Method for growing large diameter silicon carbide single creystals with low dislocation defect density and siliocon carbide single crystals grown using the method

Abstract

The present invention relates to a method for growing a large-diameter silicon carbide single crystal, comprising the steps of: preparing silicon carbide powder; loading the silicon carbide powder into the lower part of a crucible; mounting a first seed crystal in the crucible onto a seed crystal holder and sublimating the silicon carbide powder to grow a first silicon carbide single crystal; processing the first silicon carbide single crystal into a second seed crystal; and mounting the second seed crystal onto a seed crystal holder and sublimating the silicon carbide powder to grow a second silicon carbide single crystal.

Description

Technology Field

[0001] The present invention relates to a method for growing a large-diameter silicon carbide single crystal having a low dislocation defect density and a silicon carbide single crystal grown using the same. Background Technology

[0002] The field of semiconductor technology has recently been undergoing rapid advancements. To date, silicon (Si) single crystals have been primarily utilized as the representative semiconductor device material. However, as silicon single crystals are facing limitations due to their inability to satisfy the physical properties required in the semiconductor field, there is an increasing demand for the development of next-generation semiconductor materials capable of overcoming these challenges, including high-power, high-frequency materials and materials with excellent environmental and heat resistance.

[0003] Broadband semiconductor materials such as silicon carbide (SiC), gallium nitride (GaN), and aluminum nitride (AlN) are being developed as next-generation semiconductor device materials. In particular, silicon carbide has excellent thermal stability and oxidation resistance compared to gallium nitride and aluminum nitride. Additionally, silicon carbide has excellent thermal conductivity of about 4.6 W / Cm°C and has the advantage of being able to be produced as large-diameter substrates of 6 inches or more, leading to increased demand for silicon carbide single-crystal substrates.

[0004] Meanwhile, as silicon carbide single-crystal growth technology advances rapidly, substrate quality is also becoming increasingly important. Since substrate defects directly affect device yield and reliability, various efforts are being made, such as researching defect formation mechanisms.

[0005] Methods for manufacturing silicon carbide single crystals include Liquid Phase Epitaxy (LPE), Chemical Vapor Deposition (CVD), and Physical Vapor Transport (PVT). Among these, the Physical Vapor Transport method involves loading silicon carbide raw material into a crucible, placing a seed crystal made of a silicon carbide single crystal at the top of the crucible, and then heating the crucible using an induction heating method to sublimate the raw material and grow a silicon carbide single crystal on the seed crystal.

[0006] Physical vapor transport is currently widely used due to its advantage of being able to produce silicon carbide single crystals with high yield and high quality. However, temperature conditions during crucible heating and the seed crystal angle Depending on the factors, it can affect the quality of silicon carbide single crystals manufactured.

[0007] Among the various defects of silicon carbide single crystals, crystal defects include threading screw dislocations (TSD), basal plane dislocations, and threading edge dislocations, and the said threading screw dislocations, basal plane dislocations, and threading edge dislocations It is known that these factors cause the degradation of device characteristics in that order. In particular, helical dislocations and basal plane dislocations can continuously transfer in the growth direction, which can cause the quality of the single crystal to degrade.

[0008] For this reason, dislocation defect density must be controlled to fabricate high-quality silicon carbide substrates, and among these, silicon carbide single crystals with low helical and basal plane dislocations are required. In particular, if basal plane dislocations occur during single crystal growth, they are continuously transferred in the growth direction until growth is completed, causing a degradation in the quality of the single crystal.

[0009] Accordingly, there is a need to develop a high-quality silicon carbide single crystal growth method capable of controlling dislocation defect density during silicon carbide single crystal growth. Prior art literature

[0010] Republic of Korea Registered Patent No. 10-2239736 (2021.04.07) The problem to be solved

[0011] The present invention aims to provide a method for manufacturing a large-diameter silicon carbide single crystal having low dislocation defect density characteristics.

[0012] The present invention aims to provide a high-quality large-diameter silicon carbide single crystal with a low dislocation defect density, in particular, controlled helical dislocations and basal plane dislocations. means of solving the problem

[0013] A method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention comprises: a step of preparing silicon carbide powder; a step of loading the silicon carbide powder into the lower part of a crucible; a step of mounting a first seed crystal in the crucible onto a seed crystal holder and sublimating the silicon carbide powder to grow a first silicon carbide single crystal; a step of processing the first silicon carbide single crystal into a second seed crystal; and a step of mounting the second seed crystal onto a seed crystal holder and sublimating the silicon carbide powder to grow a second silicon carbide single crystal.

[0014] The above first seed may be processed at an angle of 9 to 17° relative to the horizontal direction of the seed.

[0015] In the first growth step above, the conversion rate from spiral dislocation (TSD) to blade dislocation (TED) may be 90 to 93%.

[0016] The above second seed may be processed at an angle of 2 to 7° relative to the horizontal direction of the seed.

[0017] In the second growth step above, the conversion rate from basal plane potential (BPD) to blade potential (TED) may be 5 to 25%.

[0018] In the step of loading the silicon carbide powder into the lower part of the crucible, the content of the silicon carbide powder may be 95 to 100 weight%.

[0019] The step of mounting the first seed crystal or the second seed crystal in the crucible onto a seed crystal holder may further include: heating the crucible to remove impurities contained within the crucible; injecting an inert gas into the crucible to remove air; heating the crucible with the seed crystal mounted thereon to a single crystal growth temperature; and reducing the internal pressure of the crucible from atmospheric pressure of 760 Torr to 0.2 to 20 Torr.

[0020] The step of heating the crucible to remove impurities contained inside the crucible comprises heating the crucible to a temperature of less than 1000℃. It may include a step of heating at a temperature under vacuum pressure for 2 to 3 hours.

[0021] The step of removing air by injecting an inert gas into the crucible may include the step of purging 2 to 3 times using the inert gas.

[0022] The step of heating the crucible to a single crystal growth temperature may include heating the crucible to a temperature of 2,000 to 2,300°C under atmospheric pressure of 760 Torr.

[0023] The first growing step and / or the second growing step may be performed while maintaining a pressure of 0.2 to 20 torr.

[0024] A large-diameter silicon carbide single crystal according to another embodiment of the present invention is grown by the large-diameter silicon carbide single crystal growth method described above, and in the first growing step, the density of spiral dislocations (TSDs) is 5 to 790 ea / cm² 2And, in the second growth stage, the basal plane dislocation (BPD) density is 5 to 1100 ea / cm 2 am. Effects of the invention

[0025] According to one embodiment of the present invention, when manufacturing a silicon carbide single crystal, the angle of the seed crystal is arbitrarily changed to grow the single crystal, thereby controlling the spiral dislocation and basal plane dislocation, so that a high-quality silicon carbide single crystal with a low dislocation defect density can be realized.

[0026] In addition, a large-diameter silicon carbide substrate can be manufactured by applying a silicon carbide single crystal according to one embodiment of the present invention. Brief explanation of the drawing

[0027] FIG. 1 is a schematic diagram of a method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention. Figure 2 is a result showing the dislocation generation and propagation direction when a single crystal is grown using a seed crystal with a high angle relative to the horizontal direction according to one embodiment of the present invention. Figure 3 is a result showing the dislocation generation and propagation direction when a single crystal is grown using a seed crystal with a low angle relative to the horizontal direction according to one embodiment of the present invention. FIG. 4 is an X-ray topography (XRT) image obtained by cutting and processing a single crystal ingot of silicon carbide grown using a seed crystal at a high angle relative to the horizontal direction according to Example 1 of the present invention. FIG. 5 is an X-ray topography (XRT) image obtained by cutting and processing a single crystal ingot of silicon carbide grown using a seed crystal at a low angle relative to the horizontal direction according to Example 2 of the present invention. Figure 6 shows the results of the change rate of threading edge dislocations of threading screw dislocations (TSD) and basal plane dislocations of a silicon carbide substrate according to Example 2 of the present invention. Specific details for implementing the invention

[0028] In this specification, terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the invention.

[0029] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0030] When it is stated that one part is "on" or "on" another part, it may be directly on or on the other part, or another part may be involved in between. In contrast, when it is stated that one part is "directly on" another part, no other part is interposed in between.

[0031] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0032] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0033] In this specification, the term “combination(s) of these” described in the Markush-type expression means one or more mixtures or combinations selected from the group consisting of the components described in the Markush-type expression, and means including any one or more selected from the group consisting of said components.

[0034] Hereinafter, embodiments of the present invention are described in detail 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.

[0036] Large-diameter silicon carbide single crystal growth method

[0037] As mentioned above, among the various defects of the substrate, transverse dislocations (TSDs) and basal plane dislocations (BPDs) are continuously transferred in the single crystal growth direction, which poses a problem of degrading the quality of the single crystal.

[0038] However, in this embodiment, this problem was solved by growing the single crystal by arbitrarily processing the angle of the seed crystal when manufacturing a large-diameter silicon carbide single crystal.

[0039] The following describes in detail a manufacturing method for producing large-diameter silicon carbide (SiC) single crystals.

[0040] Figure 1 is a schematic diagram of a silicon carbide single crystal growth method.

[0041] Referring to FIG. 1, a method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention comprises: a step of preparing silicon carbide powder; a step of loading the silicon carbide powder into the lower part of a crucible; a step of mounting a first seed crystal in the crucible onto a seed crystal holder and sublimating the silicon carbide powder to grow a first silicon carbide single crystal; a step of processing the first silicon carbide single crystal into a second seed crystal; and a step of mounting the second seed crystal onto a seed crystal holder and sublimating the silicon carbide powder to grow a second silicon carbide single crystal. The method for growing a large-diameter silicon carbide single crystal has the advantage of easily obtaining a silicon carbide single crystal by controlling the transhelix dislocation (TSD) and basal plane dislocation (BPD). In addition, the lower space within the crucible is a space where the silicon carbide powder can be located, for example, a space within 50% of the lengthwise direction from the bottom of the internal space based on the cross-section of the internal space of the crucible.

[0042] In a method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention, the first seed crystal can be processed at an angle of 9 to 17° with respect to the horizontal direction of the seed crystal, specifically at an angle of 10 to 16°, and more specifically at an angle of 12 to 15°. If the angle of the first seed crystal satisfies the above range, the transverse dislocation (TSD) is reduced, and the dislocation defect density of the silicon carbide single crystal can be lowered. On the other hand, if the angle of the first seed crystal deviates from the above range, it may be difficult to reduce the dislocation defect density of the silicon carbide single crystal.

[0043] In a method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention, the conversion rate from a spiral dislocation (TSD) to a blade dislocation (TED) in the first growth step may be 90 to 93%, specifically 91 to 92%. When the conversion rate in the first growth step satisfies the above range, the spiral dislocation (TSD) is appropriately reduced, and a high-quality silicon carbide single crystal can be manufactured.

[0044] Referring to Fig. 2, when a silicon carbide single crystal is grown after the seed crystal is processed to a high angle relative to the horizontal direction of the seed crystal, it can be observed that the basal plane dislocation (BPD) remains unchanged and the spiral dislocation (TSD) is converted into a blade dislocation (TED). This conversion is not observed in the continuously growing plane, but may occur at the interface between the first seed crystal and the crystal growth, that is, in the region where the state changes rapidly or the energy changes.

[0045] In a method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention, the second seed crystal may be processed at an angle of 2 to 7° with respect to the horizontal direction of the seed crystal, specifically at an angle of 2 to 6°, and more specifically at an angle of 2 to 4°. When the angle of the second seed crystal satisfies the above range, basal plane dislocations (BPD) are converted into blade dislocations (TED), thereby reducing the dislocation defect density of the silicon carbide single crystal. On the other hand, if the angle of the second seed crystal deviates from the above range, it may be difficult to reduce the dislocation defect density of the silicon carbide single crystal.

[0046] In a method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention, the conversion rate from basal plane dislocation (BPD) to blade dislocation (TED) in the second growth step may be 5 to 25%, specifically 7 to 23%, and more specifically 9 to 21%. When the conversion rate of the dislocation in the second growth step satisfies the above range, the basal plane dislocation (BPD) is appropriately reduced, and a high-quality silicon carbide single crystal can be manufactured.

[0047] Referring to Fig. 3, when a silicon carbide single crystal is grown after processing the seed crystal to a low angle relative to the horizontal direction of the seed crystal, the spiral dislocation (TSD) does not change, only its direction of propagation is slightly bent, but the basal plane dislocation (BPD) can be converted into a blade dislocation (TED). This conversion is not observed in the continuously growing plane, but can occur at the interface between the second seed crystal and the crystal growth, that is, in the region where the state changes rapidly or the energy changes.

[0048] In a method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention, in the step of loading the silicon carbide powder into the lower part of a crucible, the content of the silicon carbide powder may be 95 to 100 weight%, specifically 97 to 100 weight%. When the content of the silicon carbide powder satisfies the above range, a high-quality silicon carbide single crystal can be properly grown in a seed crystal within the crucible. On the other hand, if the content of the silicon carbide powder falls outside the above range, the growth of the silicon carbide single crystal may not be sufficiently achieved.

[0049] In a method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention, the step of mounting the first seed crystal or the second seed crystal in the crucible onto a seed crystal holder further comprises: a step of heating the crucible to remove impurities contained inside the crucible; a step of injecting an inert gas into the crucible to remove air; a step of heating the crucible with the mounted seed crystal to a single crystal growth temperature; and a step of reducing the internal pressure of the crucible from atmospheric pressure of 760 Torr to 0.2 to 20 Torr. Specifically, the pressure may be reduced to 0.5 to 15 Torr, and more specifically, to 1 to 10 Torr. When the internal pressure of the crucible satisfies the above range, the individual components of silicon carbide in the silicon carbide powder sublimate, allowing the single crystal to be grown normally to a desired size.

[0050] In a method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention, the step of heating the crucible to remove impurities contained inside the crucible may include the step of heating the crucible at a temperature of less than 1000°C, specifically less than 900°C, more specifically less than 800°C, and under vacuum pressure for 2 to 3 hours, specifically 2.5 to 2.7 hours. If the temperature and time of the crucible satisfy the above range, impurities inside the crucible are removed, and a silicon carbide single crystal with a low dislocation defect density can be grown. On the other hand, if the temperature and time of the crucible deviate from the above range, there may be a problem in that polymorphisms may be incorporated. Here, polymorphisms may refer to 3C-SiC, 6H-SiC, and / or 15R-SiC, etc., in addition to 4H-SiC.

[0051] In a method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention, the step of injecting an inert gas into the crucible to remove air may include a step of purging 2 to 3 times using the inert gas. When purging 2 to 3 times, the inert gas can remove air and impurities remaining inside the crucible and between the crucible and the insulating means, thereby suppressing the phenomenon of increased dislocation defect density.

[0052] In a method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention, the step of heating the crucible to a single crystal growth temperature may include heating the crucible to a temperature of 2,000 to 2,300°C, specifically 2,100 to 2,200°C, under an atmospheric pressure of 760 Torr. If the atmospheric pressure and the single crystal growth temperature satisfy the above ranges during the heating step, the occurrence of unwanted polymorphisms can be prevented during the early stages of silicon carbide crystal growth. On the other hand, if the single crystal growth temperature deviates from the above range, the dislocation defect density may increase during single crystal growth.

[0053] In a method for growing a large-diameter silicon carbide single crystal according to one embodiment of the present invention, the first growing step and / or the second growing step may be performed while maintaining a pressure of 0.2 to 20 torr. When the pressure of the first growing step and / or the second growing step satisfies the above range, the individual components of silicon carbide in the silicon carbide powder sublimate, allowing the single crystal to be grown normally to a desired size. On the other hand, if the first growing step and the second growing step are maintained at atmospheric pressure, the growth of the single crystal cannot occur, and a reverse sublimation phenomenon may occur, which may result in the formation of defects on the surface of the silicon carbide single crystal.

[0055] Large-diameter silicon carbide single crystal

[0056] A large-diameter silicon carbide single crystal according to another embodiment of the present invention is grown by the large-diameter silicon carbide single crystal growth method described above, and the density of spiral dislocations (TSDs) in the first growth step is 5 to 790 ea / cm² 2 ..., and in the second growth stage, the basal plane dislocation (BPD) density is 5 to 1100 ea / cm 2 am.

[0057] Specifically, the density of transspirated dislocations (TSDs) in the first growth stage is 50 to 750 ea / cm² 2 It can be, and more specifically, 100 to 700ea / cm 2 It could be.

[0058] Specifically, in the second growth stage, the density of basal plane potential (BPD) is 50 to 1050 ea / cm 2 It can be, more specifically, 100 to 1,000ea / cm 2 It could be.

[0059] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0060] Example 1

[0061] First, silicon carbide raw material powder is loaded into the lower inner part of the crucible. A first seed crystal made of silicon carbide is prepared, and the first seed crystal has an angle of 12° relative to the horizontal direction. A seed crystal holder combined with the first seed crystal is introduced into the growth device and mounted on the upper inner part of the crucible. Then, the crucible is heated at a temperature of less than 1000°C and under vacuum pressure for 2 to 3 hours to remove impurities contained in the crucible. Afterward, an inert gas, such as argon (Ar) gas, is injected to remove air remaining inside the crucible and between the crucible and the insulation material. Here, it is preferable to repeat the purging process using argon (Ar) gas 2 to 3 times. Subsequently, the pressure is increased to atmospheric pressure, and the crucible is heated to 2200°C using a heating means while maintaining atmospheric pressure. Then, while maintaining the temperature inside the crucible, the internal pressure of the crucible is reduced to 1 torr and maintained for a certain period of time. Then, silicon carbide powder in a crucible is sublimated to grow a first silicon carbide single crystal. The grown first silicon carbide single crystal is separated from a seed crystal holder and processed to produce a second seed crystal with an angle of 4º, then re-feeded into the equipment to sublimate the silicon carbide powder and grow a second silicon carbide single crystal, thereby obtaining a high-quality silicon carbide single crystal.

[0062] Example 2

[0063] Silicon carbide single crystals were manufactured in the same manner as in Example 1, except that a first seed crystal having a 15° angle with respect to the horizontal direction was used in the first growth step.

[0064] Example 3

[0065] Silicon carbide single crystals were manufactured in the same manner as in Example 1, except that a second seed crystal having a 2° angle with respect to the horizontal direction was used in the second growth step.

[0066] Comparative Example 1

[0067] Silicon carbide single crystals were manufactured in the same manner as in Example 1, except that a first seed crystal having a 2° angle with respect to the horizontal direction was used in the first growth step.

[0068] Comparative Example 2

[0069] Silicon carbide single crystals were manufactured in the same manner as in Example 1, except that a first seed crystal having a 4° angle with respect to the horizontal direction was used in the first growth step.

[0070] Comparative Example 3

[0071] Silicon carbide single crystals were manufactured in the same manner as in Example 1, except that a first seed crystal having an angle of 8° relative to the horizontal direction was used in the first growth step.

[0072] Comparative Example 4

[0073] Silicon carbide single crystals were manufactured in the same manner as in Example 1, except that a second seed crystal having an 8° angle with respect to the horizontal direction was used in the second growth step.

[0074] Comparative Example 5

[0075] Silicon carbide single crystals were manufactured in the same manner as in Example 1, except that a second seed crystal having a 12° angle with respect to the horizontal direction was used in the second growth step.

[0077] Experimental Example 1: Evaluation of X-ray Topography (XRT)

[0078] A silicon carbide single crystal prepared in Example 1 was cut and processed at a point 10 mm away from the seed crystal, and dislocation defects in the silicon carbide single crystal substrate were analyzed using X-ray tomography (Synchrotron White-Beam X-ray Topography, SWXRT).

[0079] Figure 4 is the result of X-ray tomography of the first silicon carbide single crystal ingot after the first seed crystal was grown during silicon carbide single crystal growth, and the grown first silicon carbide single crystal ingot was cut and processed.

[0080] Figure 5 is the result of X-ray tomography of the grown second silicon carbide single crystal ingot after growing a second seed crystal during silicon carbide single crystal growth, cutting and processing the grown second silicon carbide single crystal ingot.

[0081] Referring to Fig. 4, Example 1 is an XRT measurement image before and after the first growth step. The left image of Fig. 4 is an image before the first growth step, and the right image of Fig. 4 is an XRT image after the first growth step. It was confirmed that multiple dot-shaped spiral dislocations (TSDs) were changed into blade dislocations (TEDs) of the same dot shape but with a much smaller size.

[0082] In addition, referring to Fig. 5, the XRT measurement images before and after the second growth step of Example 1 show that the left image of Fig. 5 is the image before the second growth step and the right image of Fig. 5 is the image after the second growth step, and it can be confirmed that the pipe-shaped basal plane dislocation (BPD) in white has changed into a much smaller dot-shaped blade dislocation (TED).

[0083] Experimental Example 3: Evaluation of the conversion rate of spiral potential and basal plane potential to blade potential

[0084] In one embodiment of the present invention, a first seed crystal was first grown into a first silicon carbide single crystal, and then the first grown silicon carbide single crystal specimen was processed to 150 mm. Additionally, a second seed crystal was second grown into a second silicon carbide single crystal, and then the second grown silicon carbide single crystal substrate was processed to 150 mm, after which X-ray tomography (Synchrotron White-Beam X-ray Topography, SWXRT) was performed. After measuring the first grown silicon carbide single crystal specimen and the second grown silicon carbide single crystal specimen at 9 points using XRT, the same parts were compared and their average values ​​were calculated, and the results are shown in Tables 1 and 2 and Figure 6.

[0085] Figure 6 is an image showing the results of evaluating the rate of change from the spiral potential (TSD) and basal plane potential (BPD) to the blade potential (TED) in Example 2.

[0086] Referring to Figure 6, it can be seen that the spiral dislocation (TSD) is better transformed as the angle of the seed node increases, and the basal dislocation (BPD) is better transformed as the angle of the seed node decreases, and it can be seen that the spiral dislocation (TSD) is more affected by the angle than the basal dislocation (BPD).

[0087] Seed point angle (°) Helical Dislocation (TSD) Density (ea / cm²) 2 ) Comparative Example 1 2 ~1,500 Comparative Example 2 4 ~1,200 Comparative Example 3 8 ~800 Example 1 12 ~150 Example 2 15 ~100

[0088] Referring to Table 1 above, the helical dislocation (TSD) density of Example 1 is up to 150 ea / cm² 2 And the helical dislocation (TSD) density of Example 2 is up to 100ea / cm² 2 It can be confirmed that the density of spiral dislocations (TSD) is reduced compared to Comparative Examples 1 to 3. In this way, it can be confirmed that the silicon carbide single crystals of Examples 1 and 2, which were first grown into first silicon carbide single crystals by processing the first seed crystal at a high angle, have a lower dislocation defect density as the spiral dislocations (TSD) are converted into blade dislocations (TED).

[0089] Seed point angle (°) Base Plane Dislocation (BPD) Density (ea / cm²) 2 ) Example 3 2 ~ 900 Example 1 4 ~ 900 Comparative Example 4 8 ~ 1,200 Comparative Example 5 12 ~ 1,200

[0090] Referring to Table 2 above, the basal plane potential (BPD) density of Examples 1 and 3 is up to 900 ea / cm² 2 Therefore, it can be confirmed that the basal plane dislocation (BPD) density is reduced compared to Comparative Examples 4 and 5. In this way, it can be confirmed that the silicon carbide single crystals of Examples 1 and 3, in which the first silicon carbide single crystal was processed into a second seed crystal with a low angle and then secondarily grown into a second silicon carbide single crystal, have a lower dislocation defect density as the basal plane dislocation (BPD) is converted to a blade dislocation (TED).

[0091] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

[0092] Therefore, the substantive scope of the present invention shall be defined by the appended claims and their equivalents.

Claims

Claim 1 A method for growing a large-diameter silicon carbide single crystal, comprising: a step of preparing silicon carbide powder; a step of loading the silicon carbide powder into the lower part of a crucible; a step of mounting a first seed crystal in the crucible onto a seed crystal holder and sublimating the silicon carbide powder to grow a first silicon carbide single crystal; a step of processing the first silicon carbide single crystal into a second seed crystal; and a step of mounting the second seed crystal onto a seed crystal holder and sublimating the silicon carbide powder to grow a second silicon carbide single crystal; wherein the second seed crystal is processed at an angle of 2 to 7° relative to the horizontal direction of the seed crystal. Claim 2 A method for growing a large-diameter silicon carbide single crystal according to claim 1, wherein the first seed crystal is processed at an angle of 9 to 17° with respect to the horizontal direction of the seed crystal. Claim 3 A method for growing a large-diameter silicon carbide single crystal according to claim 1, wherein the conversion rate from a spiral dislocation (TSD) to a blade dislocation (TED) in the first growing step is 95 to 100%. Claim 4 delete Claim 5 A method for growing a large-diameter silicon carbide single crystal according to claim 1, wherein the conversion rate from basal plane dislocation (BPD) to blade dislocation (TED) in the second growing step is 5 to 25%. Claim 6 A method for growing a large-diameter silicon carbide single crystal according to claim 1, wherein, in the step of charging the silicon carbide powder into the lower part of a crucible, the content of the silicon carbide powder is 95 to 100 weight%. Claim 7 A method for growing a large-diameter silicon carbide single crystal according to claim 1, wherein the step of mounting the first seed crystal or the second seed crystal in the crucible onto a seed crystal holder further comprises: a step of heating the crucible to remove impurities contained inside the crucible; a step of injecting an inert gas into the crucible to remove air; a step of heating the crucible with the seed crystal mounted thereon to a single crystal growth temperature; and a step of reducing the internal pressure of the crucible from atmospheric pressure of 760 Torr to 0.2 to 20 Torr. Claim 8 In claim 7, the step of heating the crucible to remove impurities contained inside the crucible is as follows: heating the crucible to less than 1000℃ A method for growing a large-diameter silicon carbide single crystal, comprising the step of heating at a temperature under vacuum pressure for 2 to 3 hours. Claim 9 A method for growing a large-diameter silicon carbide single crystal, wherein, in claim 7, the step of injecting an inert gas into the crucible to remove air includes the step of purging 2 to 3 times using the inert gas. Claim 10 A method for growing a large-diameter silicon carbide single crystal, wherein, in claim 7, the step of heating the crucible to a single crystal growth temperature comprises the step of heating the crucible to a temperature of 2,000 to 2,300°C under atmospheric pressure of 760 Torr. Claim 11 A method for growing a large-diameter silicon carbide single crystal according to claim 1, wherein the first growing step and / or the second growing step are performed under a pressure maintained at 0.2 to 20 torr. Claim 12 delete

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