Apparatus for manufacturing silicon single crystal

Abstract

To provide an apparatus for manufacturing a CZ silicon single crystal, capable of easily arranging a gas exhaust pipeline and preventing a seal material between pipes from deteriorating.SOLUTION: An apparatus for manufactures a silicon single crystal by the CZ method includes: a chamber arranging inside a quartz crucible and a heater for heating and melting a silicon polycrystal raw material in the quartz crucible to form a raw material melt; a gas introduction pipeline; and a gas exhaust pipeline. The gas exhaust pipeline includes a plurality of pipes having respective joint parts and pipe clamps allowing liquid cooling by passing cooling water; the joint parts of the plurality of pipes face each other so as to sandwich the seal material; the plurality of pipes are connected by sandwiching the facing joint parts by the pipe clamps; and the liquid cooling of the pipe clamp can cool the seal material between the joint parts.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus for producing silicon single crystals by the Czochralski method (CZ method). [Background technology]

[0002] The Czochralski method is a method for manufacturing silicon single crystals, which are the basic material for semiconductor integrated circuits. In the CZ method, high-purity silicon polycrystalline raw material is placed in a quartz crucible installed in a chamber, and the silicon polycrystalline raw material is melted by heating it with a heater placed around the periphery of the quartz crucible. A seed crystal is immersed in this raw material melt (silicon melt), and the seed crystal is pulled up while rotating to grow a single crystal, producing a cylindrical silicon single crystal.

[0003] In the CZ method, a vacuum pump is connected to a silicon single crystal manufacturing device (puller) via a gas exhaust pipe, and an exhaust method is known in which an inert gas (e.g., Ar gas) introduced into the puller is sucked in by the vacuum pump (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-114709 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the manufacturing equipment configured as described above, the gas exhaust pipe is made up of multiple pipes connected together, with a seal (e.g., an O-ring) between the joints. When manufacturing silicon single crystals, the inert gas in the chamber is heated by a heater, and the inert gas becomes hot. The hot inert gas is exhausted by a vacuum pump, but heat is transferred to the seal through the joints of the gas exhaust pipes, causing it to deteriorate, which may lead to the inert gas leaking during silicon single crystal manufacturing. If there is a leak, the vacuum in the chamber of the silicon single crystal manufacturing equipment cannot be maintained, which may affect the quality.

[0006] If a leak occurs, it is necessary to identify the source of the leak and replace the sealing material. However, because there are many piping joints, inspection takes time, and during that time, silicon single crystals cannot be produced.

[0007] In addition, since silicon oxide is generated during silicon single crystal production and accumulates in the gas exhaust piping, the gas exhaust piping is removed to remove the silicon oxide after the silicon single crystal production. For cleaning purposes, a gas exhaust piping (multiple piping) with a structure that is lightweight, easy to handle, and easy to remove is desired.

[0008] FIG. 3 is an explanatory diagram showing an example of a cooling mechanism for the gas exhaust pipe 110 of the prior art. The left diagram of FIG. 3 is an explanatory diagram of the configuration as seen from the axial direction of the gas exhaust pipe 110, and the right diagram is an explanatory diagram of the configuration in the cross section B-B' of the left diagram. The joint parts 115 of two adjacent pipes 112 (112a, 112b) are connected to each other by tightening a pipe clamp 113 (113a, 113b) divided into two circular rings via a sealing material 114 with a bolt. In the prior art, a water-cooled pipe 120 is wound and welded around the outer periphery of the pipe body of the gas exhaust pipe 110 (i.e., the pipe body of the pipe 112) to prevent the joint part 115 from becoming too hot, and water is passed through the water-cooled pipe 120 to prevent the gas exhaust pipe 110 from becoming too hot.

[0009] In the above-mentioned conventional technique, the outer periphery of the gas exhaust pipe body is cooled, but the joints and the vicinity of the sealant are not cooled easily, which may cause the sealant to deteriorate due to heat. In addition, when cleaning the gas exhaust pipe, it is necessary to disassemble and remove the pipe. However, since the water-cooled pipe is welded to the pipe as described above, it is heavy and the workability is deteriorated.

[0010] The present invention has been made to solve the above-mentioned problems, and aims to provide a CZ silicon single crystal manufacturing apparatus that has easy-to-manage gas exhaust piping and can prevent deterioration of the sealing material between the pipes. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides a chamber having a quartz crucible for accommodating a polycrystalline silicon raw material and a heater for heating and melting the polycrystalline silicon raw material in the quartz crucible to form a raw material melt; a gas introduction pipe for introducing an inert gas into the chamber; a gas exhaust pipe for exhausting the inert gas introduced into the chamber, A silicon single crystal manufacturing apparatus for manufacturing a silicon single crystal from the raw material melt by the Czochralski method, the gas exhaust pipe includes a plurality of pipes each having a joint portion and a pipe clamp capable of being liquid-cooled by passing cooling water through the pipe; The joint portions of the plurality of pipes face each other with a seal material therebetween, and the opposed joint portions are clamped by the pipe clamp, thereby connecting the plurality of pipes to each other, The present invention provides a silicon single crystal manufacturing apparatus, characterized in that the sealing material between the joint portions can be cooled by liquid cooling of the piping clamp.

[0012] In the silicon single crystal manufacturing apparatus of the present invention, the sealing material between the joints in the gas exhaust pipe can be effectively cooled by liquid cooling of the pipe clamp, and deterioration of the sealing material due to heat can be prevented. Therefore, the need for leak inspection and replacement of the sealing material, which was necessary in the conventional apparatus due to deterioration of the sealing material, can be eliminated, or at least the frequency of such inspection can be reduced. As a result, maintenance costs can be reduced, and the deterioration of the quality of the silicon single crystal caused by the occurrence of leaks can be prevented, thereby reducing the production loss of the silicon single crystal.

[0013] In addition, since the sealing material can be sufficiently cooled without welding a water-cooling pipe to the outer periphery of the pipe body to prevent deterioration of the sealing material as in the conventional device, the weight of the multiple pipes that make up the gas exhaust pipe itself can be reduced and they are easy to handle. Therefore, the work of removing deposits from inside the pipe can be done easily. Moreover, the cost of retrofitting using this liquid-cooled pipe clamp is cheaper than the cost of retrofitting using the conventional water-cooled type (welding a water-cooled pipe to the outer periphery of the pipe). Effect of the Invention

[0014] The silicon single crystal manufacturing apparatus of the present invention can prevent deterioration of the seal material in the gas exhaust piping due to heat. Therefore, it is possible to prevent the occurrence of gas leaks caused by deteriorated seal materials, and it is possible to prevent the need for various operations associated with leaks, the costs involved, and the deterioration of single crystal quality. Moreover, the piping itself is lightweight, which improves the workability of cleaning the inside of the piping. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic side view showing an example of a silicon single crystal manufacturing apparatus according to the present invention. [Diagram 2] 1 is an explanatory diagram showing an example of the configuration of a gas exhaust pipe, the left diagram being an explanatory diagram of the configuration as seen from the axial direction, and the right diagram being an explanatory diagram of the configuration in the cross section taken along line A-A' in the left diagram. [Diagram 3]1 is an explanatory diagram showing an example of a cooling mechanism for a gas exhaust pipe in a conventional device, the left diagram being an explanatory diagram of the configuration as seen from the axial direction, and the right diagram being an explanatory diagram of the configuration in the cross section taken along line B-B' in the left diagram. BEST MODE FOR CARRYING OUT THEINVENTION

[0016] An example of a silicon single crystal manufacturing apparatus using the Czochralski method of the present invention is shown in Figure 1. This silicon single crystal manufacturing apparatus 1 has a chamber 2. A raw material melt 5 is filled inside a quartz crucible 4 in a graphite crucible 3 placed in the chamber 2, and a silicon single crystal 6 is pulled up from this raw material melt 5. A heater 7 for heating the raw material melt 5 is placed around the graphite crucible 3 in the chamber 2, and a heat insulating member 8 is placed around the heater 7 to insulate against heat from the heater 7.

[0017] A gas inlet pipe 9 is provided at the top of the chamber 2, and a gas exhaust pipe 10 is provided at the bottom. A vacuum pump 11 is connected to the end of the gas exhaust pipe 10. An inert gas such as argon that fills the chamber 2 is introduced from the gas inlet pipe 9, and the gas flows downward and is exhausted to the outside by the vacuum pump 11 through the gas exhaust pipe 10.

[0018] When producing silicon single crystal 6, first, silicon polycrystalline raw material is placed in quartz crucible 4 and heated by heater 7 to form raw material melt 5. After immersing a seed crystal S suspended by a wire in the raw material melt 5, the wire is pulled up to grow silicon single crystal 6. Note that an inert gas is introduced into chamber 2 through gas inlet pipe 9 and exhausted through gas exhaust pipe 10.

[0019] Here, the configuration of the gas exhaust pipe 10 in the silicon single crystal manufacturing apparatus 1 of the present invention will be described. An example of the configuration of the gas exhaust pipe 10 is shown in Fig. 2. The left diagram of Fig. 2 is an explanatory diagram of the configuration as seen from the axial direction of the gas exhaust pipe 10, and the right diagram is an explanatory diagram of the configuration in the A-A' cross section of the left diagram.

[0020] The gas exhaust pipe 10 mainly includes a plurality of pipes 12 (12a, 12b), a liquid-coolable pipe clamp 13, and a seal material 14. The pipe 12 itself only needs to have a joint (such as a flange) 15 at its end. As can be seen particularly from the right side of Fig. 2, a step is provided from the pipe body to the joint 15, but the shape of the pipe 12 of the present invention is not limited to this, and this step does not need to exist. The sealing material 14 may be, for example, an O-ring, but is not limited to this. 2, the joints 15 of adjacent pipes 12 (12a, 12b) face each other with a sealant 14 sandwiched therebetween. Then, as shown in the right diagram, the opposed joints 15 are sandwiched by clamp parts 18 of pipe clamps 13, thereby connecting the adjacent pipes 12 to each other. In the left diagram, the circular solid lines and dotted lines are drawn approximately concentrically, and these represent the pipe 12 and the clamp portion 18. The innermost circular solid line in the left diagram represents the inner peripheral surface 12s of the pipe 12 shown in the right diagram, and the outermost circular dotted line in the left diagram represents the inner bottom surface 18s of the clamp portion 18 shown in the right diagram.

[0021] The pipe clamp 13 can be made detachable from the pipe 12 (joint 15). By being detachable, both the pipe clamp 13 itself and the pipe 12 itself are easier to handle, and it is convenient to clean the inside of the pipe 12. As an example, as shown in the left diagram of FIG. 2, the pipe clamp 13 can have a two-piece structure (13a, 13b) and is made of a material with good thermal conductivity (e.g., aluminum). Of course, the number of parts is not particularly limited, and can be appropriately determined depending on the thickness of the pipe 12, etc.

[0022] The piping clamp 13 also has a liquid cooling mechanism that uses the flow of cooling water, and is provided with a through hole 16 for passing cooling water inside, for example. The inlet of the through hole 16 has a tapered screw shape for connecting a cooling water supply pipe 17 from the outside. In other words, the inlet of the through hole 16 has an internal thread, and the cooling water supply pipe 17 inserted therein has an external thread. The size (thickness) of the through hole 16 is not particularly limited, but may be, for example, 40 to 50% of the thickness of the piping clamp 13. With the through hole 16 having such a thickness, more efficient liquid cooling is possible. In addition, the tapered threads (male thread, female thread) may be made to match the sizes of each other. Although the through-hole 16 in FIG. 2 has a linear shape to allow water to pass vertically, this shape is not particularly limited and various shapes can be used taking into consideration cooling efficiency and the like. Although the type in which the through hole 16 and the cooling water supply pipe 17 are connected has been described here, it is also possible to use a type in which, for example, the cooling water supply pipe 17 is passed through the inside of the pipe clamp 13 .

[0023] When assembling the gas exhaust pipe 10, the joints 15 of the multiple pipes 12 (12a, 12b) are placed opposite each other with an O-ring or the like sandwiched between them as a sealant 14, and the two-part pipe clamps 13a, 13b are brought close to the outer periphery of the opposed joints 15 from the left and right as shown in the left diagram of Fig. 2. Then, as shown in the right diagram of Fig. 2, the opposed joints 15 are inserted into the clamp parts 18 of the pipe clamps 13a, 13b and fitted together, and the pipe clamps 13a, 13b are tightened with bolts 19 to seal them as shown in the left diagram of Fig. 2. In the left diagram of Fig. 2, the joints 15 are visible in the gap between the two pipe clamps 13a, 13b on the left and right. A cooling water supply pipe 17 is connected to the pipe clamp 13, and although the cooling water is passed from the top to the bottom in the case of FIG. 2, the opposite direction is also possible. The temperature of the cooling water can be, for example, about 20°C, but is not limited to this. The temperature of the cooling water can be appropriately determined depending on the temperature of the gas in the gas exhaust pipe 10 and the distance from the chamber 2. The passage of the cooling water liquid-cools the pipe clamp 13 itself, and can effectively cool the seal material 14 between the joints 15 sandwiched by the pipe clamp 13.

[0024] In the cooling mechanism for the gas exhaust piping of the conventional device, water-cooling was performed by using water-cooled piping welded to the outer circumference of the pipe body located on both sides of the joints of multiple pipes (with sealing material between them). However, as described above, the cooling mechanism of the manufacturing device of the present invention uses a liquid-cooled type pipe clamp that clamps the joints of the pipes (with sealing material between them), and liquid-cools the pipe clamp with cooling water to cool the joints it is holding and the sealing material between them.

[0025] By providing the gas exhaust pipe with such a cooling mechanism, the pipe itself is lighter and easier to handle than before, and the sealant can be cooled more effectively than before, preventing deterioration of the sealant due to the heat of the high-temperature gas passing through the gas exhaust pipe. This not only makes it easier to clean deposits in the pipe, but also prevents gas leaks due to deterioration of the sealant. This reduces the cost of maintenance such as various tasks such as inspections when leaks occur and replacement of the sealant, and prevents the quality of the silicon single crystal produced from being reduced due to gas leaks.

[0026] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention. [Explanation of symbols]

[0027] 1...silicon single crystal manufacturing apparatus of the present invention; 2...chamber; 3...graphite crucible; 4... quartz crucible, 5... raw material melt, 6... silicon single crystal, 7... heater, 8...insulating member; 9...gas inlet pipe; 10...gas exhaust pipe; 11... vacuum pump, 12 (12a, 12b)... piping, 12s... inner surface of piping, 13 (13a, 13b)...piping clamp (liquid-cooled type), 14...sealing material, 15...joint portion, 16...through hole, 17...cooling water supply pipe, 18... clamp portion; 18s... inner bottom surface of clamp portion; 19... bolt; S... Seed crystal.

Claims

[Claim 1] a chamber in which a quartz crucible for accommodating a polycrystalline silicon raw material and a heater for heating and melting the polycrystalline silicon raw material in the quartz crucible to form a raw material melt are disposed; a gas introduction pipe for introducing an inert gas into the chamber; a gas exhaust pipe for exhausting the inert gas introduced into the chamber, A silicon single crystal manufacturing apparatus for manufacturing a silicon single crystal from the raw material melt by the Czochralski method, the gas exhaust pipe includes a plurality of pipes each having a joint portion and a pipe clamp capable of being liquid-cooled by passing cooling water through the pipe; The joint portions of the plurality of pipes face each other with a seal material therebetween, and the opposed joint portions are clamped by the pipe clamp, thereby connecting the plurality of pipes to each other, 4. A silicon single crystal manufacturing apparatus, comprising: a pipe clamp that is liquid-cooled to cool the sealing material between the joints.

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