Ingot grower

Abstract

The embodiment relates to a single-crystal ingot growth apparatus capable of varying the thermal insulation performance of a thermal shield assembly according to the process. According to one aspect of an embodiment, the apparatus comprises: a chamber; a crucible provided inside the chamber and containing molten silicon; a heater provided around the crucible and heating the crucible; a magnet provided outside the chamber and forming a magnetic field distribution; and a thermal shield assembly located inside the crucible and cooling a single-crystal ingot grown from the molten silicon; wherein the thermal shield assembly provides a single-crystal ingot growth apparatus having varying thermal insulation performance according to changes in the magnetic field of the magnet.

Description

Technology Field

[0001] The embodiment relates to a single-crystal ingot growth apparatus capable of varying the thermal insulation performance of a thermal shield assembly according to the process. Background Technology

[0002] Generally, single-crystal ingots used as materials for producing electronic components such as semiconductors are manufactured by the Czochralski method (hereinafter referred to as CZ).

[0003] The method for manufacturing a single-crystal ingot by the CZ method involves filling a quartz crucible with solid raw materials such as polycrystalline silicon, heating it with a heater to melt it to form a silicon melt, removing bubbles in the silicon melt through a stabilization process, and then sequentially proceeding with a necking process, a shouldering process, a body growth process, and a tailing process.

[0004] In detail, polysilicon is introduced into a crucible, the crucible is heated by a heater which is a graphite heating element, a seed crystal is brought into contact with the molten silicon formed as a result of the melting, and crystallization occurs at the interface, and the seed crystal is slowly pulled up while rotating to grow a silicon single crystal ingot with a desired diameter.

[0005] Typically, a thermal shield assembly through which a single-crystal ingot is pulled from a silicon melt is applied to rapidly cool the single-crystal ingot being grown by pulling from a silicon melt.

[0006] According to Korean Published Patent No. 2020-0079799 (filed on December 26, 2018), a lifting device having a melting furnace and a support member is disclosed, and includes a thermal shielding assembly composed of an outer member having a first upper end protruding outward from the upper side and resting on the support member, an inner member having a second upper end coupled to a part of the upper surface of the first upper end, and an inner insulating material that fills the insulating space formed by the coupling of the outer member and the inner member, wherein the inner insulating material includes: an upper insulating material having a lower portion cut so that a void space without the inner insulating material is formed in a part of the insulating space; a heat conductive part formed of a graphite material having a thermal conductivity of a certain value or higher in the portion cut and optionally insertable; and a lower insulating material that can be inserted into the void space without the upper insulating material.

[0007] According to conventional technology, since the thermal shielding assembly is configured differently and the process proceeds according to the product, the same thermal insulation performance is achieved through the thermal shielding assembly during the series of processes.

[0008] However, while it is advantageous to maintain a high overall thermal insulation performance of the thermal shield assembly to keep power consumption low during the melting process of heating solid raw materials to form molten silicon, it is advantageous to maintain a low upper thermal insulation performance of the thermal shield assembly to improve the growth rate of the defect-free region in the single crystal ingot by increasing the temperature gradient between the molten silicon and the ingot during the ingot growth process. The problem to be solved

[0009] The embodiments aim to solve the aforementioned problems and other problems.

[0010] Another objective of the embodiment is to provide a single-crystal ingot growth apparatus capable of varying the thermal insulation performance of a thermal shield assembly according to the process. means of solving the problem

[0011] According to one aspect of an embodiment, the apparatus comprises: a chamber; a crucible provided inside the chamber and containing molten silicon; a heater provided around the crucible and heating the crucible; a magnet provided outside the chamber and forming a magnetic field distribution; and a thermal shield assembly located inside the crucible and cooling a single-crystal ingot grown from the molten silicon; wherein the thermal shield assembly provides a single-crystal ingot growth apparatus having varying thermal insulation performance according to changes in the magnetic field of the magnet.

[0012] According to one aspect of an embodiment, the thermal shielding assembly may include a case through which the single crystal ingot is penetrated, an insulating material embedded in the case, and a ferromagnetic material laminated on the insulating material and compressing or relaxing the insulating material according to changes in the magnetic field of the magnet.

[0013] According to one aspect of the embodiment, the internal space of the case may be configured to become wider from the top to the bottom.

[0014] According to one aspect of the embodiment, the insulating material may be composed of a highly elastic insulating part disposed in the internal space of the case to support the ferromagnetic material.

[0015] According to one aspect of the embodiment, the high-elasticity insulating member may be composed of a porosity of 90% or more.

[0016] According to one aspect of the embodiment, the high-elasticity insulating part can be reused by heat treating it after the single-crystal ingot growth process.

[0017] According to one aspect of the embodiment, the high-elasticity insulating member may be composed of soft felt.

[0018] According to one aspect of the embodiment, the insulating material may be composed of a low-elasticity insulating part disposed in the lower part of the internal space of the case to support the high-elasticity insulating part.

[0019] According to one aspect of the embodiment, the low-elasticity insulation may be composed of rigid felt.

[0020] According to one aspect of the embodiment, the ferromagnetic material may be coated with a quartz material. Effects of the invention

[0021] According to an embodiment, the thermal insulation performance of the entire or upper / lower parts of the thermal shielding assembly can be varied according to changes in the magnetic field of the magnet.

[0022] Therefore, since the thermal insulation performance of the entire thermal shielding assembly is maintained at a high level during the melting process, there is an advantage in that power consumption can be reduced.

[0023] In addition, since the upper thermal insulation performance of the thermal shield assembly is kept low and the lower thermal insulation performance of the thermal shield assembly is kept high during the ingot growth process, there is an advantage in that the G value of the ingot is improved by increasing the temperature gradient between the silicon melt and the single crystal ingot, thereby improving the growth rate of the defect-free region.

[0024] Furthermore, since the thermal insulation performance can be adjusted in detail by batch or process depending on the change in the magnetic field of the magnet or the position of the ferromagnetic material in the thermal shield assembly, there is an advantage in that the quality of the single crystal ingot can be improved. Brief explanation of the drawing

[0025] FIG. 1 is a side cross-sectional view schematically illustrating a single-crystal ingot growth apparatus of an embodiment. FIG. 2 is a drawing showing the operating state of the thermal shield assembly of the first embodiment during the melting process. FIG. 3 is a drawing showing the operating state of the thermal shield assembly of the first embodiment during the body growth process. FIG. 4 is a drawing showing the operating state of the thermal shield assembly of the second embodiment during the melting process. FIG. 5 is a drawing showing the operating state of the thermal shield assembly of the second embodiment during the body growth process. Specific details for implementing the invention

[0026] Hereinafter, the present embodiment will be examined in detail with reference to the attached drawings.

[0027] FIG. 1 is a side cross-sectional view schematically illustrating a single-crystal ingot growth apparatus of an embodiment.

[0028] As shown in FIG. 1, the single crystal ingot growth apparatus of the embodiment includes a chamber (110) which is a sealed space, a crucible (120) provided inside the chamber (110), a heater (130) for heating the crucible (120), an insulating member (140) for preventing heat from the heater (130) from escaping to the outside of the chamber (110), a crucible driving unit (150) for rotating or raising the crucible (120), a heat shielding assembly (160) for cooling the single crystal ingot raised from the crucible (120), and a magnet (M) provided outside the chamber (110).

[0029] The chamber (110) provides a predetermined sealed space in which a single crystal ingot is grown, and various components can be mounted on the inside and outside.

[0030] The chamber (110) may be composed of a cylindrical body (111) in which various components are housed, and a dome-shaped cover (112) coupled to the upper side of the body (111). The cover (112) may be equipped with a view port for observing the ingot growth process, and a long cylindrical furnace in which a single crystal ingot is grown may be provided on the upper side.

[0031] The crucible (120) is a container for holding high-temperature molten silicon and can be supported by a crucible driving unit (150) inside the main body (111).

[0032] The crucible (120) may be composed of a quartz crucible (121) in which molten silicon is contained, and a graphite crucible (122) in which the quartz crucible (121) is accommodated. The crucible (120) may be seated on the top of the crucible drive unit (150) by a separate supporter.

[0033] When the crucible drive unit (150) is operated during the ingot growth process, the crucible (120) is rotated or raised, and the interface of the molten silicon can be maintained at a constant height.

[0034] The heater (130) is a graphite heating element capable of heating the crucible (120) and may be spaced apart from the crucible (120). When the heater (130) is operated, the polysilicon contained in the crucible (120) can be liquefied into molten silicon, and the temperature of the molten silicon can be controlled by adjusting the operation of the heater (130).

[0035] The insulating member (140) is provided on the inner surface of the main body (111) and is spaced apart from the heater (130) so as to prevent heat from the heater (130) from escaping to the outside through the main body (111).

[0036] The crucible drive unit (150) is provided on the lower side of the crucible (120) and can rotate and raise the crucible (120). The crucible drive unit (150) may include a drive shaft, a drive motor, etc.

[0037] When a seed crystal is immersed in molten silicon inside a crucible (120) and the crucible drive unit (150) slowly rotates the crucible (120), a single crystal grows around the seed crystal, and when the seed crystal is slowly raised, the diameter of the single crystal gradually increases so that it can be grown into a single crystal ingot. As the ingot growth process progresses and the molten silicon contained in the crucible (120) decreases, the crucible drive unit (150) slowly raises and lowers the crucible (120), thereby maintaining a constant height of the molten silicon interface.

[0038] That is, as the ingot growth process progresses, the rotational speed and lifting speed of the crucible (120) can be controlled by adjusting the operation of the crucible drive unit (150).

[0039] The thermal shield assembly (160) is installed to be suspended above the crucible (120) and can directly cool the ingot growing from the high-temperature molten silicon. The thermal shield assembly (160) can be configured so that its thermal insulation performance varies according to the magnetic field of the magnet (M), which will be examined in detail below.

[0040] The magnet (M) is provided on the outside of the chamber (110) and can apply a horizontal magnetic field.

[0041] A heater (130) can perform a melting process by heating polycrystalline silicon inside a crucible (120) to melt it into molten silicon. Since the magnet (M) does not apply a magnetic field during the melting process, the overall thermal insulation performance of the thermal shielding assembly (160) can be maintained at a high level, thereby reducing power consumption.

[0042] While the heater (130) heats the molten silicon in the crucible (120), an ingot growth process can be carried out in which the seed is immersed in the molten silicon and pulled up while rotating the seed or the crucible (120). During the ingot growth process, natural convection occurs in the molten silicon, and forced convection may occur in the molten silicon as the rotation speed of the seed or the crucible (130) is adjusted. However, since the magnet (M) applies a horizontal magnetic field during the ingot growth process, the natural convection and forced convection occurring in the molten silicon due to the horizontal magnetic field can be suppressed to produce a single crystal of uniform quality, and the growth rate of the defect-free region in the single crystal ingot can be improved by lowering the upper thermal insulation performance of the thermal shield assembly (160).

[0043] The configuration of the thermal shielding assembly (160), which can vary the thermal insulation performance according to the process, will be examined in detail below.

[0045] FIG. 2 is a drawing showing the operating state of the thermal shield assembly of the first embodiment during the melting process, and FIG. 3 is a drawing showing the operating state of the thermal shield assembly of the first embodiment during the body growth process.

[0046] The thermal shielding assembly (160) of the first embodiment may be composed of a cylindrical case (162) through which a single crystal ingot (IG) can pass, as shown in FIGS. 2 and 3, a low-elasticity insulating part (164) and a high-elasticity insulating part (166) stacked to act as insulating material embedded in the case (162), and a ferromagnetic body (168) stacked on the high-elasticity insulating part (166) within the case (162) to compress or relax the high-elasticity insulating part (166) according to changes in the magnetic field of the magnet (M).

[0047] The case (162) is generally cylindrical in shape, but may include an internal space of the case (162) in which a low-elasticity insulating part (164), a high-elasticity insulating part (166), and a ferromagnetic body (168) can be embedded. In order to configure the insulation performance to be higher towards the lower side of the case (162), the internal space of the case (162) may be configured to become wider from the top to the bottom, but is not limited thereto. The case (162) may be made of a graphite material that can withstand high temperatures, but is not limited thereto.

[0048] The low-elasticity insulation section (164) may be configured in a cylindrical shape placed in the lower part of the internal space of the case (162). It is preferable that the low-elasticity insulation section (164) be composed of a material with a lower porosity than the high-elasticity insulation section (166). In the embodiment, the low-elasticity insulation section (164) may be configured in a cylindrical shape by rolling up rigid felt, but is not limited thereto.

[0049] The high-elasticity insulation part (166) may be configured in a cylindrical shape to be placed in the upper part of the internal space of the case (162) so as to be laminated on top of the low-elasticity insulation part (164). The high-elasticity insulation part (166) may be configured to be easily compressed or expanded according to the movement of the ferromagnetic body (166) described below, and it is preferable that it be composed of a material with a higher porosity and strain rate than the low-elasticity insulation part (164). In the embodiment, the high-elasticity insulation part (166) may be configured in a cylindrical shape by rolling up a soft felt with a porosity of 90% or more, but is not limited thereto.

[0050] The ferromagnetic body (168) may be configured in the shape of a ring plate placed at the top of the internal space of the case (162) so as to be laminated on the high-elasticity insulating part (166). The ferromagnetic body (168) may be composed of a metal material such as Fe that can be installed to move up and down according to changes in the magnetic field applied by the magnet (M), but it is preferable to be coated with a quartz material so that the metal component does not leak out.

[0051] By adjusting the material of the high-elasticity insulation part (166), the change in the magnetic field of the magnet (M), and the position of the ferromagnetic body (168), the insulation performance of the thermal shielding assembly (160) can be adjusted more precisely.

[0053] Looking at the operation of the single-crystal ingot growth apparatus configured as above, as shown in FIG. 2, polycrystalline poly(P) is introduced into a crucible (120), and as the heater (130) is operated, a melting process is carried out in which the polycrystalline poly(P) melts and turns into molten silicon.

[0054] Since the magnet (M) does not apply a magnetic field during the melting process, the ferromagnetic body (168) does not move inside the thermal shielding assembly (160), and the low-elasticity insulating part (164) and the high-elasticity insulating part (166) can be maintained in a relaxed state. In this way, the overall thermal insulation performance of the thermal shielding assembly (160) can be maintained at a high level during the melting process, thereby reducing power consumption.

[0055] When the melting process is completed, an ingot growth process is carried out to grow a single crystal ingot (IG) by slowly rotating and pulling the seed while it is dipped in the molten silicon contained in the crucible (120) as shown in FIG. 3.

[0056] Since the magnet (M) applies a magnetic field during the ingot growth process, the ferromagnetic body (168) descends within the thermal shielding assembly (160), thereby compressing the high-elasticity insulating part (166) above the low-elasticity insulating part (168). In this way, the lower insulating performance of the thermal shielding assembly (160) can be maintained at a high level while the upper insulating performance of the thermal shielding assembly (160) can be maintained at a low level during the ingot growth process, so that the G value of the ingot is improved by increasing the temperature gradient between the silicon melt and the single crystal ingot (IG), thereby improving the growth rate of the defect-free region.

[0057] During the ingot growth process, impurities may accumulate on the surface of the high-elasticity insulation part (166) as the high-elasticity insulation part (166) is compressed or relaxed, but the high-elasticity insulation part can be reused by removing surface impurities through heat treatment at a high temperature after repeated ingot processes.

[0059] FIG. 4 is a drawing showing the operating state of the thermal shield assembly of the second embodiment during the melting process, and FIG. 5 is a drawing showing the operating state of the thermal shield assembly of the second embodiment during the body growth process.

[0060] The thermal shielding assembly (260) of the second embodiment is a structure in which the low-elasticity insulation part is omitted from the thermal shielding assembly of the first embodiment, and as shown in FIGS. 4 and 5, it may be composed of a cylindrical case (262) through which a single crystal ingot (IG) can pass, a high-elasticity insulation part (264) which acts as an insulating material embedded in the case (262), and a ferromagnetic body (266) which is laminated to the high-elasticity insulation part (166) within the case (262) and compresses or relaxes the high-elasticity insulation part (264) according to the change in the magnetic field of the magnet (M).

[0061] Since the components and operating state of the thermal shielding assembly of the second embodiment are identical to those of the thermal shielding assembly of the first embodiment, a detailed description will be omitted.

[0063] The above description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications and variations within the scope of the essential characteristics of the present invention.

[0064] Accordingly, the embodiments disclosed in this invention are intended to explain, not limit, the technical concept of the invention, and the scope of the technical concept of the invention is not limited by these embodiments.

[0065] The scope of protection of the present invention shall be interpreted by the claims below, and all technical ideas within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention. Explanation of the symbols

[0066] 110: Chamber 120: Crucible 130 : Heater 140 : Insulation 150: Crucible drive unit 160: Thermal shield assembly 162 : Case 164 : Low-elasticity insulation 166 : High-elasticity insulating part 168 : Ferromagnetic material M : Magnet

Claims

Claim 1 A single-crystal ingot growth apparatus comprising: a chamber; a crucible provided inside the chamber and containing molten silicon; a heater provided around the crucible and heating the crucible; a magnet provided outside the chamber and forming a magnetic field distribution; and a thermal shield assembly located inside the crucible and cooling a single-crystal ingot grown from the molten silicon, wherein the thermal shield assembly has varying thermal insulation performance according to changes in the magnetic field of the magnet. Claim 2 A single-crystal ingot growth apparatus according to claim 1, wherein the thermal shielding assembly comprises a case through which the single-crystal ingot is penetrated, an insulating material embedded in the case, and a ferromagnetic material laminated on the insulating material and compressing or relaxing the insulating material according to changes in the magnetic field of the magnet. Claim 3 A single-crystal ingot growth apparatus according to paragraph 2, wherein the internal space of the case is configured to become wider from the top to the bottom. Claim 4 In paragraph 2, the single crystal ingot growth apparatus comprises a high-elasticity insulating part disposed in the upper space inside the case to support the ferromagnetic body. Claim 5 In paragraph 4, the high-elasticity insulating part is a single-crystal ingot growth apparatus composed of a porosity of 90% or more. Claim 6 In paragraph 4, the high-elasticity insulating part is a single-crystal ingot growth device that is reused after heat treatment following the single-crystal ingot growth process. Claim 7 In paragraph 4, the high-elasticity insulating part is a single-crystal ingot growth apparatus composed of soft felt. Claim 8 A single crystal ingot growth apparatus according to any one of claims 4 to 7, wherein the insulating material further comprises a low-elasticity insulating part having lower elasticity than the high-elasticity insulating part and disposed in the lower space inside the case to support the high-elasticity insulating part. Claim 9 In claim 8, the low-elasticity insulating part is a single-crystal ingot growth apparatus composed of rigid felt. Claim 10 In paragraph 2, the ferromagnetic body is a single-crystal ingot growth apparatus coated with quartz material.

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