JPH05270976A - Single crystal pulling apparatus and pulling method - Google Patents

Abstract

PURPOSE:To provide a single crystal pulling apparatus and pulling method capable of pulling up e.g. a silicon single crystal rod of 8 in. diameter, 2m long and about 150kgf weight by reinforcing the Dash's neck part of a silicon single crystal rod to improve the mechanical strength of the material. CONSTITUTION:A quartz crucible 3 holding molten silicon liquid 4 is placed in a state freely rotatable on its axis and movable in vertical direction. A seed crystal 8 of silicon single crystal is held with a pulling mechanism and a silicon single crystal rod 9 having a diameter larger than that of the seed crystal 8 is grown from the molten silicon by pulling up the seed crystal 8 from the molten silicon 4 with the pulling mechanism. When the seed crystal 8 is pulled up from the surface of the molten silicon to a height of about 1m, a carbon fiber 11 wound on a drum 15 is wound around the Dash's neck part 10 of the silicon single crystal rod 9 in a state interlocked with the rotation of the crystal.

Description

Detailed Description of the Invention

[0001]

The present invention relates to CZ (Czochralski)
The present invention relates to a single crystal pulling apparatus and a pulling method thereof.

[0002]

2. Description of the Related Art Conventionally, the CZ method, which is suitable for manufacturing a large-diameter and long cylindrical silicon single crystal ingot, immerses a silicon single crystal seed crystal in a silicon melt and gradually rotates the seed crystal while rotating the seed crystal. It is pulled up to grow a large diameter silicon single crystal ingot having the same crystal orientation as the seed crystal. In this case, when growing from the seed crystal so that the dislocations existing in the seed crystal do not propagate into the silicon single crystal rod,
Form a so-called Dash's neck, which is made by narrowing the silicon single crystal ingot once and making it thick.
Dislocation-free silicon single crystal rods have been performed. On the other hand, the silicon single crystal ingot tends to have a larger diameter and a longer length, increasing its own weight.

[0003]

[Problems to be Solved by the Invention] Such a conventional CZ
In the single crystal pulling method of the method, the diameter of the dash's neck portion is 3 to 4 mm, and the length thereof is several tens mm.
Its mechanical strength was 100 to 200 kgf / cm ² . This strength is the tensile strength of the silicon single crystal rod. However, since the dash's neck of the silicon single crystal rod is narrowed as described above, there is a problem in that it is weak in terms of material dynamics and limits the increase in diameter and length of the silicon single crystal rod. On the other hand, if the dash-neck portion of the silicon single crystal rod exceeds the limit value and becomes thick, dislocations in the seed crystal propagate to the silicon single crystal rod, and there is a problem that the silicon single crystal rod cannot be dislocation-free.

Therefore, the present invention provides a single crystal pulling apparatus and a pulling method for the same which can strengthen the dash neck portion of a silicon single crystal rod to improve the material mechanical strength. , And its purpose.

[0005]

A single crystal pulling apparatus according to claim 1, wherein a crucible holding a crystal melt and a seed crystal are held, and the seed crystal is pulled from the crystal melt, In a single crystal pulling apparatus equipped with a pulling mechanism for growing a single crystal rod having a diameter larger than that of the seed crystal, when the seed crystal is pulled a predetermined distance from the liquid surface of the crystal melt, The flexible material is wound around the dash neck portion of the single crystal rod.

Further, in the single crystal pulling method according to the second aspect, the dash's neck portion, shoulder portion and straight body portion of the single crystal rod are
In the single crystal pulling method of continuously forming while rotating, one end of the flexible material is engaged with the dash neck portion when the dash neck portion reaches a predetermined height due to the rise of the single crystal rod. And a step of winding a flexible material from the dash neck portion through the shoulder portion to the straight body portion by rotating the single crystal ingot.

[0007]

In the method for pulling a single crystal according to the present invention, the seed crystal is formed while rotating the dash neck portion, shoulder portion and straight body portion of the single crystal rod. Then, the straight body portion of the single crystal ingot is grown by a predetermined length. The dash neck portion of the single crystal rod reaches a predetermined height. At this time, one end of a flexible material, for example, a fiber made of carbon fiber is engaged with the dash neck portion. For example, a pin is attached to the seed crystal, and one end of the thread wound on the drum is locked to this pin. The locked thread is wound while engaging with the dash neck portion by the rotation rise of the single crystal rod. Then, this thread passes through the shoulder portion of the single crystal rod and is wound up to its straight body portion. As a result, the dash neck portion of the single crystal rod is reinforced. Therefore, the dash's neck portion of the single crystal ingot is reinforced by material dynamics.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a single crystal pulling apparatus according to an embodiment of the present invention.

As shown in this figure, a chamber (not shown)
Inside, a crucible shaft 1 is provided in an upright state so as to be rotatable and to move up and down. A cylindrical graphite susceptor 2 having a bottom is fixed to the upper end of the crucible shaft 1. A quartz crucible 3 is detachably held in the graphite susceptor 2. This quartz crucible 3 also has a bottomed cylindrical shape.
A silicon melt 4 in a melted state is injected and held in the quartz crucible 3. A heater 5 for heating the silicon melt 4 is disposed outside the graphite susceptor 2 so as to surround the graphite susceptor 2. Further, above the quartz crucible 3, its radius is substantially constant (for example, a diameter of 8 inches).
A pulling mechanism (not shown) for pulling up the silicon single crystal ingot 9 is provided.

By this pulling mechanism, the pulling wire 6 is moved above the quartz crucible 3 while rotating in the direction opposite to the quartz crucible 3 while moving up and down. A seed crystal 8 of silicon single crystal is attached to the tip of the pulling wire 6 via a seed chuck 7. A C-shaped pin 14 made of molybdenum projects from the seed crystal 8. By immersing the seed crystal 8 in the silicon melt 4 and then raising it, the silicon single crystal rods 9 sequentially grown with the seed crystal 8 as a starting point are pulled in an argon atmosphere. At the time of this pulling up, when growing from the seed crystal 8 so that dislocations existing in the seed crystal 8 do not propagate into the silicon single crystal rod 9, the silicon single crystal rod 9 is once narrowed and then thickened. The silicon necks 10 are formed to make the silicon single crystal ingots 9 dislocation-free.

A support plate 13 is fixed to the inner wall of the chamber above the quartz crucible 3 at a predetermined height position. The bobbin winding mechanism 20 is installed on the support plate 13. The bobbin winding mechanism 20 includes a traveling carriage 21 that can move horizontally on the support plate 13 and a drum 15 that is axially mounted on the traveling carriage 21. The traveling carriage 21 is locked to one end of a spring 22. The other end of the spring 22 is locked to the vertical plate 23 of the support plate 13. The spring 22 biases the traveling carriage 21 in a direction away from the silicon single crystal rod 9. Drum 15
A flexible material, for example, a fiber 11 made of carbon fiber is wound around the. The diameter of this thread 11 is 0.2-0.3 mm. A hook is fixed to a part of the thread 11. Thread 11
When the hook of is locked to the pin 14 of the seed crystal 7, the thread 1
1 is wound while engaging with the dash neck portion 10 as the silicon single crystal rod 9 is rotated and raised. Then, the thread 11 passes through the shoulder portion 12 of the silicon single crystal rod 9 and is wound up to the straight body portion 16. As a result, the dash neck portion 10 of the silicon single crystal ingot 9 is reinforced.

Next, a method for pulling up a silicon single crystal ingot will be described. Prior to the pulling, high-purity polycrystalline silicon and a small piece of silicon crystal doped with boron at a high concentration are put in a quartz crucible 3 in the graphite susceptor 2. The whole of these is attached to the crucible shaft 1. After the inside of the chamber is evacuated with a vacuum device, argon gas is supplied to make the inside of the chamber 1
Argon atmosphere of 0 to 20 Torr. The heater 5 is energized to heat the quartz crucible 3 to melt the raw material silicon or the like. A seed crystal 8 of silicon single crystal is attached to the seed chuck 7, and this seed crystal 8 is brought into contact with the center of the liquid surface of the silicon melt 4. Simultaneously with this contact, the motor will move the crucible shaft 1
Is rotated in one direction at a predetermined crucible rotation speed, and the pulling mechanism slowly raises the seed crystal 8 at a crystal rotation speed of 15 rotations / minute while rotating the seed crystal 8 in a direction opposite to the crucible rotation speed.

After the pulling is started, the seed crystal 8 is pulled at a predetermined speed to form a dash neck portion 10 of a silicon single crystal ingot 9 at the lower end of the seed crystal 8. This dash neck 1
The diameter of the large diameter part of 0 is 10 mm, and the diameter of the small diameter part is 3 m
m, and its length is 200 mm. After this, the pulling speed is slowed down, the diameter of the silicon single crystal ingot 9 is increased, and the shoulder 12
To form. Thereafter, the pulling speed and the like are changed to form the straight body portion 16 (diameter 200 mm) of the silicon single crystal ingot 9. Then, the straight body portion 16 is pulled up from the liquid surface of the silicon melt 4 to a length of about 1 m and grown. The thread 11 wound on the drum 15 before the straight body portion 16 becomes 1 m long
Is pulled out from the drum 15 so as not to come into contact with the pulling wire 6 and pulled out to the opposite side of the bobbin winding mechanism 20.

Next, the yarn 11 is moved horizontally around the drum 15. A hook fixed to a part of the thread 11 is locked to the pin 14 of the seed crystal 7. After this locking, the portion of the thread 11 pulled out to the opposite side of the thread winding mechanism 20 is cut. As a result, the thread 11 is locked to the pin 14 by the hook fixed to one end thereof, and the other end of the thread 11 is wound around the drum 15 of the thread winding mechanism 20. The locked thread 11 is wound while being engaged with the dash's neck portion 10 by the rotation rise of the silicon single crystal rod 9. At this time, the thread 11 is wound around the same place in about three layers. The thread 11 is the shoulder 1 of the silicon single crystal rod 9.
It continues to be wound up to a predetermined portion of the straight body portion 16 after passing through 2. Tensile force of this thread 11 (dash neck 1
(Adjustable with spring 22 so that 0 is not scratched)
The yarn 11 itself receives a load, and its rigidity is improved. Next, after the thread 11 is wound up to a predetermined position on the straight body portion 16 of the silicon single crystal rod 9, the thread 11 is wound on the thread 11 in the thread winding mechanism 20.
A solution of ethylene fluoride (PTFE) is applied. This PT
While applying the FE liquid, the yarn 11 is continuously wound around the straight body portion 16 several times. The thread 11 continues to adhere to the straight body portion 16 with the PTFE liquid. Then, the thread 11 is cut in the thread winding mechanism 20. As a result of this winding, the section modulus of the dash's neck portion 10 of the silicon single crystal ingot 9 becomes large, and its bending rigidity is reinforced. Therefore, the dash's neck portion 10 of the silicon single crystal ingot 9 is reinforced by material dynamics. Next, the straight body portion 16 of the silicon single crystal ingot 9
Is pulled up to a length of 2 m and grown. After that, the crystal diameter of the silicon single crystal ingot 9 is gradually reduced, and the tail treatment is completed.

In place of the PTFE liquid adhesive, a dash neck portion 10, a shoulder portion 12, and a shoulder portion 12 of the silicon single crystal rod 9 are used.
The entire thread 11 wound around the straight body portion 16 may be covered with a supporter after the winding. This supporter is thread 11
Is to be released from the silicon single crystal ingot 9. Further, after covering a predetermined portion of the straight body portion 16, the thread 11 may be pulled up along with the lifting and rotation of the silicon single crystal rod 9 without cutting the thread 11. The thread 11 may be continuously wound until the silicon single crystal rod 9 is tail-treated to cover the entire silicon single crystal rod 9. At this time, the thread 11 serves to keep the silicon single crystal rod 9 warm. Further, the flexible material is not limited to the carbon fiber thread, and may be a fiber such as fluororesin. Further, the flexible material may be in a tape shape. In addition, PTFE is used for bonding the thread 11.
In addition to liquid, polyfluorinated ethylene propylene (FEP),
PFA, polychlorotrifluoroethylene (PCTF
E), FR-EPT, polyethylene (PE), polyolefin, fluororubber (FKM), or silicone rubber (Q), polyimide, polypyrrole, or other thermosetting resin having good heat resistance may be used.

As a result of the above, by reinforcing the dash's neck portion 10 of the silicon single crystal ingot 9 mechanically,
The silicon single crystal ingot 9 does not drop into the silicon melt 4 due to its own weight. Therefore, 8 inches in diameter and 2 in length
A silicon single crystal ingot 9 having a weight of about 000 mm and a weight of about 150 kgf can be safely pulled up and grown.

[0017]

As described above, according to the apparatus for pulling a single crystal and the method for pulling the same according to the present invention, the dash-neck portion of the single crystal rod is mechanically reinforced to form a crystal melt. The single crystal rod does not fall inside due to its own weight.

[Brief description of drawings]

FIG. 1 is a sectional view of a single crystal pulling apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 3 Quartz Crucible 4 Silicon Melt (Crystal Melt) 5 Heater 8 Silicon Single Crystal Seed Crystal 9 Silicon Single Crystal Rod 10 Dash's Neck Part 11 Carbon Fiber Thread (Flexible Material) 12 Shoulder 15 Drum 16 Body Department

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeaki Sahira 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Central Research Laboratory, Mitsubishi Materials Corporation

Claims (2)

[Claims] 1. A crucible for holding a crystal melt, and a pulling means for growing a single crystal rod having a diameter larger than that of the seed crystal while holding the seed crystal and pulling the seed crystal from the crystal melt. In a single crystal pulling apparatus including an upper mechanism, a flexible material that is wound around a dash neck portion of the single crystal rod when the seed crystal is pulled up by a predetermined distance from the liquid surface of the crystal melt. An apparatus for pulling a single crystal, comprising: 2. A dash's neck portion, a shoulder portion of a single crystal rod,
In the single crystal pulling method for continuously forming the straight body portion while rotating, when the dash neck portion reaches a predetermined height by the raising of the single crystal rod, one end of the flexible material is attached to the dash neck portion. And a step of winding the flexible material from the dash neck portion through the shoulder portion to the straight body portion by the rotation of the single crystal ingot, the single crystal pulling. Upper way.