Facility and method for manufacturing single crystal silicon ingot

Abstract

To provide a facility and a method for manufacturing a single crystal silicon ingot that can promote combustion of an oxide depositing inside of an exhaust pipe.SOLUTION: A manufacturing facility includes: an exhaust pipeline connected to a single crystal silicon ingot manufacturing apparatus; and a vacuum pump for sucking an inert gas that is supplied into the manufacturing apparatus through the exhaust pipeline. The exhaust pipeline includes: a first air supply part comprising a first exhaust pipe connected to an exhaust gas port of the manufacturing apparatus and a second exhaust pipe for connecting between the first exhaust pipe and the vacuum pump, connected to the first exhaust pipe, and supplying air into the first exhaust pipe; and a second air supply part connected to the second exhaust pipe to supply air. A manufacturing method uses the single crystal silicon ingot manufacturing apparatus to supply air to the inert gas flowing through the exhaust pipeline and burn the oxide inside the exhaust pipeline in any one or more steps of the dipping step, single crystal growing step, and single crystal cooling step.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] A typical method for manufacturing a single crystal silicon ingot is the Czochralski method (CZ method). In the manufacturing of a single crystal silicon ingot by the CZ method, a quartz crucible is filled with silicon raw material such as polycrystalline silicon, and the silicon raw material is heated and melted in a chamber of a single crystal silicon ingot manufacturing device under an inert gas atmosphere to form a silicon melt. Next, a 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, thereby growing a single crystal silicon ingot below the seed crystal. An exhaust system for exhausting the inert gas supplied into the chamber is connected to the single crystal silicon ingot manufacturing device, and an exhaust gas port is provided at the bottom of the single crystal silicon ingot manufacturing device, and the inert gas is sucked and exhausted by a vacuum pump through an exhaust pipe from the exhaust gas port.

[0003] The multiple pulling method is known as an application of the above CZ method. In the multiple pulling method, after pulling up the first single crystal silicon ingot, silicon raw material is additionally charged and melted in the same quartz crucible, and the second single crystal silicon ingot is pulled up from the obtained silicon melt. By repeating such a raw material charging process and pulling process, multiple single crystal silicon ingots are manufactured from one quartz crucible. According to the multiple pulling method, the cost of the quartz crucible per single crystal silicon ingot can be reduced. In addition, the frequency of dismantling the chamber and replacing the quartz crucible can be reduced, thereby improving the operating efficiency.

[0004] When pulling up a single crystal silicon ingot by the CZ method, oxygen dissolves from the inner surface of the quartz crucible into the silicon melt, which reacts with the silicon melt to generate oxides (SiOx), which evaporate from the surface of the silicon melt. These oxides flow through the exhaust pipe together with the inert gas in the single crystal silicon ingot manufacturing equipment and are collected in the dust chamber, but since the exhaust pipe from the exhaust gas outlet to the dust chamber is long, the oxides cool and condense as they flow through the exhaust pipe, and over time they adhere to and accumulate on the exhaust pipe. For this reason, there is a tendency for the amount of oxide accumulation to be greater on the dust chamber side at the rear of the exhaust pipe than on the exhaust gas outlet side at the front.

[0005] In the CZ method, since the manufacturing time per unit is long, the accumulation of oxides in the exhaust pipe becomes a problem. That is, if the amount of oxides accumulated in the exhaust pipe becomes large, the accumulated oxides may flow back from the exhaust pipe to the single crystal silicon ingot manufacturing equipment, causing dislocations in the single crystal silicon ingot, or the oxides may cause fluctuations in the pressure in the exhaust pipe, causing a sudden rise in temperature and pressure, which may cause the oxides to ignite.

[0006] In response to this, it has been proposed to supply air into the exhaust pipe after the pulling of the single crystal silicon ingot is completed, to burn off the oxides accumulated in the exhaust pipe (for example, Patent Documents 1 and 2). According to this, it is possible to reduce the oxides accumulated in the exhaust pipe after the pulling of the single crystal silicon ingot is completed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2001-097797 A [Patent Document 2] JP 2002-316889 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, when dislocations occur during pulling of the 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 one quartz crucible by the multiple pulling method, the operation time until the pulling is completed increases. Since the amount of oxides deposited in the exhaust pipe increases with an increase in operation time, the oxides cannot be burned during pulling even if the oxides are burned after the pulling of the single crystal silicon ingot is completed as described in Patent Documents 1 and 2. Therefore, the oxides in the exhaust pipe cannot be burned sufficiently until 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 a sudden fire will occur.

[0009] In addition, since the exhaust pipe from the exhaust gas port at the bottom of the single crystal silicon ingot manufacturing equipment to the dust chamber is long, when the power supply of the heater in the single crystal silicon ingot manufacturing equipment is turned off after the pulling of the single crystal silicon ingot is completed and the combustion operation is performed by supplying air, the oxides in the exhaust pipe close to the single crystal silicon ingot manufacturing equipment are burned, but the oxides in the exhaust pipe close to the vacuum pump, which is far away, are not sufficiently burned. This is considered to be due to the fact that the temperature inside the exhaust pipe close to the single crystal silicon ingot manufacturing equipment is relatively high immediately after the heater power supply is turned off, so the combustion reaction of the oxides is likely to occur, while the temperature inside the exhaust pipe close to the dust chamber, which is far away, is low, so the combustion reaction of the oxides is difficult to occur. Thus, it has become clear that the combustion operation by supplying air performed after the pulling is completed and the heater power supply is turned off cannot sufficiently burn the oxides over the entire length of the exhaust pipe.

[0010] Therefore, an object of the present invention is to provide a single crystal silicon ingot manufacturing equipment and a single crystal silicon ingot manufacturing method that can promote the combustion of oxides accumulated inside an exhaust pipe. [Means for solving the problem]

[0011] The inventors have realized that the above-mentioned problems can be advantageously solved by supplying air to a predetermined portion of the exhaust pipe in a predetermined step during the pulling of a single crystal silicon ingot. In the present invention, "air" refers to the total gas surrounding the earth, and includes oxygen, nitrogen, hydrogen, argon, carbon dioxide, ozone, neon, helium, water vapor, and the like.

[0012] The gist and configuration of the present invention are as follows. (1) an exhaust pipe connected to a single crystal silicon ingot manufacturing apparatus; a vacuum pump that sucks in the inert gas supplied into the single crystal silicon ingot manufacturing apparatus through the exhaust pipeline, the exhaust pipeline includes a first exhaust pipe connected to an exhaust gas outlet of the single crystal silicon ingot manufacturing apparatus, and a second exhaust pipe connecting 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.

[0013] (2) the second exhaust pipe is provided with a pressure adjusting unit that adjusts the pressure inside the first exhaust pipe, The single crystal silicon ingot manufacturing equipment described in (1) above, wherein when the exhaust gas port 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 rearward of the pressure adjustment unit. It should be noted that the "forward side" includes not only the inside of the second exhaust pipe, but also the inside of the first exhaust pipe.

[0014] (3) A method for producing a single crystal silicon ingot by the Czochralski method, comprising the steps of: a raw material melting step of heating and melting the silicon raw material filled in the quartz crucible; a step of lowering a seed crystal to make it contact with the silicon melt in the quartz crucible; a single crystal growing 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, a single crystal silicon ingot manufacturing method, characterized in that, in one or more of the liquid application step, the single crystal growing step, and the single crystal cooling step, air is supplied to an inert gas flowing in an exhaust pipe connected to an apparatus for manufacturing a single crystal silicon ingot, thereby burning oxides in the exhaust pipe.

[0015] (4) A method for producing a single crystal silicon ingot according to the above (3) by a Czochralski method using the single crystal silicon ingot production equipment according to the above (1) or (2), comprising: In one or more of the liquid application 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 combust oxides in the second exhaust pipe.

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

[0017] (6) The method for producing a single crystal silicon ingot according to any one of (3) to (5) above, wherein a multiple-pulling method is performed in which a plurality of the single crystal silicon ingots are produced using the same quartz crucible by repeating the raw material melting step, the liquid application step, the single crystal growing step, and the single crystal cooling step.

[0018] (7) The method for producing a single crystal silicon ingot according to (6) above, wherein, when producing a plurality of the single crystal silicon ingots, air is supplied into the second exhaust pipe by the second air supply unit for each production of the single crystal silicon ingot, thereby burning oxides in the second exhaust pipe.

[0019] (8) The method for producing a single crystal silicon ingot according to any one of (3) to (7) above, wherein, after the single crystal cooling step of the single crystal silicon ingot, before the pressure inside a chamber of the production apparatus for the single crystal silicon ingot is returned to normal pressure, air is supplied into the first exhaust pipe by the first air supply unit to combust oxides in the first exhaust pipe.

[0020] (9) The method for producing a single crystal silicon ingot according to any one of (3) to (7) above, wherein, after the single crystal cooling step of the single crystal silicon ingot, before returning an inside of a chamber of the production 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, thereby burning oxides in the first exhaust pipe and the second exhaust pipe. Effect of the Invention

[0021] According to the present invention, it is possible to provide a single crystal silicon ingot manufacturing equipment and a single crystal silicon ingot manufacturing method capable of promoting the combustion of oxides accumulated inside an exhaust pipe. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic diagram showing a manufacturing facility for a single crystal silicon ingot according to an embodiment of the present invention. [Diagram 2] 1 is a flowchart of a method for producing a single crystal silicon ingot according to an embodiment of the present invention. [Diagram 3] 1 is a schematic diagram showing a manufacturing facility for a single crystal silicon ingot used in Comparative Example 1. FIG. [Figure 4]FIG. 2 is a schematic diagram showing a manufacturing facility for a single crystal silicon ingot used in Comparative Examples 2 and 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0024] <Single crystal silicon ingot manufacturing equipment> Fig. 1 is a schematic diagram showing a single crystal silicon ingot manufacturing facility according to one embodiment of the present invention. As shown in Fig. 1, the single crystal silicon ingot manufacturing facility 1 of this embodiment includes an exhaust pipe 3 connected to a single crystal silicon ingot manufacturing device 2, a vacuum pump 4 that sucks in an inert gas supplied into the single crystal ingot manufacturing device 2 through the exhaust pipe 3, and a dust chamber 11 that collects oxides. The single crystal silicon ingot manufacturing device 2 is located directly above a floor FL in a clean room CR, the exhaust pipe 3 is located below the floor FL, and the vacuum pump 4 and the dust chamber 11 are located in a pump room PR outside the clean room CR.

[0025] The manufacturing apparatus 2 for the 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 not shown, the main chamber 2a accommodates a quartz crucible for storing silicon melt, a heater surrounding the quartz crucible for heating the silicon melt, and the like. The upper end of the pull chamber 2b is provided with 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 pipe 3. An inert gas supply pipe 5a is connected to the pull chamber 2b. The inert gas supply pipe 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 pipe 5a is also connected to a tank (not shown) for storing an inert gas (Ar gas in this example). The switch valves 5b and 5c are, for example, electrically operated, and are configured to be able to control the pressure in the main chamber 2a by adjusting the flow rate of the Ar gas, respectively.

[0026] As shown in Fig. 1, the exhaust pipe 3 is composed of a first exhaust pipe 3a connected to an exhaust gas port 6 of the single crystal ingot manufacturing apparatus 2, and a second exhaust pipe 3b connecting the first exhaust pipe 3a and a vacuum pump 4. The first exhaust pipe 3a has a pair of first and second branch pipes 3a1 and 3a2, one end of which is connected to the lower surface of the main chamber 2a and the other end of which joins together, and a third branch pipe 3a3, one end of which is connected to the first and second branch pipes 3a1 and 3a2 and the other end of which is connected to a flapper valve 13. When oxides deposited in the exhaust pipe 3 are burned and the pressure in the exhaust pipe 3 rises suddenly, the flapper valve 13 is operated to release the pressure in the exhaust pipe 3.

[0027] This single crystal silicon ingot manufacturing equipment 1 is equipped with a first air supply unit 7 that is connected to the 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 so that when turned on, the switch valve opens, and when turned off, the switch valve closes. In this example, the above operation of the first air supply unit 7 can be controlled by the control unit 12. Any known controller can be used as the control unit 12.

[0028] This single crystal silicon ingot manufacturing equipment 1 further includes a second air supply unit 9 that is connected to the 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-mentioned control unit 12. It is preferable that the second air supply unit 9 has high controllability for the amount of air supplied and the timing of supply, and as an example, it is not limited to only a solenoid valve but can be a ball valve or a flow meter. If the air supply speed is too fast, dust clouds are likely to form in the exhaust pipe 3, and dust explosions due to the rapid combustion of oxides are likely to occur. Since the second air supply unit 9 is only a vacuum solenoid valve, there is a risk of a dust explosion occurring because air is supplied all at once. Therefore, it is preferable to add a silencer and a ball valve capable of slow-opening (taking 10 seconds to open) to prevent air supply from occurring all at once. In addition, if the total exhaust volume of the Ar gas flow rate and the air supply volume is too large, the pump may overload and stop or break down if it exceeds the exhaust capacity of the vacuum pump 4 (for example, the exhaust capacity is 592 L / min when the furnace pressure is 30 Torr). Therefore, it is also preferable to add a flow meter with a flow rate adjustment function next to the vacuum solenoid valve to prevent the air supply volume from exceeding 200 L / min.

[0029] In the manufacturing equipment 1 for producing a single crystal silicon ingot according to the present embodiment, the second exhaust pipe 3b is provided with a pressure adjusting unit 8 for adjusting the pressure inside the first exhaust pipe 3a. In this example, the pressure adjusting unit 8 is a control valve, but it is preferable to use a butterfly valve or the like. By providing the pressure adjustment unit 8, it is possible to suppress pressure fluctuations in the first exhaust pipe 3a that occur when air is supplied from the second air supply unit 9 into the second exhaust pipe 3b while the single crystal silicon ingot is being pulled up. As a result, it is possible to prevent pressure fluctuations in the main chamber 2a, and it is possible to perform a combustion operation of oxides that accumulate in the second exhaust pipe 3b while the single crystal silicon ingot is being pulled up, without causing a backflow of exhaust gas into the main chamber 2a.

[0030] In this example, when the exhaust gas port 6 side is the front side of the exhaust pipe 3 and the vacuum pump 4 side is the rear side of the exhaust pipe 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 at 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 is set to a distance at which the oxides can be burned by the second air supply unit 9, and this distance can be set appropriately. 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 3) is preferably 50% or less of the distance from the pressure adjustment unit 8 to the vacuum pump 4. The closer to the vacuum pump 4, the lower the temperature in the exhaust pipe 3 and the lower the temperature of the oxides, so there is a tendency for the ignition phenomenon itself to be less likely to occur in order to burn the oxides. However, by positioning the air supply position close to the pressure adjustment unit 8, where the temperature in the exhaust pipe 3 is relatively high, the ignition ability of the oxides due to the air supply is improved, and the oxides accumulated in the second exhaust pipe 3b can be burned.

[0031] In this example, a pressure gauge 10 that measures the pressure in the chamber 2a by measuring the pressure in the first exhaust pipe 3a is placed immediately before the pressure adjustment unit 8. The measurement value of the pressure gauge 10 is sent to a control unit 12, and the pressure adjustment unit 8 is controlled based on the pressure fluctuation in the first exhaust pipe 3a obtained from there.

[0032] The vacuum pump 4 may be a combination of a water seal pump and a mechanical booster, an oil rotary pump, a dry vacuum pump, or the like. 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 in by a cyclone 14 and collected in this dust chamber 11.

[0033] <Method for manufacturing single crystal silicon ingot> Fig. 2 is a flow chart 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 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 exhausted to evacuate the main chamber 2a (step S102: vacuum process in the chamber). When exhausting 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, the silicon raw material in the quartz crucible is heated and melted by a heater while flowing inert gas Ar, forming a silicon melt in the quartz crucible. After that, the quartz crucible is raised to the lifting start position.

[0036] Next, the seed crystal is lowered to be immersed in the silicon melt in the quartz crucible (step S104: immersion step), which can be performed, for example, by lowering the pulling 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 the next pulling is to be performed, the pressure inside the pulling chamber 2b is returned to normal pressure (step S108), the single crystal silicon ingot is removed (step S109), and the process returns to step S101 to produce the next single crystal silicon ingot.

[0042] On the other hand, if the next pulling is not performed, 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), and the single crystal silicon ingot is taken out (step S113), and the manufacturing is completed. Here, the method of the present embodiment further includes an air supply (step S111) in which air is supplied into 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, after the single crystal cooling step (step S106) of the single crystal silicon ingot, and before the pressure inside the chamber of the manufacturing apparatus 2 for the single crystal silicon ingot is returned to normal pressure (prior to step S112), to burn oxides in the first exhaust pipe 3a, or the first exhaust pipe 3a and the second exhaust pipe 3b.

[0043] In this embodiment, in one or more steps of the liquid-attaching step (step S104), the single crystal growing step (step S105), and the single crystal cooling step (step S106), air is supplied (from the second air supply unit 9 in this example) to the inert gas flowing in the exhaust pipe 3 (in the second exhaust pipe 3b in this example) to combust the oxides in the exhaust pipe 3 (in the second exhaust pipe 3b in this example). SiOx, which is the cause of the oxides that accumulate in the exhaust pipe 3, is evaporated from the silicon melt surface and is generated in large amounts when the silicon raw material is melted, which makes the temperature in the main chamber 2a higher. For this reason, it is effective to perform a combustion operation in the exhaust pipe 3 (in the second exhaust pipe 3b in this example) after the raw material melting step (step S103), and it is desirable to perform it in the steps after the liquid-attaching step (step S104). In particular, it is desirable to carry out a combustion operation in the single crystal cooling step (step S106). As a result, even if some trouble occurs such that SiOx flows back from inside the exhaust pipe 3 (in the second exhaust pipe 3b in this example) into the main chamber 2a during the oxide combustion operation, the growth of the single crystal silicon ingot is already completed, and therefore dislocations will not occur in the grown single crystal silicon ingot.

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

[0045] The manufacturing equipment 1 for a single crystal silicon ingot of this 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 independently to each of the first exhaust pipe 3a and the second exhaust pipe 3b, and air can be supplied only to the second exhaust pipe 3b during pulling. This allows the oxide in the second exhaust pipe 3b to be burned during pulling by supplying air as described in the embodiment of the manufacturing method for a single crystal silicon ingot, and prevents a sudden combustion of the oxide during pulling and a sudden rise in pressure. Moreover, since the oxide combustion operation is performed during pulling, a higher temperature Ar gas flows in the second exhaust pipe 3b compared to the oxide combustion operation performed after the heater power is turned off after the pulling is completed, and the oxide combustion effect is enhanced, and the oxide deposited in the second exhaust pipe 3b on the vacuum pump 4 side can be sufficiently burned. In addition, a pressure adjustment unit 8 that adjusts the pressure in the first exhaust pipe 3a is provided in the second exhaust pipe 3b, and the second air supply unit 9 is connected rearward of the pressure adjustment unit 8. This makes it possible to eliminate pressure fluctuations in the first exhaust pipe 3a that occur when air is supplied into the second exhaust pipe 3b, and as a result, contamination due to exhaust gas backflow into the main chamber 2a can be avoided.

[0046] In addition, in the method for producing a single crystal silicon ingot according to the present embodiment, in one or more steps 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 the second air supply unit 9 in this example) to the inert gas flowing in the exhaust pipe 3 (in the second exhaust pipe 3b in this example) to combust the oxides in the exhaust pipe 3 (in the second exhaust pipe 3b in this example). This allows the oxides in the exhaust pipe 3 (in the second exhaust pipe 3b in this example) to be combusted during pulling. Therefore, it is possible to prevent the oxides from being suddenly burned or the pressure from being suddenly increased during pulling of the single crystal silicon ingot, and it is possible to promote the combustion of the oxides accumulated in the exhaust pipe. Furthermore, it is preferable to measure the pressure in the first exhaust pipe 3a that occurs when air is supplied into the exhaust pipe 3 (in the second exhaust pipe 3b in this example) and adjust the pressure in the first exhaust pipe 3a by the pressure adjustment unit 8 based on the measured pressure fluctuation value, thereby making it possible to carry out the above-mentioned air supply more safely.

[0047] In the method for producing a single crystal silicon ingot of this embodiment, it is preferable to further include an air supply (step S111) in which air is supplied into 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, before the pressure inside the chamber of the single crystal silicon ingot production apparatus 2 is returned to normal pressure after the single crystal cooling step (step S106) of the single crystal silicon ingot, to burn 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, the oxides in the first exhaust pipe 3a and the second exhaust pipe 3b can be further burned and the deposition of oxides can be effectively reduced by burning the oxides. Furthermore, the method for producing a single crystal silicon ingot in this embodiment is preferably a multiple-pulling method in which a plurality of single crystal silicon ingots are produced using the same quartz crucible by repeating the raw material melting step (step S103), the liquid application step (step S104), the single crystal growing step (step S105), and the single crystal cooling step (step S106), because this can advantageously obtain the above-mentioned effects by promoting the combustion of oxides in the exhaust pipe, particularly during long-term operation. Furthermore, when producing multiple single crystal silicon ingots, it is preferable to supply the above air (from the second air supply unit 9 in this example) for each single crystal silicon ingot produced, which allows the oxides to be burned before they accumulate in large quantities in the exhaust pipe 3 (in the second exhaust pipe 3b in this example), thereby preventing the oxides from burning suddenly and causing a sudden rise in pressure while the single crystal silicon ingot is being pulled up.

[0048] Examples of the present invention will be described below, but the present invention is not limited to the following examples in any way. EXAMPLES

[0049] Example 1 In order to confirm the effects of the present invention, an experiment was conducted to pull up one single crystal silicon ingot using the single crystal silicon ingot manufacturing equipment shown in Fig. 1 for invention examples 1 to 3 and Fig. 3 and Fig. 4 for comparative examples 1 and 2. The conditions for pulling up the single crystal silicon ingot were the same for each example, and experiments were conducted by changing the timing of air supply in various ways. After that, an oxide combustion evaluation test when the dust chamber was opened and an oxide forced ignition test were conducted. Here, the "test to evaluate the combustion of oxides when the dust chamber is opened" refers to a test in which the lid of the dust chamber 11 is opened 6 hours after the completion of lifting, and whether or not the oxides collected in the dust chamber 11 have burned is confirmed. Also, the "forced ignition test" refers to a test in which the oxides that were not burned in the "test to evaluate the combustion of oxides when the dust chamber is opened" are collected, and the oxides are forcibly ignited with a lighter or the like to evaluate whether or not they have burned.

[0050] In Comparative Example 1, air was not supplied into the exhaust pipe 3. Specifically, after completing the growth of the single crystal silicon ingot and moving the single crystal silicon ingot from the main chamber 2a into the pull chamber 2b, the heater power supply was turned off. After the heater power supply was turned off and six hours had passed since the completion of pulling, an oxide 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 oxides collected in the dust chamber 11 burned violently. For this reason, a forced ignition test was not conducted in Comparative Example 1.

[0051] In Comparative Example 2, an experiment was performed under the same conditions as Comparative Example 1, except that after the heater power supply was turned off, air was supplied from the air supply unit into the exhaust pipe 3 before the pressure inside the chamber was returned to normal. As a result, no combustion reaction of the oxides was observed when the lid of the dust chamber 11 was opened. In addition, when the oxides were recovered from the dust chamber 11 and a forced ignition test was performed, it was confirmed that the oxides burned violently. That is, in Comparative Example 2, although the oxides were burned by supplying air, it was confirmed that the combustion effect of the oxides accumulated in the exhaust pipe 3 was low when air was supplied after the completion of pulling up.

[0052] In Example 1, air was supplied from the second air supply unit 9 into the second exhaust pipe 3b during the liquid landing step (step S104). As a result, no combustion reaction of the oxide was observed when the lid of the dust chamber 11 was opened. In addition, when a forced ignition test was performed on the oxide recovered from the dust chamber 11, a small amount of combustion of the oxide was confirmed. In addition, in Example 1, even though an oxide combustion operation was performed by supplying air during the deposition process, no pressure fluctuation was observed in the main chamber 2a, and a dislocation-free single crystal silicon ingot was able to be grown.

[0053] In Example 2, air was supplied from the second air supply unit 9 into the second exhaust pipe 3b during the single crystal cooling step (step S106). When the lid of the dust chamber 11 was opened, no combustion of oxides was observed, and a small amount of combustion of oxides was confirmed in the forced ignition test.

[0054] In Example 3, air was supplied from the second air supply unit 9 into the second exhaust pipe 3b during the single crystal cooling step (step S106), and air was 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, before the pressure inside the chamber was returned to normal pressure (step S111). When the lid of the dust chamber 11 was opened, no combustion of the oxide was observed, and no combustion was confirmed in the forced ignition test.

[0055] Example 2 In order to confirm the effect of the present invention in the multiple pulling method, a pulling experiment was carried out to continuously grow two single crystal silicon ingots using the single crystal silicon ingot manufacturing equipment shown in Fig. 1 for Inventive Examples 4 to 6 and Fig. 4 for Comparative Example 3. Except for the fact that pulling was carried out using the multiple pulling method, an oxide ignition evaluation test when the dust chamber was opened and an oxide forced ignition test were carried out under the same conditions as in Example 1.

[0056] In Comparative Example 3, two single crystal silicon ingots were pulled by the multiple pulling method, and the heater power was turned off, after which air was supplied from the first air supply unit 7 into the exhaust pipe 3. When the lid of the dust chamber 11 was opened, violent combustion of the oxide was observed. For this reason, a forced ignition test was not performed.

[0057] In Example 4, air was supplied from the second air supply unit 9 into the second exhaust pipe 3b during the cooling process of the second single crystal in the multiple ring method. No combustion was observed in the oxide when the dust chamber 11 was opened, and it was confirmed that the oxide burned slightly in the forced ignition test.

[0058] In Example 5, air was supplied from the second air supply unit into the second exhaust pipe 3b during the cooling process of the first and second single crystals in the multiple ring method. As a result, similar to Example 4, no combustion was observed when the dust chamber 11 was opened, but it was confirmed that the oxide burned slightly in the forced ignition test. It was confirmed that the amount of oxides burned during the evaluation test was smaller than that of Example 4. This is presumably because the amount of oxides accumulated in the second exhaust pipe 3b was small, since the oxides in the second exhaust pipe 3b were burned every time the single crystal cooling process was performed.

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

[0060] [Table 1]

[0061] Table 1 shows the evaluation results of Examples 1 to 6 and Comparative Examples 1 to 3 in Examples 1 and 2. In Examples 1 to 3, it was confirmed that when air was supplied to the second exhaust pipe 3b during pulling, the oxides were more effectively burned than when air was supplied into the exhaust pipe 3 after pulling was completed. Furthermore, when growing multiple single crystal silicon ingots by the multiple pulling method, the amount of oxides accumulated in the exhaust pipe 3 also increases, and it is expected that the oxides cannot be sufficiently burned. However, as is clear from the results of invention examples 4 to 6, it was confirmed that when air was supplied into the second exhaust pipe during pulling, the oxides can be sufficiently burned in the multiple pulling method. [Explanation of symbols]

[0062] 1: Manufacturing equipment for single crystal silicon ingots, 2: Single crystal silicon ingot manufacturing equipment, 3: exhaust pipe, 4: Vacuum pump, 5a: inert gas supply port, 5b, 5c: Switch valve, 6: exhaust gas outlet, 7: first air supply section, 8: Pressure adjusting section, 9: second air supply section, 10: Pressure gauge, 11: dust chamber, 12: control unit, 13: Flapper valve (explosion-proof valve), 14: Cyclone

Claims

1. An exhaust pipe connected to the single crystal silicon ingot manufacturing apparatus; a vacuum pump that sucks in the inert gas supplied into the single crystal silicon ingot manufacturing apparatus through the exhaust pipeline, the exhaust pipeline includes a first exhaust pipe connected to an exhaust gas outlet of the single crystal silicon ingot manufacturing apparatus, and a second exhaust pipe connecting 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.

2. a pressure adjusting unit that adjusts a pressure inside the first exhaust pipe is provided in the second exhaust pipe, 2. The single crystal silicon ingot manufacturing equipment of claim 1, wherein when the exhaust gas port 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 rearward of the pressure adjustment unit.

3. A method for producing a single crystal silicon ingot by the Czochralski method, comprising the steps of: a raw material melting step of heating and melting the silicon raw material filled in the quartz crucible; a step of lowering a seed crystal to make it contact with the silicon melt in the quartz crucible; a single crystal growing 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, a single crystal growing step of growing a single crystal of a silicon ingot by heating the single crystal ingot in a temperature range of 100° C. to 150° C.; and a single crystal cooling step of growing a single crystal of a silicon ingot by heating the single crystal ingot in a temperature range of 100° C. to 150° C.

4. A method for producing a single crystal silicon ingot according to claim 3 by a Czochralski method using the equipment for producing a single crystal silicon ingot according to claim 1 or 2, In one or more of the liquid application process, the single crystal growth process, and the single crystal cooling process, air is supplied from the second air supply unit to the inert gas flowing in the second exhaust pipe to combust oxides in the second exhaust pipe.

5. A method for producing a single crystal silicon ingot according to claim 4, using the equipment for producing a single crystal silicon ingot according to claim 2, A method for manufacturing a single crystal silicon ingot, comprising: measuring a pressure in the first exhaust pipe generated when air is supplied into the second exhaust pipe; and adjusting the pressure in the first exhaust pipe by the pressure adjustment unit based on the measured pressure fluctuation value.

6. The method for producing a single crystal silicon ingot according to any one of claims 3 to 5, wherein a multiple pulling method is performed in which the raw material melting step, the liquid application step, the single crystal growing step, and the single crystal cooling step are repeated to produce a plurality of the single crystal silicon ingots using the same quartz crucible.

7. 7. The method for producing a single crystal silicon ingot according to claim 6, wherein, when producing a plurality of the single crystal silicon ingots, air is supplied into the second exhaust pipe by the second air supply unit for each production of the single crystal silicon ingot, thereby burning oxides in the second exhaust pipe.

8. 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, before returning a pressure inside a chamber of the production apparatus for the single crystal silicon ingot to normal pressure, air is supplied into the first exhaust pipe by the first air supply unit to combust oxides in the first exhaust pipe.

9. 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, before returning a pressure inside a chamber of the production apparatus for 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, thereby burning oxides in the first exhaust pipe and the second exhaust pipe.

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