Device for the production of silicon single crystals

Abstract

The present invention is an apparatus for producing silicon single crystals using a CZ process, wherein the apparatus comprises a chamber in which a quartz crucible and a heating device, configured to heat and melt a polycrystalline silicon raw material in the quartz crucible to form the raw material melt, are arranged, a gas inlet tube and a gas outlet tube, wherein the gas outlet tube comprises a plurality of tubes and a tube clamp, wherein the plurality of tubes each have connecting sections, wherein the tube clamp is capable of liquid cooling by a flow of cooling water, the connecting sections of the plurality of tubes face each other with a sealing element arranged between them, and the connecting sections facing each other are clamped together by the tube clamp, thereby connecting the plurality of tubes to each other.and the sealing element between the connection sections can be cooled by the liquid cooling of the pipe clamp. This provides the CZ device for the production of silicon single crystals, which simplifies handling of the gas outlet pipe and prevents deterioration of the sealing element between the pipes.

Description

Technical field

[0001] The present invention relates to a device for the production of silicon single crystals using a Czochralski (CZ) method. State of the art

[0002] Manufacturing processes for silicon single crystals, which serve as base materials for integrated semiconductor circuits, include the Czochralski process. In the CZ process, high-purity polycrystalline silicon raw material is placed in a quartz crucible housed in a chamber, and the polycrystalline silicon raw material is then melted by heating with a heating device arranged around the outer circumference of the quartz crucible. A seed crystal is immersed in this raw material melt (molten silicon), and a single crystal is grown by pulling it upwards while rotating it, thus producing a cylindrical silicon single crystal.

[0003] In the CZ process, a vacuum pump is connected via a gas outlet pipe to a device for producing silicon single crystals (pulling system). Additionally, a configuration in which the vacuum pump extracts the inert gas (e.g., Ar gas) introduced into the pulling system is known as an outlet process (Patent Document 1). List of citations Patent literature

[0004] Patent Document 1: JP 2017-114709 A Summary of the invention: Technical problem

[0005] In a manufacturing apparatus with the configuration described above, the gas outlet pipe is configured by connecting multiple pipes, such that these multiple pipes are connected by a sealing element (e.g., an O-ring) positioned between their connecting sections. During the fabrication of a silicon single crystal, an inert gas in a chamber is heated by a heating device, causing the inert gas to reach a high temperature. The high-temperature inert gas is extracted by a vacuum pump, and the heat can be transferred through the connecting sections of the gas outlet pipe to the sealing element, causing deterioration of the sealing element and creating a risk of inert gas leakage during silicon single crystal fabrication.If the leak occurs, a vacuum in the chamber of the device for producing silicon single crystals may not be maintained, which could affect the quality of the products.

[0006] If a leak occurs, the leak point must be located and the sealing element replaced. However, due to the large number of interconnected sections, the inspection takes time, and the production of the silicon single crystal cannot continue during this period.

[0007] Additionally, silicon oxide is generated during silicon single-crystal fabrication, and this silicon oxide is deposited in the gas outlet tube. Consequently, the gas outlet tube is removed to clean off the silicon oxide after the silicon single-crystal fabrication. For cleaning purposes, it is desirable that the gas outlet tube (or multiple tubes) be lightweight, easy to handle, and easily removable.

[0008] Fig. Figure 3 is an explanatory view showing an example of a cooling mechanism for a gas outlet pipe 110 according to conventional technology. The left figure of Fig. Figure 3 is an explanatory view showing a configuration of the gas outlet pipe 110 from an axial direction, and the right-hand figure is an explanatory view showing a configuration at a cross-section along line BB' in the left-hand figure. Two adjacent pipes 112 (112a, 112b) are connected by a pipe clamp 113 (113a, 113b) designed as a two-part ring, and the pipe clamp 113 is secured by bolts to connecting sections 115 in which a sealing element 114 is arranged between the connecting sections. In the conventional technique, to prevent the connecting sections 115 from reaching the high temperature, a water cooling tube 120 is wrapped around the outer circumference of a tube body of the gas outlet tube 110 (i.e. the tube body of the tubes 112) and welded to it, and water flows in the water cooling tube 120, thus preventing the connecting sections 115 from reaching the high temperature.

[0009] In the conventional technique described above, cooling is applied to the outer circumference of the gas outlet pipe body, thus failing to effectively cool the area around the joints and the sealing element; consequently, the sealing element may deteriorate due to heat in some cases. Furthermore, cleaning the gas outlet pipe requires disassembly and removal of these pipes. However, as described above, the water cooling pipe is welded to the pipes, which increases their weight and reduces their machinability.

[0010] The present invention was developed with regard to the problem described above. One objective of the present invention is to provide a CZ device for the production of silicon single crystals in which a gas outlet tube can be easily handled and deterioration of a sealing element between tubes can be prevented. Solution to the problem

[0011] To achieve this objective, the present invention provides an apparatus for the production of silicon single crystals, which is configured to produce a silicon single crystal from a raw material melt by a Czochralski process, wherein the apparatus comprises: a chamber in which a quartz crucible, designed to hold a polycrystalline silicon raw material, and a heating device, designed to heat and melt the polycrystalline silicon raw material in the quartz crucible to form the raw material melt, are arranged; a gas inlet pipe for introducing an inert gas into the chamber; and a gas outlet pipe for releasing the inert gas introduced into the chamber, wherein the gas outlet pipe comprises a plurality of pipes and a pipe clamp, wherein the plurality of pipes each have connecting sections, and wherein the pipe clamp is capable of liquid cooling by a flow of cooling water, the connecting sections of the majority of pipes face each other with an intermediate sealing element, and the connecting sections facing each other are clamped together by the pipe clamp, thereby connecting the majority of pipes together, and The sealing element between the connecting sections can be cooled by the liquid cooling of the pipe clamp.

[0012] According to the device for producing silicon single crystals according to the invention, the sealing element between the connecting sections of the gas outlet pipe can be effectively cooled by liquid cooling of the pipe clamp, thus preventing deterioration of the sealing element due to heat. Consequently, the need for leakage inspection and replacement of the sealing element, which is essential in a conventional device due to deterioration of the sealing element, can be eliminated or at least reduced in frequency. As a result, maintenance costs can be reduced, and manufacturing losses of the silicon single crystal can be minimized by preventing quality deterioration of the silicon single crystal caused by leakage.

[0013] Furthermore, it is possible to adequately cool the sealing element without welding a water cooling tube to the outer circumference of the pipe body to prevent deterioration of the sealing element, as in the conventional device. Consequently, multiple pipes configuring the gas outlet pipe can be made lightweight, thus facilitating handling. Accordingly, the removal of deposits inside the pipe can also be easily accomplished. Moreover, the cost of retrofitting using this liquid-cooled pipe clamp can be lower than the cost of retrofitting using the conventional water-cooled type (where the water cooling tube is welded to the outer circumference of the pipes). Advantageous effects of the invention

[0014] According to the inventive device for producing silicon single crystals, the deterioration of the sealing element in the gas outlet pipe due to heat can be prevented. Consequently, the occurrence of gas leaks caused by the deteriorated sealing element can be prevented, and the need for various leak-related repairs, the associated costs, and the deterioration of the single crystal quality can be avoided. Furthermore, the pipes themselves become lighter, and their machinability during cleaning can be improved. Brief description of the drawings [ Fig. Figure 1] is a schematic side view illustrating an example of a device for producing silicon single crystals according to the present invention. [ Fig. Figure 2 is an explanatory view showing an example of a gas outlet pipe configuration. The left figure is an explanatory view showing a configuration from one axial direction. The right figure is an explanatory view showing a configuration at a cross-section along line AA' in the left figure. [ Fig. Figure 3] is an explanatory view showing an example of a cooling mechanism for a gas outlet pipe in a conventional device. The left figure is an explanatory view showing a configuration from one axial direction. The right figure is an explanatory view showing a configuration at a cross-section along line BB' in the left figure. Description of embodiments

[0015] Fig. Figure 1 shows an example of the apparatus according to the invention for producing silicon single crystals using a Czochralski process. This apparatus 1 for producing silicon single crystals comprises a chamber 2. A raw material melt 5 is filled into a quartz crucible 4, which is arranged in a graphite crucible 3 located in the chamber 2, and a silicon single crystal 6 is drawn up from this raw material melt 5. A heating device 7 for heating the raw material melt 5 is arranged around an outer circumference of the graphite crucible 3 inside the chamber 2, and an insulating element 8 is arranged outside the heating device 7 to insulate heat from the heating device 7.

[0016] Furthermore, a gas inlet pipe 9 is arranged at an upper section of chamber 2, and a gas outlet pipe 10 is arranged at a lower section. A vacuum pump 11 is connected to a distal end of the gas outlet pipe 10. An inert gas such as argon is introduced from the gas inlet pipe 9 and fills chamber 2, and the gas flows downwards and is discharged to the outside through the gas outlet pipe 10 by a vacuum pump 11.

[0017] In the production of the silicon single crystal 6, a polycrystalline silicon raw material is first placed in the quartz crucible 4 and shaped into the raw material melt 5 by applying heat from the heating device 7. A seed crystal S suspended by a wire is immersed in the raw material melt 5, and the wire is pulled up to grow the silicon single crystal 6. Note that the inert gas is introduced into chamber 2 from the gas inlet tube 9 and released through the gas outlet tube 10.

[0018] Here, a configuration of the gas outlet tube 10 in the device 1 according to the invention for the production of silicon single crystals is described.

[0019] Fig. Figure 2 shows an example of the configuration of the gas outlet pipe 10. The left figure of Fig. Figure 2 is an explanatory view showing the configuration of the gas outlet pipe 10 from an axial direction. The right-hand figure is an explanatory view showing the configuration at a cross-section along the line AA' in the left-hand figure.

[0020] The gas outlet pipe 10 mainly comprises a plurality of pipes 12 (12a, 12b), a pipe clamp 13 which can be liquid-cooled, and a sealing element 14.

[0021] The pipes 12 themselves only need to be fitted with connecting sections 15 (such as flanges) at one end section. As shown in particular in the right-hand figure in Fig. Figure 2 shows a step from a pipe body to the connecting sections 15; however, the shape of the pipes 12 of the present invention is not limited to this shape, and this step may be omitted.

[0022] Furthermore, examples of sealing element 14 include an O-ring, but are not limited to it.

[0023] As shown in the left image of Fig. As shown in Figure 2, the majority of adjacent pipes 12 (12a, 12b) have respective connecting sections 15 which face each other with the sealing element 14 arranged between them. In addition, as shown in the right-hand figure, the majority of adjacent pipes 12 are connected by clamping the mutually facing connecting sections 15 by a clamping section 18 of the pipe clamp 13.

[0024] Note that the circular solid line and dashed line in the left-hand figure are shown almost concentrically and indicate the locations of the tubes 12 and the clamping section 18. The innermost circular solid line in the left-hand figure shows an inner circumferential surface 12s of the tubes 12, which is shown in the right-hand figure, and the outermost circular dashed line in the left-hand figure shows an inner bottom surface 18s of the clamping section 18, which is shown in the right-hand figure.

[0025] The pipe clamp 13 can be removed from the pipes 12 (connecting sections 15). This removal improves the handling of both the pipe clamp 13 and the pipes 12 themselves, and simplifies cleaning the inside of the pipes 12. For example, as shown in the left figure of Fig. As shown in Figure 2, the pipe clamp 13 has a two-part structure (13a, 13b) and is made of a material with favorable thermal conductivity (such as aluminum). Naturally, the number of subdivisions is not particularly limited and can be appropriately determined according to the diameter of the pipes 12 and the like.

[0026] Additionally, the pipe clamp 13 incorporates a liquid cooling mechanism by means of a flow of cooling water and is provided, for example, with through-holes 16 to allow the cooling water to flow inside the pipe clamp 13. Furthermore, an inlet of the through-holes 16 is designed as a tapered threaded form to connect cooling water supply pipes 17 from the outside. That is, the inlet of the through-holes 16 is provided with an internal thread, and the cooling water supply pipes 17 to be inserted therein are provided with an external thread.

[0027] The size (diameter) of the through-hole 16 is not particularly limited and can, for example, be 40 to 50% of the thickness of the pipe clamp 13. If the diameter of the through-holes 16 is of such a size, more efficient liquid cooling can be achieved. Furthermore, the tapered threads (internal and external) can be selected to match each other in size.

[0028] The through holes 16 in Fig. 2 have a straight shape to allow water to flow vertically, but the shape is not limited to this and can take on different forms taking into account the cooling effect and the like.

[0029] One type in which the through-holes 16 and the cooling water supply pipes 17 are connected is described here. However, a type can also be assumed, for example, in which the cooling water supply pipes 17 run through the interior of the pipe clamp 13.

[0030] During the assembly of the gas outlet pipe 10, the connecting sections 15 of the majority of pipes 12 (12a, 12b) are oriented towards each other, with the sealing element 14, such as an O-ring, positioned between them, and the two-part pipe clamps 13a and 13b are brought closer to the outer circumference of the facing connecting sections 15 from both sides, as shown in the left-hand figure. Fig. 2 shown. The connecting sections 15, facing each other, are then inserted into the clamping section 18 of the pipe clamps 13a and 13b and fitted, as shown in the right-hand figure of Fig. 2 shown. The pipe clamps 13a and 13b are then tightened with bolts 19 to seal, as shown in the left-hand figure. Fig. 2 shown. In the left illustration of Fig. 2 the connecting section 15 can be seen in the gap between two pipe clamps 13a and 13b on the left and right.

[0031] Furthermore, the cooling water supply pipes 17 are connected to the pipe clamp 13, and in the case of Fig. 2. The cooling water flows from the top to the bottom; alternatively, flow in the opposite direction is also acceptable. Note that the temperature of the cooling water can be approximately 20 °C, for example, but is not limited to this. A suitable cooling water temperature can be determined based on the gas temperature within the gas outlet pipe 10, the distance from the chamber 2, and the like. By allowing the cooling water to flow, the pipe clamp 13 itself is liquid-cooled, and the sealing element 14 can be effectively cooled, with the sealing element 14 being located between the connecting sections 15 that are clamped together by the pipe clamp 13.

[0032] In a cooling mechanism for a gas outlet pipe of a conventional device, pipe bodies are located on both sides of connecting sections (where a sealing element is arranged) of a plurality of pipes. A water cooling pipe is welded to an outer circumference of the pipe bodies, and water cooling is carried out using this water cooling pipe. In contrast, as described above, in the cooling mechanism of the manufacturing device according to the invention, a liquid-cooled pipe clamp is used to clamp the connecting sections (where the sealing element is arranged) of the pipes, and the pipe clamp is liquid-cooled by the cooling water, thereby cooling the clamped connecting sections and the sealing element between them.

[0033] Since the gas outlet pipe is equipped with such a cooling mechanism, its pipes are superior to conventional gas outlet pipes in terms of lightness and handling. This pipe is also capable of significantly effective cooling of the sealing element, preventing its deterioration due to heat generated by the high-temperature gas flowing through the gas outlet pipe. Consequently, cleaning deposits inside the pipes becomes easier, and gas leaks caused by sealing element deterioration can be prevented. Therefore, various tasks, including inspections and maintenance costs, such as replacing the sealing element in the event of a leak, can be reduced. Furthermore, the deterioration of the quality of a silicon single crystal being manufactured due to gas leakage can be prevented.

[0034] It should be noted that the present invention is not limited to the embodiments described above. The embodiments are merely examples, and all examples that exhibit essentially the same features and demonstrate the same functions and effects as those disclosed in the claims of the present invention are included within the scope of the present invention. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2017-114709 A

[0004]

Claims

[1] Apparatus for the production of silicon single crystals, which is configured to produce a silicon single crystal from a raw material melt by a Czochralski process, the apparatus comprising: a chamber in which a quartz crucible, designed to hold a polycrystalline silicon raw material, and a heating device, designed to heat and melt the polycrystalline silicon raw material in the quartz crucible to form the raw material melt, are arranged; a gas inlet pipe for introducing an inert gas into the chamber; and a gas outlet pipe for releasing the inert gas introduced into the chamber, wherein the gas outlet pipe comprises a plurality of pipes and a pipe clamp, wherein the plurality of pipes each have connecting sections, and wherein the pipe clamp is capable of liquid cooling by a flow of cooling water, the connecting sections of the majority of pipes face each other with an intermediate sealing element, and the connecting sections facing each other are clamped together by the pipe clamp, thereby connecting the majority of pipes together, and The sealing element between the connecting sections can be cooled by the liquid cooling of the pipe clamp.

Images