JP2002068888A - Method of disassembling semiconductor single crystal pulling device and piping for exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of disassembling a silicon single crystal pulling device, by which an activated silicon oxide accumulated in a piping for an exhaust gas can be made inert so as to prevent a small ignition at the time of cleaning work of the inside of the piping for the exhaust gas when the silicon single crystal pulling device is disassembled, and to provide a piping for the exhaust gas, whose inside can be easily cleaned. SOLUTION: The method of disassembling the silicon single crystal pulling device comprises introducing at least one time air into a chamber and/or the piping for the exhaust gas before disassembling the chamber, insulating the chamber from the outside, exhausting the introduced air, and disassembling the chamber. The piping for the exhaust gas is used in the silicon single crystal pulling device, and a leak valve is installed to the piping for the exhaust gas, and the whole body of the piping is formed using electro-conductive tubes and an earth is attached to the piping.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dismantling a silicon single crystal pulling apparatus and an exhaust gas pipe.

[0002]

2. Description of the Related Art A silicon single crystal wafer used as a substrate of a semiconductor integrated circuit is manufactured by a Czochralski method (CZ).
) To produce a silicon single crystal. Here, a conventional CZ method silicon single crystal pulling apparatus illustrated in FIG. 2 and its exhaust gas piping will be described.

[0003] The silicon single crystal pulling apparatus 1 comprises a chamber in which a pull chamber 2 and a main chamber 3 are connected via a gate valve 4, and has a structure in which an exhaust gas pipe 6 is connected to a lower part of the main chamber 3.

A quartz crucible (not shown) installed in the main chamber 3 is filled with polycrystalline silicon as a raw material,
The quartz crucible is held by a graphite crucible and heated by a cylindrical graphite heater provided on the outer periphery of the quartz crucible to melt the polycrystalline silicon. Then, a wire is drawn out from a crystal winding mechanism (not shown) at the upper part of the pull chamber 2 to obtain a single crystal. The seed crystal is immersed in the silicon melt, and while rotating the quartz crucible and the seed crystal in opposite directions, the seed crystal is pulled up from the silicon melt and a single crystal can be grown to a desired diameter and length. I have.

During the pulling of the single crystal, an inert gas such as argon is introduced from the upper part of the pull chamber 2 to eliminate reaction products such as silicon oxide, thereby preventing the single crystal from being contaminated. The exhaust gas is exhausted by the exhaust gas pipe 6. The exhaust gas pipe 6 is connected with an exhaust ball valve 15, a vacuum pump 11, a blower 12, and the like, and finally discharges the exhaust gas into the atmosphere. As the exhaust gas pipe 6 after the vacuum pump, plastic pipes such as vinyl chloride or flexible pipes made of plastic are used in large quantities, and there are many elbows 13 (bent portions) that avoid the utility pipes 14.

The pulled single crystal rod is drawn into the pull chamber 2, closes the gate valve 4 and is cut off from the main chamber 3. Thereafter, after cooling, the wafer is carried out of the pull chamber door 5 for pulling out a single crystal rod provided in the pull chamber 2 to the outside of the chamber. Alternatively, the single crystal rod can be taken out from the pull chamber door 5 after the furnace temperature is cooled to a predetermined temperature after the completion of the single crystal production.

After the removal of the single crystal rod, during the growth of the single crystal, silicon adhered to the furnace equipment (hereinafter sometimes referred to as a hot zone) such as a pulling apparatus chamber, a crucible, a heater, a heat insulating material or mainly to an exhaust gas pipe. Oxide removal, replacement of consumable parts, etc. are performed, and disassembly and maintenance work of the single crystal pulling apparatus is started in preparation for the next pulling.

First, the pull chamber 2 is moved to the side of the pulling device, and then the main chamber 3 is moved to the side of the pulling device. Next, the in-furnace members such as crucibles, heaters, and heat insulating materials are carried out of the pulling apparatus, disassembled, and cleaned, maintained, and replaced. After completion of these operations, the furnace inner member is moved to the original position of the pulling device in the reverse order to the above, assembled, the main chamber 3 is returned to the original position, a predetermined crucible and raw materials are charged, and finally the main chamber 3 The pull chamber 2 is installed on the upper side to complete the maintenance and preparation, and prepare for the next pulling of the single crystal.

During the growth of the single crystal, the inner surface of the quartz crucible is eroded by the silicon melt, and quartz (SiO ₂ ) and silicon (Si) react to produce silicon oxide (SiO _x , hereinafter referred to as active silicon oxide). ) Is vaporized from the surface of the melt as a gas of active silicon oxide.
The vaporized active silicon oxide is mixed with an inert gas flowing from the upper portion of the melt, and discharged out of the furnace through the exhaust gas pipe 6 by the vacuum pump 11. When exhausting the inert gas containing the vaporized active silicon oxide, the gaseous active silicon oxide comes into contact with a relatively low-temperature member in the furnace and is cooled, and further contacts the inner surface of the low-temperature exhaust gas pipe 6. Then, it becomes dust and adheres and accumulates there. Since the growth of a silicon single crystal having a crystal growth rate of about 1 mm / min requires a long time, a large amount of active silicon oxide is generated during the production of the single crystal, and adheres to the inner surface of an exhaust gas pipe for exhausting mainly inert gas. As a result, a deposited layer having a thickness of several mm is formed.

[0010]

As described above, the active silicon oxide deposited in the exhaust gas pipe remains in a powdery state at a high temperature for a while after the completion of the growth of the single crystal. There was a risk of fire when reacted. For this reason, the exhaust gas pipe is provided with a depressurizing valve or the like in order to cope with it. However, when the inside of the exhaust gas pipe is cleaned, a small fire may occur locally. For this reason, part of the piping was sometimes damaged.

The present invention has been made in view of such a conventional problem, and is intended to prevent such a small ignition in the disassembly of a single crystal pulling apparatus, particularly in a cleaning operation of an exhaust gas pipe. A method for dismantling a silicon single crystal pulling apparatus capable of disassembling a chamber after inactivating active silicon oxide deposited in an exhaust gas pipe, and reducing the deposition of active silicon oxide in the pipe, Another object of the present invention is to provide an exhaust gas pipe that can easily clean the inside of the pipe.

[0012]

According to the present invention, there is provided a method for disassembly of a silicon single crystal pulling apparatus according to the present invention, comprising the steps of: The method is characterized in that air is introduced into the chamber and / or the exhaust gas pipe at a time, and after shutting off from the outside world, the introduced air is exhausted and then the chamber is disassembled.

[0013] In this case, the air introduced into the chamber and / or the exhaust gas pipe is forcibly exhausted through the exhaust gas pipe. Therefore, the active silicon oxide deposited on the inner surface of the exhaust gas pipe is particularly air. Hydrogen gas generated by reacting with the moisture in the air at the same time as being oxidized into an inert silicon oxide is sufficiently diluted by the introduced air flow and exhausted without staying in the pipe, so that the chamber and / or Most of the ignition factors in the exhaust gas pipe can be eliminated. Therefore, the subsequent disassembly of the chamber and the cleaning of the exhaust gas pipe can be performed extremely safely.

In this case, it is preferable to use a leak valve of an exhaust gas pipe for introducing the air. In this way, the air is directly blown into the entire exhaust gas pipe, and the deactivation reaction of the active silicon oxide deposited on the inner surface of the exhaust gas pipe proceeds easily, so that the inert silicon oxide is efficiently converted to the inert silicon oxide. Can be. Also, compared to opening and closing the pull chamber door for taking out the single crystal rod and introducing air, the operation of introducing air into the exhaust gas pipe can be performed with a simple operation, which has the advantage of shortening the operation time. is there.

In the exhaust gas piping of the silicon single crystal pulling apparatus according to the present invention, a leak valve is provided in the exhaust gas piping. By doing so, air can be easily introduced into the exhaust gas pipe to deactivate the active silicon oxide as described above.

In this case, it is preferable that the entire exhaust gas pipe is piped with a conductor pipe, and the conductor pipe is provided with a grounding earth. With this configuration, static electricity that may be generated in the conductor tube can be quickly removed, and the possibility of ignition in the conductor tube can be further reduced.

In this case, it is preferable that the exhaust gas pipe is a seamless pipe without any joints. With this configuration, since there is no unevenness or surface roughness due to the seam in the exhaust gas pipe, the amount of active silicon oxide deposited on the pipe inner surface can be reduced.

In this case, it is preferable that a blind cover is provided at an elbow portion of the exhaust gas pipe. In this way, inspection (for example, observation of the adhesion state of active silicon oxide) in the exhaust gas pipe and cleaning work accompanying the dismantling work of the silicon single crystal pulling apparatus can be easily performed. No leftovers occur.

[0019]

DETAILED DESCRIPTION OF THE INVENTION The inventors of the present invention have found that ignition is mainly caused by the reaction between active silicon oxide and water (water vapor) in the air when the silicon single crystal pulling apparatus is disassembled or when exhaust gas piping is cleaned. It was presumed that hydrogen gas would be generated, and this was confirmed in the following surveys and experiments.

Before growing the silicon single crystal, a sampling trap (sealable container) is attached in the middle of the exhaust gas pipe, and active silicon oxide is deposited on the inner surface of the trap during the growth of the single crystal. The furnace gas containing active silicon oxide unreacted with the furnace was collected in the trap, and pure water was introduced into the trap to cause a reaction. As a result, hydrogen having a high concentration of about 16000 ppm was detected. The lower limit of the concentration range in which hydrogen in air burns is 4
% (40000 ppm), it is understood that there is a high risk of ignition and burning depending on the conditions.

In order to avoid the danger of igniting the active silicon oxide in the exhaust gas pipe, the active silicon oxide is sufficiently oxidized by oxygen or moisture in the air and the
It is important from O _X changes to stabilize an inactive SiO _2. However, if the active silicon oxide is rapidly oxidized before being cooled, it is considered that there is a high possibility that the generated hydrogen is ignited by the heat of the oxide. Therefore, it is necessary to quickly remove the generated hydrogen.

In order to verify this inference, a sampling trap similar to the above was provided in the exhaust gas pipe of the silicon single crystal pulling apparatus, and the oxygen concentration in the nitrogen gas in the exhaust gas pipe after growing the silicon single crystal was gradually increased. The furnace gas containing the silicon oxide reacted with oxygen was collected in the trap, and pure water was introduced into the trap in the same manner as described above.
pm (about 0.4%), and about 1/1 of the lower limit of combustion
It turned out that it has decreased to zero.

Based on the findings described above, the present invention provides:
At the time of disassembly of the silicon single crystal pulling apparatus, air is introduced at least once into the chamber and / or the exhaust gas pipe before the chamber is disassembled, and is shut off from the outside world.
The inlet air was evacuated and then the chamber was dismantled. As described above, according to the present invention, once the introduced air is exhausted, the active silicon oxide in the exhaust gas pipe can be reliably deactivated, and the hydrogen generated at this time is also quickly exhausted, thereby oxidizing. Things no longer ignite.

Specifically, in the silicon single crystal pulling apparatus having the exhaust gas pipe of the present invention shown in FIG. 1, the silicon single crystal pulling apparatus was disassembled in the following order, for example. First, after the single crystal rod contained in the pull chamber 2 of the silicon single crystal pulling apparatus 1 is taken out, before the chamber is disassembled, the pull chamber door 5 and the gate valve 4 for taking out the single crystal rod of the pull chamber 2 are opened. Under the condition, outside air is taken into the chamber for several minutes. Thereafter, the door 5 is closed, and a mixed gas of inert gas (Ar) and air in the chamber is evacuated by the vacuum pump 11 through the exhaust gas pipe 6 to squeeze the exhaust ball valve 15 so that the inside of the chamber becomes about 100 mbar. Evacuate for minutes. It is important that the evacuation is performed at least once, preferably at least twice.

As described above, by forcibly exhausting the air through the exhaust gas pipe by the vacuum pump, the active silicon oxide deposited in the exhaust gas pipe and the air (containing moisture) gradually react with each other. The active silicon oxide inside can be inactivated, and the generated hydrogen gas can be quickly diluted and exhausted, so the subsequent disassembly of the silicon single crystal pulling apparatus and the cleaning work in the exhaust gas piping It is possible to prevent ignition, combustion, and the like, which are likely to occur with the above.

In order to introduce the external air generated into the exhaust gas pipe, the air can be introduced from the pull chamber as described above. However, a leak valve 7 is provided near the inlet of the exhaust gas pipe 6 on the main chamber 3 side. The leak valve 7 may be opened to introduce outside air. When the air is introduced by providing the leak valve 7, the air can be directly introduced into the exhaust gas pipe, and the operation can be performed with a simple operation as compared with opening and closing the pull chamber door 5 for removing the single crystal rod. It has the advantage that it is efficient and the working time can be reduced.

Further, the less active silicon oxide that adheres and accumulates in the exhaust gas pipe, the lower the possibility of ignition, etc., so that a pipe structure in which the exhaust gas flows smoothly so that the active silicon oxide does not easily accumulate in the exhaust gas pipe. Preferably
Further, it is preferable that the number of times of cleaning the exhaust gas pipe to remove the deposited silicon oxide is larger. However, there are utility pipes 14 such as an inert gas supply facility pipe, an exhaust gas recovery facility pipe, and a cooling water pipe around the single crystal pulling apparatus, and the flow path of these pipes allows a smooth flow of the exhaust gas in the exhaust gas pipe. It is difficult to provide piping so as not to hinder the operation, and several bent parts are inevitably formed. Active silicon oxide tends to be particularly easily deposited on these bent portions (elbows).
Oxides cannot be completely removed by cleaning because the cleaning brush is difficult to pass when cleaning. Further, for example, when the material of the exhaust gas pipe after the vacuum pump is a non-conductive material such as PVC, there is a concern that active silicon oxide deposited in the pipe may be ignited due to generation of static electricity.

Therefore, the exhaust gas pipe 6 in the silicon single crystal pulling apparatus according to the present invention uses, for example, a flexible conductor pipe 8 from the main chamber 3 to the vacuum pump 11 and a conductor pipe 9 from the vacuum pump 11 to the blower 12. In both cases, a grounding earth 10 is provided. In order to avoid various utility pipes 14, an elbow 13
(Bent portion) was not used as much as possible, and was piped with a straight pipe. A blind lid 20 is provided on the elbow 13 which is unavoidably used.

Further, in the invention of the exhaust gas piping in the silicon single crystal pulling apparatus according to the present invention, a stainless steel pipe, a steel pipe (SGP), a flexible steel pipe and the like are used.
The entire pipe was piped with a conductor pipe, and the conductor pipe was provided with a grounding earth. This makes it possible to quickly remove static electricity that may be generated in the conductor tube,
This does not cause a fire.

In this case, it is preferable that the exhaust gas pipe is a seamless pipe without a seam. Since there is no unevenness or surface roughness due to the seam in the exhaust gas pipe formed by the seamless conductor pipe, the active silicon oxide is particularly located at the seam position. It is possible to reduce the amount of accumulation of dust such as objects. that's all,
With the piping structure described above, there is almost no possibility that ignition, combustion, or the like will occur, and the safety of the exhaust gas piping can be maintained.

Further, it is preferable to provide a blind cover at an elbow portion of the exhaust gas pipe. In the exhaust gas pipe, pipes are to be bent so as to have as few bends as possible, but in the pipe section that has been bent without interruption, a T-shaped joint is connected to the elbow of the pipe so that the deposited active silicon oxide can be easily removed. By providing a blind cover that can be easily opened and closed at the opening, the blind cover is removed during the cleaning operation in the pipe, so that the bending portion can be easily cleaned.

FIG. 3 shows an example of a specific blind lid and its opening / closing mechanism.
It was shown to. This blind lid and its opening / closing mechanism cover the opening 24 of the T-shaped joint with the blind lid 20 and connect the clamp 21 to the blind lid 2.
0, and turn the holding screw 23 to turn the holding plate 2
2 is pressed against the blind lid 20 to close the opening 24. Opening is a one-touch opening and closing mechanism that can be performed in the reverse order.

[0033]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to these. (Example) Before pulling up a silicon single crystal, a sampling trap (sealable container) was attached in the middle of an exhaust gas pipe, and active silicon oxide was deposited on the inner surface of the trap during pulling up the single crystal. After the growth of the silicon single crystal, the crystal was pulled into the pull chamber, the gate valve was closed, and the crystal was taken out from the pull chamber door. The main chamber is sealed in an argon gas atmosphere at atmospheric pressure until the silicon melt remaining in the quartz crucible in the single crystal pulling apparatus solidifies and is sufficiently cooled. The single crystal take-out door of the pull chamber was opened for 10 minutes, and outside air was introduced. Then, after the door is closed and shut off from the outside, a mixed gas of inert gas (Ar) and air in the pull chamber and the main chamber is exhausted for about 10 minutes by a vacuum pump connected to an exhaust gas pipe of the pulling device. The active silicon oxide in the exhaust gas pipe and the air were gradually reacted.

After completing the evacuation operation for 10 minutes, Ar gas was introduced into the pulling device, and the inside of the exhaust gas pipe including the sampling trap and the inside of the pulling device were brought to atmospheric pressure. Thereafter, a furnace gas containing silicon oxide reacted with oxygen in the air was sealed in the trap and collected, and pure water was introduced into the trap to cause a reaction. The hydrogen gas concentration was about 3800 ppm. (About 0.38%), which is less than or equal to 1/10 of the lower limit of the combustion concentration range of the hydrogen gas, indicating that there is almost no possibility of ignition or combustion.

(Comparative Example) Before the silicon single crystal was pulled, a sampling trap was installed in the exhaust gas pipe so that active silicon oxide was deposited on the inner surface of the trap during the single crystal pulling. After the silicon single crystal was pulled out and taken out in the same manner as in the example, the main chamber was kept at atmospheric pressure until the silicon melt remaining in the quartz crucible in the single crystal pulling apparatus was solidified and sufficiently cooled. After being sealed in an argon gas atmosphere and allowed to stand for about 2 hours, the gate valve was opened, and the pull chamber and the main chamber were separated and opened. After opening the main chamber for about 10 minutes, the furnace gas containing silicon oxide reacted with oxygen in the air is sealed in the trap and collected, and pure water is introduced into the trap to react. As a result, the hydrogen gas concentration was detected to be about 19500 ppm (about 1.95%), which was about 1/2 of the lower limit of the combustion concentration range of the hydrogen gas.

In the comparative example, the reason why hydrogen was detected at a higher concentration than that in the example is that simply opening the chamber does not allow sufficient air to flow into the exhaust gas pipe, so that active silicon oxide is deposited. It is considered that only the surface of the layer reacts with air, and unreacted active silicon oxide remains inside the deposition layer. Therefore, it is necessary to perform a step of forcibly exhausting the air introduced into the chamber through the exhaust gas pipe at least once using a vacuum pump as in the embodiment.

The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the scope of the claims of the present invention. It is included in the technical scope of the invention.

[0038]

According to the present invention, the air is introduced into the chamber and / or the exhaust gas pipe at least once before the chamber is disassembled, and the introduced air is forcibly exhausted after being shut off from the outside world. The active silicon oxide forming the deposited layer in the exhaust gas pipe reacts sufficiently with the introduced air to be inactivated, and the generated hydrogen gas is quickly diluted and exhausted. Therefore, the active silicon oxide does not ignite or burn when cleaning the inside of the exhaust gas pipe.

Further, a leak valve for taking in external air is provided in the exhaust gas pipe, and a pipe is formed with a conductor pipe in which active silicon oxide is hardly attached to the exhaust gas pipe and static electricity is hardly generated. With the piping structure provided, air can be easily taken into the exhaust gas piping,
The active silicon oxide can be easily passivated, and no longer ignites due to static electricity. Furthermore, the active silicon oxide is less likely to stagnate, adhere, or accumulate in the pipe by frequently using the seamless pipe. By providing a T-shaped joint at the elbow portion of the pipe and attaching a blind lid that can be easily opened and closed to the opening thereof, the exhaust gas pipe can be easily cleaned. Therefore, active silicon oxide does not easily accumulate in the exhaust gas pipe. Even if it accumulates, it can be easily deactivated and easily removed. It hardly burns or burns.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of an exhaust gas pipe in a silicon single crystal pulling apparatus of the present invention.

FIG. 2 is an explanatory view showing an exhaust gas pipe in a conventional silicon single crystal pulling apparatus.

FIG. 3 is an explanatory view showing an example of a blind lid and an opening / closing mechanism thereof.

[Explanation of symbols]

1 ... silicon single crystal pulling device 2 ... pull chamber
3 ... Main chamber, 4 ... Gate valve, 5 ... Pull chamber door, 6 ... Exhaust gas piping, 7 ... Leak valve, 8
... Flexible conductor tube, 9 ... Conductor tube, 10 ... Ground ground, 11 ... Vacuum pump, 12 ... Blower, 13 ... Elbow (bent part), 14 ... Utility piping, 15 ... Exhaust ball valve, 20 ... Blind lid, 21 ... Clamp (fastening), 22 ... holding plate, 23 ... holding screw, 24 ... opening of T-shaped joint.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiharu Uesugi 150 Odakura Osaikura, Nishigo-mura, Nishishirakawa-gun, Fukushima Prefecture Inside the Shirakawa Plant of Shin-Etsu Semiconductor Co., Ltd. No. Shin-Etsu Semiconductor Co., Ltd. Takefu Plant F-term (reference) 4G077 AA02 BA04 CF10 EG28 HA12 PA11 PA16 5F053 AA12 DD01 FF04 GG01 HH04 PP01 PP20 RR20

Claims (6)

[Claims] 1. A method for dismantling a silicon single crystal pulling apparatus, wherein air is introduced into a chamber and / or an exhaust gas pipe at least once before disassembling a chamber, and after shutting off from outside, the introduced air is exhausted. And then disassembling the chamber. 2. The disassembly method of a silicon single crystal pulling apparatus according to claim 1, wherein a leak valve of an exhaust gas pipe is used for introducing the air. 3. An exhaust gas pipe in a silicon single crystal pulling apparatus, wherein the exhaust gas pipe is provided with a leak valve. 4. The exhaust gas pipe according to claim 3, wherein the entire pipe is piped with a conductor pipe, and the conductor pipe is provided with a grounding earth. 5. The exhaust gas pipe of the silicon single crystal pulling apparatus according to claim 3, wherein the exhaust gas pipe is a seamless pipe without a seam. 6. The exhaust gas pipe in the silicon single crystal pulling apparatus according to claim 3, wherein a blind lid is provided at an elbow portion of the exhaust gas pipe.