Manufacturing Equipment for Single-Crystal Silicon Ingot and Method for Manufacturing Single-Crystal Silicon Ingot

Abstract

To provide a manufacturing facility of a single crystal silicon ingot and a manufacturing method of the single crystal silicon ingot, capable of promoting the combustion of oxide deposited in an exhaust pipe.SOLUTION: A manufacturing facility 1 of a single crystal silicon ingot includes: an exhaust pipe conduit 3 connected to a manufacturing apparatus 2; and a vacuum pump 4 for sucking inert gas supplied into the manufacturing apparatus 2 through the exhaust pipe conduit 3, wherein the exhaust pipe conduit 3 is composed of a first exhaust pipe 3a connected to an exhaust gas port 6 of the manufacturing apparatus 2 and a second exhaust pipe 3b connecting between the first exhaust pipe 3a and the vacuum pump 4, and further includes: a first air supply part 7 connected to the first exhaust pipe 3a for supplying air into the first exhaust pipe 3a; and a second air supply part 9 connected to the second exhaust pipe 3b for supplying air into the second exhaust pipe 3b. A manufacturing method of the single crystal silicon ingot includes supplying air to the inert gas flowing in the exhaust pipe conduit 3 to combust oxide in the exhaust pipe conduit 3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a manufacturing facility for single crystal silicon ingots and a method for manufacturing single crystal silicon ingots.

Background Art

[0002] As a typical method for manufacturing single crystal silicon ingots, the Czochralski method (CZ method) can be cited. In the manufacture of single crystal silicon ingots by the CZ method, a silicon raw material such as polycrystalline silicon is filled into a quartz crucible, and the silicon raw material is heated and melted in a chamber of a manufacturing apparatus for single crystal silicon ingots under an inert gas atmosphere to obtain a silicon melt. Next, a seed crystal is brought into contact with the silicon melt in the quartz crucible, and while rotating the seed crystal and the quartz crucible in a predetermined direction, the seed crystal is gradually raised, whereby a single crystal silicon ingot is grown below the seed crystal. An exhaust facility for exhausting the inert gas supplied into the chamber is connected to the manufacturing apparatus for single crystal silicon ingots, and an exhaust gas port is provided at the lower part of the manufacturing apparatus for single crystal silicon ingots. The inert gas is sucked by a vacuum pump through an exhaust gas line from the exhaust gas port and discharged.

[0003] As an application of the above CZ method, the multiplication method is known. In the multiplication method, after pulling up the first single crystal silicon ingot, the quartz crucible is refilled with a silicon raw material and melted, and the second single crystal silicon ingot is pulled up from the obtained silicon melt. By repeating such a raw material filling step and a pulling up step, a plurality of single crystal silicon ingots are manufactured from one quartz crucible. According to the multiplication method, the cost of the quartz crucible per single crystal silicon ingot can be reduced. In addition, since the frequency of disassembling the chamber and replacing the quartz crucible can be reduced, the operation efficiency can be improved.

[0004] When pulling up a single-crystal silicon ingot by the Czochralski (CZ) method, oxygen dissolves from the inner surface of the quartz crucible into the silicon melt. This oxygen reacts with the silicon melt to form an oxide (SiOx), which evaporates from the surface of the silicon melt. These oxides flow through the exhaust pipe together with the inert gas in the manufacturing apparatus of the single-crystal silicon ingot and are dust-collected in the dust chamber. However, since the exhaust pipe from the exhaust gas outlet to the dust chamber is long, the oxides are cooled and condensed during the process of flowing through the exhaust pipe, and adhere to and accumulate in the exhaust pipe over time. For this reason, the amount of oxide deposition tends to be larger on the dust chamber side at the rear than on the exhaust gas outlet side at the front of the exhaust pipe.

[0005] In the CZ method, since the manufacturing time per unit is long, the deposition of oxides in the exhaust pipe becomes a problem. That is, when the amount of oxide deposition in the exhaust pipe increases, the deposited oxides may flow back from the exhaust pipe into the manufacturing apparatus of the single-crystal silicon ingot, causing dislocation of the single-crystal silicon ingot, or the pressure in the exhaust pipe may fluctuate due to oxide adhesion, resulting in a rapid increase in temperature and pressure, and there is a risk of ignition of the oxides.

[0006] In contrast, after the pulling up of the single-crystal silicon ingot is completed, it has been proposed to supply air into the exhaust pipe to burn the oxides deposited in the exhaust pipe (for example, Patent Documents 1 and 2). According to this, after the pulling up of the single-crystal silicon ingot is completed, the oxides deposited in the exhaust pipe can be reduced.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, when dislocation occurs during the pulling of a single-crystal silicon ingot and the pulled single-crystal silicon ingot is remelted and then pulled again, or when multiple single-crystal silicon ingots are pulled from a single quartz crucible by the multiplication method, the operating time until the pulling is completed will increase. As the operating time increases, the amount of oxide deposited in the exhaust pipe also increases. Therefore, even if an oxide combustion operation is performed after the pulling of the single-crystal silicon ingot is completed, as described in Patent Documents 1 and 2, it cannot be performed during the pulling. Therefore, the oxide in the exhaust pipe cannot be sufficiently burned until after the pulling of the single-crystal silicon ingot is completed, and there is a risk that the pressure in the exhaust pipe will change or that there will be a sudden ignition.

[0009] In addition, since the exhaust pipe from the exhaust gas outlet at the bottom of the single-crystal silicon ingot manufacturing apparatus to the dust chamber is long, after the pulling of the single-crystal silicon ingot is completed and the power supply of the heater in the single-crystal silicon ingot manufacturing apparatus is turned off, when air is supplied for a combustion operation, the oxide in the exhaust pipe close to the single-crystal silicon ingot manufacturing apparatus is burned, but there are scattered cases where the oxide in the exhaust pipe close to the vacuum pump at a distance is not sufficiently burned. This is presumably because immediately after the heater power is turned off, the temperature inside the exhaust pipe close to the single-crystal silicon ingot manufacturing apparatus is relatively high, so the combustion reaction of the oxide is likely to occur, while on the exhaust pipe side close to the dust chamber at a distance, the temperature inside the pipe is low, making it difficult for the combustion reaction of the oxide to occur. Thus, it has become clear that the combustion operation by air supply performed after the pulling is completed and the heater power is turned off cannot sufficiently burn the oxide over the entire length of the exhaust pipe.

[0010] Therefore, an object of the present invention is to provide a manufacturing facility for a single-crystal silicon ingot and a manufacturing method for a single-crystal silicon ingot that can promote the combustion of the oxide deposited in the exhaust pipe.

Means for Solving the Problem

[0011] The inventors recalled that the above problems can be advantageously solved by supplying air to a predetermined part of the exhaust pipeline in a predetermined process during the pulling of a single crystal silicon ingot. In the present invention, "air" means the total gas surrounding the earth, which contains oxygen and is composed of components such as nitrogen, hydrogen, argon, carbon dioxide, ozone, neon, helium, and water vapor.

[0012] The gist configuration of the present invention is as follows. (1) An exhaust pipeline connected to a manufacturing apparatus for a single crystal silicon ingot, and a vacuum pump that sucks the inert gas supplied into the manufacturing apparatus for the single crystal silicon ingot through the exhaust pipeline, and a manufacturing facility for a single crystal silicon ingot, the exhaust pipeline consists of a first exhaust pipe connected to the exhaust gas outlet of the manufacturing apparatus for the single crystal silicon ingot, and a second exhaust pipe connecting between the first exhaust pipe and the vacuum pump, a first air supply unit connected to the first exhaust pipe and supplying air into the first exhaust pipe, a second air supply unit connected to the second exhaust pipe and supplying air into the second exhaust pipe, and a manufacturing facility for a single crystal silicon ingot, characterized in that it comprises these.

[0013] (2) A pressure adjustment unit for adjusting the pressure in the first exhaust pipe is provided in the second exhaust pipe, When the exhaust gas outlet side is the front side of the exhaust pipeline and the vacuum pump side is the rear side of the exhaust pipeline, the second air supply unit is connected to the rear side of the pressure adjustment unit. The manufacturing facility for a single crystal silicon ingot according to (1) above. Note that the "front side" includes not only the second exhaust pipe but also the first exhaust pipe.

[0014] (3) A method for manufacturing a single crystal silicon ingot by the Czochralski method, a raw material melting step of heating and melting the silicon raw material filled in a quartz crucible, A liquid landing step of dropping the seed crystal to land on the silicon melt in the quartz crucible; A single crystal growth step of pulling up a single crystal silicon ingot from the silicon melt in the quartz crucible; A single crystal cooling step of cooling the grown single crystal silicon ingot, comprising: In any one or more of the liquid landing step, the single crystal growth step, and the single crystal cooling step, air is supplied to the inert gas flowing in the exhaust pipeline connected to the manufacturing apparatus of the single crystal silicon ingot to burn the oxides in the exhaust pipeline, and a method for manufacturing a single crystal silicon ingot is characterized in that.

[0015] (4) A method for manufacturing a single crystal silicon ingot according to (3) above by the Czochralski method using the manufacturing equipment for a single crystal silicon ingot according to (1) or (2) above, In any one or more of the liquid landing 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 to burn the oxides in the second exhaust pipe, and a method for manufacturing a single crystal silicon ingot is provided.

[0016] (5) A method for manufacturing a single crystal silicon ingot according to (4) above using the manufacturing equipment for a single crystal silicon ingot according to (2) above, The pressure in the first exhaust pipe is measured when air is supplied into the second exhaust pipe, and based on the measured pressure fluctuation value, the pressure in the first exhaust pipe is adjusted by the pressure adjustment unit, and a method for manufacturing a single crystal silicon ingot is provided.

[0017] (6) By repeating the raw material melting step, the liquid landing step, the single crystal growth step, and the single crystal cooling step, a plurality of the single crystal silicon ingots are manufactured using the same quartz crucible, and a multiplexing method is performed, and the method for manufacturing a single crystal silicon ingot according to any one of (3) to (5) above is provided.

[0018] (7) When manufacturing a plurality of the single-crystal silicon ingots, for each production of one single-crystal silicon ingot, the second air supply unit supplies air into the second exhaust pipe to burn the oxides in the second exhaust pipe. The method for manufacturing a single-crystal silicon ingot according to (6) above.

[0019] (8) After the single-crystal cooling step of the single-crystal silicon ingot, before returning the inside of the chamber of the manufacturing apparatus of the single-crystal silicon ingot to normal pressure, the first air supply unit supplies air into the first exhaust pipe to burn the oxides in the first exhaust pipe. The method for manufacturing a single-crystal silicon ingot according to any one of (3) to (7) above.

[0020] (9) After the single-crystal cooling step of the single-crystal silicon ingot, before returning the inside of the chamber of the manufacturing apparatus of the single-crystal silicon ingot to normal pressure, the first air supply unit and the second air supply unit supply air into the first exhaust pipe and the second exhaust pipe to burn the oxides in the first exhaust pipe and the second exhaust pipe. The method for manufacturing a single-crystal silicon ingot according to any one of (3) to (7) above.

Advantages of the Invention

[0021] According to the present invention, it is possible to provide a manufacturing facility for a single-crystal silicon ingot and a method for manufacturing a single-crystal silicon ingot that can promote the combustion of oxides deposited in the exhaust pipe.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be exemplified and described in detail with reference to the drawings.

[0024] <Manufacturing Equipment for Single-Crystal Silicon Ingot> FIG. 1 is a schematic diagram showing the manufacturing equipment of a single-crystal silicon ingot according to an embodiment of the present invention. As shown in FIG. 1, the manufacturing equipment 1 of the single-crystal silicon ingot according to this embodiment includes an exhaust pipeline 3 connected to the manufacturing apparatus 2 of the single-crystal silicon ingot, and a vacuum pump 4 that sucks the inert gas supplied into the manufacturing apparatus 2 of the single-crystal ingot through the exhaust pipeline 3, and a dust chamber 11 for collecting oxides. The manufacturing apparatus 2 of the single-crystal silicon ingot is directly above the floor F.L. in the clean room C.R., the exhaust pipeline 3 is below the floor F.L., and the vacuum pump 4 and the dust chamber 11 are arranged in the pump chamber P.R. outside the clean room C.R., respectively.

[0025] The manufacturing apparatus 2 for a single-crystal silicon ingot has a main chamber 2a and a pull chamber 2b connected to the upper end of the main chamber 2a. Although illustration is omitted, inside the main chamber 2a, there are accommodated a quartz crucible in which a silicon melt is stored, a heater that surrounds the quartz crucible and heats the silicon melt, and the like. Further, at the upper end of the pull chamber 2b, there is provided a pulling means 2c for pulling up the single-crystal silicon ingot. The vacuum pump 4 is connected to the lower surface of the main chamber 2a through an exhaust pipeline 3. Also, an inert gas supply pipeline 5a is connected to the pull chamber 2b. The inert gas supply pipeline 5a is connected to the upper and lower surfaces of the pull chamber 2b via switch valves 5b and 5c, and the inert gas supply pipeline 5a is also connected to a tank (not shown) in which an inert gas (Ar gas in this example) is stored. The switch valves 5b and 5c are, for example, electric ones, and are configured to be able to control the pressure inside the main chamber 2a by adjusting the flow rates of the Ar gas respectively.

[0026] As shown in FIG. 1, the exhaust pipeline 3 is composed of a first exhaust pipe 3a connected to the exhaust gas port 6 of the manufacturing apparatus 2 for a single-crystal ingot and a second exhaust pipe 3b connecting between the first exhaust pipe 3a and the vacuum pump 4. One end of the first exhaust pipe 3a is connected to the lower surface of the main chamber 2a and has a pair of first branch pipelines 3a1 and 3a2 whose other ends merge, and one end is connected to the first branch pipeline 3a1 and the second branch pipeline 3a2 and the other end is connected to a flapper valve 13. When oxides deposited in the exhaust pipeline 3 burn and the pressure inside the exhaust pipeline 3 rapidly rises, the flapper valve 13 is operated to release the pressure inside the exhaust pipeline 3.

[0027] The manufacturing facility 1 for this single-crystal silicon ingot is provided with a first air supply unit 7 that is connected to a first exhaust pipe 3a and supplies air into the first exhaust pipe 3a. In this example, the first air supply unit 7 is a switch valve. The switch valve can be, for example, a two-port two-position switching solenoid valve, and is configured to open when it is turned on and close when it is turned off. Note that in this example, the above operation of the first air supply unit 7 can be controlled by a control unit 12. As the control unit 12, any known controller can be used.

[0028] The manufacturing facility 1 for this single-crystal silicon ingot further includes a second air supply unit 9 that is connected to a second exhaust pipe 3b and supplies air into the second exhaust pipe 3b. In this example, the second air supply unit 9 is a control valve. In this example, the operation of the second air supply unit 9 can be controlled by the above control unit 12. The second air supply unit 9 preferably has high controllability over the air supply amount and the supply timing. As an example, it can be configured using not only a solenoid valve but also a ball valve or a flow meter. If the air supply speed is too fast, a dust cloud is likely to form in the exhaust pipe 3, and it is considered that a dust explosion due to the rapid combustion of oxides is likely to occur. Since the second air supply unit 9 is only a vacuum solenoid valve, it may cause a dust explosion because it supplies air all at once. Therefore, it is preferable to add a silencer and a ball valve capable of a slow OPEN operation (opening over 10 seconds) to prevent the air supply from occurring all at once. In addition, if the total exhaust volume of the Ar gas flow rate and the air supply amount is too large and exceeds the exhaust capacity of the vacuum pump 4 (for example, the exhaust capacity at a furnace internal pressure of 30 Torr is 592 L / min), there is a risk of pump overload, pump stop, or pump failure. Therefore, it is also preferable to add a flow meter with a flow rate adjustment function next to the vacuum solenoid valve to ensure that the air supply amount does not exceed 200 L / min.

[0029] In the manufacturing equipment 1 of the single-crystal silicon ingot of the present embodiment, the second exhaust pipe 3b is provided with a pressure adjustment unit 8 for adjusting the pressure in the first exhaust pipe 3a. In this example, the pressure adjustment unit 8 is a control valve, but it is desirable to use a butterfly valve or the like. By providing the pressure adjustment unit 8, it is possible to suppress the pressure fluctuation in the first exhaust pipe 3a that occurs when air is supplied into the second exhaust pipe 3b from the second air supply unit 9 during the pulling up of the single-crystal silicon ingot. As a result, it is possible to prevent the pressure fluctuation in the main chamber 2a, and without causing the backflow of exhaust gas into the main chamber 2a, etc., it is possible to perform the combustion operation of the oxide deposited in the second exhaust pipe 3b during the pulling up of the single-crystal silicon ingot.

[0030] In this example, when the exhaust gas port 6 side is the front side of the exhaust pipe line 3 and the vacuum pump 4 side is the rear side of the exhaust pipe line 3, the second air supply unit 9 is connected to the rear side of the pressure adjustment unit 8. For example, in this example, the pressure adjustment unit 8 is installed on the tip side (front side) of the second exhaust pipe 3b, and the second air supply unit 9 is provided immediately after the pressure adjustment unit 8. More specifically, the distance at which the oxide can be combusted by the second air supply unit 9 can be appropriately set. Even more specifically, the distance from the pressure adjustment unit 8 to the second air supply unit 9 (the distance along the path of the exhaust pipe line 3) is preferably 50% or less of the distance from the pressure adjustment unit 8 to the vacuum pump 4. Since the temperature in the exhaust pipe line 3 is lower and the temperature of the oxide is also lower closer to the vacuum pump 4 side, there is a tendency that the ignition phenomenon itself for combusting the oxide is difficult to occur. However, by arranging the air supply position close to the pressure adjustment unit 8 where the temperature in the exhaust pipe line 3 is relatively high, the ignitability of the oxide due to air supply is improved, and the oxide deposited in the second exhaust pipe 3b can be combusted.

[0031] In this example, immediately before the pressure adjustment unit 8, a pressure gauge 10 for measuring the pressure in the chamber 2a by measuring the pressure in the first exhaust pipe 3a is arranged. The measured value of the pressure gauge 10 is transmitted to the control unit 12, and based on the pressure fluctuation of the first exhaust pipe 3a obtained therefrom, the pressure adjustment unit 8 is controlled.

[0032] As the vacuum pump 4, a combination of a water-sealed pump and a mechanical booster, an oil rotary pump, a dry vacuum pump, or the like is used. In this example, a dust chamber 11 is provided immediately before the vacuum pump 4, and oxides can be separated from the inert gas sucked by the cyclone 14 and collected in this dust chamber 11.

[0033] <Method for manufacturing single crystal silicon ingot> FIG. 2 is a flowchart of a method for manufacturing a single crystal silicon ingot according to an embodiment of the present invention. As shown in FIG. 2, in the method for manufacturing a single crystal silicon ingot of this embodiment, first, a silicon raw material such as a polycrystalline silicon nugget is filled into a quartz crucible located in the main chamber 2a (step S101: raw material filling step).

[0034] Next, the atmosphere in the main chamber 2a is discharged to evacuate the main chamber 2a (step S102: vacuum process in the chamber). When discharging the atmosphere in the main chamber 2a, the pressure adjustment unit 8 is fully opened.

[0035] Next, the silicon raw material filled in the quartz crucible is heated and melted (step S103: raw material melting step). Specifically, while flowing inert gas Ar, the silicon raw material in the quartz crucible is heated and melted by a heater to form a silicon melt in the quartz crucible. Then, the quartz crucible is raised to the starting position for pulling.

[0036] Next, the seed crystal is lowered and landed on the silicon melt in the quartz crucible (step S104: landing step). For example, it can be performed by lowering the lifting wire using a wire lifting mechanism or the like.

[0037] Next, a single crystal silicon ingot is pulled up from the silicon melt in the quartz crucible (step S105: single crystal growing step). Specifically, while rotating the quartz crucible and the pulling wire in a predetermined direction, the pulling wire is pulled up, and the single crystal silicon ingot is grown below the seed crystal. As the ingot growth progresses, the amount of silicon melt decreases, but the quartz crucible is raised to maintain the level of the silicon melt surface.

[0038] As shown in FIG. 2, the single crystal growth process (step S105) includes the following steps. In the single crystal growth process, first, seed narrowing (necking) is performed by the Dash neck method to make the single crystal silicon ingot dislocation-free, and a necking portion is formed (step S105-1: necking portion growth process). Next, a shoulder portion is grown to obtain an ingot with a required diameter (step S105-2: shoulder portion growth process). Next, when the single crystal silicon ingot reaches a desired diameter, a body portion is grown with the diameter kept constant (step S105-3: body portion growth process). Next, after the body portion is grown to a predetermined length, tail narrowing is performed to separate the single crystal silicon ingot from the silicon melt in a dislocation-free state, and a tail portion is formed (step S105-4: tail portion growth process).

[0039] Next, the grown single crystal silicon ingot is cooled (step S106: single crystal cooling step). For example, the single crystal silicon ingot is left in the pull chamber 2b with the valve closed until the removal temperature reaches preferably 500° C. or less, and cooled.

[0040] In this embodiment, a multiple pulling method is performed in which a raw material melting step (step S103), a liquid application step (step S104), a single crystal growing step (step S105), and a single crystal cooling step (step S106) are repeated to produce multiple single crystal silicon ingots using the same quartz crucible. In step S107, it is determined whether or not to perform the next pulling (based on the planned number of single crystal silicon ingots to be produced, for example).

[0041] When performing the next pulling-up, the inside of the pull chamber 2b is returned to normal pressure (step S108), the single crystal silicon ingot is taken out (step S109), and in order to obtain the next single crystal silicon ingot, the process returns to step S101 to manufacture the next single crystal silicon ingot.

[0042] On the other hand, when not performing the next pulling-up, first, the power supply of the heater is turned off (step S110). Then, the main chamber 2a and the pull chamber 2b are returned to normal pressure (step S112), the single crystal silicon ingot is taken out (step S113), and the manufacturing is terminated. Here, the method of the present embodiment further includes an air supply (step S111) in which, after the single crystal cooling step (step S106) of the single crystal silicon ingot and before returning the inside of the chamber of the manufacturing apparatus 2 of the single crystal silicon ingot to normal pressure (prior to step S112), air is supplied into the pipes of the first exhaust pipe 3a, or the first exhaust pipe 3a and the second exhaust pipe 3b, respectively, by the first air supply unit 7, or the first air supply unit 7 and the second air supply unit 9, to burn the oxides in the first exhaust pipe 3a, or the first exhaust pipe 3a and the second exhaust pipe 3b.

[0043] In this embodiment, in any one or more of the liquid application step (step S104), the single crystal growth step (step S105), and the single crystal cooling step (step S106), air is supplied from (in this example, from the second air supply unit 9) to the inert gas flowing in the exhaust pipe 3 (in this example, in the second exhaust pipe 3b) to burn the oxide in the exhaust pipe 3 (in this example, in the second exhaust pipe 3b). A large amount of SiOx evaporating from the surface of the silicon melt, which is the cause of the oxide deposited in the exhaust pipe 3, is generated during the melting of the silicon raw material when the temperature in the main chamber 2a is higher. Therefore, it is effective to perform the combustion operation of the exhaust pipe 3 (in this example, in the second exhaust pipe 3b) after the raw material melting step (step S103), and it is desirable to perform it in the steps after the liquid application step (step S104). In particular, it is desirable to perform the combustion operation in the single crystal cooling step (step S106). Thus, even if, due to some trouble, SiOx flows back from the exhaust pipe 3 (in this example, in the second exhaust pipe 3b) into the main chamber 2a during the combustion operation of the oxide, since the growth of the single crystal silicon ingot has been completed, no dislocation occurs in the grown single crystal silicon ingot.

[0044] Hereinafter, the effects of the manufacturing equipment for the single crystal silicon ingot of this embodiment and the manufacturing method of the single crystal silicon ingot of this embodiment will be described respectively.

[0045] The manufacturing equipment 1 of the single-crystal silicon ingot according to this embodiment is not only connected to the first exhaust pipe 3a and supplies air into the first exhaust pipe 3a, but also connected to the second exhaust pipe 3b and supplies air into the second exhaust pipe 3b, and is provided with a second air supply unit 9. According to this configuration, air can be supplied independently to each of the first exhaust pipe 3a and the second exhaust pipe 3b, and it is possible to supply air only to the second exhaust pipe 3b during the pulling-up process. Thereby, as described in the embodiment of the method for manufacturing the single-crystal silicon ingot, air can be supplied to burn the oxide in the second exhaust pipe 3b during the pulling-up process, and a sudden combustion of the oxide or a sudden increase in pressure during the pulling-up process can be prevented. Moreover, since the combustion operation of the oxide is performed during the pulling-up process, compared with the combustion operation of the oxide performed after the pulling-up is completed and the heater power is turned off, a higher-temperature Ar gas flows in the second exhaust pipe 3b, the combustion effect of the oxide is further enhanced, and the oxide deposited in the second exhaust pipe 3b on the side of the vacuum pump 4 can be sufficiently burned. Further, a pressure adjustment unit 8 for adjusting the pressure in the first exhaust pipe 3a is provided in the second exhaust pipe 3b, and since the second air supply unit 9 is connected to the rear side of the pressure adjustment unit 8, the pressure fluctuation in the first exhaust pipe 3a generated when air is supplied into the second exhaust pipe 3b can be eliminated. As a result, contamination due to the backflow of exhaust gas into the main chamber 2a can be avoided.

[0046] In addition, in the method for manufacturing a single-crystal silicon ingot according to the present embodiment, in any one or more of the liquid landing step (step S104), the single-crystal growth step (step S105), and the single-crystal cooling step (step S106), air is supplied from (in this example, from the second air supply unit 9) to the inert gas flowing in the exhaust pipe line 3 (in this example, in the second exhaust pipe 3b) to burn the oxides in the exhaust pipe line 3 (in this example, in the second exhaust pipe 3b). Thereby, the oxides in the exhaust pipe line 3 (in this example, in the second exhaust pipe 3b) can be burned while being lifted. Therefore, it is possible to prevent a sudden combustion of the oxides and a sudden increase in pressure during the pulling of the single-crystal silicon ingot, and it is possible to promote the combustion of the oxides deposited in the exhaust pipe. Further, it is preferable to measure the pressure in the first exhaust pipe 3a generated when air is supplied into the exhaust pipe line 3 (in this example, in the second exhaust pipe 3b), and based on the measured pressure fluctuation value, adjust the pressure in the first exhaust pipe 3a by the pressure adjustment unit 8, whereby the above air supply can be performed more safely.

[0047] In the method for manufacturing a single-crystal silicon ingot according to the present embodiment, after the single-crystal cooling step (step S106) of the single-crystal silicon ingot and before returning the inside of the chamber of the manufacturing apparatus 2 of the single-crystal silicon ingot to normal pressure, the first exhaust pipe 3a, or the first exhaust pipe 3a and the second exhaust pipe 3b are respectively supplied with air by the first air supply unit 7, or the first air supply unit 7 and the second air supply unit 9, It is preferable to further include an air supply (step S111) for burning the oxides in the first exhaust pipe 3a, or the first exhaust pipe 3a and the second exhaust pipe 3b. This is because even after the pulling of one single-crystal silicon ingot is completed, by burning the oxides in the first exhaust pipe 3a and the second exhaust pipe 3b, the oxides can be further burned and the deposition of the oxides can be effectively reduced. In addition, the method for manufacturing a single-crystal silicon ingot according to the present embodiment preferably performs a multiplication method in which a plurality of single-crystal silicon ingots are manufactured using the same quartz crucible by repeating a raw material melting step (step S103), a liquid landing step (step S104), a single-crystal growth step (step S105), and a single-crystal cooling step (step S106). This is because, particularly in the case of long-term operation, the combustion of oxides in the exhaust pipe can be promoted, and the above-described effects can be advantageously obtained. Further, it is preferable to supply air (from the second air supply unit 9 in this example) for each production of a single-crystal silicon ingot when manufacturing a plurality of single-crystal silicon ingots. As a result, the oxides are burned before a large amount of oxides accumulates in the exhaust pipe 3 (in the second exhaust pipe 3b in this example), and it is possible to prevent the pressure from rising suddenly due to the sudden combustion of the oxides during the pulling up of the single-crystal silicon ingot.

[0048] Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples at all.

Example

[0049] (Example 1) To confirm the effects of the present invention, experiments were conducted to pull up one single-crystal silicon ingot using the manufacturing equipment for single-crystal silicon ingots shown in FIG. 1 for Invention Examples 1 to 3 and FIGS. 3 to 4 for Comparative Examples 1 to 2. The pulling-up conditions of the single-crystal silicon ingot were the same for each example, and experiments were conducted with various changes in the timing of air supply. Thereafter, a combustion evaluation test of oxides at the time of opening the dust chamber and a forced ignition test of oxides were conducted. Here, the "combustion evaluation test of oxides at the time of opening the dust chamber" is a test in which, 6 hours after the completion of pulling up, the lid of the dust chamber 11 is opened to confirm the presence or absence of combustion of the oxides collected in the dust chamber 11. The "forced ignition test" is a test in which oxides that were not burned in the "combustion evaluation test of oxides at the time of opening the dust chamber" are collected and the presence or absence of combustion is evaluated when the oxides are forcibly ignited with a lighter or the like.

[0050] In Comparative Example 1, air supply into the exhaust pipe 3 was not carried out. Specifically, after the growth of the single-crystal silicon ingot was completed and the single-crystal silicon ingot was moved from the main chamber 2a into the pull chamber 2b, an operation to turn off the heater power supply was performed. After turning off the heater power supply and 6 hours had elapsed since the end of the pulling, an oxidation combustion evaluation test was conducted when the lid of the dust chamber 11 was opened. As a result, when the lid of the dust chamber 11 was opened, the oxide collected in the dust chamber 11 burned violently. For this reason, the forced ignition test was not performed in Comparative Example 1.

[0051] In Comparative Example 2, an experiment was conducted under the same conditions as in Comparative Example 1, except that after turning off the heater power supply and before returning the pressure inside the chamber to normal pressure, air was supplied from the air supply unit into the exhaust pipe 3. As a result, no combustion reaction of the oxide was observed when the lid of the dust chamber 11 was opened. Also, when the oxide was recovered from the dust chamber 11 and a forced ignition test was conducted, it was confirmed that the oxide burned violently. That is, in Comparative Example 2, although the combustion operation of the oxide by air supply was performed, 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.

[0052] In Invention Example 1, air was supplied from the second air supply unit 9 into the second exhaust pipe 3b during the liquid application step (step S104). As a result, no combustion reaction of the oxide was observed when the lid of the dust chamber 11 was opened. Also, when a forced ignition test was conducted on the oxide recovered from the dust chamber 11, slight combustion of the oxide was confirmed. Also, in Invention Example 1, despite performing the combustion operation of the oxide by air supply during the liquid application step, no pressure fluctuation was observed inside the main chamber 2a, and a dislocation-free single-crystal silicon ingot could be grown.

[0053] In Invention Example 2, air was supplied from the second air supply unit 9 into the second exhaust pipe 3b during the single-crystal cooling process (step S106). When the lid of the dust chamber 11 was opened, combustion of the oxide was not observed, and slight combustion of the oxide was confirmed in the forced ignition test.

[0054] In Invention Example 3, air was supplied from the second air supply unit 9 into the second exhaust pipe 3b during the single-crystal cooling process (step S106), and air was supplied (step S111) 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, before returning the pressure inside the chamber to normal pressure. When the lid of the dust chamber 11 was opened, combustion of the oxide was not observed, and combustion was not confirmed even in the forced ignition test.

[0055] (Example 2) To confirm the effects of the present invention in the multiplication method, for Invention Examples 4 to 6, a pulling-up experiment was conducted to continuously grow two single-crystal silicon ingots using the manufacturing equipment for single-crystal silicon ingots shown in FIG. 1, and for Comparative Example 3, using the manufacturing equipment shown in FIG. 4. An ignition evaluation test of the oxide and a forced ignition test of the oxide were conducted under the same conditions as in Example 1, except that pulling-up by the multiplication method was performed.

[0056] In Comparative Example 3, after pulling up two single-crystal silicon ingots by the multiplication method and turning off the heater power supply, air was supplied from the first air supply unit 7 into the exhaust pipe line 3. When the lid of the dust chamber 11 was opened, intense combustion of the oxide was observed. Therefore, the forced ignition test was not conducted.

[0057] In Invention Example 4, air was supplied from the second air supply unit 9 into the second exhaust pipe 3b during the second single-crystal cooling process of the multiplication method. When the dust chamber 11 was opened, combustion of the oxide was not observed, and it was confirmed that the oxide burned slightly in the forced ignition test.

[0058] In Invention Example 5, air was supplied from the second air supply unit into the second exhaust pipe 3b during the first and second single crystal cooling processes of the multiplication method. As a result, as in Invention Example 4, combustion was not observed when the dust chamber 11 was opened, and it was confirmed that the oxide slightly burned in the forced ignition test. When compared with Invention Example 4, it was confirmed that the combustion amount of the oxide during the evaluation test was small. This is presumably because the oxide in the second exhaust pipe 3b was burned each time during the single crystal cooling process, resulting in a small amount of oxide deposited in the second exhaust pipe 3b.

[0059] In Invention Example 6, air was supplied from the second air supply unit 9 into the second exhaust pipe 3b during the first and second single crystal cooling processes of the multiplication method, and air was supplied from the first and second air supply units before returning the inside of the chamber to normal pressure. However, air supply (step S111) was not performed during the first single crystal cooling process of the multiplication method and after turning off the heater power supply. The oxide did not burn when the dust chamber was opened and also did not burn in the forced ignition test.

[0060]

Table 1

[0061] Table 1 summarizes the evaluation results of Invention Examples 1 to 6 and Comparative Examples 1 to 3 in Examples 1 and 2. In Invention Examples 1 to 3, when air was supplied to the second exhaust pipe 3b during pulling up, it was confirmed that the combustion effect of the oxide was higher than when air was supplied into the exhaust pipe line 3 after the completion of pulling up. Also, when growing a plurality of single crystal silicon ingots by the multiplication method, the amount of oxide deposited in the exhaust pipe line 3 also increases, so it is expected that the oxide cannot burn sufficiently. However, as is clear from the results of Invention Examples 4 to 6, when air was supplied into the second exhaust pipe during pulling up, it was confirmed that the oxide can burn sufficiently in the multiplication method.

Explanation of Reference Signs

[0062] 1: Manufacturing equipment for single-crystal silicon ingots, 2: Manufacturing apparatus for single-crystal silicon ingots, 3: Exhaust pipeline, 4: Vacuum pump, 5a: Inert gas supply port, 5b, 5c: Switch valves, 6: Exhaust gas port, 7: First air supply section, 8: Pressure adjustment section, 9: Second air supply section, 10: Pressure gauge, 11: Dust chamber, 12: Control section, 13: Flapper valve (explosion-proof valve), 14: Cyclone

Claims

1. An exhaust pipeline connected to a manufacturing apparatus for a single crystal silicon ingot, and a vacuum pump for sucking an inert gas supplied into the manufacturing apparatus for a single crystal silicon ingot through the exhaust pipeline, wherein the manufacturing facility for a single crystal silicon ingot comprises: the exhaust pipeline consists of a first exhaust pipe connected to an exhaust gas outlet of the manufacturing apparatus for a single crystal silicon ingot, and a second exhaust pipe connecting between the first exhaust pipe and the vacuum pump; a first air supply unit connected to the first exhaust pipe for supplying air into the first exhaust pipe; a second air supply unit connected to the second exhaust pipe for supplying air into the second exhaust pipe; a pressure adjustment unit for adjusting the pressure in the first exhaust pipe is provided in the second exhaust pipe; when the exhaust gas outlet side is the front side of the exhaust pipeline and the vacuum pump side is the rear side of the exhaust pipeline, the second air supply unit is connected to a position behind the pressure adjustment unit; a manufacturing facility for a single crystal silicon ingot, characterized in that a distance from the pressure adjustment unit to the second air supply unit is 50% or less of a distance from the pressure adjustment unit to the vacuum pump.

2. A method for manufacturing a single crystal silicon ingot by the Czochralski method using the manufacturing facility for a single crystal silicon ingot according to Claim 1, wherein the method for manufacturing a single crystal silicon ingot includes a raw material melting step of heating and melting a silicon raw material filled in a quartz crucible, a liquid attachment step of lowering a seed crystal to attach it to a silicon melt in the quartz crucible, a single crystal growth step of pulling up a single crystal silicon ingot from the silicon melt in the quartz crucible, and a single crystal cooling step of cooling the grown single crystal silicon ingot in a pull chamber of the manufacturing apparatus for a single crystal silicon ingot. In any one or more of the liquid attachment step, the single crystal growth step, and the single crystal cooling step, air is supplied to an inert gas flowing in the exhaust pipeline connected to the manufacturing apparatus for a single crystal silicon ingot to burn oxides in the exhaust pipeline; A method for manufacturing a single crystal silicon ingot, wherein in any one or more of the liquid attachment step, the single crystal growth step, and the single crystal cooling step, air is supplied from the second air supply unit to an inert gas flowing in the second exhaust pipe to burn oxides in the second exhaust pipe.

3. A method for manufacturing a single-crystal silicon ingot according to claim 2, using the manufacturing equipment for a single-crystal silicon ingot according to claim 1, wherein when air is supplied into the second exhaust pipe, the pressure in the first exhaust pipe that occurs is measured, and based on the measured pressure fluctuation value, the pressure in the first exhaust pipe is adjusted by the pressure adjustment unit. A method for manufacturing a single-crystal silicon ingot.

4. A method for manufacturing a single-crystal silicon ingot according to claim 2 or 3, which performs a multiplexing method of manufacturing a plurality of the single-crystal silicon ingots using the same quartz crucible by repeating the raw material melting step, the liquid deposition step, the single-crystal growth step, and the single-crystal cooling step.

5. When manufacturing a plurality of the single-crystal silicon ingots, for each manufacture of one of the single-crystal silicon ingots, air is supplied into the second exhaust pipe by the second air supply unit to burn the oxides in the second exhaust pipe. A method for manufacturing a single-crystal silicon ingot according to claim 4.

6. After the single-crystal cooling step of the single-crystal silicon ingot and before returning the inside of the chamber of the manufacturing apparatus of the single-crystal silicon ingot to normal pressure, air is supplied into the first exhaust pipe by the first air supply unit to burn the oxides in the first exhaust pipe. A method for manufacturing a single-crystal silicon ingot according to any one of claims 2 to 5.

7. After the single-crystal cooling step of the single-crystal silicon ingot and before returning the inside of the chamber of the manufacturing apparatus of the single-crystal silicon ingot to normal pressure, air is supplied into the first exhaust pipe and the second exhaust pipe by the first air supply unit and the second air supply unit to burn the oxides in the first exhaust pipe and the second exhaust pipe. A method for manufacturing a single-crystal silicon ingot according to any one of claims 2 to 5.

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