JP2002316896A - Manufacturing apparatus and manufacturing method for silicon single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single crystal manufacturing apparatus and manufacturing method which prevent the deposition of oxides in an air exit of a growth furnace, assures a stable exhaust capacity and makes crystal growth work possible for a long period of time by surely holding a silicon melt within a growth furnace even when the silicon melt of a high temperature flows out of a crucible, and in addition, by suppressing the deposition of the oxides near on air exit of the growth furnace and preventing the degradation in the exhaust capacity of inert gas. SOLUTION: The manufacturing apparatus for growing the silicon single crystal by a Czochralski method is provided with a waste gas pipe extension member 34 so as to communicate with the air exit 31 disposed in the lower part of the growth furnace to exhaust the inert gas flowing in the growth furnace and is provided with a protective gas pipe 32 so as to enclose this waste gas pipe extension member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Czochralski method (hereinafter referred to as CZ method).
The present invention relates to a silicon single crystal manufacturing apparatus for growing a silicon semiconductor single crystal (hereinafter, referred to as a silicon single crystal) using the method, and a silicon single crystal manufacturing method using the apparatus.

[0002]

2. Related Art As an apparatus for producing a silicon single crystal using a general CZ method, there is known a production apparatus having a structure as disclosed in Japanese Patent Application Laid-Open No. 2-225393 (JP-B-6-43276). ing. FIG. 5 shows a manufacturing apparatus described in the above publication. FIG. 5 is an explanatory sectional view showing an example of a conventional silicon single crystal manufacturing apparatus.

A silicon single crystal manufacturing apparatus 1 shown in FIG.
0 has a growth furnace 12. Inside the growth furnace 12,
A quartz crucible 14 containing the silicon melt M and a graphite crucible 16 are arranged outside the quartz crucible 14 for holding and protecting the quartz crucible 14.

On the outer periphery of the graphite crucible 16, a graphite heater 18 for heating and melting the polycrystalline silicon as a raw material contained in the quartz crucible 14 to form a silicon melt M is provided. is set up. At the time of growing the silicon single crystal, power is supplied to the heater 18 from a heater electrode (not shown) provided at the lower part of the silicon single crystal manufacturing apparatus 10 to generate heat and melt the polycrystalline silicon.
The purpose is to maintain the temperature of the silicon melt M at a desired value to grow a silicon single crystal.

[0005] Further, between the heater 18 and the furnace wall 12a of the growth furnace 12, the metal furnace wall 12a is protected and the growth furnace 1 is protected.
A heat insulating material 22 made of a graphite material is placed in order to efficiently keep the inside of the device 2 warm.

On the other hand, a graphite crucible 16 disposed substantially at the center of the growth furnace 12 has a bottom portion supported by a graphite crucible support shaft 24, and a crucible shaft drive attached to a lower end portion of the crucible support shaft 24. Up and down movement by the mechanism 20,
It is designed to be rotatable. This allows the liquid surface of the silicon melt M to be maintained at a fixed position during the growth of the single crystal, and the crucibles 14 and 16 can be rotated in a desired direction and at a desired speed.

A bottom insulating material 26 is also placed on the bottom of the growth furnace 12 to prevent the bottom wall 12b of the growth furnace 12 from being exposed to a high temperature due to radiant heat of the heater 18 or the like.
It plays a role of enhancing the heat retaining effect of the breeding furnace 12.

During the growth of the silicon single crystal, oxides evaporating from the silicon melt M are deposited on the furnace wall 1 of the growth furnace 12.
In order to prevent adherence to furnace members such as 2 a and the heat insulating material 22, it is necessary to carry out crystal growth while passing an inert gas G such as argon (Ar) gas through the growth furnace 12. For this purpose, an exhaust gas pipe 28 for exhausting the inert gas G to the outside of the furnace and a pressure control device 30 for adjusting the pressure inside the growth furnace 12 are provided at the bottom of the growth furnace 12. When growing a silicon single crystal, the pressure in the furnace is adjusted to a desired value by the pressure control device 30.

When growing a silicon single crystal, impurities such as SiO (silicon monoxide) evaporating from the molten raw material M are removed from the growing furnace 1.
2 so that the evaporant does not adhere to the furnace wall 12a or the above-described furnace members arranged in the furnace, so that the growing furnace 1
2, an inert gas G such as an argon gas is supplied to the growth furnace 12 from above the silicon melt M to operate.

When the evaporant from the silicon melt M adheres to the structure in the furnace, it falls into the raw material melt M at the time of growing the single crystal to cause slip dislocation in the crystal, or the inside of the furnace provided in the growth furnace 12 A glass window (not shown) for monitoring the fogging is fogged, and it becomes impossible to observe the inside of the growth furnace.

Therefore, the inert gas G flowing from above the silicon melt (raw material melt) M is transferred to the outer wall of the graphite crucible 16 along with the evaporated material from the melt along the surface of the raw material melt M and heat-insulated. It flows under the growth furnace 12 from between the materials 22, and is finally discharged to the outside from an exhaust gas pipe 28 provided at the bottom of the growth furnace. By forming such a flow of the inert gas G, the adhesion of oxides above the growth furnace 12 is suppressed, and the evaporated matter from the melt is efficiently discharged to the outside.

Further, the pressure inside the growth furnace 12 is set to 50 to
By operating while maintaining a reduced pressure of about 500 hPa, oxides such as SiO evaporated from the raw material are hardly adhered to walls and members in the furnace, and silicon single crystal is manufactured.

At this time, the exhaust gas pipe 28 of the growth furnace 12 is generally made of a metal pipe such as stainless steel. A lower part of the growth furnace 12, for example, an exhaust port 31 opening to the bottom wall 12 b, is provided with a cylindrical protective gas pipe 32 having a gas inlet 33 at an upper part and having an open bottom part. The protective gas pipe 32 is made of a graphite material having excellent heat resistance because it is exposed to a high temperature.
However, on the other hand, a temperature difference is apt to occur near the connection between the protective gas pipe 32 made of graphite material and the exhaust gas pipe 28 made of metal because of the high thermal conductivity of the metal, and the gas flows from the inside of the growth furnace 12. The inert gas G is rapidly cooled in the vicinity of the connection, and tends to precipitate in the vicinity of the connection and deposit and deposit as a precipitate D as shown in FIG.

The provision of the protective gas pipe 32 made of graphite so as to stand upright in the furnace is performed as described in Japanese Patent Publication No. 6-43276 in order to protect the exhaust port 31 and to provide a raw material. This is to prevent the melt M from leaking out of the growth furnace 12 in the event of an accident such as leakage.

[0015]

As described above, when the oxide adheres and accumulates near the connecting portion between the exhaust gas pipe 28 and the protective gas pipe 32, the inside of the exhaust gas pipe 28 is narrowed and the inert gas G is reduced.
Of the inert gas G flowing through the growth furnace 12
Does not flow smoothly, so that oxides easily adhere to walls and structures in the furnace, or hinder the operation of an exhaust pump (not shown) of the silicon single crystal manufacturing apparatus 10 and generate extra power. There are problems such as consumption.

Further, when the amount of oxides attached in the growth furnace 12 increases, the oxides fall into the silicon melt M to hinder crystal growth, and the window for observing the inside of the furnace becomes cloudy. In the production of silicon single crystals, there are adverse effects such as the inability to observe the crystal and the continuation of operation becomes difficult.
How to prevent this oxide from adhering to the inside of the growth furnace 12 is an important problem in performing a stable operation for a long time.

In addition, in growing a silicon single crystal, as described above, the inside of the growth furnace 12 is maintained at a reduced pressure, and the pressure and the amount of inert gas in the furnace are adjusted to adjust the impurities (mainly, impurities) taken into the crystal. It is necessary to grow the crystal while controlling the oxygen (eluted from the quartz crucible 14) to a desired value, etc. In order to obtain a single crystal of stable quality, it is necessary to stabilize the exhaust capacity during operation. It is also an important requirement to achieve this.

The present invention has been made in view of the above-mentioned problems in the conventional silicon single crystal manufacturing technique, and ensures that even when a high-temperature silicon melt flows out of a crucible, the silicon melt is reliably introduced into the growth furnace. In addition to holding the oxide, the deposition and accumulation of oxides near the exhaust port of the growth furnace are suppressed, and the reduction of the inert gas exhaustion capacity is prevented, thereby preventing the adhesion of oxides in the growth furnace and ensuring stable operation. It is an object of the present invention to provide a silicon single crystal manufacturing apparatus and a manufacturing method capable of securing a reduced evacuation capacity and enabling a crystal growth operation for a long time.

[0019]

In order to solve the above-mentioned problems, an apparatus for producing a silicon single crystal according to the present invention is a production apparatus for growing a silicon single crystal by the Czochralski method. An exhaust gas pipe extension member is provided so as to communicate with an exhaust port provided at a lower portion of the growth furnace for exhausting gas, and a protective gas pipe is provided so as to surround the exhaust gas pipe extension member. The lower part of the growth furnace means a part below the silicon melt surface held in a crucible provided inside the growth furnace.

A first feature of the apparatus of the present invention is that an exhaust gas pipe connected to an exhaust port formed on the bottom wall of the growth furnace is extended to the inside of the growth furnace either integrally with or separately from the exhaust gas pipe. An extended exhaust gas pipe portion, that is, an exhaust gas pipe extension member is provided, and a protective gas pipe is covered to protect the radiant heat from a heater or the like.

By extending the exhaust gas pipe to the inside of the growth furnace and providing an exhaust gas pipe extension member, a temperature change near the exhaust port of the exhaust gas pipe of the growth furnace is reduced, and oxides are deposited around the exhaust port. Deposition can be suppressed. As a result, a stable pumping capacity can be secured, and a long-term crystal growth operation can be stably performed. Also,
Since the contamination of the exhaust gas pipe due to the adhesion of oxides is also reduced
It is also possible to reduce the maintenance work of the manufacturing equipment after the end of the manufacturing work (eg, the work of removing oxides attached to the inside of the growth furnace).

The exhaust gas pipe extension member may be disposed inside the protective gas pipe, and its dimensions are not particularly limited, but the height of the exhaust gas pipe extension member is determined by adjusting the height of the protection gas pipe. Is preferably in the range of 30% to 80% of the height.

When the height of the exhaust gas pipe extension member is 30% or less of the height of the protective gas pipe, the protruding portion into the furnace is short.
Although the amount of deposited oxide is much smaller than when the exhaust gas pipe extension member is not provided, a certain amount of oxide adheres to the inside of the protective gas pipe, so that the oxide cannot be sufficiently prevented from adhering. On the other hand, if the length is increased to more than 80%, the temperature is likely to be affected by the high temperature atmosphere inside the growth furnace, and the possibility that the upper end of the extended portion of the exhaust gas pipe is melted increases. For this reason, the length of the exhaust gas pipe extension
(Height) is 30-80% of the length (height) of the protective gas pipe
It is preferable to be within the range.

The exhaust gas pipe extension member may be formed integrally with the exhaust gas pipe, that is, may be formed by extending the exhaust gas pipe. However, it is formed separately from the exhaust gas pipe, and is detachably attached to the exhaust port of the exhaust gas pipe. It is preferable to provide them so that they can communicate with each other.

After the production of the single crystal is completed, the members inside the growth furnace are temporarily removed for maintenance work such as removing oxides adhered to the inside of the growth furnace and replacing consumable parts in the furnace. It is necessary to take it out and disassemble it.At this time, if the exhaust gas pipe extension member can be removed, maintenance work becomes easier, and oxides and silicon deposits adhered to the exhaust gas pipe extension member Etc. can be easily removed, and workability can be improved.

Further, since the exhaust gas pipe extension member exposed to high temperature is easily deteriorated, it can be easily replaced with a new one if necessary by forming it separately from the exhaust gas pipe.
This leads to an increase in the reliability of the device.

In order to facilitate dismantling of the hot zone parts near the exhaust port during maintenance work of the growth furnace, an exhaust pipe extension member extending into the furnace and a protective gas pipe for protecting the exhaust pipe extension member are provided. Preferably, a gap of about 1 mm to 3 mm is provided between them.
By providing a gap between the exhaust gas pipe extension member and the protective gas pipe, silicon vapor deposition and oxides are firmly attached and the protective gas pipe and the exhaust gas pipe extension member cannot be removed.
Alternatively, it is possible to prevent the protection gas pipe from being damaged due to thermal expansion.

The inner diameter of the exhaust pipe extension member is not particularly limited, but may be the same as the inner diameter of the exhaust pipe.
As long as the exhaust capacity of the exhaust gas pipe is not impaired, it can be smaller than the inner diameter of the exhaust gas pipe.

As the material of the exhaust gas pipe and the exhaust gas pipe extension member, a material having high strength, high heat resistance, and high corrosion resistance is preferable. Steel or carbon steel is suitable. Since these metal materials have high thermal conductivity, heat in a portion exposed to a high temperature is easily released, and also has an effect of suppressing the temperature of the metal material itself from becoming high due to radiant heat. It is most practical to use stainless steel in view of cost and the like. On the other hand, as a material of the protective gas pipe, a graphite material which has excellent heat resistance and is not easily eroded by a high-temperature silicon melt is preferable.

According to the method for producing a silicon single crystal of the present invention, when the silicon single crystal is grown by the Czochralski method while flowing an inert gas by using the above-described apparatus for producing a silicon single crystal of the present invention, A stable exhausting ability is secured by suppressing the deposition and deposition of the oxide in the vicinity of the exhaust port, and a long-term crystal growth operation can be stably performed.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a silicon single crystal manufacturing apparatus according to the present invention will be described below with reference to FIGS. Although described below, the present invention is not limited to these. For example, an apparatus and a method for manufacturing a silicon single crystal according to the present invention employ a MCZ method (Magnetic Field Appl.
Naturally, it can be used even in the production of a silicon single crystal using the ied Czochralski Method (magnetic field pulling method). 1 to 4, the same or similar members as those in FIGS. 5 and 6 are denoted by the same reference numerals.

FIG. 1 is a schematic sectional explanatory view of one embodiment of a silicon single crystal manufacturing apparatus according to the present invention. The basic configuration of the silicon single crystal manufacturing apparatus 10a of the present invention shown in FIG. 1 is the same as that of the conventional silicon single crystal manufacturing apparatus 10 shown in FIG. I do.

An apparatus 10a for producing a silicon single crystal according to the present invention
Then, the conventional silicon single crystal manufacturing apparatus 1 shown in FIG.
Similarly to 0, an inert gas G is supplied from above the growth furnace 12 by a gas supply device (not shown) from above the silicon melt M melted by the heater 18. And
The inert gas G is placed at the lower part of the growth furnace 12 after flowing along the surface of the silicon melt M, downstream of the gap between the graphite crucible 16 and the heater 18 and between the heater 18 and the heat insulating material 22. The gas is discharged to the outside of the growth furnace 12 through an exhaust gas pipe 28 from a gas introduction part 33 of a protective gas pipe 32 provided to stand upright from the lower heat insulating material 26.

At this time, in the silicon single crystal manufacturing apparatus 10a of the present invention, the lower part of the growth furnace 12, for example, the bottom wall 12b
The exhaust gas pipe 28 connected to the exhaust port 31 formed in the furnace is extended to the inside of the growth furnace 12 integrally or separately from the exhaust gas pipe 28 (in the example of FIG. The extended exhaust gas pipe portion, that is, the exhaust gas pipe extension member 34 is provided, and a protective gas pipe 32 is provided to protect the radiant heat from the heater 18 and the like.

By extending the exhaust gas pipe 28 to the inside of the growth furnace 12, the extended portion of the exhaust gas pipe 28 is
Heated by the radiant heat inside, the temperature change in the vicinity of the exhaust port 31 of the exhaust gas of the exhaust gas pipe 28 is reduced, and the rapid cooling of the inert gas G flowing from the growth furnace 12 into the exhaust gas pipe 28 is suppressed. Therefore, it becomes difficult for the oxide to be deposited near the exhaust port 31, and it is possible to suppress the occurrence of deposition. As a result, the inner diameter of the exhaust gas pipe 28 due to the deposition of oxides is reduced, and the occurrence of an obstacle to the exhaust of the inert gas G is reduced. As a result, a stable exhaust capability is secured, and the crystal growth operation for a long time is stabilized. You can do it.

Further, since the rapid temperature change of the exhaust gas is reduced, the deposition of oxides and silicon near the exhaust port 31 is reduced, and the burden of maintenance work of the manufacturing equipment after the end of the manufacturing work is also reduced. You.

At this time, the height h of the exhaust gas pipe extension member 34 which is an extension of the exhaust gas pipe extending into the protection gas pipe 32 is set.
Considering the effect of the radiant heat from the inside of the growth furnace 12 and the effect of reducing the temperature of the exhaust gas pipe extension member 34, the height of the protective gas pipe 32 is set to be 30% to 80% of the height H. It is preferable to arrange them.

The reason for this is that the exhaust gas pipe extension member 34
May be disposed inside the protective gas pipe 32, and there is no particular limitation on the length extending into the protective gas pipe 32. When the height h is as low as 30% or less of the height H of the protective gas pipe 32, the portion protruding into the growth furnace 12 is short, so that the effect of reducing the temperature is small. Will be formed. Thereby, the amount of the attached oxide can be suppressed as compared with the case where the exhaust gas pipe extension member 34 is not provided. However, in order to obtain a sufficient suppression effect, the height h of the exhaust gas pipe extension member 34 is set to the height of the protective gas pipe 32. It is preferable to provide a length of 30% or more with respect to H.

On the other hand, even if the height h of the exhaust gas pipe extension member 34 is increased more than necessary, the height h of the exhaust gas pipe extension member 34 is reduced by the protection gas because the height of the exhaust gas pipe extension member 34 is easily affected by the radiant heat inside the growth furnace 12. It should be less than 80% of the height H of the tube 32.

When the height h of the exhaust gas pipe extension member 34 exceeds 80% of the height H of the protective gas pipe 32, the tip of the exhaust gas pipe extension member 34 is heated by radiant heat inside the growth furnace 12 and melted. May occur. Exhaust gas pipe extension member 3
4, the height h of the exhaust gas pipe extension member 34 is 80
%, The effect can be sufficiently obtained.

For the above reasons, in the apparatus for manufacturing a silicon single crystal of the present invention, the height h of the exhaust gas pipe extension member 34 is set in the range of 30% to 80% with respect to the height H of the protective gas pipe 32. Is desirable.

It is preferable that the height of the protective gas pipe is appropriately determined according to the amount of the silicon melt held in the crucible and the space below the manufacturing apparatus. The silicon melt flows out of the crucible and is held at the bottom of the growth furnace. In this case, the height may be set so that the gas does not flow out of the furnace through the gas inlet of the protective gas pipe.

The exhaust gas pipe extension member 34 may be formed integrally with the exhaust gas pipe 28 as shown in FIG. 4, that is, so as to extend the exhaust gas pipe 28 inside the growth furnace 12. As is often shown, it may be formed separately from the exhaust gas pipe 28 so as to be detachably connected to the exhaust port 31 of the growth furnace 12.

After the single crystal is manufactured, oxides adhered to the furnace internal members such as the furnace wall 12a of the growth furnace 12, the heat insulating material 22, the heater 18, the bottom heat insulating material 26 and the like during the crystal growth are removed. In order to perform maintenance work such as replacement of the furnace, it is necessary to take out the in-furnace components provided inside the growth furnace 12 to the outside of the furnace and remove oxides. At this time, if the exhaust gas pipe extension member 34 is made detachable, the protrusions from the growth furnace bottom wall 12b are eliminated, so that the maintenance work becomes easy, and the extension part of the exhaust gas pipe 28 to the growth furnace 12, That is, it becomes easy to remove oxides and silicon deposits adhering to the exhaust gas pipe extension member 34 and the exhaust port 31 of the exhaust gas pipe 28, thereby improving workability and improving efficiency.

Furthermore, since the exhaust gas pipe extension member 34 is always located at a position where it is exposed to high temperatures, it tends to deteriorate.
Since replacement may be required depending on the degree of deterioration, it is possible to increase the reliability of the manufacturing apparatus and reduce maintenance costs by adopting a structure that can be easily replaced.

Further, in order to facilitate the removal of the furnace internal members around the exhaust port 31 during the maintenance operation of the growth furnace 12, the exhaust gas pipe extension member 34 extending into the growth furnace 12 and the protection gas pipe 32 are disposed. Alternatively, the exhaust gas pipe extension member 34 and the protective gas pipe 32 may be provided with some gap. The gap at this time is preferably such that a gap of about 1 mm to 3 mm is formed between the exhaust gas pipe extension member 34 and the protective gas pipe 32. By providing such a gap, for example, damage due to thermal expansion or By depositing the silicon evaporated from the silicon solution M during operation, the exhaust gas pipe extension member 34 and the protective gas pipe 32 can be prevented from being in close contact with each other.

The inner diameter of the exhaust gas extension member 34 is not particularly limited, but may be the same as the inner diameter of the exhaust gas pipe 28 as shown in FIG. 4 or as long as the exhaust capacity of the exhaust gas pipe 28 is not impaired. As shown in FIGS. 1 to 3, the inner diameter of the exhaust gas pipe 28 can be made smaller. The thickness and the inner diameter of the exhaust gas extension member 34 may be selected according to the inner diameter of the protective gas pipe 32 and the inert gas exhaust capacity of the manufacturing apparatus.

The material of the exhaust gas pipe 28 and the exhaust gas pipe extension member 34 is preferably a material that has high strength, withstands the high temperature of the growth furnace 12, and is resistant to erosion by evaporation from the silicon melt M. As such a material, a high melting point metal such as molybdenum, tungsten, tantalum, or titanium having a high melting point, an alloy containing these as a main component, or stainless steel is suitable. It is also preferable to use carbon steel or the like.

These metallic materials have a high thermal conductivity, so that the heat brought to the exhaust gas pipe extension member 34 extending into the growth furnace 12 is quickly transmitted to the lower exhaust gas pipe 28, and abruptly near the exhaust port 31. It has the effect of correcting any temperature changes. The exhaust gas pipe extension member 34 formed of such a metal material can also prevent itself from becoming hot due to its good thermal conductivity. Particularly, considering the cost and workability of the exhaust gas pipe extension member 34, it is practical to use stainless steel as the material of the exhaust gas pipe extension member.

On the other hand, as the material of the protective gas pipe 32 disposed outside the exhaust gas pipe extension member 34, it is preferable to use the same graphite material as the in-furnace member disposed inside the growth furnace 12. The silicon melt M accommodated in the growth furnace 12 is heated to a temperature of 1420 ° C. or more, which is the melting point thereof. A material that is also resistant to erosion is desirable. Graphite is the most suitable material for the protective gas pipe 32 in consideration of these factors.

Next, a method for producing a silicon single crystal by the CZ method of the present invention using the above-described apparatus for producing a silicon single crystal of the present invention will be described. First, a quartz crucible 14 placed inside a growing furnace 12 of a silicon single crystal manufacturing apparatus 10a is filled with a polycrystalline silicon lump, and the growing furnace 12 of the silicon single crystal manufacturing apparatus 10a is filled with an inert gas G such as an argon gas. Then, the polycrystalline silicon is heated to 1420 ° C. or higher, which is the melting point of silicon, by heating the heater 18 placed outside the graphite crucible 16 to obtain a silicon melt M.

At this time, an inert gas G is constantly supplied to the growth furnace 12 so that oxides such as SiO vaporized from the silicon melt M do not precipitate and adhere to the low-temperature portion inside the growth furnace 12. The evaporant from the silicon melt M is discharged to the outside of the growth furnace 12 while flowing to the growth furnace 12 to grow the silicon single crystal S.

This is because the crystal quality is adjusted to a desired value by always keeping the inside of the growth furnace 12 clean with the inert gas G, and at the same time, oxides and the like adhering to the inside of the growth furnace 12 fall into the silicon melt M. This is to prevent the generation of dislocations in the growing crystal so that stable crystal growth can be performed.

When all the polycrystalline silicon contained in the quartz crucible 14 has been dissolved, the temperature of the silicon melt M is adjusted to a temperature suitable for the growth of silicon single crystal and stabilized, and a pulling wire (not shown) Gently unwind
The tip of a seed crystal (not shown) attached to the seed holder is brought into contact with the surface of the silicon melt M. Then, while rotating the graphite crucible 16 and the seed crystal in opposite directions, the seed crystal brought into close contact with the silicon melt M is wound up by a pulling wire and gradually pulled up, so that the silicon single crystal is placed below the seed crystal. Is to grow.

In the production of the method of the present invention, since the silicon single crystal production apparatus 10a of the present invention is used, the silicon single crystal is grown by the Czochralski method while flowing the inert gas G. Exhaust port 31
The deposition and deposition of oxides in the vicinity can be suppressed,
Therefore, a stable exhaust capacity of the exhaust gas pipe 28 is secured,
A long-term crystal growth operation can be stably performed.

[0056]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention.

Example 1 A manufacturing apparatus similar to the silicon single crystal manufacturing apparatus of the present invention shown in FIGS.
A quartz crucible of 5 cm is placed, 60 kg of polycrystalline silicon as a raw material is charged into the quartz crucible, and a heater is heated to generate a silicon melt. When the melt temperature is stabilized, the tip of the seed crystal is brought to the surface of the silicon melt. Then, the seed crystal was gently pulled up above the melt, thereby pulling a silicon single crystal having a diameter of 150 mm below the seed crystal.

In the apparatus for producing a silicon single crystal of the present invention shown in FIG. 1 used in this production, the exhaust pipe extension member shown in FIG. 2 has a height (h) of 90 mm and an outer diameter of 58 m.
m were installed and used in communication with the exhaust port. The height (H) of the protective gas pipe surrounding the exhaust gas pipe extension member in the furnace was 150 mm, and the inner diameter of the protective gas pipe was 60 mm, the same as the inner diameter of the exhaust gas pipe.

Then, the production of the single crystal was repeated under substantially the same conditions as the growth conditions of the silicon single crystal described above, and the amount of the oxide adhered to the exhaust gas pipe or the protective gas pipe (exhaust gas pipe, protective gas pipe, exhaust gas pipe extension member) , The thickness of the deposited oxide at the portion where the oxide was most attached) was measured, and the results are shown in Table 1. Table 1 shows the measurement of the amount of attached oxide (maximum thickness) at the end of the production of the single crystal at around 100 hours.

As a result, the structure of the exhaust gas pipe was extended to the inside of the growth furnace by the exhaust gas pipe extension member, so that the adhesion of oxides near the exhaust port of the exhaust gas pipe and inside the exhaust gas pipe extension member was almost observed. Instead, it was observed that a small amount of oxide adhered to the protective gas pipe covering the exhaust gas pipe extension member as shown in FIGS.

However, as a whole, the amount of deposited oxide is extremely small, the amount of deposition is about 1 to 2 mm when used for about 100 to 200 hrs, and almost no silicon deposits are seen. Things could be easily removed.

Therefore, it was confirmed that the use of the manufacturing apparatus of the present invention can suppress the accumulation of oxides even during long-time operation, and can continue the operation without lowering the exhaust efficiency.

Comparative Example 1 A quartz crucible having a diameter of 45 cm was placed in a growth furnace in a conventional silicon single crystal manufacturing apparatus shown in FIGS. It was charged and heated and melted to pull up a silicon single crystal having a diameter of 150 mm. In this conventional silicon single crystal manufacturing apparatus, an exhaust gas pipe extension member is not used, and only a protective gas pipe having a height (H) of 150 mm and an inner diameter of 60 mm is disposed at the tip of the exhaust gas pipe.

Using this conventional silicon single crystal manufacturing apparatus, the above-described silicon single crystal was repeatedly manufactured, and the amount of oxides attached to the exhaust gas pipe or the protective gas pipe was measured in the same manner as in Example 1. The results are shown in Table 1 similar to Example 1.

In the test according to Comparative Example 1, in the exhaust gas pipe having the conventional structure, the oxide was deposited up to about 4 mm at the maximum portion inside the protective gas pipe near the exhaust port at about 100 hrs, and about 8 mm at 200 hrs. It was confirmed that it reached. In addition, a large amount of silicon deposits adhere to the surface in addition to the oxides, and it takes time and trouble to remove these deposits during maintenance work of the manufacturing apparatus.

In such a state, it is necessary to clean the exhaust gas pipe every time the manufacturing apparatus is stopped in order to secure a stable exhaust capacity. In particular, a multiple pulling method for pulling a plurality of single crystals from one crucible while refilling the crucible with raw materials without stopping the manufacturing apparatus (Multiple Cz method).
In the single crystal growth using the ochralski method), 100
Since the operation of the manufacturing equipment may be continued for a long time of more than hrs, in order to enable a further long-time operation,
It was confirmed that it was necessary to reduce the adhesion of oxides to the exhaust gas pipe.

[0067]

[Table 1]

[0068]

As described above, according to the present invention, in addition to reliably preventing the high-temperature silicon melt from flowing out of the growth furnace, the deposition and deposition of oxide near the exhaust port of the growth furnace By preventing the exhaust pipe from lowering the inert gas exhaust capacity by the exhaust pipe, it prevents oxides from adhering in the growth furnace and secures a stable exhaust capacity, stabilizing the crystal growth work over a long time. The great effect that it can be performed is achieved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional explanatory view showing one embodiment of an apparatus for producing a silicon single crystal of the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is an enlarged sectional view showing the exhaust gas pipe extension member shown in FIG. 2;

FIG. 4 is a cross-sectional view similar to FIG. 2, showing another example of an exhaust gas pipe extension member according to the present invention.

FIG. 5 is a schematic cross-sectional explanatory view showing one example of a conventional silicon single crystal manufacturing apparatus.

FIG. 6 is an enlarged sectional view of a main part of FIG.

[Explanation of symbols]

10: conventional silicon single crystal manufacturing apparatus, 10a: silicon single crystal manufacturing apparatus of the present invention, 12: growing furnace, 12a: furnace wall, 12b: bottom wall, 14: quartz crucible, 16: graphite crucible, 18: Heating heater, 20: crucible shaft drive mechanism,
22: heat insulating material, 24: crucible support shaft, 26: bottom heat insulating material, 28: exhaust gas pipe, 30: pressure control device, 31: exhaust port, 32: protective gas pipe, 33: gas inlet, 34: exhaust gas pipe extension Member, 34b: extension member connection, G: inert gas, M: silicon melt.

Claims (5)

[Claims] In a manufacturing apparatus for growing a silicon single crystal by the Czochralski method, an exhaust gas pipe communicates with an exhaust port provided at a lower portion of the growth furnace for exhausting an inert gas flowing in the growth furnace. An apparatus for producing a silicon single crystal, wherein an extension member is provided and a protective gas pipe is provided so as to surround the exhaust gas pipe extension member. 2. The apparatus for producing a silicon single crystal according to claim 1, wherein the height of the exhaust gas pipe extension member is in the range of 30% to 80% of the height of the protective gas pipe. 3. The silicon unit according to claim 1, wherein the exhaust gas pipe extension member is formed separately from the exhaust gas pipe, and is detachably connected to an exhaust port of the exhaust gas pipe. Crystal manufacturing equipment. 4. The exhaust gas pipe and the exhaust gas pipe extension member are formed of a high melting point metal such as molybdenum, tungsten, and tantalum, stainless steel or carbon steel, while the protective gas pipe is formed of a graphite material. The apparatus for producing a silicon single crystal according to claim 1. 5. When the silicon single crystal is grown by the Czochralski method while flowing an inert gas by using the silicon single crystal manufacturing apparatus according to claim 1, the exhaust gas is exhausted. A method for producing a silicon single crystal, characterized in that the deposition and deposition of oxides in the vicinity of the mouth are suppressed to ensure a stable exhaust capability of the exhaust gas pipe, and a long-term crystal growth operation can be performed stably. .