Seed crystal fixation unit and crystal growing method using same

Abstract

As a technical means for achieving the above-described technical problem, according to one aspect of the present invention, a seed crystal fixation unit for crystal growth comprises a first portion configured to contact a seed crystal, wherein at least a portion of the first portion is configured to be spaced apart from the upper inner surface of a crucible for crystal growth, forming a first cavity.

Description

Seed crystal fixing part and crystal growth method using the same

[0001] The present invention relates to a seed crystal fixing part and a crystal growth method using the same, and more specifically, to a seed crystal fixing part capable of high-quality crystal growth and a crystal growth method using the same.

[0002] As technology advances, there is a growing demand for high-performance semiconductor devices. In particular, with the recent development of Artificial Intelligence (AI), eco-friendly vehicles, and next-generation communication technologies, the need for high integration and efficiency in semiconductor devices is increasing even further.

[0003] Semiconductor devices can be manufactured by forming devices on a substrate, and the performance of the device can be significantly influenced by the quality of the substrate. Conventionally, silicon substrates were primarily used; however, with the demand for high-performance semiconductor devices, research on manufacturing technologies for compound semiconductor substrates such as silicon carbide (SiC), gallium oxide (Ga2O3), and gallium arsenide (GaAs) has recently been actively conducted.

[0004] The compound semiconductor substrate described above can be manufactured through various methods. For example, it can be manufactured by growing a compound semiconductor crystal based on a seed crystal to produce an ingot, and then processing the ingot to produce a compound semiconductor substrate.

[0005] There are various methods for growing compound semiconductor crystals, such as the liquid phase method, in which a raw material is liquefied and then brought into contact with a seed crystal to grow the crystal, and the gas phase method, in which a raw material is sublimated and brought into contact with a seed crystal to grow the crystal. In all of the above methods, crystal growth is induced from a seed crystal.

[0006] Meanwhile, since the seed crystal is fixed in contact with the seed crystal holder, the temperature of the holder affects the seed crystal and forms a temperature gradient, which can induce thermal stress during the crystal growth process. Such thermal stress can cause defects during crystal growth and lead to problems that degrade crystal quality. (For example, “Growth of Crack-Free 100mm-Diameter 4H-SiC Crystals with Low Micropipe Densities”, Nakabayashi, Masashi, et al. Materials Science Forum. Vol. 600. Trans Tech Publications Ltd, 2009. or, “Evolution of thermoelastic strain and dislocation density during sublimation growth of silicon carbide”, Zhmakin, IA, et al. Diamond and related materials 9.3-6 (2000): 446-451.)

[0007] In addition, since the constituent materials of the seed crystal fixing part and the seed crystal may differ from each other, a difference in cooling rate may occur between the seed crystal fixing part and the seed crystal during the cooling stage. In this case, thermal stress is induced due to the difference in the coefficient of thermal expansion between the seed crystal fixing part and the seed crystal, causing various defects within the crystal and leading to a problem that degrades the quality of the crystal.

[0008] Accordingly, the development of technology capable of minimizing thermal stress generated during the crystal growth and cooling processes is required.

[0009] Meanwhile, the aforementioned background technology is technical information that the inventor possessed for the derivation of the present invention or acquired during the process of deriving the present invention, and it cannot be considered as prior art disclosed to the general public prior to the filing of the present invention.

[0010] One embodiment of the present invention aims to provide a seed crystal fixing part capable of minimizing thermal stress that may occur due to various causes during crystal growth, and a crystal growth method using the same.

[0011] As a technical means for achieving the aforementioned technical problem, according to one aspect of the present invention, a seed crystal fixing part for crystal growth comprises a first part configured to be in contact with the seed crystal, and at least a portion of the first part is configured to be spaced apart from the upper inner surface of the crucible for crystal growth to form a first cavity.

[0012] According to another aspect of the present invention, the seed crystal fixing part may further include a second part surrounding the first part.

[0013] According to another aspect of the present invention, the upper surface of the first part may be disposed on a plane different from the upper surface of the second part.

[0014] According to another aspect of the present invention, the upper surface of the first part may be disposed on the same plane as the upper surface of the second part.

[0015] According to another aspect of the present invention, the lower surface of the first part protrudes from the lower surface of the second part, and when the seed crystal is fixed to the lower surface of the first part, the seed crystal may be configured to protrude from the lower surface of the second part.

[0016] According to another aspect of the present invention, the length from the upper surface of the second part to the lower surface of the first part may be 3 mm to 5 mm.

[0017] According to another aspect of the present invention, the seed crystal fixing part may be provided to fix a seed crystal for sublimation single crystal growth.

[0018] According to another aspect of the present invention, the seed crystal may include SiC.

[0019] According to another aspect of the present invention as a technical means for achieving the technical problem described above, a crystal growth method comprises the steps of placing a seed crystal fixing part, in which a seed crystal is fixed, within a crucible, and growing a crystal based on said seed crystal, wherein the seed crystal fixing part comprises a first part configured to be in contact with said seed crystal, and at least a portion of said first part is spaced apart from the upper inner surface of the crucible to form a first cavity.

[0020] According to another aspect of the present invention, the seed crystal fixing part further comprises a second part surrounding the first part, and the step of placing the seed crystal fixing part on the upper part of the crucible may include the step of placing the seed crystal fixing part on the upper part of the crucible by seating the second part on a support provided on the inner surface of the crucible.

[0021] The step of placing the seed crystal fixing part on the upper part of the crucible may include the step of placing the seed crystal fixing part on the upper part of the crucible such that at least a portion of the second part is spaced apart from the upper inner surface of the crucible to form a second cavity.

[0022] According to another aspect of the present invention, the surface area of ​​the space defined by the first cavity, the second cavity, and the inner surface of the crucible may be at least 25% of the total area of ​​the space defined by the lower surface of the seed crystal fixing part and the inner surface of the crucible.

[0023] According to another aspect of the present invention, the step of growing the crystal may include the step of sublimating the raw material loaded into the crucible, and the step of inducing crystallization of the sublimated raw material in the seed crystal fixed at the upper part of the crucible having a lower temperature than the lower part of the crucible.

[0024] According to another aspect of the present invention, the step of sublimating the raw material loaded into the crucible may be performed under conditions where the internal pressure of the crucible is 5 to 20 Torr and the internal temperature of the crucible is 2300℃ or higher.

[0025] According to another aspect of the present invention, the seed crystal may include SiC.

[0026] According to any one of the means for solving the problem of the present invention described above, a cavity is formed between the seed crystal fixing part of the present invention and the upper inner surface of the crucible, so the temperature gradient of the seed crystal fixing part can be minimized and the thermal stress induced during the growth process is reduced, so that a crystal of uniform thickness can be grown.

[0027] According to any one of the means for solving the problem of the present invention described above, in the seed crystal fixing part of the present invention, the first part where the seed crystal is fixed is surrounded by the second part, and the second part comes into contact with the crucible, so that the seed crystal can be fixed, so that contact between the seed crystal and the crucible during the crystal growth process can be minimized and thermal stress caused by contact between the seed crystal and the crucible can be minimized, so that a crystal of excellent quality can be obtained.

[0028] According to any one of the means for solving the problem of the present invention described above, according to the seed crystal fixing part and the crystal growth method using the same of the present invention, the upper surface of the first part of the seed crystal fixing part is formed to be recessed compared to the upper surface of the second part, so the thickness of the first part of the seed crystal fixing part can be made thinner, and as the thickness of the seed crystal fixing part is reduced, thermal stress caused by the difference in the coefficient of thermal expansion during the cooling process can be further relieved. Accordingly, a crystal of excellent quality can be obtained.

[0029] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below.

[0030] FIG. 1 is a perspective view of a seed crystal fixing part according to one embodiment of the present invention.

[0031] Figure 2 is a cross-sectional view of II-II' of Figure 1.

[0032] Figure 3 is a schematic diagram illustrating a crystal growth method using the seed crystal fixing part of Figure 1.

[0033] FIG. 4 is a perspective view of a seed crystal fixing part according to another embodiment of the present invention.

[0034] Figure 5 is a cross-sectional view of V-V' of Figure 4.

[0035] Figure 6 is a schematic diagram illustrating a crystal growth method using the seed crystal fixing part of Figure 4.

[0036] FIG. 7 is a schematic diagram illustrating a crystal growth method using a seed crystal fixing part according to manufacturing examples and comparative examples.

[0037] Figure 8 is a graph illustrating the change in growth conditions over time in the crystal growth method of Figure 7.

[0038] FIG. 9 is a graph showing the thickness measurement results of crystals produced through a crystal growth method using a seed crystal fixing part according to the manufacturing example and comparative example of FIG. 7.

[0039] FIG. 10 shows images of the growth plane and UVF (Ultra violet fluorescence) images of crystals manufactured using seed crystal fixing parts according to the manufacturing examples and comparative examples of FIG. 7.

[0040] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0041] Throughout the specification, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members or elements interposed between them. Furthermore, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0042] The present invention will be described in detail below with reference to the attached drawings.

[0043] FIG. 1 is a perspective view of a seed crystal fixing part according to one embodiment of the present invention. FIG. 2 is a cross-sectional view taken along II-II' of FIG. 1.

[0044] Referring to FIG. 1, the seed crystal fixing part (100) of the present invention refers to a member for fixing a seed crystal in a process of manufacturing an ingot for manufacturing a substrate used in a semiconductor device. Here, the ingot may refer to a crystalline base material (e.g., a single crystal) made of a semiconductor material, and a substrate may be manufactured by processing the ingot.

[0045] The seed crystal fixing part (100) of the present invention can be applied to various methods for manufacturing ingots. For example, it can be easily applied to the sublimation method, in which a crystal is grown by sublimating a raw material. However, it is not limited thereto, and the seed crystal fixing part of the present invention can also be applied to the liquid phase method, in which a crystal is grown by contacting a seed crystal with a molten liquid after melting a raw material. For convenience of explanation, the following description will focus on crystal growth by the sublimation method.

[0046] The seed crystal fixing part (100) may be made of a material with excellent chemical resistance and excellent heat resistance capable of withstanding high-temperature crystal growth conditions, for example, the seed crystal fixing part (100) may be made of a material including graphite, carbon (C) excluding graphite, tungsten (W), or tantalum (Ta).

[0047] The seed crystal fixing part (100) includes a first part (110). The first part (110) refers to a part having a bonding surface formed to be bonded to the seed crystal, and the seed crystal can be fixed by bonding one side of the seed crystal to the first part (110). In FIG. 1, the seed crystal is configured to be fixed by bonding it to the lower surface of the first part (110).

[0048] The first part (110) may be configured as a circle in a planar shape. That is, as shown in FIG. 1, the first part (110) may include a circular lower surface and an upper surface. However, it is not limited thereto, and the shape of the first part (110) may be configured in various ways, such as a polygon or an ellipse, depending on the shape of the seed crystal to be joined.

[0049] The seed determination fixing part (100) may further include a second part (120) surrounding the first part (110).

[0050] The second part (120) may correspond to the edge of the seed crystal fixing part (100). The second part (120) is connected to the first part (110) to form an integral shape, and the first part (110) and the second part (120) may be made of the same material.

[0051] The second part (120) can function as a fixing member for fixing the seed crystal fixing part (100) inside the crucible. For example, by fixing the second part (120) inside the crucible, the first part (110) connected to the second part (120) is fixed inside the crucible, and the seed crystal bonded to the first part (110) is fixed inside the crucible.

[0052] The second part (120) can be fixed inside the crucible in various ways. For example, the second part (120) can be fixed inside the crucible by being joined or bonded to the upper inner surface of the crucible. Additionally, the second part (120) can be fixed inside the crucible by being bound or seated on a support formed on the inner surface of the crucible.

[0053] At least a portion of the first part (110) is configured to be spaced apart from the upper inner surface of the crucible for crystal growth, and as the first part (110) and the upper inner surface of the crucible are spaced apart, a first cavity (CA1) can be formed between them.

[0054] Referring to FIG. 2, the upper surface of the first part (110) may be positioned on a plane different from the upper surface of the second part (120). For example, as shown in FIG. 2, the upper surface of the first part (110) may be formed by being recessed to a lower position than the upper surface of the second part (120). In this specification, the upper surface refers to the surface located at the top in the cross-sectional view of FIG. 2, and the lower surface refers to the surface located at the bottom in the cross-sectional view of FIG. 2.

[0055] As the upper surface of the first part (110) is sunken to a lower position than the upper surface of the second part (120), an empty space is formed on the upper surface of the first part (110), and this space can function as a first cavity (CA1). In this case, the volume of the first cavity (CA1) can be determined by the size of the upper surface of the first part (110).

[0056] The lower surface of the first part (110) may be positioned on a different plane from the lower surface of the second part (120). For example, as shown in FIG. 2, the lower surface of the first part (110) may be configured to protrude to a lower position than the lower surface of the second part (120). As the lower surface of the first part (110) protrudes more than the lower surface of the second part (120), a seed crystal fixed to the lower surface of the first part (110) may be positioned to protrude more than the lower surface of the second part (120).

[0057] The length (t1) from the upper surface of the second part (120) of the seed crystal fixing part (100) to the lower surface of the first part (110) may be within 7 mm. Preferably, it may be 3 to 5 mm. In this specification, the length (t1) from the upper surface of the second part (120) to the lower surface of the first part (110) is defined as the total thickness of the seed crystal fixing part (100). If the total thickness (t1) is less than 3 mm, it may be difficult to manufacture the seed crystal fixing part (100), and when the seed crystal is fixed, the seed crystal fixing part (100) may bend or it may be difficult to stably fix the seed crystal. In addition, if the total thickness (t1) exceeds 5 mm, a temperature gradient may be formed in the seed crystal fixing part (100), which may cause thermal stress in the seed crystal, and this may not be desirable. A detailed explanation regarding this will be provided later.

[0058] In some embodiments, the thickness (t3) of the first part (110) may be the same as the thickness (t2) of the second part (120). In this case, the seed crystal fixing part (100) may be manufactured by punching a flat material having a predetermined thickness (t2, t3).

[0059] As described above, the seed crystal fixing part (100) of the present invention is provided for crystal growth. Through the seed crystal fixing part (100) of the present invention, the seed crystal can be stably fixed within the crucible, and thermal stress that may occur during the crystal growth process can be minimized. For a detailed explanation thereof, refer to FIG. 3.

[0060] Figure 3 is a schematic diagram illustrating a crystal growth method using the seed crystal fixing part of Figure 1.

[0061] Referring to FIG. 3, first, a seed crystal fixing part (100) in which a seed crystal (SC) is fixed is placed inside a crucible (200).

[0062] The raw material (MA) is a raw material for crystal growth and may be a semiconductor raw material comprising at least one of silicon (Si), gallium (Ga), aluminum (Al), zinc (Zn), indium (In), tin (Sn), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), molybdenum (Mo), and tungsten (W), and may be, for example, silicon carbide (SiC).

[0063] The seed crystal (SC) may be a solid piece made of the same material as the crystal to be grown, and its size and shape may be freely selected depending on the crystal growth conditions.

[0064] The crucible (200) is a chamber into which raw material (MA) for crystal growth is loaded, and is sealed to provide a space where crystals can grow from the raw material (MA). The crucible (200) may be made of a material with excellent thermal conductivity that can uniformly transfer heat to the internal space, and may be appropriately selected as a material with excellent chemical resistance and low reactivity with the raw material to minimize the inflow of impurities and minimize the loss of the raw material. For example, the crucible (200) may be made of a material including graphite, carbon excluding graphite, tungsten, or tantalum, but the material of the crucible (200) is not limited to these, and the material of the crucible (200) may be selected in various ways depending on the type of raw material (MA) used.

[0065] A support (300) for fixing the seed crystal fixing part (100) may be provided on the inner surface (220) of the crucible (200). The support (300) may be configured in the form of a tube extending along the inner surface (220) of the crucible (200).

[0066] The support body (300) may be made of the same material as the crucible (200), but is not limited thereto, and the support body (300) may be made of a different material from the crucible (200).

[0067] The support body (300) is placed on top of the raw material (MA) contained in the crucible (200). When the seed crystal fixing part (100) is seated on the support body (300), the seed crystal (SC) fixed through the seed crystal fixing part (100) can be located in the upper space of the raw material (MA).

[0068] The support body (300) may include a seating surface (310) for seating the seed crystal fixing part (100). Specifically, the second part (120) of the seed crystal fixing part (100) is configured to be seated on the seating surface (310) of the support body (300). In this case, the seating surface (310) may have a surface with a shape corresponding to the lower surface of the second part (120) that is seated thereon. That is, if the lower surface of the second part (120) is in the shape of a circular band, the seating surface (310) may also be in the shape of a circular band.

[0069] As described above, the second part (120) is configured to surround the first part (110), and since the second part (120) is seated on the seating surface (310) of the support (300), the first part (110) can be spaced apart from the side surface (220) of the crucible (200). Additionally, since the seed crystal (SC) is bonded to the first part (110), the seed crystal (SC) can be spaced apart from the inner surface (220) of the crucible (200).

[0070] Additionally, as described above, the seed crystal fixing part (100) of the present invention is configured such that the upper surface of the first part (110) is positioned on a plane lower than the upper surface of the second part (120), so that at least a portion of the upper surface of the first part (110) is spaced apart from the upper inner surface of the crucible, and a first cavity (CA1) is formed in the spaced-apart space between the upper surface of the first part (110) and the upper inner surface (210) of the crucible (200). Accordingly, the seed crystal (SC) can be spaced apart from the upper inner surface (210) of the crucible (200).

[0071] In some embodiments, at least a portion of the second part (120) of the seed crystal fixing part (100) may be spaced apart from the upper inner surface (210) of the crucible (200), and a second cavity (CA2) may be further formed between the second part (120) and the upper inner surface (210) of the crucible (200).

[0072] When a second cavity (CA2) is further formed, a significant portion of the upper surface of the seed crystal fixing part (100) is exposed according to the first cavity (CA1) and the second cavity (CA2). In this case, the surface area of ​​the spaced-out space formed by the first cavity (CA1) and the second cavity (CA2) may be at least 25% of the total surface area of ​​the space defined by the lower surface of the seed crystal fixing part (100) and the crucible (200). Here, the outer surface of the space defined by the upper surface of the first part (110) of the seed crystal fixing part (100), the upper inner surface (210) of the crucible (200) corresponding thereto, and the inner surface of the crucible (200) surrounding the upper surface of the first part (110) and the upper inner surface (210) of the crucible (200) corresponding thereto may be the outer surface of the spaced-out space defined by the first cavity (CA1), and the outer surface of the space defined by the upper surface of the second part (120) of the seed crystal fixing part (100), the upper inner surface (210) of the crucible (200) corresponding thereto, and the inner surface of the crucible (200) surrounding the upper surface of the second part (120) and the upper inner surface (210) of the crucible (200) corresponding thereto may be the outer surface of the spaced-out space defined by the second cavity (CA2). Additionally, the outer surface area of ​​the space defined by the lower surface of the seed crystal fixing part (100), the upper inner surface (210) of the crucible (200) corresponding to the lower surface of the seed crystal fixing part (100), and the inner surface (220) of the crucible (200) surrounding the lower surface of the seed crystal fixing part (100) and the upper inner surface (210) of the crucible (200) may be the total outer surface area of ​​the space defined by the lower surface of the seed crystal fixing part (100) and the crucible (200).

[0073] After the seed crystal fixing part (100) is placed, a crystal is grown based on the seed crystal (SC).

[0074] Based on the sublimation method, the crucible (200) is heated under specific conditions to sublimate the raw material (MA). In this case, the heating conditions of the crucible (200) can be appropriately determined according to the type of raw material (MA) loaded into the crucible (200). For example, if the raw material (MA) is silicon carbide, the crucible (200) can be heated to a temperature of 2,300°C or higher under pressure conditions of 5 to 20 Torr. Under these conditions, the raw material (MA) containing silicon carbide is sublimated, and crystal growth can be induced as the sublimated raw material (MA) particles aggregate and crystallize on a seed crystal (SC) placed at the top of the crucible (200), which has a relatively lower temperature than the bottom of the crucible (200).

[0075] In the crystal growth process of the present invention, since a part of the seed crystal fixing part (100) is spaced apart from the upper inner surface (210) of the crucible (200) by the first cavity (CA1) and the second cavity (CA2), the temperature gradient of the seed crystal fixing part (100) can be minimized. Specifically, the temperature of the lower surface of the first part (110) of the seed crystal fixing part (100) can be maintained uniformly over the entire area.

[0076] If the first cavity (CA1) and the second cavity (CA2) do not exist, the upper surface of the seed crystal fixing part (100) may come into contact with the upper inner surface (210) of the crucible (200). In this case, due to thermal contact with the upper inner surface (210) of the crucible (200), the temperature of the seed crystal fixing part (100) may become relatively higher. Additionally, the temperature may become relatively higher in the corner portion of the seed crystal fixing part (100), where the contact area is relatively large, so that the temperature gradient between the center and the corner portion of the seed crystal fixing part (100) may widen significantly.

[0077] On the other hand, when the first cavity (CA1) and the second cavity (CA2) exist, the upper surface of the seed crystal fixing part (100) is spaced apart from the upper inner surface (210) of the crucible (200), and since the radiant heat from the upper part of the crucible (200) through the first cavity (CA1) further heats the central part of the seed crystal fixing part (100), the temperature gradient between the central part and the corner part of the seed crystal fixing part (100) can be reduced. As the temperature gradient between the central part and the corner part of the seed crystal fixing part (100) is reduced, the horizontal temperature in the first part (110) of the seed crystal fixing part (100) can become uniform. As the temperature of the seed crystal fixing part (100) becomes uniform, the temperature of the seed crystal (SC) can also become uniform, and thermal stress can be minimized during the crystal growth process. Accordingly, the dislocation density within the crystal is reduced, and the crystal quality can be improved.

[0078] Additionally, the seed crystal fixing part (100) of the present invention is configured such that the second part (120) surrounds the first part (110), and the seed crystal (SC) is attached to the lower surface of the first part (110) and is spaced apart from the inner surface (220) of the crucible (200). In this case, the crystal growing through the seed crystal (SC) can be sufficiently spaced apart from the inner surface (220) of the crucible (200), the heat inflow and outflow concentrated at the contact area of ​​the grown crystal with the crucible (200) can be minimized, and thermal stress caused by the temperature gradient between the contact area and the non-contact area can be relieved.

[0079] In particular, since the upper surface of the first part (110) of the seed crystal fixing part (100) is recessed compared to the upper surface of the second part (120), the thickness (t3) of the first part (110) and the thickness (t2) of the second part (120) can be substantially the same, and the thickness (t2, t3) of the seed crystal fixing part (100) can be kept sufficiently thin while sufficiently securing the cavity (CA1, CA2). In this case, thermal stress caused by the difference in the coefficient of thermal expansion between the seed crystal fixing part (100) and the grown crystal can be relieved during the cooling process. That is, the difference in the coefficient of thermal expansion can be relieved in the thin seed crystal fixing part (100) compared to the thick seed crystal fixing part (100), and the thermal stress induced by the difference in the coefficient of thermal expansion during the cooling process can be relieved compared to the thick seed crystal fixing part (100). In particular, the second part (120) of the seed crystal fixing part (100) is configured to surround the first part (110) to compensate for the rigidity of the first part (110), so that even if the weight of the grown crystal is heavy, the seed crystal and the grown crystal can be stably adhered to the first part (110), thus providing the advantage of enabling more stable crystal growth.

[0080] FIG. 4 is a perspective view of a seed crystal fixing part according to another embodiment of the present invention.

[0081] Figure 5 is a cross-sectional view of V-V' of Figure 4.

[0082] A seed crystal fixing part (400) according to another embodiment of the present invention is substantially identical to a seed crystal fixing part (100) according to one embodiment of the present invention, except that the upper surface of the first part (410) is located on the same plane as the upper surface of the second part (420), compared to a seed crystal fixing part (100) according to one embodiment of the present invention. Accordingly, the description of the overlapping components is omitted.

[0083] Referring to FIGS. 4 and 5, the upper surface of the first part (410) of the seed crystal fixing part (400) is placed in the same plane as the upper surface of the second part (420). Accordingly, the upper surfaces of the first part (410) and the second part (420) are connected.

[0084] The lower surface of the first part (410) of the seed determination fixing part (400) is positioned on a different plane from the lower surface of the second part (420). For example, as shown in FIG. 5, the lower surface of the first part (410) is positioned to protrude at a lower position relative to the lower surface of the second part (420).

[0085] The total thickness (t1), defined as the distance (t1) from the upper surface of the second part (420) of the seed crystal fixing part (400) to the lower surface of the first part (410), may be within 7 mm. Preferably, it may be 3 to 5 mm. As described above, since the lower surface of the first part (410) is positioned to protrude more than the lower surface of the second part (420), the total thickness (t1) of the seed crystal fixing part (400) may be thicker than the thickness (t2) of the second part (420).

[0086] At least a portion of the first part (410) of the seed crystal fixing part (400) is configured to be spaced apart from the upper inner surface of the crucible, and a first cavity is formed in the spaced-apart area between the first part (410) and the upper inner surface of the crucible. Additionally, at least a portion of the second part (420) of the seed crystal fixing part (400) is configured to be spaced apart from the upper inner surface of the crucible, and a second cavity is formed in the spaced-apart area between the second part (420) and the upper inner surface of the crucible. For a more detailed explanation of this, refer to FIG. 6.

[0087] Figure 6 is a schematic diagram illustrating a crystal growth method using the seed crystal fixing part of Figure 4.

[0088] Referring to FIG. 6, first, a seed crystal fixing part (400) in which a seed crystal (SC) is fixed is placed on the upper part of a crucible (200).

[0089] Specifically, the second part (420) of the seed crystal fixing part (400) is placed on the seating surface (310) of the support (300) placed on the inner surface (220) of the crucible (200), so that the seed crystal fixing part (400) is placed on the upper part of the crucible (200).

[0090] The seed crystal (SC) is attached to the first part (410) of the seed crystal fixing part (400), and since the lower surface of the first part (410) is positioned to protrude more than the lower surface of the second part (420), the seed crystal (SC) attached to the lower surface of the first part (410) is positioned and fixed to protrude lower than the second part (420).

[0091] Meanwhile, at least a portion of the first portion (410) and at least a portion of the second portion (420) of the seed crystal fixing portion (400) are configured to be spaced apart from the upper inner surface (210) of the crucible (200). Accordingly, a first cavity (CA1) is formed in the spaced-apart area between the first portion (410) and the upper inner surface (210) of the crucible (200), and a second cavity (CA2) is formed in the spaced-apart area between the second portion (420) and the upper inner surface (210) of the crucible (200).

[0092] Afterwards, the crystal is grown based on the seed decision (SC).

[0093] Specifically, the crucible (200) is heated under specific conditions, and sublimation of the raw material (MA) loaded into the bottom portion of the crucible (200) may occur. The sublimated raw material (MA) rises to the top of the crucible (200) and aggregates into a seed crystal (SC) having a relatively lower temperature compared to the bottom portion of the crucible (200), thereby growing a crystal.

[0094] In this case, since a first cavity (CA1) and a second cavity (CA2) are provided between the seed crystal fixing part (400) and the upper inner surface (210) of the crucible (200), thermal contact between the seed crystal fixing part (400) and the crucible (200) can be minimized, and during the heating step of the crucible (200), radiant heat through the first cavity (CA1) and the second cavity (CA2) additionally reaches the center of the seed crystal fixing part (400), thereby maintaining the temperature of the corners and the center of the seed crystal fixing part (400) uniformly.

[0095] Additionally, the second part (420) of the seed crystal fixing part (400) is configured to surround the first part (410), and contact between the inner surface (220) of the crucible (200) and the seed crystal fixing part (400) occurs only at the second part (420). Accordingly, when a crystal grows around the seed crystal (SC) attached to the first part (410), the grown crystal can be separated from the inner surface (220) of the crucible (200). Accordingly, thermal contact between the crystal and the crucible (200) can be minimized, and the horizontal temperature gradient of the crystal can be minimized during the cooling stage of the crucible (200).

[0096] Meanwhile, since the total thickness (t1) of the seed crystal fixing part (400) in the first part (410) is greater than the thickness (t2) of the second part (420), the rigidity of the first part (410) may be greater than the rigidity of the second part (420). Accordingly, the seed crystal (SC) attached to the first part (410) can be attached more stably, and even if a crystal grows from the seed crystal (SC), the rigidity of the first part (410) can be sufficiently secured, so that the seed crystal (SC) and the crystal can be maintained in a stably fixed state during the cooling stage of the crucible (200).

[0097] As described above, the seed crystal fixing part (100, 400) of the present invention and the crystal growth method using the same can minimize the temperature gradient in the seed crystal fixing part (100, 400) by intentionally forming cavities (CA1, CA2) between the seed crystal fixing part (100, 400) and the crucible (200). In addition, by designing the seed crystal fixing part (100, 400) by dividing it into a first part (110, 410) and a second part (120, 420), the seed crystal (SC) can be sufficiently separated from the crucible (200), and the thickness of the seed crystal fixing part (100, 400) can be formed thinner. Accordingly, thermal stress that may occur during the cooling step can be minimized while ensuring the adhesion stability of the seed crystal (SC). Accordingly, the increase in crystal dislocation density caused by thermal shock can be minimized, and high-quality crystal growth can be enabled. For a detailed explanation of this, please refer to the following examples.

[0098]

[0099] (Design of Seed Determination Fixing Part - Comparative Example)

[0100] The inventors of the present invention manufactured seed crystal fixing parts according to FIG. 7 to verify the effect of reducing the temperature gradient and improving crystal quality based on the morphological characteristics of the seed crystal fixing part. All seed crystal fixing parts were manufactured from graphite material.

[0101] FIG. 7 is a schematic diagram illustrating a crystal growth method using a seed crystal fixing part according to manufacturing examples and comparative examples.

[0102] First, a seed crystal fixing part (700) according to a comparative example was manufactured with a shape as shown in FIG. 7 (a). The seed crystal fixing part (700) according to the comparative example was designed to consist of a first part and a second part. Specifically, the lower surface of the first part was manufactured as a circle with a diameter of 100 mm, and the upper surface of the second part was manufactured as a circle having an upper surface with a diameter of 120 mm. The total thickness of the seed crystal fixing part (700) in the first part was 7 mm, and the thickness of the first part and the thickness of the second part were each 3.5 mm.

[0103] (Design of seed crystal fixing part - Manufacturing Examples 1 and 2)

[0104] A seed crystal fixing part (100, 400) according to the manufacturing example was manufactured with a shape as shown in (b) and (c) of FIG. 7.

[0105] Specifically, the seed crystal fixing part (100) according to Manufacturing Example 1 is composed of a first part and a second part, the lower surface of the first part is circular with a diameter of 100 mm, and the upper surface of the second part is in the shape of a circular band with a width of 120 mm. The total thickness of the seed crystal fixing part (100) in the first part was 5 mm, and the thickness of both the first part and the second part was 2.5 mm.

[0106] Additionally, the seed crystal fixing part (400) according to Manufacturing Example 2 is composed of a first part and a second part, the lower surface of the first part is a circle with a diameter of 100 mm, and the upper surface of the seed crystal fixing part (400) is a circle with a diameter of 120 mm. The total thickness of the seed crystal fixing part (400) in the first part was 4 mm, and the thickness of the second part was 2 mm.

[0107]

[0108] (Arrangement of seed determination fixed part)

[0109] A seed crystal is attached to a seed crystal fixing part (100, 400, 700) designed and manufactured by the method described above, and the seed crystal fixing part (100, 400, 700) with the attached seed crystal is placed on a support provided on the inner surface of the crucible and mounted in the crucible.

[0110] At this time, the seed crystal fixing part (700) according to the comparative example is positioned so that its upper surface contacts the upper inner surface of the crucible, the seed crystal fixing part (700) according to manufacturing example 1 is positioned so that the upper surface of the second part is spaced 1 mm from the upper inner surface of the crucible, and the seed crystal fixing part (400) according to manufacturing example 2 is positioned so that the upper surface of the second part is spaced 1 mm from the upper inner surface of the crucible.

[0111]

[0112] (Example 1) Comparison of area ratios of separation spaces caused by cavities

[0113] First, the surface area of ​​the space created by the cavity was calculated, and the total surface area of ​​the space defined by the lower surface of the seed crystal fixing part (100, 400, 700) and the crucible was calculated, and the ratio of the surface area of ​​the space created by the cavity to the total surface area was calculated to calculate the area ratio of the manufacturing example and the comparative example.

[0114] That is, the interview fee is defined by the following [Mathematical Formula 1].

[0115]

[0116] Each result is as shown in [Table 1] below.

[0117] Classification Area Ratio (%) Comparative Example 0 Manufacturing Example 188 Manufacturing Example 226

[0118] As can be seen from [Table 1] above, the seed crystal fixing part (700) according to the comparative example had no cavity as its upper surface was in contact with the upper inner surface of the crucible, and thus there was no space defined by the cavity, so the area ratio was 0%.

[0119] Meanwhile, in Manufacturing Examples 1 and 2, the first part and the second part are spaced apart from the upper inner surface of the crucible, so the first cavity and the second cavity are formed, and the area ratio of each Manufacturing Example was calculated based on [Equation 1]. As can be seen from [Table 1] above, the results were 88% and 26%, respectively, and it can be confirmed that the seed crystal fixing part (100) of Manufacturing Example 1, in which the upper surface of the first part is recessed more than the upper surface of the second part, has a larger first cavity space compared to the seed crystal fixing part (400) of Manufacturing Example 2, and thus the area ratio of the seed crystal fixing part (100) of Manufacturing Example 1 is larger compared to the seed crystal fixing part (400) of Manufacturing Example 2.

[0120]

[0121] (Single crystal growth)

[0122] Silicon carbide raw material was loaded into a crucible, and silicon carbide single crystals were grown by sublimating the raw material under conditions as shown in Fig. 8.

[0123] Figure 8 is a graph illustrating the change in growth conditions over time in the crystal growth method of Figure 7.

[0124] Referring to Fig. 8, a silicon carbide seed crystal with an off-angle of 4° was used as the seed crystal, and as shown in Fig. 8, a silicon carbide single crystal was manufactured through the steps of pre-heating, heating, crystal growth, and cooling. The inside of the crucible was filled with argon (Ar) gas, and growth by sublimation was carried out in an argon atmosphere, with the total growth time set to 50 hours.

[0125]

[0126] (Example 2) Comparison of horizontal temperature gradient, growth thickness variation, and growth rate

[0127] First, the radial temperature gradient of the first part of the seed crystal fixing part (100, 400, 700) according to Comparative Example 1 to Manufacturing Example 2 was measured through a growth simulation according to the growth conditions of Fig. 8.

[0128] Subsequently, actual silicon carbide single crystal growth was carried out under the growth conditions of FIG. 8, and the radial thickness and maximum thickness deviation of the single crystal corresponding to the first part of the seed crystal fixing part (100, 400, 700) were measured.

[0129] In addition, the single crystal growth rate was calculated based on the thickness measurement results and growth time.

[0130] The results are as shown in [Table 2] below, and the radial thickness measurement results of the single crystal are as shown in Fig. 9.

[0131] FIG. 9 is a graph showing the thickness measurement results of crystals produced through a crystal growth method using a seed crystal fixing part according to the manufacturing example and comparative example of FIG. 7.

[0132] Radial Temperature gradient(T center - T edge) (℃)Thickness deviation(H max - H min) (mm)Growth rate(mm / hr)Comparative example1.953.54156.29Example 11.250.409128.65Example 20.590.639143.45

[0133] As can be seen by referring to [Table 2] above, the radial temperature gradient in the seed crystal fixing parts (100, 400) according to Manufacturing Examples 1 and 2 is significantly reduced compared to the seed crystal fixing part (700) according to the comparative example. In particular, it can be confirmed that the temperature gradient in the seed crystal fixing part (400) according to Manufacturing Example 2, in which the upper surface of the first part and the upper surface of the second part exist on the same plane, is reduced to one-third of the level compared to the seed crystal fixing part according to the comparative example. This is believed to be because the temperature difference between the central part and the corner part is lowered as heat radiation is further transmitted to the central part of the seed crystal fixing part (400) through the cavity.

[0134] In addition, as can be seen by referring to FIG. 9 and [Table 2], the single crystal grown in the seed crystal fixing part (100, 400) according to Manufacturing Examples 1 and 2 has a smaller thickness variation and a uniform thickness compared to the single crystal grown in the seed crystal fixing part (700) according to the Comparative Example.

[0135] In particular, in the case of a single crystal grown using the seed crystal fixing part (100) according to Manufacturing Example 1, it can be seen that both the thickness variation in the radial direction and the thickness variation in the vertical direction are uniform, and the maximum thickness variation in the radial direction is at the level of 0.409 mm, which is reduced to about 1 / 9 of the level compared to a single crystal grown using the seed crystal fixing part (700) according to the Comparative Example. This is believed to be a result of the temperature gradient being reduced by the cavity.

[0136] Meanwhile, it can be seen that the thickness variation of a single crystal grown using the seed crystal fixing part (100) according to Manufacturing Example 1 is further reduced compared to a single crystal grown using the seed crystal fixing part (400) according to Manufacturing Example 2. This is because, as the first part is formed to be sunken from the second part, the thickness of the first part of the seed crystal fixing part (100) can be further reduced, and thus the thermal stress caused by the difference in the coefficient of thermal expansion between the seed crystal fixing part (100) and the single crystal in the first part can be further alleviated, thereby further improving the stability of single crystal growth.

[0137]

[0138] (Experimental Example 3) Evaluation of single-crystal ingots

[0139] To evaluate the quality of the silicon carbide single crystal produced by the method described above, the morphology of the growth planes of the single crystal was observed, and UVF (Ultra violet fluorescence) analysis was performed. The results are shown in Fig. 10.

[0140] FIG. 10 shows images of the growth plane and UVF (Ultra violet fluorescence) images of crystals produced using the seed crystal fixing part according to the manufacturing example and comparative example of FIG. 7.

[0141] Referring to FIG. 10, it can be seen that the single crystal grown using the seed crystal fixing part (700) according to the comparative example has a concave growth plane and that cracks are observed, and as can be seen through the UVF image, crystal polymorphism existing inside the crystal can be confirmed.

[0142] In contrast, it can be seen that the single crystal grown using the seed crystal fixing part (100, 400) according to Manufacturing Examples 1 and 2 has a flat growth plane and is free of cracks, and it can be confirmed that the crystal polymorphism distribution is reduced due to a stable radial temperature gradient in the UVF image. This is because, as described above, the radial temperature gradient is reduced by the cavity, thereby alleviating the thermal stress caused by it, and because the thickness of the seed crystal fixing part (100, 400) is reduced, the thermal stress caused by the difference in the coefficient of thermal expansion can be alleviated, and thus the thermal stress during the cooling stage is further alleviated.

[0143] As a result, the seed crystal fixing part (100, 400) of the present invention can mitigate the temperature gradient in the radial direction through structural features and intentional cavity formation, and by making the thickness of the seed crystal fixing part (100, 400) thin, the thermal stress caused during the cooling stage can be minimized, thereby providing the advantage of being able to stably grow flat, high-quality crystals.

[0144] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0145] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

[0146] The present invention can be applied to the electronic components industry. Specifically, the present invention can be applied for single-crystal growth to form a substrate or thin film used as a semiconductor component.

Claims

As a seed crystal fixing part for crystal growth, It includes a first part configured to be in contact with the above seed determination, and A seed crystal fixing part, wherein at least a portion of the first part is configured to form a first cavity spaced apart from the upper inner surface of the crucible for crystal growth. In paragraph 1, A seed crystal fixing part further comprising a second part surrounding the first part. In paragraph 2, A seed crystal fixing part, wherein the upper surface of the first part is disposed on a plane different from the upper surface of the second part. In paragraph 2, A seed crystal fixing part, wherein the upper surface of the first part is disposed on the same plane as the upper surface of the second part. In paragraph 2, The lower surface of the first part above protrudes from the lower surface of the second part above, and A seed crystal fixing part configured such that when the seed crystal is fixed to the lower surface of the first part, the seed crystal protrudes from the lower surface of the second part. In paragraph 5, A seed crystal fixing part, wherein the length from the upper surface of the second part to the lower surface of the first part is 3 mm to 5 mm. In paragraph 1, The above seed crystal fixing part is a seed crystal fixing part provided for fixing a seed crystal for sublimation single crystal growth. In Paragraph 7, The above seed crystal is a seed crystal fixing part comprising SiC. A step of placing a seed crystal fixing part, in which a seed crystal is fixed, inside a crucible; and It includes a step of growing a crystal based on the above seed determination, and The above seed determination fixing part is, It includes a first part configured to be in contact with the above seed determination, and A crystal growth method in which at least a portion of the first part is spaced apart from the upper inner surface of the crucible to form a first cavity. In Paragraph 9, The above seed determination fixing part is, It further includes a second part surrounding the first part, and The step of placing the seed crystal fixing part on the upper part of the crucible is, A crystal growth method comprising the step of placing the seed crystal fixing part on the upper part of the crucible by seating the second part on a support provided on the inner surface of the crucible. In Paragraph 10, The step of placing the seed crystal fixing part on the upper part of the crucible is, A crystal growth method comprising the step of placing the seed crystal fixing part on the upper part of the crucible such that at least a portion of the second part is spaced apart from the upper inner surface of the crucible to form a second cavity. In Paragraph 11, A crystal growth method in which the outer surface area of ​​the space defined by the first cavity, the second cavity, and the inner surface of the crucible is at least 25% of the total area of ​​the space defined by the lower surface of the seed crystal fixing part and the inner surface of the crucible. In Paragraph 9, The step of growing the above-mentioned crystal is, A step of sublimating the raw material loaded into the above crucible; and A crystal growth method comprising the step of inducing crystallization of the sublimated raw material in the seed crystal fixed at the upper part of the crucible having a lower temperature than the lower part of the crucible. In Paragraph 13, The step of sublimating the raw material loaded into the crucible is, A crystal growth method performed under conditions where the internal pressure of the crucible is 5 to 20 Torr and the internal temperature of the crucible is 2300℃ or higher. In Paragraph 14, A crystal growth method in which the above seed crystal includes SiC.

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