JPH0446088A - Method and apparatus for producing single crystal - Google Patents

Abstract

PURPOSE:To prevent the generation of the dislocation of the crystal occurring in the evaporated matter from the liquid surface of a melt by disposing a hollow annular body having vent ports near the surface of the melt so as to enclose a single crystal and supplying an inert gas from the vent ports at the time of producing the single crystal by a CZ method. CONSTITUTION:A crucible 5 housing the melt 9 is provided in a chamber 2. Further, the hollow annular body 17 having the vent ports 16 discretely or continuously over the entire circumference on the outer peripheral side is supported by a tubular support 18 communicating with this annular body 17 in the inside and is so disposed as to enclose the single crystal body 10 in the position near the surface of the melt 9 and near the outer peripheral surface of the single crystal body 10 to be pulled up. The inert gas is run out of the vent ports 16 of the annular body 17 to form the flow of the inert gas heading from the central part toward the outer side of the crucible 5 near the liquid surface of the melt 9 at the time of bringing a seed crystal 12 into contact with the melt 9 and pulling up and growing the single crystal body 10. The evaporated matter of SiO, etc., evaporating from the liquid surface of the melt 9 is thereby efficiently discharged to the outside of the system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method and apparatus for producing a single crystal. More specifically, the present invention relates to a method and apparatus for producing a single crystal, which enables stable single crystal growth.

[Prior Art] As a method for producing single crystals of silicon, germanium, gallium arsenide, etc., the Czochralski method (CZ method), in which crystals are grown and drawn from a melt in a crucible, is widely used. ing.

Conventionally, when attempting to obtain a silicon single crystal using the C2 method, a single crystal manufacturing apparatus having a configuration as schematically shown in FIG. 5, for example, has been used.

As shown in FIG. 5, the single crystal manufacturing apparatus 1 has a chamber 2 consisting of a heating chamber section 2a and a pulling chamber section 2b. Inside the heating chamber part a, a rotating shaft 4 is supported by a drive device 3 located outside the chamber 2 and extends through the bottom of the chamber, and is rotatable during a pulling operation and can control the amount of single crystal pulled. Accordingly, a quartz crucible 5 that can be raised in the axial direction, and a cylindrical heater 6 that surrounds the quartz crucible 5 at a predetermined interval are provided. In addition, in this example, the quartz crucible 5
The outer circumference of the graphite crucible 7 is protected by a graphite crucible 7, and the graphite crucible 7 is supported on the rotating shaft 4 via a plate 8.

The pulling chamber section 2b is configured to move the heating chamber section 2 along the pulling axis of the silicon single crystal 10 that is pulled up and grown from the silicon melt 9 formed in the quartz crucible 5.
This is a portion that extends upward from point a and has a smaller inner diameter than the heating chamber portion 2a.

Further, inside the chamber 2, there is disposed a pull-up wire 14 that hangs down from above through a part of the wall surface of the chamber tlT1, and nails a chuck 13 for holding the seed crystal 12 to the tip of the pull-up wire 14. The lifting wire 14 can be moved up and down while rotating by a wire pulling device 11 provided at the L section of the pulling chamber section 2b.

In the manufacturing apparatus 1 having such a configuration, in order to grow a single crystal, first, a predetermined amount of raw materials such as polycrystalline silicon and dopants added as necessary are loaded into the quartz crucible 5, and the heater is turned on. 6 to melt the raw material and form a melt 9. Then, the seed crystal 12 attached to the tip of the pulling wire 14 is immersed in the melt 9, and pulled up while rotating the quartz crucible 5 and the seed crystal 12.
A single crystal 10 is grown on the lower end of a seed crystal 12.

By the way, in such a single-crystal product, silicon monooxide (S i O) and the like evaporate from the high-temperature melt 9 formed in the quartz crucible 5 . If such evaporated matter condenses on the wall of the chamber 2 or the surface of the single crystal 10 that has already been pulled, and falls due to some action and reaches the growth interface of the single crystal, there is a high possibility that the crystal will become dislocated. Become something. Once the crystal has dislocations and becomes polycrystalline, it can no longer be used as a product, resulting in a significant decrease in yield. If polycrystalization occurs in the early stages of bow raising, it is possible to perform 44-metal melting and restart crystal pulling, but this will result in a large loss of time, and in addition, polycrystallization will occur during the middle to final stages of bow raising. If crystallization occurs, there is a problem with the lifespan of the crucible, etc., and remelting cannot be performed, and the crystals must be pulled out as they are. Furthermore, once polycrystallization occurs, dislocations and the like are introduced into the parts of the crystal that have already been pulled, so these parts also become quality-problematic and cannot be practically commercialized, resulting in lower productivity and lower productivity. This results in a significant decrease in yield, etc.

For this reason, conventionally, during the above-mentioned single crystal pulling operation, argon gas G as an inert gas is flowed down from the pulling chamber section 2b side to the heating chamber section 2a, and the argon gas G is sent to evaporate. Efforts have been made to suppress the occurrence of dislocations as described above by discharging substances out of the system.

However, in the single crystal pulling operation as described above, the situation changes from moment to moment as the single crystal pulling progresses. That is, the single crystal 10 grows upward, and the quartz crucible 5 rises in order to keep the liquid level of the melt 9 at a constant height. Furthermore, the single crystal body 10 to be grown and the crucible 5 are rotating, although generally in opposite directions, so that the gas introduced from above, that is, introduced from the bowing chamber section 2b side to the heating chamber section. The flow of G may change. Furthermore, as described above, in the conventional single crystal manufacturing apparatus 1, the heating chamber part 2a of the chamber 2 is relatively long in the axial direction, partly because the quartz crucible 5 moves upward therein during the pulling operation. The diameter of the heating chamber section 2a increases considerably from the first chamber section 2b to the heating chamber section 2a. Therefore, from the pulling chamber part 2b side to the heating chamber part 2
The argon gas G introduced into a does not flow with sufficient strength near the surface of the melt 9, and it not only cannot effectively remove the evaporated matter generated from the surface of the melt 9. , there is a large possibility that a vortex flow in which the evaporated matter will remain will be formed in the heating chamber section 2 . In this way, in the conventional silicon single crystal manufacturing method, the chamber 2 is used to discharge evaporated matter generated from the surface of the melt 9 to the outside of the system.
Although an inert gas is introduced into the system, the flow of this gas is not always appropriate for discharging evaporated substances out of the system.

Therefore, an object of the present invention is to provide a novel method and apparatus for producing a single crystal, which allows stable single crystal growth without the risk of dislocations occurring in the single crystal during pulling. A further object of the present invention is to provide a method and apparatus for producing a single crystal, which prevents the formation of dislocations during single-crystal production and improves productivity, yield, and product quality. .

[Means for Solving the Problems] The above methods include: 1. bringing a seed crystal into contact with a melt formed in a crucible; In a method for producing a single crystal in which a single crystal is grown by growing a single crystal, a hollow annular body having ventilation holes discretely or continuously over the entire outer periphery is formed by a tubular support internally communicating with the annular body. The annular body is supported so as to surround the single crystal at a position near the liquid surface of the melt and near the outer peripheral surface of the single crystal to be pulled, and the annular body is ventilated during the single crystal lifting operation. This is achieved by a single crystal manufacturing method characterized by causing an inert gas to flow out through the opening to form a flow of inert gas near the liquid surface of the melt from the center of the crucible to the outside. Ru.

The above-mentioned features further include a single crystal manufacturing apparatus used for growing a single crystal by bringing a seed crystal into contact with a melt formed in a crucible and pulling it, which is directed against the pulling axis direction of the single crystal. A hollow annular body with a vent hole opened at an angle within a range of 10 to 120 degrees from the melt surface side, which is connected discretely or continuously over the entire circumference, and a tubular shape that communicates with this annular body internally. The single crystal body is supported by a support body and arranged so as to surround the single crystal body at a position near the liquid surface of the melt and near the outer peripheral surface of the single crystal body to be pulled. This can also be achieved by a crystal manufacturing device.

"Function" As described above, the present invention can be used as an inert gas introduction system in transporting evaporated substances generated from F& liquid into hazardous gases and discharging them out of the system. By providing an annular air supply pipe having a ventilation hole around the entire circumference of the single crystal at a position near the liquid surface and near the outer circumferential surface of the single crystal to be pulled, and supplying air to this pipe, the melt can be cooled. A uniform gas flow from the center of the crucible to the outside is reliably formed near the liquid surface, and evaporated substances such as SiO gas generated from the raw material melt during single crystal pulling are removed from near the melt surface. Immediately discharge it from the system. This prevents the evaporated matter from condensing and crystallizing in the region where the gas remains in the chamber, becoming coarser, and forming f-1 stones on the chamber wall surface or the surface of the crystal that has already been pulled. This eliminates the occurrence of dislocations or defects caused by such evaporated substances.

Hereinafter, the present invention will be explained in more detail based on embodiments.

FIG. 1 is a sectional view schematically showing the configuration of a silicon single crystal manufacturing apparatus as an embodiment of the single crystal manufacturing apparatus of the present invention, and FIG. FIG. .

A single crystal manufacturing apparatus 1 shown in FIG. 1 has a chamber 2 consisting of a heating chamber part 2a and a pulling chamber part 2b, similar to the conventional single crystal manufacturing apparatus as described above.

Here, the pulling chamber part 2b is connected to the heating chamber part 2a along the pulling axis of the silicon single crystal 10 to be grown.
It is a portion that is extended in one direction than the heating chamber portion 2a and has a smaller inner diameter than the heating chamber portion 2a.

In addition, in this single crystal manufacturing apparatus 1, in the heating chamber part a, there is a rotating shaft extending through the bottom of the chamber from a drive device 3 located outside the chamber 2, in the same way as in conventional single crystal manufacturing apparatuses. A quartz crucible 5 supported by a shaft 4 and a cylindrical heater 6 surrounding the quartz crucible 5 at a predetermined interval are provided. The drive device 3 applies rotational force to the quartz crucible 5 via the rotating shaft 4, and
A mechanism for moving the quartz crucible 5 in the axial direction is fixed.

The outer periphery of the quartz crucible 5 is protected by a graphite crucible 7, and the graphite crucible 7 is supported on the rotating shaft 4 via a graphite support plate 8.

In addition, in the chamber 2, a seed crystal 1 is inserted into the upper wall surface of the l-shaped chamber part 2b and is attached to the tip part hanging down from above.
A pulling wire 14 having a chuck 13 for holding the pulling chamber part 2b is arranged, and the pulling wire 14 is raised and lowered while rotating by a wire pulling device 11 provided at the upper part of the pulling chamber part 2b. It is said that it is possible.

Therefore, in this single crystal manufacturing apparatus 1, as shown in FIGS. 1 and 2, the liquid near the liquid surface of the silicon melt 9 formed in the quartz crucible 5, for example, 0 on the surface
, 5-5 Q m m and a single crystal 1
0 near the outer peripheral surface, for example, 2 to 2 from the outer peripheral surface of the single crystal body 10
At a position of 50 mm, a hollow annular body 17 having a vent hole 16 is supported by a tubular support 18 that communicates with the annular body 17 inside, and is arranged so as to surround the single crystal body 10. be.

In the present invention, the vent 1 provided in this annular body 17
6, the inert gas led out from the vent 16 can form an inert gas flow from the center side of the quartz crucible 5 to the outside near the liquid surface of the melt 9. like,
This vent hole 16 is provided on the outer peripheral side of the annular body 17, and the opening angle θ (see FIG. 4) from the melt 9 side to the bowing axis direction of the single crystal body 10 is usually 10 to 120°. range,
More preferably, the angle is in the range of 30 to 90 degrees. Further, the vent hole 16 is provided all around the annular body 17 so that the inert gas can flow uniformly around the entire circumference of the quartz crucible 5, but its shape is not particularly limited. It is also possible to provide a continuous slit as shown in Figure 3a, or a third slit.
It is also possible to provide small holes discretely as shown in Figure b. Note that the size of the vent hole 6 is based on the size of the annular body 1.
7 and the diameter of the tubular support 18.
When the vent 16 is a slit, the gap width is, for example, about 0.1 to 1.5 mm, and the vent 16 is a slit.
When 6 is a small hole, its diameter is, for example, 0.1 to 1.
．． It is said to be about 5mm.

The tubular support 18 not only supports the annular body 17 having such a vent 16, but also serves as an inert gas flow path that communicates with the inside of the annular body 17. It is desirable that there be two or more. That is, inert gas is supplied from one of the tubular supports 18, passed through the inside of the annular body 17, a part of it is led out through the vent 16, and the rest is returned through the other tubular supports 18. be.

Note that the JrA award constituting the annular body 17 and the annular support 18 is usually made of quartz, although it is not particularly limited. Generally, during a single crystal pulling operation, a monitor camera (not shown) is installed outside the chamber 2 in order to obtain a single crystal 10 with a desired diameter.
Accordingly, the growth interface of the single crystal body 10 is observed through a window (not shown) provided in the upper wall surface of the heating chamber section 2a, and the annular body 17 is made of transparent quartz. Therefore, there will be no problem with implementing such diameter control.

Furthermore, in this single crystal manufacturing apparatus 1, an inert gas supply duct 15 is separately connected in the middle of the pulling chamber section 2b. Further, a gas exhaust duct (not shown) is provided in the lower part of the heating chamber section 2a.

In the single crystal manufacturing apparatus 1 of the present invention, the shapes, types, etc. of the quartz crucible 5, heater 6, drive device 3, etc. described above are not particularly limited. For example, the quartz crucible 5 is made up of an inner crucible partially having a through hole and an outer crucible surrounding the inner crucible, as seen in an apparatus for continuous single crystal pulling. A double-layered structure capable of changing the relative positional relationship of It can also be made into divided artifacts, etc. Further, as the heater 6, one using a resistance heating method or one using an induction heating method can be used. Further, in this embodiment, the quartz crucible 5 is rotated by an external drive device 3, but it is also possible to use a mode in which no such rotation means is provided, or a quartz crucible instead of the above-mentioned rotation means. It is also possible to adopt an embodiment in which a rotating magnetic field is applied to the melt 9 formed in the crucible 5 to rotate the melt 9. Furthermore, through the single crystal pulling operation,
In order to keep the amount of the melt 9 constant, it is also possible to adopt an embodiment in which a raw material supply pipe for replenishing the raw material in the crucible 5 is arranged.

A silicon single crystal is grown using the single crystal manufacturing apparatus 1 of the present invention having the configuration shown in FIG. 1 as follows.

That is, first, a predetermined amount of raw materials such as polycrystalline silicon and a dopant added as necessary are loaded into a quartz crucible 5, and heated by a heater 6 to melt the raw materials to form a melt 9. .

When starting the lifting operation, from a gas exhaust duct (not shown) connected to the lower part of the heating chamber part 2a,
The gas in the chamber 2 is discharged to the outside of the system, and argon gas G is introduced into the rechamber 2 through the inert gas supply duct 15 to make the entire interior of the chamber 2 a reduced pressure argon atmosphere or a normal pressure argon atmosphere. Note that the flow in the heating chamber section 2a of the argon gas G supplied from the inert gas supply duct 15, that is, the pulling chamber section 2a side, descends approximately along the pulling axis of the single crystal body 10, It gradually spreads laterally until reaching the vicinity of 5. Furthermore, in the present invention, the argon gas G sent through the tubular support 18 is led out into the chamber 2 from the vent 16 of the annular body 17. The argon gas G led out from this vent 16 is delivered near the silicon melt 9 formed in the quartz crucible 5.
A flow that spreads in the radial direction from the center side of the crucible 5 toward the outside, which is the arrangement of the vent holes 16, is formed uniformly around the entire circumference.

Then, the seed crystal 12 attached to the tip of the pulling wire 14 is immersed in the melt 9, and pulled up while rotating the quartz crucible 5 and the seed crystal 12.
Grow 0.

During the pulling operation, vaporized substances such as SiO are generated from the surface of the melt 9, but as mentioned above, near the surface of the melt 9,
A flow is formed that spreads in the radial direction from the center side of the crucible 5 to the outside, and the evaporated matter is carried by this flow and immediately removed from near the liquid surface of the melt 9 and discharged to the outside of the system. .

This prevents evaporated substances from staying in the chamber 2 or condensing on the surface of the chamber 2 or the single crystal 10 that has already grown.

Moreover, in this way, near the liquid surface of the melt 9, argon gas G
However, since the flow is from the center to the outside, the surface of the melt 9, which forms the growth interface of the single crystal 10, is disturbed, resulting in polycrystalization. Nor.

Note that the amount of melt decreases as the single crystal 10 grows, but as the pulling operation progresses, the quartz crucible 5 is "pushed in one direction" and the liquid level of the melt 9 is lowered. Since the height is constant, the annular body 17 having the vent hole 16 does not change its position during the pulling operation (it always exists near the surface of the melt 9).

Although the single crystal manufacturing apparatus of the present invention has been described above by taking as an example the case of pulling a silicon single crystal, the present invention can be similarly applied to a device for growing single crystals of materials other than silicon, such as germanium. Applicable.

[Example code] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Using a single crystal manufacturing apparatus as shown in FIG. 1, which is equipped with an annular body 17 having a vent hole 16 near the surface of the melt 9, a p-type crystal with a diameter of 5 inches is produced from a quartz crucible 5 with a diameter of 16 inches. A silicon single crystal was grown. The vent hole 16 formed in this annular body 17 was a continuous slit with a gear pump width of 0.8 mm and an opening angle θ of approximately 60''. Pressure inside 2 is 20mb
Argon gas G was flowed from the pulling chamber 2b side at a rate of 15 Ω/min, and argon gas was flowed from the vent of the annular body 17 at a rate of 15 Ω/min. Moreover, the pulling speed was about 1 mm/min.

On the other hand, for comparison, a single crystal manufacturing apparatus as shown in FIG. 5 having the same configuration as above except that it does not have the annular body 17 as described above was used, and a quartz crucible 5 with a diameter of 16 inches was used in the same manner as above. A p-type silicon single crystal with a diameter of 5 inches was grown from. During the pulling operation, the pressure inside chamber 2 was adjusted to 20 mb, and argon gas G was flowed from the pulling chamber side at a rate of 20 g/min. Also pull 1-
The elongation speed was approximately 1 mm/min, and in this respect, no difference was observed by 1° from the above example.

As a result, in the comparative example related to the conventional example, the polycrystallinity rate of the grown crystal was 14.6% (n-253), whereas in the example related to the method of the present invention, the polycrystallinity rate was 14.6% (n-253). It was 3.7% (n=189), and in the method of the present invention, there were multiple results! The υ conversion rate has drastically decreased. In addition, in the comparative example related to the conventional method, 8.7% of the charge was remelted even though it was successful in pulling a single crystal, but in the example related to the present invention, only 0.5% was remelted. .

As described above, the method of the present invention improved productivity and yield. Furthermore, the argon consumption was reduced by 3 g per minute, and it was also possible to reduce the IQ units of argon, which accounted for a considerable proportion of the variable costs of the pulling process.

[Effects of the Invention] As described above, the present invention provides a method for forming a hollow annular body having a vent hole around the entire outer periphery near the liquid surface of the melt in the pulling operation. The inert gas is placed in the vicinity of the outer peripheral surface of the single crystal body to be melted, and the inert gas is flowed out from the vent, so that the inert gas flows from the center of the crucible to the outside and near the liquid surface of the melt. Therefore, in order to remove evaporated substances such as SiO generated from the liquid surface of the molten liquid out of the system, and to prevent dislocations in the crystals caused by the evaporated substances, production Improvements in performance and yield can be expected. Furthermore, when raising a silicon single crystal, it is possible to exhaust SiO gas out of the system in an auxiliary manner, which has the added effect of making the oxygen level within the pulled crystal uniform. Ta.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing the structure of an embodiment of the single crystal manufacturing apparatus of the present invention, FIG. 2 is a perspective view schematically showing the main structure of the same embodiment, and FIGS. 3a and 3b 4 is an elevational view showing an example of an annular body used in the single crystal production apparatus of the present invention, and FIG. 4 is a cross section showing the opening angle θ of the vent provided in the annular body used in the single crystal production apparatus of the present invention. FIG. 5 is a sectional view schematically showing the configuration of an example of a conventional single crystal manufacturing apparatus. 1... Single crystal manufacturing device, 2... Chamber, 2a...
・Heating chamber section, 2b... Pulling chamber section, 3.
... Drive device, 4... Rotating shaft, 5... Quartz crucible,
6... Heater, 7... Graphite crucible, 8... Graphite underwriter 111 [, 9... Melt, 10... Single crystal, 1
DESCRIPTION OF SYMBOLS 1... Wire pulling device, 12... Seed crystal, 13...
...Chuck, 14...pull'', wire, 15...
Inert gas supply duct, 16... Vent, 17... Annular body, 18... Tubular support, G... Argon gas, θ... Opening angle.

Claims (2)

[Claims] (1) In a single crystal production method in which a seed crystal is brought into contact with a melt formed in a crucible and pulled up to grow a single crystal,
A hollow annular body having vent holes discretely or continuously over the entire outer periphery is supported by a tubular support that communicates with the annular body internally, and is pulled up near the liquid surface of the melt. The single crystal is placed in a position near the outer peripheral surface of the single crystal so as to surround the single crystal, and during the single crystal pulling operation, an inert gas is flowed out through the vent of the annular body to close to the liquid surface of the melt. A method for producing a single crystal, characterized by forming a flow of inert gas from the center of the crucible to the outside. (2) A single crystal manufacturing device used for growing a single crystal by bringing a seed crystal into contact with the melt formed in a crucible and pulling it, in which the melt is A hollow annular body having vent holes opened at an angle within a range of 10 to 120 degrees from the surface side, discretely or continuously over the entire circumference, is provided by a tubular support that internally communicates with this annular body. An apparatus for producing a single crystal, characterized in that the single crystal is supported and disposed near the surface of the melt and near the outer peripheral surface of the single crystal to be pulled so as to surround the single crystal.