CN116695244A

CN116695244A - Apparatus for producing single crystal silicon ingot and method for producing single crystal silicon ingot

Info

Publication number: CN116695244A
Application number: CN202310167124.8A
Authority: CN
Inventors: 林田寿男; 横山隆
Original assignee: Sumco Corp
Current assignee: Sumco Corp
Priority date: 2022-03-03
Filing date: 2023-02-27
Publication date: 2023-09-05
Also published as: TW202346662A; JP2023128581A

Abstract

The present invention aims to provide a single crystal silicon ingot manufacturing apparatus and a single crystal silicon ingot manufacturing method capable of promoting combustion of oxides accumulated in an exhaust pipe. The apparatus for producing a single crystal silicon ingot according to the present invention comprises an exhaust line connected to a device for producing a single crystal silicon ingot, a vacuum pump for sucking an inert gas supplied into the device for producing a single crystal silicon ingot through the exhaust line, wherein the exhaust line includes a first exhaust pipe connected to an exhaust port of the device for producing a single crystal silicon ingot, a second exhaust pipe connected between the first exhaust pipe and the vacuum pump, and a first air supply unit connected to the first exhaust pipe and supplying air into the first exhaust pipe, and a second air supply unit connected to the second exhaust pipe and supplying air into the second exhaust pipe. In the method for producing a single crystal silicon ingot according to the present invention, the apparatus for producing a single crystal silicon ingot is used to supply air to the inert gas flowing through the exhaust pipe and burn the oxide in the exhaust pipe in any one of the liquid contact step, the single crystal growth step and the single crystal cooling step, or in any one of the steps of 1 or more.

Description

Apparatus for producing single crystal silicon ingot and method for producing single crystal silicon ingot

Technical Field

The present invention relates to an apparatus for producing a single crystal silicon ingot and a method for producing a single crystal silicon ingot.

Background

As a typical method for producing a single crystal silicon ingot, the czochralski method (CZ method) is exemplified. In the CZ method for producing a single crystal silicon ingot, a silicon raw material such as polycrystalline silicon is filled in a quartz crucible, and the silicon raw material is heated and melted in a chamber of a device for producing a single crystal silicon ingot under an inert gas atmosphere to form a silicon melt. Then, the seed crystal is brought into contact with the silicon melt in the quartz crucible, and the seed crystal is gradually raised while rotating the seed crystal and the quartz crucible in a predetermined direction, whereby a single crystal silicon ingot is grown below the seed crystal. The apparatus for producing a silicon single crystal ingot is connected to an exhaust device for exhausting an inert gas supplied into the chamber, and an exhaust port is provided at a lower part of the apparatus for producing a silicon single crystal ingot, and the inert gas is pumped and exhausted from the exhaust port by a vacuum pump through an exhaust pipe.

As an application of the CZ method, a multi-stage pulling (multi-pulling) method is known. In the multi-stage pulling method, after a first single crystal silicon ingot is pulled, a silicon raw material is additionally charged into the same quartz crucible and melted, and a second single crystal silicon ingot is pulled from the obtained silicon melt. By repeating such a raw material filling step and a pulling step, a plurality of single crystal silicon ingots were produced from 1 quartz crucible. According to the multi-stage pulling method, the production cost of the quartz crucible per 1 single crystal silicon ingot can be reduced. In addition, the frequency of replacing the quartz crucible by detaching the chamber can be reduced, so that the working efficiency can be improved.

In pulling up a single crystal silicon ingot by the CZ method, oxygen is dissolved out from the inner surface of a quartz crucible into a silicon melt, reacts with the silicon melt to form oxide (SiOx), and evaporates from the surface of the silicon melt. These oxides flow through the exhaust line together with the inert gas in the apparatus for producing a single crystal silicon ingot and collect dust in the dust chamber, but since the exhaust line from the exhaust port to the dust chamber is long, the oxides are cooled and condensed while flowing through the exhaust line, and adhere to and accumulate in the exhaust line with the passage of time. Therefore, the amount of oxide deposited tends to increase not on the exhaust port side in front of the exhaust line but on the dust chamber side in rear.

In the CZ method, since the production time per 1 piece is long, the oxide gradually accumulates in the exhaust pipe, which causes a problem. That is, if the amount of oxide deposited in the exhaust pipe increases, the deposited oxide flows back from the exhaust pipe to the apparatus for producing a silicon single crystal ingot, and there is a concern that dislocation of the silicon single crystal ingot occurs, or that pressure in the exhaust pipe fluctuates due to oxide adhesion, temperature or pressure rises sharply, and the oxide may ignite.

In response to this, there has been proposed a technique in which, after the pulling of a single crystal silicon ingot is completed, air is supplied into an exhaust pipe to burn oxides deposited in the exhaust pipe (for example, patent documents 1 and 2). Thus, after the pulling of the single crystal silicon ingot is completed, the oxide deposited in the exhaust pipe can be reduced.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2001-097797,

patent document 2: japanese patent laid-open No. 2002-316889.

Disclosure of Invention

Problems to be solved by the invention

However, dislocation occurs during pulling of a single crystal silicon ingot, and when the single crystal silicon ingot after pulling is remelted and then pulled again, or when a plurality of single crystal silicon ingots are pulled from 1 quartz crucible by a multi-stage pulling method, the operation time until the completion of pulling increases.

As the operation time increases, the amount of oxide deposited in the exhaust pipe increases, and therefore, even if the combustion operation of oxide is performed after the completion of the pulling of the single crystal silicon ingot as described in patent documents 1 and 2, this cannot be performed during the pulling. Therefore, the oxide in the exhaust pipe may not burn sufficiently until the pulling of the single crystal silicon ingot is completed, and there is a concern that the pressure of the exhaust pipe may change or may be abruptly ignited.

Further, since the exhaust line from the exhaust port in the lower part of the apparatus for producing a silicon single crystal ingot to the dust removal chamber is long, when the power supply to the heater in the apparatus for producing a silicon single crystal ingot is turned off and then the air supply is performed to perform the combustion operation after the pulling of the silicon single crystal ingot is completed, there is a case where the oxide in the exhaust pipe near the apparatus for producing a silicon single crystal ingot burns but the oxide in the exhaust pipe far from the vacuum pump cannot sufficiently burn. One of the reasons for this is considered to be that, immediately after the heater is turned off, the temperature in the tube is high on the exhaust pipe side close to the apparatus for producing a single crystal silicon ingot, so that the combustion reaction of the oxide is likely to occur, and on the other hand, the temperature in the tube is low on the exhaust pipe side close to the dust chamber, which is far away, so that the combustion reaction of the oxide is unlikely to occur. From this, it was found that in the combustion operation by the air supply performed after the heater power supply was turned off after the completion of the pulling, the oxide could not be sufficiently combusted over the entire length of the exhaust pipe.

Accordingly, an object of the present invention is to provide an apparatus for producing a single crystal silicon ingot and a method for producing a single crystal silicon ingot, which can promote combustion of oxides deposited in an exhaust pipe.

Means for solving the problems

The present inventors have conceived that the above-described problems can be advantageously solved by supplying air to a predetermined portion of the exhaust line in a predetermined step in the pulling process of the single crystal silicon ingot. In the present invention, the term "air" refers to a gas that surrounds the earth, and includes oxygen, and includes nitrogen, hydrogen, argon, carbon dioxide, ozone, neon, helium, water vapor, and the like.

The gist of the present invention is constructed as follows.

(1) An apparatus for producing a single crystal silicon ingot, comprising:

an exhaust line connected to a device for producing a single crystal silicon ingot, and

a vacuum pump for sucking an inert gas supplied into the apparatus for producing a silicon single crystal ingot through the exhaust line,

the apparatus for manufacturing a single crystal silicon ingot is characterized in that,

the exhaust line includes a first exhaust pipe connected to an exhaust port of the apparatus for manufacturing a silicon single crystal ingot and a second exhaust pipe connecting the first exhaust pipe and the vacuum pump,

the apparatus for producing a single crystal silicon ingot comprises:

a first air supply unit connected to the first exhaust pipe and supplying air into the first exhaust pipe, and

and a second air supply unit connected to the second exhaust pipe and configured to supply air into the second exhaust pipe.

(2) The apparatus for producing a single crystal silicon ingot according to the above (1), wherein a pressure adjusting portion for adjusting the pressure in the first exhaust pipe is provided on the second exhaust pipe,

when the exhaust port side is the front side of the exhaust line and the vacuum pump side is the rear side of the exhaust line, the second air supply unit is connected to the rear side of the pressure adjustment unit.

The "front side" includes not only the second exhaust pipe but also the first exhaust pipe.

(3) A method for producing a single crystal silicon ingot by using a czochralski method, comprising:

a raw material melting step of heating and melting a silicon raw material filled in a quartz crucible,

a liquid contact step of lowering the seed crystal to contact with the silicon melt in the quartz crucible,

a single crystal growing step of pulling up single crystal silicon from a silicon melt in the quartz crucible, and

a single crystal cooling step of cooling the grown single crystal silicon ingot;

in any one or more steps of the liquid contact step, the single crystal growth step, and the single crystal cooling step, air is supplied to an inert gas flowing in an exhaust pipe connected to a single crystal silicon ingot manufacturing apparatus, and the oxide in the exhaust pipe is burned.

(4) The method for producing a single crystal silicon ingot according to the above (3), which is a method for producing a single crystal silicon ingot by the Czochralski method using the apparatus for producing a single crystal silicon ingot according to the above (1) or (2), wherein,

in any one or more steps of the liquid contact step, the single crystal growth step, and the single crystal cooling step, air is supplied from the second air supply unit to the inert gas flowing in the second exhaust pipe, and the oxide in the second exhaust pipe is burned.

(5) The method for producing a single crystal silicon ingot according to the above (4), which is a method for producing a single crystal silicon ingot using the apparatus for producing a single crystal silicon ingot according to the above (2), wherein,

the pressure in the first exhaust pipe generated when air is supplied into the second exhaust pipe is measured, and the pressure in the first exhaust pipe is adjusted by the pressure adjusting unit based on the measured pressure fluctuation value.

(6) The method for producing a single crystal silicon ingot according to any one of the above (3) to (5), wherein a multi-stage pulling method is performed in which a plurality of single crystal silicon ingots are produced using the same quartz crucible by repeating the raw material melting step, the liquid contacting step, the single crystal growing step, and the single crystal cooling step.

(7) The method for producing a single crystal silicon ingot according to (6) above, wherein, when 1 single crystal silicon ingot is produced in the case of producing a plurality of single crystal silicon ingots, air is supplied from the second air supply unit into the tube of the second exhaust tube, and the oxide in the second exhaust tube is burned.

(8) The method for producing a single crystal silicon ingot according to any one of the above (3) to (7), wherein after the single crystal cooling step of the single crystal silicon ingot and before returning the chamber of the apparatus for producing a single crystal silicon ingot to normal pressure, air is supplied from the first air supply unit into the tube of the first exhaust tube, and the oxide in the first exhaust tube is burned.

(9) The method for producing a single crystal silicon ingot according to any one of the above (3) to (7), wherein after the single crystal cooling step of the single crystal silicon ingot and before returning the chamber of the apparatus for producing a single crystal silicon ingot to normal pressure, air is supplied from the first air supply unit and the second air supply unit into the pipes of the first exhaust pipe and the second exhaust pipe, and oxides in the first exhaust pipe and the second exhaust pipe are burned.

Effects of the invention

According to the present invention, it is possible to provide an apparatus for producing a single crystal silicon ingot and a method for producing a single crystal silicon ingot, which can promote combustion of oxides deposited in an exhaust pipe.

Drawings

Fig. 1 is a schematic view of an apparatus for producing a single crystal silicon ingot according to an embodiment of the present invention.

Fig. 2 is a flowchart of a method for producing a single crystal silicon ingot according to an embodiment of the present invention.

FIG. 3 is a schematic view showing an apparatus for producing a single crystal silicon ingot used in comparative example 1.

Fig. 4 is a schematic view showing an apparatus for producing a single crystal silicon ingot used in comparative examples 2 and 3.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

< apparatus for producing Single Crystal silicon ingot >

Fig. 1 is a schematic view showing an apparatus for producing a single crystal silicon ingot according to an embodiment of the present invention. As shown in fig. 1, the apparatus 1 for producing a single crystal silicon ingot according to the present embodiment includes: an exhaust line 3 connected to the apparatus 2 for producing a silicon single crystal ingot, a vacuum pump 4 for sucking an inert gas supplied into the apparatus 2 for producing a silicon single crystal ingot through the exhaust line 3, and a dust chamber 11 for collecting dust from oxides. The apparatus 2 for producing a single crystal silicon ingot is disposed directly above a floor F.L. in a clean room C.R., an exhaust pipe 3 is disposed below the floor F.L., and a vacuum pump 4 and a dust removing chamber 11 are disposed in a pump chamber P.R. located outside the clean room C.R.

The apparatus 2 for producing a single crystal silicon ingot has a main chamber 2a and a pull chamber 2b connected to the upper end of the main chamber 2 a. Although not shown, a quartz crucible for storing a silicon melt, a heater for surrounding the quartz crucible and heating the silicon melt, and the like are contained in the main chamber 2 a. A pulling device 2c for pulling the single crystal silicon ingot is provided at the upper end of the pulling chamber 2b. The vacuum pump 4 is connected to the lower surface of the main chamber 2a through an exhaust line 3. An inert gas supply line 5a is connected to the pull chamber 2b. The inert gas supply line 5a is connected to the upper and lower surfaces of the pull chamber 2b via switching valves 5b and 5c, and the inert gas supply line 5a is also connected to a tank (not shown) for storing an inert gas (in this example, ar gas). The switching valves 5b and 5c are, for example, electrically operated, and are configured to control the pressure in the main chamber 2a by adjusting the flow rate of Ar gas.

As shown in fig. 1, the exhaust line 3 includes a first exhaust pipe 3a connected to an exhaust port 6 of the single crystal ingot manufacturing apparatus 2, and a second exhaust pipe 3b connecting the first exhaust pipe 3a and the vacuum pump 4. The first exhaust pipe 3a has: a pair of first branch pipes 3a1 and second branch pipes 3a2, one end of which is connected to the lower surface of the main chamber 2a, and the other end of which merges; and a third branch pipe 3a3, one end of which is connected to the first branch pipe 3a1 and the second branch pipe 3a2, and the other end of which is connected to the flap valve 13. When the oxides accumulated in the exhaust line 3 burn and the pressure in the exhaust line 3 increases sharply, the flap valve 13 is operated to release the pressure in the exhaust line 3.

The single crystal silicon ingot manufacturing apparatus 1 includes a first air supply unit 7 connected to the first exhaust pipe 3a and supplying air into the first exhaust pipe 3 a. In this example, the first air supply 7 is a changeover valve. The switching valve may be, for example, a two-port two-position switching solenoid valve configured to be opened when on and closed when off. In this example, the operation of the first air supply unit 7 may be controlled by the control unit 12. As the control unit 12, any known controller can be used.

The apparatus 1 for producing a single crystal silicon ingot further includes a second air supply unit 9 connected to the second exhaust pipe 3b and supplying air into the second exhaust pipe 3b. In this example, the second air supply 9 is a control valve. In this example, the operation of the second air supply portion 9 can be controlled by the control portion 12. The second air supply unit 9 is preferably a device with high controllability of the air supply amount and the supply timing, and as an example, a ball valve or a flowmeter may be used instead of the solenoid valve.

If the air supply speed is too high, dust cloud is likely to be generated in the exhaust duct 3, and dust explosion due to rapid combustion of oxides is likely to occur. Since the second air supply unit 9 is only a vacuum solenoid valve, there is a concern that dust explosion is caused by air supply at a time. Therefore, it is preferable to add a muffler and a ball valve capable of performing a slow opening operation (it takes 10 seconds to open), and to form a structure that does not perform air supply at once. If the total amount of the Ar gas flow rate and the air supply amount is too large, if the total amount of the Ar gas flow rate and the air supply amount exceeds the evacuation capability of the vacuum pump 4 (for example, the evacuation capability at the time of 30Torr in the furnace is 592L/min), the pump may be overloaded, and the pump may be stopped or may be broken. Therefore, it is preferable to add a flowmeter having a flow rate adjusting function to the vacuum solenoid valve so that the air supply amount does not exceed 200L/min.

In the apparatus 1 for producing a single crystal silicon ingot according to the present embodiment, the second exhaust pipe 3b is provided with a pressure adjusting portion 8 for adjusting the pressure in the first exhaust pipe 3 a. In this example, the pressure adjusting portion 8 is a control valve, and a butterfly valve or the like is preferably used.

By providing the pressure adjusting portion 8, pressure fluctuation in the first exhaust pipe 3a generated when air is supplied from the second air supplying portion 9 into the second exhaust pipe 3b during pulling of the single crystal silicon ingot can be suppressed. As a result, the pressure in the main chamber 2a is prevented from varying, and the back flow of the exhaust gas into the main chamber 2a and the like do not occur, so that the combustion operation of the oxide deposited in the second exhaust pipe 3b can be performed during the pulling of the single crystal silicon ingot.

In this example, when the exhaust port 6 side is the front side of the exhaust line 3 and the vacuum pump 4 side is the rear side of the exhaust line 3, the second air supply unit 9 is connected to the rear side of the pressure adjusting unit 8. For example, in this example, the pressure adjusting portion 8 is provided on the front end side (front side) of the second exhaust pipe 3b, and the second air supply portion 9 is provided immediately behind the pressure adjusting portion 8. More specifically, the distance at which the oxide can be burned by the second air supply portion 9 is set to be appropriately set. More specifically, the distance from the pressure adjusting portion 8 to the second air supplying portion 9 (the distance along the path of the exhaust pipe 3) is preferably 50% or less of the distance from the pressure adjusting portion 8 to the vacuum pump 4. The lower the temperature in the exhaust pipe 3 is, the less likely the ignition phenomenon itself for burning the oxide is, but by disposing the air supply position in the exhaust pipe 3 at a position close to the pressure adjusting portion 8 where the temperature is high, the ignitability of the oxide by the air supply is improved, and the oxide deposited in the second exhaust pipe 3b can be burned.

In this example, a pressure gauge 10 that measures the pressure in the chamber 2a by measuring the pressure of the first exhaust pipe 3a is disposed immediately in front of the pressure adjusting portion 8. The measured value of the pressure gauge 10 is sent to the control unit 12, and the pressure adjustment unit 8 is controlled based on the pressure fluctuation of the first exhaust pipe 3a obtained in this way.

As the vacuum pump 4, a pump in which a water seal pump and a supercharger are combined, an oil rotary pump, a dry vacuum pump, or the like can be used. In this case, a dust chamber 11 is provided immediately in front of the vacuum pump 4, and oxides can be separated from the sucked inert gas by a cyclone 14 and collected in the dust chamber 11.

< method for producing Single Crystal silicon ingot >

Fig. 2 is a flowchart of a method for producing a single crystal silicon ingot according to an embodiment of the present invention. As shown in fig. 2, in the method for producing a single crystal silicon ingot according to the present embodiment, first, a silicon raw material such as a polycrystalline silicon ingot is filled in a quartz crucible located in a main chamber 2a (step S101: raw material filling step).

Then, the atmosphere in the main chamber 2a is exhausted, and the main chamber 2a is evacuated (step S102: vacuum process in the chamber). When the atmosphere in the main chamber 2a is exhausted, the pressure adjusting portion 8 is fully opened.

Then, the silicon raw material filled in the quartz crucible is heated and melted (step S103: raw material melting step). Specifically, while the inert gas Ar is flowing, the silicon raw material in the quartz crucible is heated by a heater to be melted, and a silicon melt is formed in the quartz crucible. Then, the quartz crucible is raised to the lift start position.

Then, the seed crystal is lowered to be in contact with the silicon melt in the quartz crucible (step S104: liquid contacting step). For example, the pulling wire can be lowered by using a wire lifting mechanism or the like.

Next, a single crystal silicon ingot is pulled up from the silicon melt in the quartz crucible (step S105: single crystal growing step). Specifically, the quartz crucible and the pulling wire are rotated in a predetermined direction, and the pulling wire is pulled upward to grow a single crystal silicon ingot below the seed crystal. As the ingot growth proceeds, the amount of silicon melt decreases, and the quartz crucible is raised to maintain the level of the silicon melt level.

As shown in fig. 2, the single crystal growth step (step S105) includes the following steps. In the single crystal growth step, first, in order to dislocation-free the single crystal silicon ingot, a seed crystal is extruded (necked) by a Dash neck method to form a necked portion (step S105-1: a necked portion growth step). Then, the shoulder is grown to obtain an ingot having a desired diameter (step S105-2: shoulder growing step). Next, when the single crystal silicon ingot reaches a desired diameter, the body is grown with a constant diameter (step S105-3: body growth step). Then, after the body portion is grown to a predetermined length, the single crystal silicon ingot is separated from the silicon melt in a dislocation-free state, and then the tail portion is extruded to form a tail portion (step S105-4: a tail portion growing step).

Next, the grown single crystal silicon ingot is cooled (step S106: single crystal cooling step). For example, a single crystal silicon ingot is cooled by being placed in the pull chamber 2b of the shut valve to a take-out temperature of preferably 500 ℃ or lower.

The present embodiment performs a multi-stage pulling method in which a raw material melting step (step S103), a liquid contacting step (step S104), a single crystal growing step (step S105), and a single crystal cooling step (step S106) are repeatedly performed to produce a plurality of single crystal silicon ingots using the same quartz crucible. In step S107, it is determined (for example, based on a predetermined number of manufacturing steps of the single crystal silicon ingot) whether or not the next pulling is performed.

When the next pulling is performed, the inside of the pulling chamber 2b is returned to normal pressure (step S108), the single crystal silicon ingot is taken out (step S109), and the process returns to step S101 to produce the next single crystal silicon ingot.

On the other hand, when the next pulling is not performed, first, the heater power supply is turned off (step S110). Then, the main chamber 2a and the pull chamber 2b are returned to normal pressure (step S112), and the single crystal silicon ingot is taken out (step S113), thereby ending the production. The method of the present embodiment further includes air supply (step S111), wherein after the single crystal cooling step (step S106) of the single crystal silicon ingot and before the room in the single crystal silicon ingot manufacturing apparatus 2 is returned to normal pressure (before step S112), air is supplied from the first air supply unit 7 or the first air supply unit 7 and the second air supply unit 9 to the inside of the first exhaust pipe 3a or the first exhaust pipe 3a and the second exhaust pipe 3b, respectively, and the oxide in the first exhaust pipe 3a or the first exhaust pipe 3a and the second exhaust pipe 3b is burned.

In the present embodiment, in any 1 or more steps of the liquid contact step (step S104), the single crystal growth step (step S105), and the single crystal cooling step (step S106), air (in this example, from the second air supply unit 9) is supplied to the inert gas flowing in the exhaust pipe 3 (in this example, in the second exhaust pipe 3 b), and the oxide in the exhaust pipe 3 (in this example, in the second exhaust pipe 3 b) is burned. The cause of oxides deposited in the exhaust line 3, that is, siOx evaporated from the surface of the silicon melt, is largely generated when the silicon raw material having a higher temperature than that in the main chamber 2a is melted. Therefore, it is effective to perform the combustion operation of the exhaust pipe 3 (in this example, in the second exhaust pipe 3 b) after the raw material melting step (step S103), and it is preferable to perform the combustion operation in the step after the liquid contact step (step S104). In particular, it is preferable to perform the combustion operation in the single crystal cooling step (step S106), and therefore, if SiOx flows backward from the inside of the exhaust pipe 3 (in this example, the inside of the second exhaust pipe 3 b) into the main chamber 2a during the combustion operation of the oxide due to a certain trouble, the grown single crystal silicon ingot does not undergo dislocation because the growth of the single crystal silicon ingot is completed.

Hereinafter, the operation and effects of the apparatus for producing a single crystal silicon ingot and the method for producing a single crystal silicon ingot according to the present embodiment will be described, respectively.

The apparatus 1 for producing a single crystal silicon ingot according to the present embodiment includes not only a first air supply unit 7 connected to the first exhaust pipe 3a and supplying air into the first exhaust pipe 3a, but also a second air supply unit 9 connected to the second exhaust pipe 3b and supplying air into the second exhaust pipe 3b. According to this configuration, air can be supplied to the first exhaust pipe 3a and the second exhaust pipe 3b independently, and air can be supplied only to the second exhaust pipe 3b during pulling. This allows the air supply described in the embodiment of the method for producing a single crystal silicon ingot to be performed, and the oxide in the second exhaust pipe 3b to be burned during the pulling, so that rapid combustion of the oxide and rapid increase in pressure during the pulling can be prevented. Further, since the combustion operation of the oxide is performed during the pulling, the Ar gas at a higher temperature flows in the second exhaust pipe 3b than in the combustion operation of the oxide performed after the heater is turned off after the pulling is completed, and the combustion effect of the oxide is further improved, so that the oxide deposited in the second exhaust pipe 3b on the vacuum pump 4 side can be sufficiently combusted. Further, by providing the second exhaust pipe 3b with the pressure adjusting portion 8 for adjusting the pressure in the first exhaust pipe 3a and connecting the second air supply portion 9 to the rear side of the pressure adjusting portion 8, it is possible to eliminate pressure fluctuation in the first exhaust pipe 3a generated when air is supplied into the second exhaust pipe 3b, and as a result, contamination due to backflow of exhaust gas into the main chamber 2a can be avoided.

In the method for producing a single crystal silicon ingot according to the present embodiment, in any one or more of the step of contacting (step S104), the step of growing (step S105), and the step of cooling (step S106), air is supplied to the inert gas flowing in the exhaust pipe 3 (in the second exhaust pipe 3b in this example) (in this example, from the second air supply unit 9), so that the oxide in the exhaust pipe 3 (in the second exhaust pipe 3b in this example) is burned. This allows the oxide in the exhaust pipe 3 (in this example, in the second exhaust pipe 3 b) to burn during the pulling process. Therefore, rapid combustion of the oxide and rapid pressure rise during the pulling of the single crystal silicon ingot can be prevented, and combustion of the oxide deposited in the exhaust pipe can be promoted. In addition, it is preferable that the pressure in the first exhaust pipe 3a generated when air is supplied into the exhaust pipe 3 (in this example, into the second exhaust pipe 3 b) is measured, and the pressure in the first exhaust pipe 3a is adjusted by the pressure adjusting unit 8 based on the measured pressure fluctuation value, whereby the air supply can be performed more safely.

The method for producing a single crystal silicon ingot according to the present embodiment preferably further includes air supply (step S111), wherein after the single crystal cooling step (step S106) of the single crystal silicon ingot and before the room in the apparatus 2 for producing a single crystal silicon ingot is returned to normal pressure, air is supplied from the first air supply unit 7 or the first air supply unit 7 and the second air supply unit 9 to the inside of the first exhaust pipe 3a or the first exhaust pipe 3a and the second exhaust pipe 3b, respectively, to burn the oxide in the first exhaust pipe 3a or the first exhaust pipe 3a and the second exhaust pipe 3b. The reason is that by burning the oxides in the first exhaust pipe 3a and the second exhaust pipe 3b also after the completion of the pulling of 1 single crystal silicon ingot, the oxides can be further burned, and the accumulation of oxides can be effectively reduced.

In the method for producing a single crystal silicon ingot according to the present embodiment, it is preferable to perform a multi-stage pulling method in which a raw material melting step (step S103), a liquid contacting step (step S104), a single crystal growing step (step S105), and a single crystal cooling step (step S106) are repeatedly performed to produce a plurality of single crystal silicon ingots using the same quartz crucible; the reason is that, in particular, in the case of long-term operation, combustion of oxides in the exhaust pipe can be promoted, and the above-described effects can be advantageously obtained.

In addition, it is preferable that the air (from the second air supply unit 9 in this example) is supplied every time 1 single crystal silicon ingot is produced in the case of producing a plurality of single crystal silicon ingots, and thereby a large amount of oxide is burned before being deposited in the exhaust pipe 3 (in this example, in the second exhaust pipe 3 b), and the oxide is prevented from being burned sharply and the pressure is prevented from rising sharply during the pulling of the single crystal silicon ingot.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples.

Examples

Example 1

In order to confirm the effects of the present invention, experiments were performed in which 1 single crystal silicon ingot was pulled up by using the apparatus for producing a single crystal silicon ingot shown in fig. 1 for inventive examples 1 to 3 and using the apparatus for producing a single crystal silicon ingot shown in fig. 3 to 4 for comparative examples 1 to 2. In each example, the pulling conditions of the single crystal silicon ingot were the same, and experiments were performed in which the timing of air supply was variously changed. Then, a combustion evaluation test of the oxide at the time of opening the dust chamber and a forced ignition test of the oxide were performed.

Here, the "combustion evaluation test of oxide when the dust chamber is opened" is a test in which the lid of the dust chamber 11 is opened after the completion of the pulling for 6 hours, and whether or not the oxide collected in the dust chamber 11 is burned is confirmed. In addition, the "forced ignition test" is a test for recovering unburned oxide in the "combustion evaluation test of oxide at the time of opening the dust chamber" and for evaluating whether or not the oxide is burned by an igniter or the like.

In comparative example 1, air was not supplied into the exhaust line 3. Specifically, the operation of turning off the heater power is performed after the growth of the single crystal silicon ingot is completed and the single crystal silicon ingot is moved from the main chamber 2a into the pull chamber 2b. After the heater was turned off, after the pulling was completed and 6 hours passed, a combustion evaluation test of the oxide was performed when the lid of the dust chamber 11 was opened. As a result, when the lid of the dust chamber 11 is opened, the oxides collected in the dust chamber 11 are burned drastically. Therefore, no forced ignition test was performed in comparative example 1.

In comparative example 2, an experiment was performed under the same conditions as in comparative example 1, except that air was supplied from the air supply unit into the exhaust duct 3 after the heater was turned off and before the room was returned to normal pressure. As a result, no combustion reaction of the oxide was observed when the lid of the dust chamber 11 was opened. In addition, oxides were recovered from the dust chamber 11 and subjected to a forced ignition test to confirm that the oxides burned vigorously. That is, in comparative example 2, although the combustion operation of the oxide was performed by the air supply, it was confirmed that the combustion effect of the oxide deposited in the exhaust pipe 3 was low in the air supply after the completion of the pulling.

In the invention example 1, in the liquid contacting step (step S104), air is supplied from the second air supply unit 9 into the second exhaust pipe 3b. As a result, no combustion reaction of the oxide was observed when the lid of the dust chamber 11 was opened. In addition, when the forced ignition test was performed on the oxide recovered from the dust chamber 11, it was confirmed that the oxide was slightly burned.

In addition, in the invention example 1, although the combustion operation of the oxide was performed by the air supply in the liquid contact step, the pressure fluctuation in the main chamber 2a was not observed, and the dislocation-free single crystal silicon ingot could be grown.

In the invention example 2, in the single crystal cooling step (step S106), air is supplied from the second air supply unit 9 into the second exhaust pipe 3b. Oxide combustion was not observed when the lid of the dust chamber 11 was opened, and slight combustion was confirmed in the forced ignition test.

In the invention example 3, in the single crystal cooling step (step S106), air is supplied from the second air supply unit 9 into the second exhaust pipe 3b, and before the room is returned to normal pressure, air is supplied from the first air supply unit 7 and the second air supply unit 9 into the first exhaust pipe 3a and the second exhaust pipe 3b, respectively (step S111). The oxide was not burned when the lid of the dust chamber 11 was opened, nor was it confirmed in the forced ignition test.

Example 2

In order to confirm the effect of the present invention in the multi-stage pulling method, a pulling experiment was performed in which 2 single crystal silicon ingots were continuously grown using the apparatus for producing single crystal silicon ingots shown in fig. 1 for examples 4 to 6 of the present invention, and using the apparatus for producing single crystal silicon ingots shown in fig. 4 for comparative example 3. A combustion evaluation test of the oxide and a forced ignition test of the oxide were performed under the same conditions as in example 1 except that the pulling was performed by the multistage pulling method.

In comparative example 3, the pulling of 2 single crystal silicon ingots was completed by the multi-stage pulling method, and after the heater was turned off, air was supplied from the first air supply unit 7 into the exhaust line 3. The oxide was observed to burn vigorously when the lid of the dust chamber 11 was opened. Thus, no forced ignition test was performed.

In the invention example 4, in the second single crystal cooling step of the multi-stage pulling method, air is supplied from the second air supply unit 9 into the second exhaust pipe 3b. The oxide was not burned when the dust chamber 11 was opened, and slight burning was confirmed in the forced ignition test.

In the invention example 5, in the single crystal cooling step of the first and second ingot of the multi-stage pulling method, air is supplied from the second air supply unit into the second exhaust pipe 3b. As a result, as in the case of inventive example 4, the oxide was not burned when the dust chamber 11 was opened, and slight burning was confirmed in the forced ignition test.

Comparing with the invention example 4, it was confirmed that the combustion amount of the oxide at the time of the evaluation test was small. This is presumably because the amount of oxide deposited in the second exhaust pipe 3b is small because the oxide in the second exhaust pipe 3b is burned every time the single crystal cooling process is performed.

In the invention example 6, in the cooling step of the first and second single crystals of the multi-stage pulling method, air is supplied from the second air supply unit 9 into the second exhaust pipe 3b, and air is supplied from the first air supply unit and the second air supply unit before the room is returned to the normal pressure. However, in the single crystal cooling step of the first root of the multi-stage pulling method, air supply is not performed after the heater is turned off (step S111). The oxides do not burn when the chamber is open and do not burn during the forced ignition test.

TABLE 1

Table 1 summarizes the evaluation results of each of invention examples 1 to 6 and comparative examples 1 to 3 in example 1 and example 2.

In the invention examples 1 to 3, the combustion effect of the oxide was confirmed to be higher when the air was supplied to the second exhaust pipe 3b during the pulling, than when the air was supplied to the exhaust pipe 3 after the pulling was completed.

Further, when a plurality of single crystal silicon ingots were grown by the multi-stage pulling method, the amount of oxide deposited in the exhaust line 3 was also increased, and therefore, it was expected that the oxide could not be burned sufficiently, but as apparent from the results of invention examples 4 to 6, it was confirmed that the oxide could be burned sufficiently in the multi-stage pulling method when air was supplied into the second exhaust line during the pulling.

Symbol description

1: an apparatus for producing a silicon single crystal ingot,

2: an apparatus for producing a single crystal silicon ingot,

3: an exhaust pipeline is arranged on the inner side of the air inlet pipe,

4: the vacuum pump is used for the vacuum pump,

5a: an inert gas supply port for supplying an inert gas,

5b, 5c: the switching valve is provided with a valve,

6: an exhaust port, a gas outlet, a gas inlet, a gas outlet,

7: a first air supply portion for supplying air to the first air supply portion,

8: a pressure adjusting part, which is used for adjusting the pressure of the air,

9: a second air supply portion for supplying air to the air-conditioning unit,

10: the pressure of the pressure gauge is measured,

11: a dust-removing chamber,

12: the control part is used for controlling the control part to control the control part,

13: a flap valve (explosion-proof valve),

14: a cyclone separator.

Claims

1. An apparatus for producing a single crystal silicon ingot, comprising:

the apparatus for producing a single crystal silicon ingot comprises:

2. The apparatus for producing a single crystal silicon ingot according to claim 1, wherein a pressure adjusting portion for adjusting a pressure in the first exhaust pipe is provided on the second exhaust pipe,

3. A method for producing a single crystal silicon ingot by using a czochralski method, comprising:

4. A method for producing a single crystal silicon ingot according to claim 3, which is a method for producing a single crystal silicon ingot by the Czochralski method using the apparatus for producing a single crystal silicon ingot according to claim 1 or 2, wherein,

5. The method for producing a single crystal silicon ingot according to claim 4, which is a method for producing a single crystal silicon ingot using the apparatus for producing a single crystal silicon ingot according to claim 2, wherein,

6. The method for producing a single crystal silicon ingot according to claim 3, wherein a multi-stage pulling method is performed in which a plurality of single crystal silicon ingots are produced using the same quartz crucible by repeating the raw material melting step, the liquid contacting step, the single crystal growing step, and the single crystal cooling step.

7. The method for producing a single crystal silicon ingot according to claim 6, wherein, when 1 single crystal silicon ingot is produced in the case of producing a plurality of single crystal silicon ingots, air is supplied from the second air supply unit into the second exhaust pipe, and the oxide in the second exhaust pipe is burned.

8. The method for producing a single crystal silicon ingot according to claim 3, wherein after the single crystal cooling step of the single crystal silicon ingot and before returning the chamber of the apparatus for producing a single crystal silicon ingot to normal pressure, air is supplied from the first air supply unit into the tube of the first exhaust tube, and the oxide in the first exhaust tube is burned.

9. The method for producing a single crystal silicon ingot according to claim 3, wherein after the single crystal cooling step of the single crystal silicon ingot and before returning the chamber of the apparatus for producing a single crystal silicon ingot to normal pressure, air is supplied from the first air supply unit and the second air supply unit into the first exhaust pipe and the second exhaust pipe, and oxides in the first exhaust pipe and the second exhaust pipe are burned.