data captured by the CCD camera, and the aperture diameter is PID controlled by operating the high-frequency current based on this result, and the crystal feed rate is also controlled. The aperture position was PID controlled. The above-described drawing process was performed three times to obtain three single crystal samples.

  On the other hand, as a comparative example, the silicon single crystal drawing step was performed by manual control. In manual control of the drawing process, an operator controls the drawing diameter and drawing position by manipulating the oscillator output (high-frequency current) and the crystal feed rate while directly observing the drawing diameter and drawing position of the single crystal in the chamber. did. The narrowing process by manual control was performed under the same conditions as in the example except that manual control was performed. The above-described drawing process was performed twice to obtain two single crystal samples.

  FIGS. 8A and 8B are graphs showing the control results of the drawing process. In particular, FIG. 8A shows the result of automatic control performed on three samples, and FIG. 8B shows two samples. The results of manual control for each are shown. In the graph, the horizontal axis indicates the length of the single crystal (diaphragm portion), the left vertical axis indicates the aperture diameter (relative value), and the right vertical axis indicates the aperture position (relative value). Further, a group of graphs drawn in the upper part of the graph frames in FIGS. 8A and 8B show changes in the aperture position, and a group of graphs drawn in the lower side show changes in the aperture diameter. Yes.

  As shown in FIG. 8 (a), when the squeezing process was automatically controlled by the method of the present invention, the squeezing positions of the two samples changed stably without hunting as time passed. Similarly, the diameter of the diaphragm also changed stably over time without hunting within a range of ± 0.25 mm.

  On the other hand, as shown in FIG. 8B, when the diaphragm process is manually controlled, the diaphragm position of one of the two samples is greatly hunted with time, and the diaphragm position of the other sample is the diaphragm. Hunting occurred in the second half of the part, and the control of the aperture position became unstable in all cases. Similarly, hunting was performed in the range of ± 0.5 mm for the aperture diameter, and the control of the aperture diameter became unstable.

  From the above results, the drawing process is performed by performing PID control on the single crystal drawing diameter using the high frequency current supplied to the induction heating coil as the operation item, and controlling the single crystal drawing position using the single crystal descending speed as the operation item. It was confirmed that can be automated. In addition, it was confirmed that when the automatic control of the drawing process is performed, variations in the drawing position and the drawing diameter can be suppressed as compared with the manual control.

DESCRIPTION OF SYMBOLS 1 Raw material rod 1a Raw material rod tip 1b Raw material rod cone 1c Raw material rod straight body 2 Seed crystal 3 Single crystal ingot 3a Single crystal constriction 3b Single crystal cone 3c Single crystal straight body 3d Single Crystal bottom part 4 Melting zone 10 Single crystal production apparatus 11 Upper shaft 12 Raw material feed mechanism 12a Feed control unit 12b Rotation control unit 13 Lower shaft 14 Crystal feed mechanism 14a Feed control unit 14b Rotation control unit 15 Induction heating coil 16 Oscillator 17 CCD Camera 18 Image processing unit 19 Control unit 19a Diameter calculation unit 19b Position calculation unit 20 Moving average processing unit 21 Subtractor 22 Correction unit 23 Conversion unit 24 Adder 25 Aperture diameter profile recording unit 26 Oscillation voltage profile recording unit 27 Gain setting unit 28 Drive circuit 29 Elevating variable speed motor 30 Moving average processing unit 31 Subtractor 32 Correction unit 33 Conversion unit 4 adder 35 stop position profile recording unit 36 lowering speed profile recording unit 37 gain setting unit 38 adder

Claims (6)

A material feed mechanism that lowers the material rod;
A crystal feed mechanism for lowering a single crystal grown using a raw material disposed coaxially with the raw material feed mechanism; and
A method for producing a single crystal by a floating zone melting method using a single crystal production apparatus comprising an induction heating coil for heating and melting the lower end of the raw material rod,
A fusion process of fusing the seed rod attached to the crystal feed mechanism after heating and melting the tip of the raw material rod;
A drawing step of reducing the diameter of the single crystal so as to be dislocation-free;
A cone forming step of growing the single crystal while expanding the diameter;
A straight body forming step of growing the single crystal while keeping the diameter constant,
In the drawing step, a drawing diameter control for controlling the drawing diameter of the single crystal by PID control by operating a high-frequency current supplied to the induction heating coil, and a drawing position of the single crystal by operating a descent speed of the single crystal. A method for producing a single crystal comprising: aperture position control for PID control. In the initial stage of the drawing process in which the single crystal grows to a predetermined length, the gain of each operation item for PID control of the drawing diameter and the drawing position is relatively reduced,
2. The method for producing a single crystal according to claim 1, wherein after the initial stage, each gain of each operation item for performing PID control of the aperture diameter and the aperture position is made larger than in the initial stage.   The method for producing a single crystal according to claim 2, wherein the predetermined length is at least 10 mm. The aperture diameter control is
Manipulating the high frequency current by manipulating an oscillation voltage of an oscillator that supplies the high frequency current to the induction heating coil based on an oscillation voltage profile;
4. The method for producing a single crystal according to claim 1, wherein the oscillation voltage profile is corrected based on a difference between a measured value of the aperture diameter and a target value. 5. The aperture position control is
Manipulating the descent rate of the single crystal based on the crystal feed rate profile,
5. The method for producing a single crystal according to claim 1, wherein the crystal feed speed profile is corrected based on a difference between a measured value of the aperture position and a target value. 6. An apparatus for producing a single crystal by a floating zone melting method,
A material feed mechanism that lowers the material rod;
A crystal feed mechanism for lowering a single crystal grown using a raw material disposed coaxially with the raw material rod;
An induction heating coil for heating and melting the lower end of the raw material rod;
A CCD camera for photographing a melting zone between the raw material rod and the single crystal;
An image processing unit for processing image data captured by the CCD camera;
A control unit for controlling the high-frequency current to the raw material feeding mechanism, the crystal feeding mechanism and the induction heating coil based on the image data;
In the drawing step of reducing the diameter of the single crystal so as to be dislocation-free, the control unit operates a high-frequency current supplied to the induction heating coil to perform PID control of the drawn diameter of the single crystal; ,
In the drawing step, a single crystal manufacturing apparatus comprising: a drawing position control unit that operates the descent speed of the single crystal to perform PID control of the drawing position of the single crystal.