Single crystal manufacturing equipment

Abstract

To provide a single crystal manufacturing apparatus including a dopant supply device capable of responding even to the movement of a heat shield member in a vertical direction without breaking or falling a component.SOLUTION: A single crystal manufacturing apparatus 1 includes a crucible 12 installed in a chamber 10 and a dopant supply device 20 for supplying a dopant to the crucible 12 from the outside of the chamber 10. The dopant supply device 20 includes a dopant supply pipe 21; the dopant supply pipe 21 includes a first dope pipe 24 penetrating the chamber 10 and independently separated from a heat shield member 16 and a second dope pipe 25 independently separated from the chamber 10 and the first dope pipe 24 and arranged right under the first dope pipe 24; and the second dope pipe 25 includes a large diameter part having an opening diameter larger than an inner diameter of a lower end of the first dope pipe 24, a small diameter part having an opening diameter smaller than that of the large diameter part and a taper part connecting the large diameter part and the small diameter part and does not contact the lower end part of the first dope pipe 24.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a single crystal manufacturing apparatus, and more particularly to a dopant supply device used for supplying a dopant before or during the pulling process of a single crystal by the Czochralski method (CZ method).

Background Art

[0002] Most of the silicon single crystals used as substrate materials for semiconductor devices are manufactured by the CZ method. The CZ method involves immersing a seed crystal in a silicon melt contained in a quartz crucible and gradually pulling up the seed crystal while rotating the seed crystal and the quartz crucible, thereby growing a single crystal with a large diameter below the seed crystal. According to the CZ method, it is possible to manufacture high-quality silicon single crystal ingots with a high yield.

[0003] Various dopants are used to adjust the electrical resistivity of silicon single crystals (hereinafter simply referred to as resistivity). Representative dopants include phosphorus (P), arsenic (As), antimony (Sb), boron (B), etc. These dopants are, for example, put into the quartz crucible together with polycrystalline silicon raw materials and melted together with the silicon raw materials by heating with a heater. Thereby, a silicon melt containing a predetermined amount of dopant is generated.

[0004] The dopant may be introduced into the silicon melt during the crystal pulling process. For example, antimony has a lower melting point than phosphorus or boron and a very high evaporation rate under reduced pressure. Therefore, if it is melted together with polycrystalline silicon raw materials like phosphorus or boron, a large amount of dopant will evaporate from the raw material melting to the beginning of the crystal pulling process, and the dopant concentration in the silicon melt cannot be increased. Therefore, the dopant is additionally supplied during the crystal pulling process to suppress the decrease in the dopant concentration in the silicon melt.

[0005] Furthermore, even when using dopants with a relatively slow evaporation rate, the supplied dopant can segregate along the pulling direction of the single crystal, making it difficult to obtain a uniform resistivity in the pulling direction. To resolve this problem, it is effective to supply dopants not only during the initial charging of the polycrystalline silicon raw material but also during the crystal pulling process. For example, by supplying additional dopants of the same conductivity type as the initially charged dopant, it is possible to pull two types of silicon single crystals with significantly different resistivity. Also, by supplying additional dopants of the opposite conductivity type to the initially charged dopant, the crystal length of a single crystal with a uniform resistivity in the pulling direction can be made as long as possible.

[0006] Regarding a method for supplying dopants immediately before or during the pulling of single crystals, for example, Patent Document 1 describes a doping device comprising a dope supply pipe that penetrates the top of a chamber and reaches above the crucible inside the chamber, a sealing cap that seals the portion of the dope supply pipe that penetrates the chamber, a dope hopper attached to the dope supply pipe outside the chamber via a dope supply cock, and a connecting pipe that connects the dope hopper to the inside of the chamber. When supplying dopants, the inside of the chamber is under reduced pressure and in an argon gas atmosphere, but with this doping device, it is possible to adjust the atmosphere inside the doping device to be the same as the atmosphere inside the chamber.

[0007] Furthermore, Patent Document 2 describes a structure in which, in order to ensure that dopants can be supplied to the molten raw material inside the crucible without any problems even when a heat shielding member is positioned above the crucible, a dope supply pipe, which is positioned inside the heat shielding member above the heat shielding member, is led out to the outside of the heat shielding member from a certain point, and at least the lower end of the dope supply pipe faces the outside of the heat shielding member. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 9-227275 [Patent Document 2] Japanese Patent Application Publication No. 11-343196 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, conventional dopant supply devices have a structure in which a single dopant supply tube is fixed to the chamber or thermal shielding member, which often resulted in component breakage or detachment. Furthermore, conventional dopant supply devices were either unable to accommodate a structure in which the thermal shielding member could move vertically, or the movement of the thermal shielding member was restricted.

[0010] Therefore, the object of the present invention is to provide a single crystal manufacturing apparatus equipped with a dopant supply device that prevents breakage or detachment of parts and can accommodate vertical movement of the heat shielding member. [Means for solving the problem]

[0011] To solve the above problems, the single crystal manufacturing apparatus according to the present invention comprises a chamber, a crucible installed in the chamber, a heat shielding member disposed above the crucible, and a dopant supply device that supplies dopants into the crucible from outside the chamber, wherein the dopant supply device includes a dopant supply pipe that penetrates the chamber and reaches above the crucible, and the dopant supply pipe has a first dope pipe that penetrates the chamber and a second dope pipe that is separated and independent from the first dope pipe and disposed directly below the lower end of the first dope pipe, wherein the first dope pipe is separated and independent from the heat shielding member, and the second dope pipe is separated and independent from the chamber and installed on the heat shielding member.

[0012] According to the present invention, it is possible to provide a single crystal manufacturing apparatus that allows for easy installation of the dopant supply pipe, prevents breakage or detachment of parts, and can accommodate vertical movement of the heat shielding member.

[0013] In the present invention, the first dope tube and the second dope tube may be completely separated from each other, and a part of the first dope tube may be inserted into the interior of the second dope tube. Furthermore, when the first dope tube and the second dope tube are completely separated from each other, it is preferable to position the upper opening of the second dope tube directly below the lower end of the first dope tube. By making the first dope tube and the second dope tube a structure that separates and is independent of each other, the first dope tube can be separated and independent from the heat shielding member, and the second dope tube can be separated and independent from the chamber (particularly the top chamber).

[0014] In the present invention, it is preferable that the second doped tube is installed so as to be vertically movable relative to the heat shielding member. With this configuration, the second doped tube is easy to install, there is no risk of breakage or detachment of parts, and it can accommodate vertical movement of the heat shielding member.

[0015] In the present invention, it is preferable that the second dope tube has a large-diameter portion having an opening diameter larger than the inner diameter of the lower end of the first dope tube, a small-diameter portion having an opening diameter smaller than the large-diameter portion, and a tapered portion connecting the large-diameter portion and the small-diameter portion. In this case, the large-diameter portion is positioned above the small-diameter portion, i.e., on the side of the first dope tube. With this configuration, the transfer of dopant from the first dope tube to the second dope tube can be reliably performed, and the installation of the second dope tube to the heat shielding member is also easy.

[0016] In the present invention, the taper angle (acute angle) of the outer surface of the tapered portion with respect to the vertical axis is preferably less than or equal to the inclination angle of the inner wall surface of the heat shielding member facing the tapered portion with respect to the vertical axis, and is particularly preferably approximately equal to the inclination angle of the inner wall surface of the heat shielding member. This allows the second doped pipe to be supported in a state of point contact or line contact with the heat shielding member, thereby suppressing damage or deformation of the second doped pipe.

[0017] In the present invention, it is preferable that the axis of the second doped tube extends in a straight line from the upper end to the lower end of the second doped tube. This allows for the use of a second doped tube that is easy to manufacture and inexpensive.

[0018] In the present invention, it is preferable that the dopant supply tube is made of quartz. For example, if a carbon dopant supply tube is used, the carbon concentration in the silicon single crystal may increase due to carbon contamination of the dopant. However, if the dopant supply tube is made of quartz, contamination of the dopant with impurities can be prevented. Quartz tubes are prone to cracking at room temperature and may deform at high temperatures. However, if the second dope tube is simply inserted into a through-hole in the heat shielding member, damage or deformation of the dopant supply tube can be prevented.

[0019] In the present invention, it is preferable that the heat shielding member is configured to be able to move up and down within the chamber, and that the relative positional relationship between the first dope tube and the second dope tube changes in accordance with the movement of the heat shielding member. This allows the overall length of the dopant supply tube to be adjusted in accordance with the vertical movement of the heat shielding member, and the vertical movement of the heat shielding member is not restricted by the dopant supply tube. Furthermore, if the heat shielding member is able to move up and down, even if a pile of solid raw materials is filled into the crucible, interference between the heat shielding member and the solid raw materials can be avoided by moving the heat shielding member upward, and the initial charge amount of molten material can be increased.

[0020] In the present invention, the chamber has a main chamber in which the crucible is installed and a top chamber that covers the upper opening of the main chamber. The top chamber is configured to be detachable from the main chamber, and preferably, the relative positional relationship between the first dope tube and the second dope tube changes according to the attachment and detachment of the top chamber. In this case, since the first dope tube is fixed to the top chamber side and the second dope tube is attached to the heat shielding member in the main chamber, it is easy to attach the top chamber to the main chamber or remove it from the main chamber.

[0021] In the present invention, the second dope tube is inserted into a through hole formed in the heat shielding member, and the lower end of the second dope tube terminates inside the lower opening end of the through hole without being exposed, and preferably, the lower end of the second dope tube is covered with a carbon ring cap. Since the second dope tube is only inserted into the through hole of the heat shielding member, its installation is easy. Further, since the lower end of the second dope tube is covered with the ring cap without being exposed, the lower end of the second dope tube can be protected from heat, and heat deformation and the like can be prevented.

[0022] In the present invention, it is preferable that the outer opening of the ring cap is obliquely downward and faces the side wall portion side of the crucible. Thereby, even when the second dope tube has a shape extending straight downward, the dopant can be introduced as close as possible to the inner wall surface in the crucible, and liquid splashing of the molten liquid during introduction and dislocation of the single crystal can be prevented.

Effects of the Invention

[0023] According to the present invention, it is possible to provide a single crystal manufacturing apparatus provided with a dopant supply device that has no breakage or dropout of parts and can also cope with the vertical movement of the heat shielding member.

Brief Description of the Drawings

[0024] [Figure 1]FIG. 1 is a schematic side cross-sectional view showing the configuration of a single crystal manufacturing apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of the dopant supply device of FIG. 1. [Figure 3] FIG. 3 is a schematic cross-sectional view showing a state in which a heat shielding member is raised in a preparation stage before starting a crystal pulling process. [Figure 4] FIG. 4 is a schematic side cross-sectional view showing a state in which the chamber is disassembled. BEST MODE FOR CARRYING OUT THE INVENTION

[0025] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0026] FIG. 1 is a schematic side cross-sectional view showing the configuration of a single crystal manufacturing apparatus according to an embodiment of the present invention.

[0027] As shown in FIG. 1, the single crystal manufacturing apparatus 1 includes a chamber 10, a quartz crucible 12 installed in the chamber 10, a graphite susceptor 13 that supports the quartz crucible 12, a shaft 14 that supports the susceptor 13 so as to be movable up and down and rotatable, a heater 15 disposed around the susceptor 13, a heat shielding member 16 disposed above the quartz crucible 12, a single crystal pulling wire 17 disposed above the quartz crucible 12 and coaxial with the shaft 14, a wire winding mechanism 18 disposed above the chamber 10, and a dopant supply device 20 that supplies a dopant into the quartz crucible 12.

[0028] Chamber 10 consists of a main chamber 10a, a top chamber 10b that covers the upper opening of the main chamber 10a, and an elongated cylindrical pull chamber 10c connected to the upper opening of the top chamber 10b. The quartz crucible 12, susceptor 13, heater 15, and heat shielding member 16 are located inside the main chamber 10a. The susceptor 13 is fixed to the upper end of a shaft 14 that is vertically mounted through the center of the bottom of the chamber 10, and the shaft 14 is driven to move up and down and rotate by a shaft drive mechanism 19.

[0029] The heater 15 is used to melt the polycrystalline silicon raw material packed inside the quartz crucible 12 to produce a silicon melt 3. The heater 15 is a carbon resistance heater and is positioned to surround the quartz crucible 12 inside the susceptor 13. An insulating material 11 is provided on the outside of the heater 15. The insulating material 11 is arranged along the inner wall surface of the main chamber 10a, thereby improving the heat retention inside the main chamber 10a.

[0030] The heat shielding member 16 is provided to prevent the silicon single crystal 2 from being heated by radiant heat from the heater 15 and the quartz crucible 12, and to suppress temperature fluctuations in the silicon molten material 3. The heat shielding member 16 is a substantially cylindrical member whose diameter decreases from top to bottom, and is provided to cover the top of the silicon molten material 3 and surround the silicon single crystal 2 being grown. Graphite is preferably used as the material for the heat shielding member 16. Since the lower end of the heat shielding member 16 is located inside the quartz crucible 12, it does not interfere with the heat shielding member 16 even when the quartz crucible 12 is raised. An opening larger than the diameter of the silicon single crystal 2 is provided in the center of the heat shielding member 16, and the silicon single crystal 2 is pulled upward through the opening.

[0031] As will be described in detail later, it is preferable that the heat shielding member 16 is configured to be able to move up and down within the chamber 10. The heat shielding member 16 may be lifted by a jack or the like, or pulled up by a wire or the like. If the heat shielding member 16 is able to move up and down, even if a pile of solid silicon raw material is filled into the quartz crucible 12, interference between the heat shielding member 16 and the solid silicon raw material can be avoided by moving the heat shielding member 16 upward, and the initial charge amount of molten silicon 3 in the quartz crucible 12 can be increased.

[0032] Above the quartz crucible 12, a wire 17, which serves as the pulling axis for the silicon single crystal 2, and a wire winding mechanism 18 for winding the wire 17 are provided. The wire winding mechanism 18 has the function of rotating the silicon single crystal 2 together with the wire 17. The wire winding mechanism 18 is located above the pull chamber 10c, and the wire 17 extends downward from the wire winding mechanism 18 through the pull chamber 10c, with the tip of the wire 17 reaching the internal space of the main chamber 10a. Figure 1 shows the silicon single crystal 2 in the process of being grown suspended from the wire 17. When pulling up the single crystal, the seed crystal is immersed in the silicon melt 3, and the single crystal is grown by gradually pulling up the wire 17 while rotating the quartz crucible 12 and the seed crystal respectively.

[0033] A gas intake port 10d for introducing argon gas into the chamber 10 is provided at the top of the pull chamber 10c, and a gas exhaust port 10e for exhausting the argon gas from the chamber 10 is provided at the bottom of the main chamber 10a. The argon gas is introduced into the chamber 10 from the gas intake port 10d, and the amount introduced is controlled by a valve. In addition, since the argon gas inside the sealed chamber 10 is exhausted to the outside of the chamber from the gas exhaust port 10e, it is possible to recover SiO gas and CO gas inside the chamber 10 and keep the inside of the chamber 10 clean.

[0034] The dopant supply device 20 includes a dopant supply pipe 21 that penetrates the chamber 10 and whose lower end reaches above the quartz crucible 12, a dopant hopper 22 installed outside the chamber 10 and connected to the upper end of the dopant supply pipe 21, and a seal cap 23 that seals the opening 10f of the top chamber 10b through which the dopant supply pipe 21 penetrates.

[0035] In the production of silicon single crystal 2, polycrystalline silicon raw material is packed into a quartz crucible 12, and a seed crystal is attached to the tip of a wire 17. Next, the silicon raw material in the quartz crucible 12 is heated with a heater 15 to generate silicon melt 3.

[0036] In the single crystal pulling process, first, a seed crystal is necked using the dash neck method to make the single crystal dislocation-free. Next, to obtain a single crystal of the required diameter, a shoulder portion with a gradually expanding diameter is grown, and once the single crystal reaches the desired diameter, a body portion with a constant diameter is grown. After growing the body portion to a predetermined length, a tail portion is grown to separate the single crystal from the silicon melt 3 in a dislocation-free state.

[0037] Immediately before the start of the silicon single crystal pulling process 2, or during the crystal pulling process, dopants 5 are supplied from the dopant supply device 20 to the silicon melt 3.

[0038] Figure 2 is an enlarged view of the dopant supply device 20 shown in Figure 1.

[0039] As shown in Figures 1 and 2, the dopant supply device 20 includes a dopant supply pipe 21 that penetrates the chamber 10 and reaches above the quartz crucible 12, a dopant hopper 22 connected to the upper end of the dopant supply pipe 21, and a seal cap 23 that seals the opening 10f formed in the top chamber 10b. The dopant raw material supplied from the dopant hopper 22 is transferred into the chamber 10 through the dopant supply pipe 21.

[0040] The dopant supply tube 21 is made of quartz glass and consists of a first dope tube 24 that is drawn into the main chamber 10a through the opening 10f of the top chamber 10b, and a second dope tube 25 that is located inside the main chamber 10a and directly below the lower end of the first dope tube 24.

[0041] The first doped tube 24 is a curved quartz glass tube that extends from the installation position of the dopant hopper 22 through the opening 10f of the top chamber 10b to directly above the second doped tube 25. The first doped tube 24 is fixed to the top chamber 10b via a seal cap 23. The first doped tube 24 is separate from the heat shielding member 16.

[0042] The second doped tube 25 has a large-diameter section 25a with a larger opening diameter than the lower end of the first doped tube 24, a tapered section 25b with a gradually decreasing opening diameter, and a small-diameter section 25c with a smaller opening diameter than the large-diameter section 25a. In other words, the second doped tube 25 has a funnel shape in which the opening size at its upper end is wider than the opening size at its lower end.

[0043] The central axis of the second doped tube 25 extends in a straight line from its upper end to its lower end and has no curved sections. Therefore, the second doped tube 25 can be attached to the heat shield member 16 simply by inserting the small-diameter portion 25c of the second doped tube 25 into the through hole 16a. Because such a second doped tube 25 has a relatively simple shape, it is easy to manufacture and inexpensive to manufacture. The second doped tube 25 is simply inserted into the through hole 16a of the heat shield member 16 and is installed so as to be able to move up and down relative to the heat shield member 16. Furthermore, the second doped tube 25 is separate and independent from the chamber 10.

[0044] The heat shielding member 16 is provided with a through hole 16a that penetrates vertically from its inner circumferential surface to its outer circumferential surface, and the small-diameter portion 25c of the second doped tube 25 is inserted into this through hole 16a. Since the area around the small-diameter portion 25c of the second doped tube 25 is surrounded by the heat shielding member 16, the influence of radiant heat from the heater 15 and the molten silicon 3 can be suppressed, and thermal deformation of the second doped tube 25 can be prevented.

[0045] Preferably, the taper angle (acute angle) of the outer surface of the tapered portion 25b of the second doped pipe 25 with respect to the vertical axis is approximately equal to the inclination angle of the inner wall surface 16b of the heat shielding member 16 facing the tapered portion 25b with respect to the vertical axis. This allows the second doped pipe 25 to be supported in line contact with the heat shielding member 16, thereby suppressing damage and deformation of the second doped pipe 25. The peak of the taper angle is at the lower end of the tapered portion 25b. The taper angle of the outer surface of the tapered portion 25b may be smaller than the inclination angle of the inner wall surface 16b facing the tapered portion 25b. In this case, the second doped pipe 25 is supported by the heat shielding member 16 at a single point at the base of the tapered portion 25b, but it can be supported without any problems.

[0046] As described above, both the first doped tube 24 and the second doped tube 25 are made of quartz. For example, if at least one of the first doped tube 24 and the second doped tube 25 is made of carbon, the carbon concentration in the silicon single crystal will increase due to carbon contamination of the dopant. However, if both the first doped tube 24 and the second doped tube 25 are made of quartz, contamination of the dopant with impurities can be prevented. Furthermore, quartz tubes are prone to cracking at room temperature and may deform at high temperatures, but the second doped tube 25 is simply inserted into the through-hole 16a of the heat shielding member 16 and is not firmly fixed with screws or the like, so not only is it easy to install, but damage and deformation of the second doped tube 25 can also be prevented.

[0047] The lower end of the small-diameter portion 25c of the second doped tube 25, which is inserted into the through-hole 16a of the heat shielding member 16, is not exposed and terminates inside the lower opening of the through-hole 16a, and the lower end of the second doped tube 25 is covered by a SiC-coated carbon ring cap 16c. Therefore, the lower end of the second doped tube 25 can be protected from heat and thermal deformation can be prevented.

[0048] The outer opening of the ring cap 16c is preferably angled downwards, approaching the side wall of the quartz crucible 12. This allows the dopant 5 to be introduced as close to the inner wall surface as possible inside the quartz crucible 12, even if the second doping tube 25 extends straight downwards (see Figure 1), thereby preventing splashing of the molten material and dislocation formation of the single crystal during introduction.

[0049] In the above configuration, granular dopant 5 is added to the silicon melt 3 in the quartz crucible 12 from the dopant supply device 20 immediately before the start of the silicon single crystal 2 pulling process and during the crystal pulling process. The dopant 5 discharged from the dopant hopper 22 is supplied to the silicon melt 3 through the first dope tube 24 and the second dope tube 25.

[0050] Figure 3 is a schematic cross-sectional view showing the state in which the heat shielding member 16 is raised during the preparation stage before the crystal pulling process begins.

[0051] As shown in Figure 3, in the preparation stage, as much silicon raw material 4 as possible is loaded into the quartz crucible 12, so a large amount of solid silicon raw material 4 is piled up inside the quartz crucible 12, and a large amount of molten silicon 3 can be generated by melting it. At this time, by moving the heat shielding member 16 upward so as not to interfere with the polycrystalline silicon raw material, interference between the heat shielding member 16 and the piled-up silicon raw material 4 can be avoided. Furthermore, since the dopant supply pipe 21 is divided into a first dope pipe 24 and a second dope pipe 25, it can accommodate the movement of the heat shielding member 16.

[0052] Figure 4 is a roughly side cross-sectional view showing the chamber 10 in a disassembled state.

[0053] As shown in Figure 4, the chamber 10 is composed of a main chamber 10a, a top chamber 10b, and a pull chamber 10c, which can be disassembled as shown. In this case, the dopant supply pipe 21 is divided into a first dope pipe 24 and a second dope pipe 25, making it easy to remove and attach the top chamber 10b to the main chamber 10a. Thus, the relative positional relationship between the first dope pipe 24 and the second dope pipe 25 changes depending on the attachment and detachment of the top chamber 10b.

[0054] As described above, in the single crystal manufacturing apparatus 1 according to this embodiment, the dopant supply pipe 21 for feeding dopants from the outside to the inside of the chamber 10 is divided into two parts, so the total length of the dopant supply pipe 21 can be adjusted in accordance with the vertical movement of the heat shielding member 16. Furthermore, since the second dope pipe 25 is simply inserted into the through hole 16a of the heat shielding member 16, it is not only easy to install but also prevents damage and deformation.

[0055] Although preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention, and these modifications are also included within the scope of the present invention.

[0056] For example, in the above embodiment, the dopant supply pipe 21 is composed of two independent dope pipes 24 and 25, but it is also possible to configure it using three or more dope pipes.

[0057] For example, during the crystal pulling process, the first doped tube 24 and the second doped tube 25 are separated and do not overlap in the vertical direction, but it is also possible to make them overlap. [Explanation of Symbols]

[0058] 1. Single crystal manufacturing apparatus 2. Silicon single crystal 3. Silicon melt 4. Solid silicon raw materials 5 Dopant granules 10 chambers 10a Main Chamber 10b Top Chamber 10c pull chamber 10d Gas intake 10e Gas exhaust port 10f opening 11. Insulation 12 Quartz Crucibles 13 Susceptors 14 shafts 15 Heater 15b Tapered section 16 Heat shielding material 16a Through-holes in the heat shielding member 16b Inner wall surface of heat shielding member 16c ring cap 17 wires 18. Wire winding mechanism 19. Shaft drive mechanism 20 Dopant supply device 21 Dopant supply pipe 22 Dopant Hopper 23 Seal cap 24. First doped tube 25. Second doped tube 25a Large diameter section 25b Tapered section 25c small diameter section

Claims

1. Chamber and A crucible installed inside the chamber, A heat shielding member positioned above the crucible, The system includes a dopant supply device that supplies granular dopant into the crucible from outside the chamber, The dopant supply device includes a dopant supply tube that penetrates the chamber and reaches above the crucible, The dopant supply pipe has a first dope pipe that penetrates the chamber and a second dope pipe that is separated from the first dope pipe and positioned directly below the lower end of the first dope pipe. The first doped tube is separate and independent from the heat shielding member. The second doped tube has a large-diameter section having an opening diameter larger than the inner diameter of the lower end of the first doped tube, a small-diameter section having an opening diameter smaller than the large-diameter section, and a tapered section connecting the large-diameter section and the small-diameter section. The second doped tube is separate from the chamber and installed in the heat shielding member. A single crystal manufacturing apparatus characterized in that the second doped tube does not come into contact with the lower end of the first doped tube.

2. The single crystal manufacturing apparatus according to claim 1, wherein the small-diameter portion is inserted into a through hole formed in the heat shielding member, and the second doped tube is installed so as to be vertically movable relative to the heat shielding member.

3. The single crystal manufacturing apparatus according to claim 1 or 2, wherein the taper angle of the outer surface of the tapered portion, which forms an acute angle with respect to the vertical axis, is less than or equal to the inclination angle of the inner wall surface of the heat shielding member facing the tapered portion with respect to the vertical axis.

4. The single crystal manufacturing apparatus according to any one of claims 1 to 3, wherein the axis of the second doped tube extends in a straight line from the upper end to the lower end of the second doped tube.

5. The single crystal manufacturing apparatus according to any one of claims 1 to 4, wherein the dopant supply tube is made of quartz.

6. The single crystal manufacturing apparatus according to any one of claims 1 to 5, wherein the heat shielding member is configured to be able to move up and down within the chamber, and the relative positional relationship between the first dope tube and the second dope tube changes in accordance with the movement of the heat shielding member.

7. The single crystal manufacturing apparatus according to any one of claims 1 to 6, wherein the chamber comprises a main chamber in which the crucible is installed and a top chamber covering the upper opening of the main chamber, the top chamber is configured to be detachable from the main chamber, and the relative positional relationship between the first doped tube and the second doped tube changes depending on whether the top chamber is attached or detached.

8. The single crystal manufacturing apparatus according to any one of claims 1 to 7, wherein the second doped tube is inserted into a through hole formed in the heat shielding member, the lower end of the second doped tube is terminated inside the lower opening of the through hole without being exposed, and the lower end of the second doped tube is covered with a carbon ring cap.

9. The single crystal manufacturing apparatus according to claim 8, wherein the outer opening of the ring cap is obliquely downward and faces the side wall portion of the crucible.

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