JP6652015B2 - Single crystal pulling apparatus and single crystal manufacturing method - Google Patents

Description

  The present invention relates to a single crystal pulling apparatus and a method for manufacturing a single crystal.

Conventionally, a single crystal pulling apparatus 9 as shown in FIG. 1 has been known.
The single crystal pulling apparatus 9 is an apparatus for manufacturing a silicon single crystal by the Czochralski method (CZ method), and includes a pulling apparatus main body 2 and a control unit (not shown). The lifting device main body 2 includes a chamber 21, a crucible 22, a heating unit 23, a heat insulating cylinder 24, a heat shield 25, and a water cooling body 26 as a cooling unit.

  The chamber 21 includes a main chamber 21A that houses the crucible 22, the heating unit 23, the heat insulating cylinder 24, the heat shield 25, and the water cooling body 26, and a pull chamber 21B that is connected to an upper surface of the main chamber 21A and through which a silicon single crystal passes. And The pull chamber 21B is provided with a gas inlet (not shown) for introducing an inert gas G1 such as Ar gas into the main chamber 21A. A gas exhaust port 21C for discharging the inert gas G1 from the main chamber 21A by driving a vacuum pump (not shown) is provided below the main chamber 21A.

The crucible 22 melts polycrystalline silicon S, which is a raw material of silicon single crystal, to obtain a silicon melt M.
The heating unit 23 is provided so as to surround the crucible 22, and heats the crucible 22 to melt the silicon S in the crucible 22.
The heat insulating cylinder 24 is arranged so as to surround the crucible 22 and the heating unit 23.
The heat shield 25 is formed in a cylindrical shape surrounding the silicon single crystal above the crucible 22 and blocks radiant heat radiated upward from the heating unit 23.
The water cooling body 26 is formed in a cylindrical shape surrounding the silicon single crystal inside the heat shield 25, and cools the silicon single crystal by a coolant such as cooling water flowing through the inside.

  When manufacturing a silicon single crystal using such a single crystal pulling apparatus 9, first, a melting step of melting silicon S in crucible 22 is performed. The melting step includes a step of flowing cooling water through the water cooling body 26, a step of flowing the inert gas G1 from above to below in the main chamber 21A, and a step of heating the crucible 22.

However, when the melting step is performed in the single crystal pulling apparatus 9 of FIG. 1, the heat H1 from the silicon melt M in the crucible 22 and the heat H2 from the heating unit 23 reach the water-cooled body 26. Due to the heat absorption, the amount of power consumed until the melting of the silicon S is completed increases. In FIG. 1 and FIGS. 2A, 2B, 3 and 4 shown below, the behavior of heat or gas generated on one of the left and right sides of each figure may be illustrated and described. These behaviors occur throughout the circumferential direction.
Therefore, a plate-shaped shield (hereinafter, referred to as a “lid”) as described in Patent Document 1 is used, and a lid 91 is disposed so as to cover the upper part of the crucible 22 as shown in FIG. By heating the crucible 22 after that, it is possible to suppress the heat H1 and H2 from the silicon melt M and the heating unit 23 from reaching the water-cooled body 26 and reduce the power consumption during silicon melting. Conceivable.

JP-A-3-193694

However, in the method using the lid 91 described in Patent Document 1 shown in FIG. 2A, the evaporated gas EG from the silicon melt M stays between the silicon S or the silicon melt M and the lid 91. However, particles in the evaporative gas EG may be taken into the silicon melt M, which may hinder single crystallization.
In addition, even when the lid 91 is not used, the inert gas G1 is guided to the outside of the crucible 22, as shown in FIG. Although the gas is exhausted from the gas exhaust port 21C through the gas outlet, a part thereof collides with the heating unit 23 and becomes a backflow gas G2 flowing toward the inside of the crucible 22. Then, particles in the chamber 21 are carried to the silicon melt M by the backflow gas G2, and there is a possibility that single crystallization may be hindered.

  An object of the present invention is to provide a single crystal pulling apparatus and a single crystal manufacturing method capable of suppressing the inhibition of single crystallization while reducing the power consumption during melting of the raw material.

The single crystal pulling apparatus of the present invention is provided so as to surround a crucible that stores a raw material, the crucible, and a heating unit that heats the crucible to melt the raw material, and surrounds the single crystal above the crucible. A cylindrical heat shield that shields heat from the heating unit, and a cylindrical cooling unit that is arranged to surround the single crystal inside the heat shield and cools the single crystal. A main chamber that houses the crucible, the heating unit, the heat shield and the cooling unit, and a pull chamber through which the single crystal and the inert gas pass, and the inert gas supplied from the pull chamber is A single crystal pulling apparatus for producing a single crystal by the Czochralski method, comprising a chamber configured to be able to be discharged from below the main chamber, wherein the single crystal is provided inside the cooling unit. A surrounding tubular member is provided, and the tubular member suppresses the melt in the crucible and the heat from the heating portion from being absorbed by the cooling portion, and the upper end of the tubular member suppresses the heat absorption. the active gas is separated into an outer flow gas through the inner flowing gas and the outside through the inside of the tubular member-out guide to the lower of the thermal shield, its upper end is positioned within the pull chamber and the pull chamber A first outer gas passage through which the outer circulation gas passes is formed between the first outer gas passage and the inner peripheral surface of the first outer gas passage .
Further, the single crystal pulling apparatus of the present invention is provided with a crucible for storing a raw material, a heating unit provided to surround the crucible, and heating the crucible to melt the raw material, and a single crystal above the crucible. A tubular heat shield that is arranged to surround and shields heat from the heating unit; and a tubular cooling that is arranged to surround the single crystal inside the heat shield and cools the single crystal. Unit, a main chamber containing the crucible, the heating unit, the heat shield and the cooling unit, and a pull chamber through which the single crystal and the inert gas pass, and an inert gas supplied from the pull chamber. A chamber configured to be able to be discharged from below the main chamber, and a single crystal pulling apparatus for manufacturing a single crystal by the Czochralski method, wherein the cooling unit includes A cylindrical member surrounding the crystal is provided, and the cylindrical member suppresses heat from the melt in the crucible and the heating unit from being absorbed by the cooling unit, and at the upper end of the cylindrical member. The inert gas is separated into an inner flowing gas passing through the inside of the cylindrical member and an outer flowing gas passing outside, and is led to below the heat shield, and above the cooling unit, the single crystal is cooled. A cylindrical upper cooling portion that surrounds the single crystal, the upper cooling portion is connected to an upper surface portion of the main chamber or the pull chamber, and the cylindrical member has an upper end in the upper cooling portion. And a first outer gas passage through which the outer circulation gas passes is formed between the first outer gas passage and the inner peripheral surface of the upper cooling unit.

  According to the present invention, the tubular member provided inside the cooling unit can suppress the heat from the melt and the heating unit from being absorbed by the cooling unit, and can reduce the power consumption at the time of melting the raw material. Further, the inner flowing gas generated by the cylindrical member is discharged from below the main chamber through the gap between the crucible and the heating section together with the evaporating gas from the melt, and the inner flowing gas is directed toward the inside of the crucible. The backflow gas to be covered is pushed back by the outside flowing gas and discharged from below the main chamber through the gap, thereby suppressing particles in the evaporative gas and particles in the chamber from entering the melt, and thus the single crystal. Can be suppressed from being inhibited.

  According to the present invention, when the raw material is melted by a simple method in which the cylindrical member is disposed such that the upper end thereof is located in the pull chamber or the upper cooling section and the first outer gas flow path is formed. And the inhibition of single crystallization can be reduced.

  In the single crystal pulling apparatus of the present invention, a lower end of the heat shield is provided with a protrusion that protrudes in a flange shape inside the heat shield, and the lower end of the cylindrical member has an upper end of the protrusion. It is preferable that a second outer gas passage through which the outer flowing gas passes is formed between the lower end and the lower end, and between the lower end and the tip of the protrusion.

  According to the present invention, since the second outer gas flow path is narrower than the flow path between the upper side of the protruding portion and the cylindrical member, when the outer flowing gas passes through the second outer gas flow path. , Its flow rate can be increased. Therefore, the force for pushing back the backflow gas can be increased.

  In the single crystal pulling apparatus of the present invention, it is preferable that the cylindrical member is configured to be able to be carried out of the main chamber.

  According to the present invention, during the step of melting the raw material, the cylindrical member is positioned in the main chamber, and when growing the single crystal, the cylindrical member is carried out of the main chamber, so that the single crystal can be grown under the same conditions as the conventional one. Can be done with

  The method for producing a single crystal of the present invention is a method for producing a single crystal by the Czochralski method using the above-described single crystal pulling apparatus, wherein the step of melting the raw material in the crucible includes cooling the cooling unit. At the same time, by flowing an inert gas downward from above in the main chamber and heating the crucible, heat from the melt in the crucible and the heating unit is absorbed by the cooling unit. While suppressing that with the tubular member, the inert gas is separated into the inner flowing gas and the outer flowing gas by the tubular member and guided to below the heat shield, and the inner flowing gas is Discharged from below the main chamber through a gap between the crucible and the heating unit, and among the inner flowing gas, the gas that is going to flow back inside the crucible is pushed back by the outer flowing gas, and the gas is discharged through the gap. Characterized by discharging from below of the main chamber.

  The method for producing a single crystal of the present invention is a method for producing a single crystal by the Czochralski method using the above-mentioned single crystal pulling apparatus, wherein the step of melting the raw material in the crucible comprises the cooling unit and the While cooling the upper cooling unit, an inert gas is circulated downward from above in the main chamber, and by heating the crucible, the melt in the crucible and the heat from the heating unit are cooled. Along with suppressing the heat absorption by the tubular member with the tubular member, the tubular member separates the inert gas into the inner flowing gas and the outer flowing gas and guides the inert gas to below the heat shield, An inner flowing gas is discharged from below the main chamber through a gap between the crucible and the heating unit, and a gas that is going to flow back inside the crucible among the inner flowing gas is pushed by the outer flowing gas. To characterized in that it discharged from the lower side of the main chamber through the gap.

Sectional drawing of the conventional single crystal pulling apparatus. It is explanatory drawing of the subject of this invention, (A) shows the subject in the case of using a lid, (B) shows the subject in the case of not using a lid. FIG. 2 is a cross-sectional view of the single crystal pulling apparatus according to the first embodiment of the present invention. Sectional drawing of the single crystal pulling apparatus which concerns on 2nd Embodiment of this invention.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
The description of the same configuration as the single crystal pulling apparatus 9 shown in FIG. 1 will be simplified.

[Structure of single crystal pulling device]
As shown in FIG. 3, the pulling apparatus main body 2 of the single crystal pulling apparatus 1 includes a chamber 21, a crucible 22, a heating unit 23, a heat insulating cylinder 24, a heat shield 25, a water cooling body 26, And a member 27.
The crucible 22 moves up and down at a predetermined speed, and rotates around a support shaft 22A connected to a lower end thereof.
The heat shield 25 includes a cylindrical main body 25A and a protrusion 25B that protrudes inward from the lower end of the main body 25A in a flange shape. The protrusion 25B is provided at a position lower than the upper end of the heating unit 23. The protrusion 25B is provided so as to be located between the lower surface of the water cooling body 26 and the silicon melt M, and suppresses the heat from the silicon melt M from reaching the lower surface of the water cooling body 26.

The cylindrical member 27 is provided so as to surround the silicon single crystal inside the water-cooled body 26, and at the upper end thereof, the inert gas G <b> 1 flows through the inside flowing gas G <b> 11 passing through the inside of the cylindrical member 27 and the outside flowing gas G <b> 11 passing through the outside. G12. The tubular member 27 is preferably formed of a graphite material or a graphite material coated with SiC. The tubular member 27 may have a three-layer structure in which a heat insulating material is provided between graphite materials, or may have a two-layer structure or a structure having four or more layers.
The cylindrical member 27 is preferably formed in a cylindrical shape whose outer diameter is 0.5 times or more and 0.95 times or less the inner diameter of the pull chamber 21B. By making it 0.5 times or more, the gas flow velocity between the outer periphery of the cylindrical member 27 and the protruding portion 25B of the heat shield 25 becomes faster, and the backflow of gas to the upper part can be prevented. Further, by setting the ratio to 0.95 times or less, the cylindrical member 27 can easily pass through the inside of the pull chamber 21B.
The upper end of the cylindrical member 27 is located inside the pull chamber 21B (upper than the lower end 25D of the opening on the upper surface of the main chamber 21A), and the first outer side through which the outer circulation gas G12 passes between the inner peripheral surface of the pull chamber 21B. The gas passage 21E is provided so as to be formed. The cylindrical member 27 has a lower end located between an upper end 25C and a lower end 25D of the protruding portion 25B, and a second outer gas passage 21F through which the outer flowing gas G12 passes between the lower end and the tip of the protruding portion 25B. It is provided to be formed.
The cylindrical member 27 is carried out of the main chamber 21A by an unillustrated lifting cable for raising and lowering the seed crystal.

[Production method of silicon single crystal]
Next, a method for manufacturing a silicon single crystal using the single crystal pulling apparatus 1 will be described.
In producing a silicon single crystal, a melting step of silicon S in crucible 22 is performed. In this step, the tubular member 27 is carried into the main chamber 21A using a pull-up cable, and is positioned on the crucible 22 containing the silicon S, as shown in FIG. Thereafter, while cooling the water-cooled body 26, the inert gas G1 is passed downward from above the main chamber 21A, and the crucible 22 is heated by the heating unit 23. It is preferable that the flow rate of the inert gas G1 is 100 L / min or more and 600 L / min or less. Through the above processing, melting of the silicon S in the reduced-pressure inert atmosphere is started.

At this time, heat H1 and H2 are radiated from the silicon melt M and the heating unit 23, and the tubular member 27 suppresses the heat H1 and H2 being absorbed by the water-cooled body 26.
When the cylindrical member 27 is not provided, the heat H3 from the silicon melt M passes between the upper surface of the main chamber 21A and the water-cooled body 26 as shown by a two-dot chain line in FIG. It reaches the upper end side of the inner wall of 21A. Since the heat insulating tube 24 is not provided at the upper end side of the inner wall, the heat H3 is absorbed, but the tubular member 27 suppresses the heat absorption.

Further, the inert gas G1 is separated by the upper end of the tubular member 27 into an inner flowing gas G11 and an outer flowing gas G12. The inner circulation gas G11 reaches the surface of the silicon S or the silicon melt M through the inside of the cylindrical member 27, is guided along the surface to the outside of the crucible 22, and most of the gas flows from the silicon melt M. The gas is discharged from the gas exhaust port 21C through the gap between the side surface of the crucible 22 and the heating unit 23 together with the evaporated gas. At this time, a part of the inside circulation gas G11 may collide with the heating unit 23 and become a backflow gas G2 toward the inside of the crucible 22, as indicated by a two-dot chain line. However, the outer circulation gas G12 that has passed through the second outer gas flow path 21F is guided to the outside of the crucible 22 by the inner circulation gas G11, and the outer circulation gas G12 pushes back the backflow gas G2 to cause the crucible 22 and the heating unit 23 to communicate with each other. The gas is discharged from the gas exhaust port 21C through the gap.
Further, since the second outer gas flow path 21F is narrower than the upper flow path, the flow rate of the outer circulating gas G12 increases when the outer circulating gas G12 passes through the second outer gas flow path 21F. The force for pushing back the backflow gas G2 is greater than when the flow path 21F is not narrow.

When the melting step is completed, the cylindrical member 27 is raised by using the pull-up cable, and the entirety is housed in the pull chamber 21B, so that the cylindrical member 27 is carried out of the main chamber 21A.
Thereafter, if necessary, a dopant is added to the silicon melt M for adjusting the resistivity of the silicon single crystal, and then the seed crystal is brought into contact with the silicon melt M by lowering the pulling cable, and the pulling cable is appropriately adjusted. By pulling up while rotating, and raising the crucible 22 while rotating appropriately, the silicon single crystal is pulled up (growing step).

[Operation and Effect of First Embodiment]
In the first embodiment as described above, by providing the tubular member 27 inside the water cooling body 26, the heat H1, H2 from the silicon melt M and the heating unit 23 is suppressed from being absorbed by the water cooling body 26. Power consumption during melting of silicon can be reduced. In addition, the inside circulation gas G11 generated by the cylindrical member 27 is discharged from the gas exhaust port 21C together with the evaporation gas from the silicon melt M, and the backflow gas G2, which is a part of the inside circulation gas G11, is changed to the outside circulation gas G12. And the gas is exhausted from the gas exhaust port 21C, so that particles in the evaporative gas and particles in the chamber can be prevented from entering the silicon melt M, and the inhibition of single crystallization of the silicon single crystal can be suppressed.

In particular, the heat absorption from the silicon melt M at the upper end side of the inner wall of the main chamber 21A can also be suppressed by the cylindrical member 27, and the power consumption during silicon melting can be further reduced.
In addition, by increasing the flow rate of the outer circulation gas G12 in the second outer gas passage 21F, the force for pushing back the backflow gas G2 can be increased, and particles and particles in the evaporative gas can enter the silicon melt M. Performance can be further reduced.
Further, the cylindrical member 27 can be carried out of the main chamber 21A, and the silicon single crystal can be grown under the same conditions as the conventional one.

[Second embodiment]
Next, a second embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 4, the difference between the single crystal pulling apparatus 1 of the first embodiment and the single crystal pulling apparatus 1A of the second embodiment is that a draw tube 28 as an upper cooling unit is provided in the chamber 21. That is, the shape of the tubular member 27 is changed with the installation of the draw tube 28.

  The draw tube 28 is provided above the water cooling body 26 in the main chamber 21A. The draw tube 28 is formed in a cylindrical shape surrounding the silicon single crystal, and promotes the cooling of the silicon single crystal by a coolant such as cooling water flowing through the inside thereof, like the water-cooled body 26, and furthermore, the inert gas in the pull chamber 21 </ b> B. G1 is rectified and guided into the main chamber 21A. Although the draw tube 28 is connected to the pull chamber 21B, it may be connected to the upper surface of the main chamber 21A.

The cylindrical member 27A is formed in a cylindrical shape whose outer diameter is 0.5 times or more and 0.95 times or less the inner diameter of the draw tube 28, and at the upper end thereof, the inert gas G1 is supplied with the inner flowing gas G11 and the outer flowing gas G12. And separated into
The cylindrical member 27A is provided such that its upper end is located inside the draw tube 28, and the first outer gas passage 21E is formed between the cylindrical member 27A and the inner peripheral surface of the draw tube 28. Further, the cylindrical member 27A is provided such that its lower end is located between the upper end 25C and the lower end 25D of the protruding portion 25B, and the second outer gas passage 21F is formed. Furthermore, the cylindrical member 27A is provided so as to be able to be carried out of the main chamber 21A by a lifting cable.

  In such a single crystal pulling apparatus 1A, similarly to the single crystal pulling apparatus 1 of the first embodiment, the heat absorption of the heat H1, H2, and H3 at the water cooling body 26 and the upper end side of the inner wall of the main chamber 21A is suppressed. The power consumption during the melting of silicon can be reduced, and particles in the evaporative gas and particles in the chamber can be prevented from entering the silicon melt M, so that inhibition of single crystallization of the silicon single crystal can be suppressed.

[Modification]
It should be noted that the present invention is not limited only to the above embodiment, and various improvements and design changes can be made without departing from the spirit of the present invention.
For example, if the heat H1 and H2 can be suppressed from being absorbed by the water-cooled body 26 and the inert gas G1 can be separated into the inner flowing gas G11 and the outer flowing gas G12, the upper ends of the tubular members 27 and 27A can be removed. The pull chamber 21 </ b> B and the draw tube 28 may be positioned below the lower ends.
If the heat H1 and H2 can be prevented from being absorbed by the water cooling body 26, the lower ends of the tubular members 27 and 27A may be positioned above the upper ends 25C of the protruding portions 25B.
If the inert gas G1 can be separated into the inner flowing gas G11 and the outer flowing gas G12, the outer diameters of the cylindrical members 27 and 27A are made larger than the inner diameters of the pull chamber 21B and the draw tube 28, and are kept in the main chamber 21A even during the growing process. It may be located.
If the inside circulation gas G11 and the outside circulation gas G12 are guided to below the heat shield 25 of the heat shield 25, the cylindrical members 27, 27A may be fixed to the main chamber 21A or the pull chamber 21B.
The cylindrical members 27 and 27A are not limited to a cylindrical shape, and may be a truncated cone tube or a square tube.
The present invention may be applied to an apparatus for manufacturing a single crystal such as SiC, GaAs, and sapphire.

  Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

〔Example〕
First, a single crystal pulling apparatus 1A as shown in FIG. 4 was prepared. The diameter of the upper end opening of the crucible 22 is 810 mm, and the opening diameter of the lower end of the heat shield 25 (the diameter of a circular region surrounded by the tip of the protruding portion 25B (hereinafter, referred to as the “opening of the lower end of the heat shield 25”)) is 400 mm. The inner and outer diameters of the cylindrical member 27A were 310 mm and 324 mm, respectively, and the inner diameter of the draw tube 28 was 400 mm. The upper end of the cylindrical member 27A was located in the draw tube 28, and the lower end was located between the upper end 25C and the lower end 25D of the protruding portion 25B.
Then, a melting step of silicon S using the cylindrical member 27A, a step of carrying out the cylindrical member 27A to the outside of the chamber 21, and a step of growing a silicon single crystal having a diameter and a length of 310 mm and 2000 mm of the straight body are performed. The amount of power consumed by the heating unit 23 during the melting step ((average power of the heating unit 23 during the melting step) x (time from the start of heating to the completion of melting of silicon S)) and dislocation of the silicon single crystal The flow rate of the inert gas G1 was 200 L / min.

(Comparative example)
As shown in FIG. 2 (A), a lid having a lower surface with a diameter of 310 mm was prepared, and this lid was positioned at the center of the opening inside the lower end of the heat shield 25 instead of the cylindrical member 27A. The step of unloading the body out of the chamber 21 and the same growth step as in the example were performed, and the power consumption during the melting step and the occurrence of dislocations in the silicon single crystal were examined.

(Reference example)
The melting step and the growing step were performed without disposing any of the cylindrical member 27A and the lid in the single crystal pulling apparatus 1A, and the power consumption during the melting step was examined. Note that the production conditions for the silicon single crystal of the reference example are conditions generally performed.

[Evaluation]
Table 1 shows the power consumption during the melting step of the examples, comparative examples, and reference examples, and the occurrence of dislocations in silicon single crystals other than the reference examples.
The power consumption was almost the same level as the comparative example, and it was found that the power consumption in the melting step could be reduced as compared with the reference example. From this, it is considered that the tubular member 27A can suppress the heat H1, H2 from the silicon melt M and the heating unit 23 from being absorbed by the water-cooled body 26.
In the comparative example, dislocations occurred in the silicon single crystal, but not in the examples. From this, the cylindrical member 27A separates the inert gas G1 into the inner flowing gas G11 and the outer flowing gas G12, so that particles in the evaporation gas and particles in the chamber 21 enter the silicon melt M. It is considered that, as a result, dislocation of the silicon single crystal can be suppressed.

  1, 1A single crystal pulling apparatus, 21 chamber, 21A main chamber, 21B pull chamber, 21E first outer gas passage, 21F second outer gas passage, 22 crucible, 23 heating unit, 25 ... Heat shield, 25B ... Projecting part, 25C ... Top, 25D ... Bottom, 26 ... Water-cooled body (cooling part), 27, 27A ... Cylindrical member, 28 ... Draw tube (upper cooling part), G1 ... Inert gas , G11: inner flowing gas, G12: outer flowing gas, M: silicon melt (melt), S: silicon (raw material).

Claims (6)

A crucible for storing raw materials,
A heating unit provided to surround the crucible and heating the crucible to melt the raw material;
A cylindrical heat shield, which is arranged to surround the single crystal above the crucible and shields heat from the heating unit,
A tubular cooling unit arranged to surround the single crystal inside the heat shield and cooling the single crystal,
A main chamber that houses the crucible, the heating unit, the heat shield and the cooling unit, and a pull chamber through which the single crystal and the inert gas pass, and the inert gas supplied from the pull chamber is A single crystal pulling apparatus for producing a single crystal by a Czochralski method, comprising:
A cylindrical member surrounding the single crystal is provided inside the cooling unit,
The cylindrical member suppresses the heat from the melt and the heating unit in the crucible from being absorbed by the cooling unit, and the inert gas at the upper end of the cylindrical member is used as the inert gas for the cylindrical member. guide-out to the lower of the heat shield is separated into an outer flow gas through the inner flowing gas and the outside through the inner, upper end is positioned within the pull chamber, and between the inner peripheral surface of the pull chamber A single crystal pulling apparatus, wherein a first outer gas passage through which the outer flowing gas passes is formed . A crucible for storing raw materials,
A heating unit provided to surround the crucible and heating the crucible to melt the raw material;
A cylindrical heat shield, which is arranged to surround the single crystal above the crucible and shields heat from the heating unit,
A tubular cooling unit arranged to surround the single crystal inside the heat shield and cooling the single crystal,
A main chamber that houses the crucible, the heating unit, the heat shield and the cooling unit, and a pull chamber through which the single crystal and the inert gas pass, and the inert gas supplied from the pull chamber is A single crystal pulling apparatus for producing a single crystal by a Czochralski method, comprising:
A cylindrical member surrounding the single crystal is provided inside the cooling unit,
The cylindrical member suppresses the heat from the melt and the heating unit in the crucible from being absorbed by the cooling unit, and the inert gas at the upper end of the cylindrical member is used as the inert gas for the cylindrical member. Separated into an inner flowing gas passing through the inside and an outer flowing gas passing through the outside, and guided to below the heat shield,
Above the cooling unit, a cylindrical upper cooling unit for cooling the single crystal is provided so as to surround the single crystal,
The upper cooling unit is connected to an upper surface of the main chamber or the pull chamber,
The tubular member is provided such that an upper end thereof is located in the upper cooling unit, and a first outer gas flow path through which the outer flowing gas passes is formed between the cylindrical member and an inner peripheral surface of the upper cooling unit. An apparatus for pulling a single crystal, comprising: The single crystal pulling apparatus according to claim 1 or 2 ,
At the lower end of the heat shield, a protrusion is provided which protrudes in a flange shape inside the heat shield,
The cylindrical member has a lower end located between an upper end and a lower end of the protruding portion, and a second outer gas flow path through which the outer flowing gas passes between the tip of the protruding portion. A single crystal pulling apparatus characterized by being provided as described above. The single crystal pulling apparatus according to any one of claims 1 to 3 ,
The single crystal pulling apparatus, wherein the cylindrical member is configured to be able to be carried out of the main chamber. A method for producing a single crystal by the Czochralski method using the single crystal pulling apparatus according to claim 1 ,
In the step of melting the raw material in the crucible, while cooling the cooling unit, flowing an inert gas downward from above in the main chamber, and heating the crucible, thereby heating the crucible. The tubular member suppresses the heat from the melt and the heating unit from being absorbed by the cooling unit, and separates the inert gas into the inner flowing gas and the outer flowing gas at the cylindrical member. To the lower part of the heat shield, discharge the inner flowing gas from below the main chamber through a gap between the crucible and the heating unit, and return the inner flowing gas to the inside of the crucible among the inner flowing gas. A method of producing a single crystal, wherein the gas to be discharged is pushed back by the outside flowing gas and discharged from below the main chamber through the gap. A method for producing a single crystal by the Czochralski method using the single crystal pulling apparatus according to claim 2 ,
The step of melting the raw material in the crucible cools the cooling unit and the upper cooling unit, and allows an inert gas to flow downward from above in the main chamber to heat the crucible. And suppressing the heat from the melt and the heating unit in the crucible from being absorbed in the cooling unit by the cylindrical member, and the inert gas by the cylindrical member to the inert gas and the outside gas. It is separated into a circulation gas and guided to below the heat shield, and the inside circulation gas is discharged from below the main chamber through a gap between the crucible and the heating unit. A gas which is to flow back into the inside of the chamber is pushed back by the outside flowing gas and discharged from below the main chamber through the gap.

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