SiC single crystal, SiC substrate, and SiC epitaxial wafer

Abstract

The invention relates to a SiC single crystal, a SiC substrate, and a SiC epitaxial wafer. The purpose of the present invention is to provide a SiC single crystal capable of reducing the basal plane dislocation density. In the SiC single crystal according to the present embodiment, lattice planes measured along a first straight line, a second straight line, a third straight line, a fourth straight line, a fifth straight line, and a sixth straight line are each curved in a convex shape, and in the lattice planes measured along the first straight line, the second straight line, the third straight line, the fourth straight line, the fifth straight line, and the sixth straight line, the first straight line, the second straight line, the third straight line, the fourth straight line, the fifth straight line, and the sixth straight line are curved in a convex shape. The first straight line, the second straight line, the third straight line, the fourth straight line, the fifth straight line, and the sixth straight line respectively pass through the center in plan view from the thickness direction and are inclined by 30 degrees one by one with respect to the center.

Description

Technical Field

[0001] This invention relates to SiC single crystals, SiC substrates, and SiC epitaxial wafers. Background Technology

[0002] Compared to silicon (Si), silicon carbide (SiC) has an insulating breakdown electric field one order of magnitude larger and a band gap three times larger. Furthermore, SiC possesses a thermal conductivity approximately three times higher than that of silicon (Si). Therefore, SiC is expected to be used in power devices, high-frequency devices, and similar applications. Moreover, devices using SiC can operate at high temperature ranges above 150°C. Consequently, in recent years, SiC epitaxial wafers have been used in such semiconductor devices.

[0003] SiC epitaxial wafers are obtained by stacking SiC epitaxial layers on the surface of a SiC substrate. Hereinafter, the substrate before the SiC epitaxial layer is stacked will be referred to as the SiC substrate, and the substrate after the SiC epitaxial layer is stacked will be referred to as the SiC epitaxial wafer. The SiC substrate is cut from a SiC ingot. A SiC ingot is obtained by crystallizing and growing a single SiC crystal on a seed crystal.

[0004] SiC single crystals are required to be high-quality SiC single crystals with few defects and dislocations. Patent Document 1 describes a correlation between the amount of curvature of the lattice planes of SiC single crystals and the density of basal dislocations (BPDs).

[0005] Prior art literature

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2020-26373 Summary of the Invention

[0008] The basal plane dislocation (BPD) density varies as crystal growth progresses. For example, when growing a SiC single crystal on the C-plane, the basal plane dislocation densities in the Si-plane and the C-plane are different. If the basal plane dislocation density in the C-plane can be made lower than that in the Si-plane, then the SiC substrate cut from near the C-plane becomes a high-quality SiC substrate with low basal plane dislocation density.

[0009] This disclosure was made in view of the above-mentioned problems, and its purpose is to provide a SiC single crystal capable of reducing the basal dislocation density in the C-plane.

[0010] The inventors conducted in-depth research and discovered that the warping of the lattice planes of SiC single crystals affects the variation of basal dislocation density and through dislocation density within the SiC single crystal. The warping of the lattice planes of SiC single crystals is also affected by internal stresses generated during the crystal growth and cooling of the SiC single crystal, and therefore is not necessarily consistent with the shape of the SiC single crystal (e.g., the final shape of the crystal growth surface). In other words, the warping of the SiC lattice planes cannot be determined from the shape of the SiC single crystal. Simply controlling the shape of the SiC single crystal cannot completely control the warping of the SiC lattice planes, nor can it sufficiently reduce the basal dislocation density and through dislocation density in the C-plane. This disclosure discovers that it is possible to control the warping of the lattice planes of SiC single crystals and reduce the basal dislocation density and through dislocation density in the C-plane. That is, this disclosure provides the following means to solve the above-mentioned problems.

[0011] (1) In the SiC single crystal of the first method, the lattice planes measured along the first, second, third, fourth, fifth, and sixth straight lines are all bent into a convex shape. Among the lattice planes measured along the first, second, third, fourth, fifth, and sixth straight lines, the center is located closer to the C-plane than the end of the lattice plane measured along each straight line. The first straight line is a line passing through the center when viewed from above in the thickness direction. The second straight line is a line passing through the center and inclined at 30° relative to the first straight line with the center as a reference. The third straight line is a line passing through the center and inclined at 60° relative to the first straight line with the center as a reference. The fourth straight line is a line passing through the center and inclined at 90° relative to the first straight line with the center as a reference. The fifth straight line is a line passing through the center and inclined at 120° relative to the first straight line with the center as a reference. The sixth straight line is a line passing through the center and inclined at 150° relative to the first straight line with the center as a reference.

[0012] (2) In the SiC single crystal described above, the main surface can have an offset angle relative to the (0001) surface. In this case, the first straight line is a straight line extending in the <11-20> direction.

[0013] (3) For the SiC single crystal obtained in the above manner, when the diameter viewed from the thickness direction is denoted as d, the maximum diffraction peak angle of the (0004) plane at the center is denoted as ω0, and the maximum diffraction peak angle of the (0004) plane at the measurement point d / 3 away from the center is denoted as ω1, the X-ray diffraction results measured according to the first, second, third, fourth, fifth, and sixth straight lines respectively can also satisfy (ω1-ω0) / (d / 3)<-2.00×10-6 .

[0014] (4) The SiC single crystal obtained in the above manner can also satisfy (ω1-ω0) / (d / 3)<-3.00×10⁻⁶ in the X-ray diffraction results measured according to the first, second, third, fourth, fifth, and sixth straight lines, respectively. -6 .

[0015] (5) The SiC single crystal obtained in the above manner, in the X-ray diffraction results measured according to the first, second, third, fourth, fifth, and sixth straight lines respectively, can also satisfy (ω1-ω0) / (d / 3)<-4.00×10 -6 .

[0016] (6) For the SiC single crystal obtained in the above manner, when the diameter viewed from the thickness direction is denoted as d, in the X-ray diffraction results measured according to the first, second, third, fourth, fifth, and sixth straight lines respectively, the half-width of the maximum diffraction peak on the (0004) plane at the measurement point d / 3 away from the center can be less than 5.20 × 10⁻⁶. -2 .

[0017] (7) For the SiC single crystal obtained in the above manner, in the X-ray diffraction results measured according to the first, second, third, fourth, fifth, and sixth straight lines respectively, the half-width of the maximum diffraction peak on the (0004) plane at the measurement point d / 3 away from the center can be less than 4.80 × 10⁻⁶. -2 .

[0018] (8) In the SiC single crystal obtained by the above method, the half-width of the maximum diffraction peak on the (0004) plane at the measurement point d / 3 away from the center can be less than 4.40 × 10⁻⁶ in the X-ray diffraction results measured according to the first, second, third, fourth, fifth, and sixth straight lines respectively. -2 .

[0019] (9) The SiC single crystal obtained by the above method can also satisfy (BPD0-BPD1) / BPD0>64% when the basal dislocation density in the Si plane is denoted as BPD0 and the basal dislocation density in the C plane is denoted as BPD1.

[0020] (10) The SiC single crystal obtained by the above method can also satisfy (TSD0-TSD1) / TSD0 > 48.2% when the through-screw dislocation density in the Si plane is denoted as TSD0 and the through-screw dislocation density in the C plane is denoted as TSD1.

[0021] (11) The SiC single crystal obtained by the above method can also satisfy (BPD0-BPD1) / (BPD0×T)>1% / mm and (TSD0-TSD1) / (TSD0×T)>1% / mm when the basal plane dislocation density in the Si plane is denoted as BPD0, the basal plane dislocation density in the C plane is denoted as BPD1, the through screw dislocation density in the Si plane is denoted as T, and the crystal length in the thickness direction is denoted as T.

[0022] (12) The SiC single crystal obtained by the above method can also satisfy (BPD0-BPD1) / (BPD0×T)>2% / mm and (TSD0-TSD1) / (TSD0×T)>2% / mm.

[0023] (13) The SiC single crystal obtained by the above method can also satisfy (BPD0-BPD1) / (BPD0×T)>3% / mm and (TSD0-TSD1) / (TSD0×T)>3% / mm.

[0024] (14) The diameter of the SiC single crystal obtained by the above method when viewed from the thickness direction can be more than 145 mm.

[0025] (15) The diameter of the SiC single crystal obtained by the above method when viewed from the thickness direction can be more than 195 mm.

[0026] (16) The diameter of the SiC single crystal obtained by the above method when viewed from the thickness direction can be more than 295 mm.

[0027] (17) The SiC single crystal produced by the above method can have a basal dislocation density of 500 dislocations / cm² in the C-plane. 2 the following.

[0028] (18) In the SiC single crystal produced by the above method, the density of through-screw dislocations in the C-plane can be 300 dislocations / cm². 2 the following.

[0029] (19) The defect density in the C-plane of the SiC single crystal obtained by the above method can be 4000 defects / cm². 2 the following.

[0030] (20) The SiC substrate of the second type includes the SiC single crystal of the above type.

[0031] (21) The SiC epitaxial wafer of the third type includes the SiC substrate of the above type and a SiC epitaxial layer stacked on one side of the SiC substrate.

[0032] The SiC single crystal produced by the above method can reduce the basal plane dislocation density in the C-plane. Attached Figure Description

[0033] Figure 1 This is a three-dimensional view of the SiC single crystal in this embodiment.

[0034] Figure 2 This is a top view of the SiC single crystal in this embodiment.

[0035] Figure 3 This is a cross-sectional view of a characteristic portion of the SiC single crystal in this embodiment.

[0036] Figure 4 This is a perspective view of an example of the lattice plane of the SiC single crystal in this embodiment.

[0037] Figure 5 This is a three-dimensional view of an example of the lattice plane of the SiC single crystal in the first comparative example.

[0038] Figure 6 This is a three-dimensional view of an example of the lattice plane of the SiC single crystal in the second comparative example.

[0039] Figure 7 This is a cross-sectional view of the SiC single crystal manufacturing apparatus before crystal growth in this embodiment.

[0040] Figure 8 This is a cross-sectional view of the holding member of the SiC single crystal manufacturing apparatus of this embodiment.

[0041] Figure 9 This is a cross-sectional view of the SiC single crystal manufacturing apparatus in this embodiment during crystal growth.

[0042] Figure 10 This is a cross-sectional view of another example of the holding member of the SiC single crystal manufacturing apparatus of this embodiment.

[0043] Explanation of reference numerals in the attached figures

[0044] 1 SiC single crystal

[0045] 1A Si surface

[0046] 1B C side

[0047] 2 SiC seed crystals

[0048] 3 SiC raw materials

[0049] 10 crucibles

[0050] 11, 15 Retaining components

[0051] 12 Expansion section

[0052] 16 recess

[0053] 20 Thermal insulation material

[0054] 30 Heating components

[0055] 41, 42 Shielding components

[0056] 100 Manufacturing Equipment

[0057] A atom

[0058] L1, first straight line

[0059] L2, second straight line

[0060] L3, third straight line

[0061] L4, Line 4

[0062] L5, 5th straight line

[0063] L6, Line 6

[0064] p11, p21, p31, p41, p51, p61 First measurement point

[0065] p12, p22, p32, p42, p52, p62 Second measurement point

[0066] S1, S2, S3 lattice planes Detailed Implementation

[0067] Hereinafter, the SiC single crystal of this embodiment will be described in detail with appropriate reference to the accompanying drawings. In the drawings used in the following description, for ease of understanding of the features of this embodiment, some parts of the features are sometimes shown as enlarged portions, and the size ratios of the constituent elements may differ from the actual dimensions. The materials, dimensions, etc., illustrated in the following description are examples, and the present invention is not limited thereto; appropriate modifications can be made without changing its spirit.

[0068] In this specification, [] represents individual orientations, <> represents aggregate orientations, () represents individual surfaces, and {} represents aggregate surfaces. Regarding negative exponents, in crystallography a "-" (hyphen) is placed before the number, but in this specification, a minus sign is placed before the number.

[0069] First, let's define the direction. We'll define the thickness direction (crystallization growth direction) of the SiC single crystal as the Z-direction. The Z-direction can be... <0001> Direction can also be relative to <0001> The direction is tilted by the amount of the offset angle. For example, the +Z direction is made [000-1] and the -Z direction is made

[0001] . Taking the center of the thickness direction of the SiC single crystal as a reference, the principal plane in the [000-1] direction is the C plane, and the principal plane in the

[0001] direction is the Si plane. One direction of the plane orthogonal to the Z direction is taken as the X direction. The X direction is, for example, the <11-20> direction. For example, taking the center as a reference, the -X direction is made [11-20] and the +X direction is made [-1-120]. The -X direction is the upstream offset in the case of offset growth, and the +X direction is the downstream offset in the case of offset growth. In addition, in the plane orthogonal to the Z direction, the direction orthogonal to the X direction is taken as the Y direction. The Y direction is, for example, the <1-100> direction. For example, taking the center as a reference, the +Y direction is made [1-100] and the -Y direction is made [-1100].

[0070] Figure 1 This is a cross-sectional view of the SiC single crystal 1 of this embodiment. The SiC single crystal 1 is, for example, composed of n-type SiC. The polytype of the SiC single crystal 1 is not particularly limited, and it can be any of 2H, 3C, 4H, or 6H. The SiC single crystal 1 is, for example, 4H-SiC.

[0071] SiC single crystal 1 has a Si face 1A and a C face 1B. Si face 1A and C face 1B are the two end faces of SiC single crystal 1 in the Z direction. SiC single crystal 1 is grown on a SiC seed crystal. During crystal growth, Si face 1A is usually positioned on the SiC seed crystal side, and C face 1B becomes the crystal growth face. The Si face is the (0001) face or a face tilted by an offset angle relative to the (0001) face. The C face is the (000-1) face or a face tilted by an offset angle relative to the (000-1) face. That is, the main face (Si face or C face) may or may not have an offset angle relative to the (0001) face or the (000-1) face.

[0072] The offset angle is the angle formed by the plane of SiC single crystal 1 orthogonal to the Z direction, which is the thickness direction, and the (0004) plane. The crystal growth surface of SiC single crystal 1 may have a portion having an offset angle relative to the (0004) plane in the <11-20> direction. If the crystal growth surface has an offset angle relative to the (0004) plane, the generation of heterogeneous polymorphs can be suppressed. The offset angle is, for example, greater than 0° and less than 10°, preferably more than 0.1° and less than 8°, more preferably more than 3.5° and less than 4.5°, and even more preferably 4°.

[0073] The plane of SiC single crystal 1 orthogonal to the Z direction may also not have an offset angle relative to the (0004) plane. Sometimes, SiC seed crystals without an offset angle relative to the (0004) plane ({0001} plane) are used to fabricate SiC single crystal 1 (just plane growth).

[0074] The Z-direction crystal length T of the SiC single crystal 1 is, for example, 10 mm or more, preferably 20 mm or more, more preferably 30 mm or more, further preferably 40 mm or more, and particularly preferably 50 mm or more. The Z-direction crystal length T of the SiC single crystal 1 is preferably 300 mm or less. The Z-direction crystal length T of the SiC single crystal 1 is the longest length between the Si plane 1A and the C plane 1B in the Z direction. The longer the Z-direction crystal length T of the SiC single crystal 1, the more SiC substrates can be obtained. Furthermore, the longer the Z-direction crystal length T of the SiC single crystal 1, the better it is to suppress lattice plane planarization and maintain lattice plane curvature when the SiC single crystal 1 is cooled from the high-temperature environment during crystal growth.

[0075] Figure 2 This is a top view of the SiC single crystal 1 of this embodiment, viewed from the Z direction. The top view shape of the SiC single crystal 1 is approximately circular.

[0076] The diameter d of the SiC single crystal 1 is, for example, 145 mm or more, preferably 149 mm or more. Furthermore, the diameter d of the SiC single crystal 1 is preferably 155 mm or less, more preferably 151 mm or less. Additionally, the diameter d of the SiC single crystal 1 can be, for example, 195 mm or more, preferably 199 mm or more. Furthermore, the diameter d of the SiC single crystal 1 can preferably be 205 mm or less, more preferably 201 mm or less. The diameter d of the SiC single crystal 1 can be 295 mm or more, preferably 299 mm or more. The diameter d of the SiC single crystal 1 can be 305 mm or less, preferably 301 mm or less. Here, the diameter d of the SiC single crystal 1 is the minimum diameter of the SiC single crystal 1, corresponding to the minimum diameter of the SiC substrate that can be obtained. For example, when the SiC single crystal 1 expands in diameter from the Si surface toward the C surface, the diameter of the Si surface corresponds to the diameter d of the SiC single crystal.

[0077] SiC single crystal 1 is a compound of Si and C, in which equivalent atomic planes are arranged at equal intervals. These atomic planes are called lattice planes. For example, Figure 3 This is a cross-sectional view of a characteristic portion of the SiC single crystal 1 in this embodiment. Figure 3 It is a straight line extending in the direction of <11-20>. Figure 2 The first straight line L1) cuts through the cross section of SiC single crystal 1. The lattice plane S1 is formed by the atoms A that constitute SiC single crystal 1. Figure 3The SiC single crystal 1 shown has its lattice plane S1 bent into a convex shape towards the C plane 1B.

[0078] The shape of the lattice plane S1 can be determined by X-ray diffraction (XRD). The lattice plane to be measured is determined according to the measurement direction. If the measurement direction is set to [hkil], the measured plane needs to satisfy the relationship (mh mk min). Here, m is an integer greater than or equal to 0, and n is a natural number. For example, when measuring the lattice plane in the [11-20] direction, the (0004) plane (set as m=0, n=4), the (22-416) plane (set as m=2, n=16), etc., can be selected. On the other hand, when measuring the lattice plane in the [11-20] direction, the (0004) plane (set as m=0, n=4), the (3-3016) plane (set as m=3, n=16), etc., can be selected. That is, the measured plane can be different depending on the measurement direction. By satisfying the above relationship, it is possible to prevent lattice bending in the a-plane or m-plane direction, which has a small impact on crystal growth, from being mistaken for lattice bending in the c-plane direction.

[0079] Along respectively Figure 2 The lattice surfaces S1 measured along the first straight line L1, the second straight line L2, the third straight line L3, the fourth straight line L4, the fifth straight line L5, and the sixth straight line L6 are all curved into a convex shape. In the lattice surfaces S1 measured along the first straight line L1, the second straight line L2, the third straight line L3, the fourth straight line L4, the fifth straight line L5, and the sixth straight line L6, the center C is located closer to the C-plane 1B than the ends of the lattice surfaces S1 measured along each straight line. That is, the lattice surfaces S1 measured along each straight line are curved in a manner that the center convexes towards the C-plane.

[0080] X-ray diffraction measurements were performed using the first line L1, the second line L2, the third line L3, the fourth line L4, the fifth line L5, and the sixth line L6. When the crystal length T of the SiC single crystal 1 being measured is 500 μm or less, to eliminate the influence of warping of the SiC single crystal 1, it is preferable to vacuum-adsorb the SiC single crystal 1 onto the measurement stage. The first line L1 is a straight line passing through the center C when viewed from above in the Z direction. When the SiC single crystal 1 has an offset angle, the first line L1 extends in the <11-20> direction. The second line L2 is a straight line passing through the center C and inclined at 30° relative to the first line with the center C as a reference. The third line L3 is a straight line passing through the center C and inclined at 60° relative to the first line with the center C as a reference. The fourth line L4 is a straight line passing through the center C and inclined at 90° relative to the first line with the center C as a reference. The fifth line L5 is a straight line passing through the center C and inclined at 120° relative to the first line with the center C as a reference. Line L6 is the sixth line, passing through center C and inclined at 150° relative to line L1, with center C as the reference. Figure 2 In this case, clockwise rotation is set as the positive direction of rotation.

[0081] X-ray diffraction measurements are performed at three points along each straight line: the center (C), the first measurement point (p11), and the second measurement point (p12). For the first straight line L1, X-ray diffraction measurements are performed at the center (C), the first measurement point (p21), and the second measurement point (p22). For the third straight line L3, X-ray diffraction measurements are performed at the center (C), the first measurement point (p31), and the second measurement point (p32). For the fourth straight line L4, X-ray diffraction measurements are performed at the center (C), the first measurement point (p41), and the second measurement point (p42). For the fifth straight line L5, X-ray diffraction measurements are performed at the center (C), the first measurement point (p51), and the second measurement point (p52). For the sixth straight line L6, X-ray diffraction measurements are performed at the center (C), the first measurement point (p61), and the second measurement point (p62).

[0082] The first and second measurement points are points that have moved d / 3 away from the center C. For example, in the case of offset growth of SiC single crystal 1, the point in the +X direction is taken as the first measurement point, and the point in the -X direction is taken as the second measurement point. However, since the fourth line L4 is orthogonal to the offset direction, the point that has moved d / 3 away from the center C in the -Y direction is taken as the first measurement point p41, and the point that has moved d / 3 away from the center C in the +Y direction is taken as the second measurement point p42. In the case of non-offset growth of SiC single crystal 1, the +X and -X directions are equivalent, and the +Y and -Y directions are equivalent. Therefore, in the case of non-offset growth of SiC single crystal 1, the first and second measurement points are not distinguished.

[0083] When the lattice plane S1 is bent, the diffraction direction of X-rays changes, and therefore the positions of the peak angles (ω angles) of the diffraction peaks in the X-ray diffraction images obtained at the center, the first measurement point, and the second measurement point change. The bending direction of the lattice plane S1 along each straight line can be determined based on the changes in the position of the peak angles of the diffraction peaks.

[0084] Figure 4 This is a perspective view of an example of the lattice plane S1 of the SiC single crystal 1 in this embodiment. Figure 4 The crystal lattice surface S1 shown is mountain-shaped. Figure 4 The lattice plane S1 shown has its center bent into a convex shape towards plane C 1B compared to its outer periphery. The center of lattice plane S1 is located on the side closer to plane C 1B than its outer periphery. The center of lattice plane S1 bends away from plane Si 1A. Regardless of which direction in the XY plane is cut, lattice plane S1 always bends into a convex shape towards plane C. That is, in Figure 4In the example shown, the lattice plane S1 measured along the first straight line L1, the second straight line L2, the third straight line L3, the fourth straight line L4, the fifth straight line L5, and the sixth straight line L6 are all bent into a convex shape, which satisfies the conditions of SiC single crystal 1 in this embodiment.

[0085] In contrast, Figure 5 This is a three-dimensional view of the S2 lattice plane of the SiC single crystal in the first comparative example. Figure 5 The lattice plane S2 shown is shaped like a potato chip (saddle). Figure 5 The lattice plane S2 shown is bent into a convex shape with its center towards plane C1B in the X direction, but bent into a concave shape with its center away from plane C1B in the Y direction. Therefore, when lattice plane S2 is cut with the XZ plane, it is bent into a convex shape towards plane C, but when cut with the YZ plane, it is not bent into a convex shape towards plane C.

[0086] in addition, Figure 6 This is a three-dimensional view of the lattice plane S3 of the SiC single crystal in the second comparative example. Figure 6 The lattice plane S3 shown is bowl-shaped. Figure 6 The crystal lattice surface S3 shown has a concave shape at its center, which is further away from the C-plane 1B than at its outer periphery. The center of the crystal lattice surface S3 is located closer to the Si-plane 1A than the outer periphery. The center of the crystal lattice surface S3 is bent away from the C-plane 1B. Regardless of which direction the crystal lattice surface S3 is cut in the XY plane, it is always bent into a concave shape away from the C-plane.

[0087] In this embodiment, the X-ray diffraction results of the SiC single crystal 1 measured along the first line L1, the second line L2, the third line L3, the fourth line L4, the fifth line L5, and the sixth line L6 preferably satisfy (ω1-ω0) / (d / 3) < -2.00 × 10⁻⁶. -6 More preferably, (ω1-ω0) / (d / 3) < -3.00×10 -6 Further optimization is performed to satisfy (ω1-ω0) / (d / 3)<-4.00×10 -6 d is the diameter of the SiC single crystal 1 viewed from above in the Z direction. ω0 is the maximum diffraction peak angle of the (0004) plane at center C. ω1 is the maximum diffraction peak angle of the (0004) plane at the first measurement point. The larger this value, the greater the curvature of the lattice plane S1. The larger this value, the smaller the ratio of the basal dislocation density in plane C1B to the basal dislocation density in plane Si1A. The X-ray diffraction results measured according to the first line L1, the second line L2, the third line L3, the fourth line L4, the fifth line L5, and the sixth line L6 can all satisfy (ω1-ω0) / (d / 3)>-1.00×10 -5 .

[0088] Furthermore, the X-ray diffraction results of the SiC single crystal 1 in this embodiment, measured along the first straight line L1, the second straight line L2, the third straight line L3, the fourth straight line L4, the fifth straight line L5, and the sixth straight line L6, preferably satisfy (ω2-ω0) / (d / 3)<-2.00×10⁻⁶. -6 More preferably, (ω2-ω0) / (d / 3) < -3.00×10 -6 Further optimization is performed to satisfy (ω2-ω0) / (d / 3)<-4.00×10 -6 ω2 is the maximum diffraction peak angle of the (0004) plane at the first measurement point. The larger this value, the greater the curvature of the lattice plane S1. The larger this value, the smaller the ratio of the basal dislocation density in the C plane 1B to the basal dislocation density in the Si plane 1A. The X-ray diffraction results measured according to the first line L1, the second line L2, the third line L3, the fourth line L4, the fifth line L5, and the sixth line L6 can all satisfy (ω2-ω0) / (d / 3)>-1.00×10 -5 .

[0089] In the X-ray diffraction results measured along the first line L1, the second line L2, the third line L3, the fourth line L4, the fifth line L5, and the sixth line L6, the half-width of the maximum diffraction peak on the (0004) plane at the first and second measurement points is preferably less than 5.20 × 10⁻⁶. -2 More preferably less than 4.80×10 -2 Further preferred is less than 4.40×10 -2 Especially preferred is less than 4.00×10 -2 The half-width at half-maximum (WWHM) of the maximum diffraction peak in X-ray diffraction indicates the crystallinity of SiC single crystal 1. The narrower the WWHM of the maximum diffraction peak, the higher the crystallinity of SiC single crystal 1. For example, the WWHM of the maximum diffraction peak on the (0004) plane at the first and second measurement points can be 2.00 × 10⁻⁶. -2 above.

[0090] In this embodiment, the SiC single crystal 1 preferably satisfies (BPD0-BPD1) / BPD0 > 64%, more preferably (BPD0-BPD1) / BPD0 > 70%, more preferably (BPD0-BPD1) / BPD0 > 80%, more preferably (BPD0-BPD1) / BPD0 > 90%, more preferably (BPD0-BPD1) / BPD0 > 95%, and more preferably (BPD0-BPD1) / BPD0 > 99%. BPD0 is the basal plane dislocation density (dislocations per cm⁻¹) in the Si plane 1A. 2 BPD1 is the density of basal dislocations in the C-plane (dislocations per cm²). 2In the SiC single crystal 1, the Si surface 1A is located on the seed side, and the C surface 1B is used as the crystal growth surface for crystal growth. Therefore, this value represents the reduction rate of basal plane dislocations during the crystal growth of SiC single crystal 1. The greater the reduction rate of basal plane dislocations in SiC single crystal 1, the higher the quality of the SiC substrate cut from near the C surface 1B. The SiC single crystal 1 in this embodiment can also satisfy (BPD0-BPD1) / BPD0<100%.

[0091] Furthermore, in this embodiment, the SiC single crystal 1 preferably satisfies (TSD0-TSD1) / TSD0 > 48.2%, more preferably (TSD0-TSD1) / TSD0 > 50%, more preferably (TSD0-TSD1) / TSD0 > 60%, more preferably (TSD0-TSD1) / TSD0 > 70%, more preferably (TSD0-TSD1) / TSD0 > 80%, more preferably (TSD0-TSD1) / TSD0 > 90%, more preferably (TSD0-TSD1) / TSD0 > 95%, and more preferably (TSD0-TSD1) / TSD0 > 99%. TSD0 is the density of through-screw dislocations (dislocations / cm²) in the Si plane 1A. 2 TSD1 is the density of through-screw dislocations in the C-plane (numbers / cm²). 2 This value represents the reduction rate of through-spiral dislocations during the crystal growth of SiC single crystal 1. The greater the reduction rate of through-spiral dislocations in SiC single crystal 1, the higher the quality of the SiC substrate cut from near C-plane 1B. The SiC single crystal 1 in this embodiment can also satisfy (TSD0-TSD1) / TSD0 < 100%.

[0092] Furthermore, the SiC single crystal 1 of this embodiment preferably satisfies (BPD0-BPD1) / (BPD0×T) > 1% / mm and (TSD0-TSD1) / (TSD0×T) > 1% / mm. More preferably, the SiC single crystal 1 of this embodiment satisfies (BPD0-BPD1) / (BPD0×T) > 2% / mm and (TSD0-TSD1) / (TSD0×T) > 2% / mm. Even more preferably, the SiC single crystal 1 of this embodiment satisfies (BPD0-BPD1) / (BPD0×T) > 3% / mm and (TSD0-TSD1) / (TSD0×T) > 3% / mm. T is the crystal length of the SiC single crystal 1. (BPD0-BPD1) / (BPD0×T) represents the reduction rate of basal plane dislocations per unit length in the Z direction. (TSD0-TSD1) / (TSD0×T) represents the reduction rate of through-screw dislocations per unit length in the Z direction. Furthermore, the SiC single crystal 1 in this embodiment can also satisfy (BPD0-BPD1) / (BPD0×T)<5% / mm, and can also satisfy (TSD0-TSD1) / (TSD0×T)<10% / mm.

[0093] The basal plane dislocation density (BPD1) in the C-plane 1B of a SiC single crystal can be, for example, 500 dislocations / cm². 2 The basal dislocation density (BPD1) in plane C1B can be, for example, 400 dislocations / cm². 2 The following can be 300 pieces / cm 2 The following can be 200 pieces / cm 2 The following can be 100 pieces / cm 2 The following can be 50 pieces / cm 2 The lower the basal dislocation density in the C-plane, the higher the quality of the SiC substrate can be obtained.

[0094] The through-screw dislocation density (TSD1) in the C-plane 1B of a SiC single crystal can be, for example, 300 dislocations / cm². 2 The density of through-screw dislocations (TSD1) in surface C1B can be, for example, 200 dislocations / cm². 2 The following can be 172 per cm. 2 The following can be 150 pieces / cm 2 The following can be 100 pieces / cm 2 The following can be 50 pieces / cm 2 The lower the density of through-screw dislocations in the C-plane, the higher the quality of the SiC substrate.

[0095] The defect density (EPD) in plane 1B of SiC single crystal 1 can be, for example, 4000 defects / cm².2 The defect density (EPD) in surface C1B can be, for example, 3000 defects / cm². 2 The following can be 2000 pieces / cm 2 The following can be 1300 pieces / cm 2 The following can be 1000 pieces / cm 2 The following can be 500 pieces / cm 2 The lower the defect density in the C-plane, the higher the quality of the SiC substrate can be obtained.

[0096] The basal dislocation density, through-spiral dislocation density, and defect density in the C-plane 1B of SiC single crystal 1 can also be determined by irradiating the C-plane 1B with X-rays and performing reflected X-ray morphology analysis. Alternatively, the C-plane 1B can be polished before measurement.

[0097] Next, the manufacturing method of SiC single crystal 1 in this embodiment will be described. Figures 7-9 This is a diagram illustrating the manufacturing method of SiC single crystal 1 in this embodiment.

[0098] The manufacturing apparatus 100 includes, for example, a crucible 10, a holding member 11, a heat insulation material 20, a heating member 30, and shielding members 41 and 42. Figure 7 This indicates the state before the crystallization and growth of SiC single crystal 1 begins.

[0099] The crucible 10 is made of graphite, for example. The crucible 10 encloses a growth space. SiC seed crystal 2 and SiC raw material 3 are arranged within the growth space of the crucible 10. The SiC single crystal 1 crystallizes and grows by recrystallizing the surface of the SiC seed crystal 2 with gas sublimated from the SiC raw material 3.

[0100] The retaining member 11 holds the SiC seed crystal 2. The retaining member 11 may also be integrated with the crucible 10. The thermal expansion rate of the retaining member 11 relative to the thermal expansion rate of the SiC seed crystal 2 is within ±10%. The retaining member 11 is made of graphite, for example. The SiC seed crystal 2 is bonded to the retaining member 11 using a carbon binder or the like.

[0101] Figure 8 This is an enlarged cross-sectional view of the vicinity of retaining member 11. The thickness T of retaining member 11 is shown. 11 For example, the thickness T2 of the SiC seed crystal 2 is set to be 200% or more and 800% or less. The thickness T2 of the SiC seed crystal 2 is set to be 0.3 mm or more and less than 7 mm.

[0102] An expansion portion 12 is present inside the retaining member 11. The expansion portion 12 has a greater expansion rate than the graphite constituting the retaining member 11 under the high-temperature environment of SiC crystal growth. The expansion portion 12 contains a high-melting-point metal or a high-melting-point metal compound. For example, the expansion portion 12 contains SiC, Ta, TaC, Nb, NbC, etc. The thickness T of the expansion portion 12 is... 12 For example, the thickness T2 of the SiC seed crystal 2 is set to be more than 50% and less than 100%. The diameter d of the expansion portion 12 12 For example, it is set to be 30% to 70% of the diameter d2 of the SiC seed crystal 2. The expansion portion 12 is disposed at a position at a distance of 10% to 70% of the thickness T2 of the SiC seed crystal 2 from the interface with the SiC seed crystal 2. That is, the thickness T of the retaining member 11 between the expansion portion 12 and the SiC seed crystal 2 is... 13 For example, the thickness T2 of SiC seed crystal 2 is more than 10% and less than 70%.

[0103] The size of retaining member 11 and expansion portion 12 affects the curvature state of lattice plane S1. For example, if the thickness T of retaining member 11 is increased... 11 The thickness T2 of the SiC seed crystal 2 is set to be more than 200% and less than 300%, and the thickness T of the expansion portion 12 is set to be... 12 The thickness T2 of the SiC seed crystal 2 is set to be more than 50% and less than 70%, and the thickness T of the retaining member 11 between the expansion portion 12 and the SiC seed crystal 2 is set to be... 13 Assuming the thickness T2 of SiC seed crystal 2 is greater than 50% and less than 70%, and satisfying the film formation conditions described later, then the lattice plane S1 satisfies (ω1-ω0) / (d / 3) < -2.00×10⁻⁶. -6 .

[0104] Additionally, for example, if the thickness T of retaining member 11 is... 11 Assuming the thickness T2 of the SiC seed crystal 2 is more than 300% but less than 500%, the thickness T of the expansion portion 12 is... 12 The thickness T2 of the SiC seed crystal 2 is set to be more than 70% but less than 85%, and the thickness T of the retaining member 11 between the expansion portion 12 and the SiC seed crystal 2 is set to be less than 70% but less than 85%. 13 Assuming the thickness T2 of SiC seed crystal 2 is greater than 30% and less than 50%, and the film formation conditions described later are met, then the lattice plane S1 satisfies (ω1-ω0) / (d / 3) < -3.00 × 10⁻⁶. -6 .

[0105] Additionally, for example, if the thickness T of retaining member 11 is... 11 Assuming the thickness T2 of the SiC seed crystal 2 is more than 500% but less than 800%, the thickness T of the expansion portion 12 is... 12The thickness T2 of the SiC seed crystal 2 is set to be more than 85% but less than 100%, and the thickness T of the retaining member 11 between the expansion portion 12 and the SiC seed crystal 2 is set to be less than 85% but less than 100%. 13 Assuming the thickness T2 of SiC seed crystal 2 is greater than 10% and less than 30%, and the film formation conditions described later are satisfied, then the lattice plane S1 satisfies (ω1-ω0) / (d / 3) < -4.00 × 10⁻⁶. -6 .

[0106] The heat insulation material 20 covers the area around the crucible 10. The heat insulation material 20 is, for example, graphite felt, or a molded heat insulation material obtained by fixing graphite felt into a shape.

[0107] Heating element 30 surrounds the outer periphery of crucible 10. Heating element 30 heats SiC raw material 3. Heating element 30 is, for example, a heating coil.

[0108] Viewed from the Z direction, shielding members 41 and 42 are disposed between the crucible 10 and the heating member 30. The radial width of the shielding members 41 and 42 is, for example, more than 2% and less than 30% of the radial width of the heating member 30. The shielding members 41 and 42 contain, for example, copper.

[0109] Figure 9 This indicates the state of SiC single crystal 1 during its crystallization growth. The shielding member 42 can change its position in the Z direction to cooperate with the crystallization growth of SiC single crystal 1. By changing the positions of the shielding members 41 and 42, the temperature distribution of the growth space within the crucible 10 can be altered.

[0110] When using the manufacturing apparatus 100 described above to crystallize and grow SiC single crystal 1, the temperature of the SiC raw material 3 is maintained at 2100°C or higher and 2400°C or lower, and the temperature of the SiC seed crystal 2 is heated to 2000°C or higher and 2300°C or lower. By heating the growth space, the SiC raw material 3 sublimates. At this time, the expansion portion 12 expands relative to the holding member 11. Due to the expansion of the expansion portion 12, the SiC seed crystal 2 during crystallization is bent into a convex shape with its center protruding towards the SiC raw material 3. By bending the center of the SiC seed crystal 2 towards the SiC raw material 3 into a convex shape, the bending direction of the lattice plane of the SiC single crystal 1 can be controlled.

[0111] In addition, the temperature distribution within the growth space is controlled during the crystallization growth of SiC single crystal 1 and during the cooling of the growth space.

[0112] First, during the crystal growth of SiC single crystal 1, the temperature distribution near SiC seed 2 (the boundary between SiC seed 2 and SiC single crystal 1) is made to satisfy the following first condition.

[0113] Condition 1: 0℃ / mm < (T1-T0) / d < 5.00℃ / mm

[0114] T1 is the temperature of the outer periphery of the SiC seed crystal 2, and T0 is the temperature of the central part of the SiC seed crystal 2. d is the diameter of the SiC single crystal 1. The above conditions can be achieved by setting the lower end of the shielding member 41 to the same height as the upper end of the holding member 11. By controlling the temperature distribution near the SiC seed crystal 2, the bending direction of the SiC single crystal 1 can be controlled.

[0115] In addition, during the latter half of the crystal growth of SiC single crystal 1 and during the cooling period, the temperature distribution near the crystal growth surface of SiC single crystal 1 is made to satisfy the following second condition, and the temperature distribution at the height position at the center of the thickness direction of the holding member 11 is made to satisfy the following third condition.

[0116] Second condition: -5.00℃ / mm < (T1'-T0') / d < -0.01℃ / mm

[0117] Condition 3: -5.00℃ / mm < (T1” - T0”) / d 2＜ <-0.01℃ / mm

[0118] T1' is the temperature of the outer periphery of SiC single crystal 1, and T0' is the temperature of the central part of SiC single crystal 1. T1" is the temperature of the outer periphery of holding member 11, and T0" is the temperature of the central part of holding member 11. d2 is the diameter of holding member 11. The latter half of crystal growth refers to the period between 2% and 10% of the growth time, calculated from the last part of the growth time when the temperature of SiC raw material 3 is greater than 2100°C. The cooling period refers to the time until the temperature of SiC seed crystal 2 drops below 1000°C. The above conditions can be achieved by aligning the height of the upper end of the shielding member 42 with the height of the crystal growth surface of the SiC single crystal 1 undergoing crystal growth.

[0119] During the latter half of the crystal growth of SiC single crystal 1 and during the cooling period, by making the isothermal surface near the SiC seed crystal 2 a convex shape protruding towards the SiC raw material 3 in the center, and making the isothermal surface near the crystal growth surface of SiC single crystal 1 a concave shape away from the SiC raw material in the center, the lattice surface of SiC single crystal 1 can be made to be convex towards the C-plane 1B.

[0120] The SiC single crystal 1 is grown to a thickness T that forms the holding member 11. 11 The thickness is more than three times that of the original. By making the thickness of the SiC single crystal 1 sufficient, the bending of the lattice plane can be prevented during cooling in the growth space and restoration of the expansion portion 12.

[0121] As described above, by providing an expansion portion 12 within the holding member 11, the temperature distribution within the growth space during the crystallization growth and cooling of the SiC single crystal 1 is controlled, and the amount of crystallization growth of the SiC single crystal 1 is determined, thus enabling the fabrication of the SiC single crystal 1 of this embodiment. Specifically, by controlling the shape of the crystallization growth surface of the SiC single crystal during the initial stage of crystallization growth, and by providing an expansion portion 12 within the holding member 11 to control the stress generated inside the SiC single crystal 1, the warping (shape) of the lattice planes can be controlled, resulting in the SiC single crystal 1 of this embodiment.

[0122] Alternatively, it can be used in place of the aforementioned retaining member 11. Figure 10 The retaining member 15 is shown. Figure 10 The retaining member 15 shown has a recess 16. Viewed from the Z direction, the recess 16 is located at the position overlapping with the SiC seed crystal 2. The curvature of the lattice plane of the SiC seed crystal 2 is measured using X-ray diffraction, and is only observed when the curvature is r ≥ -8.00 × 10⁻⁶. 2 It is formed in the direction of. Here, the curvature is positive when it bends into a concave shape towards the C-plane (so that the center is located closer to the -Z direction than the end).

[0123] The thickness T of the graphite component between SiC seed crystal 2 and recess 16 17 The thickness T2 of the SiC seed crystal is set to be more than 10% and less than 70%. The thickness T in the Z direction of component 15 is maintained. 15 The thickness T2 of the SiC seed crystal 2 is set to be 200% or more and 800% or less. The radial width W of the recess 16 is set to be 1% or more and 20% or less of the diameter of the retaining member 15.

[0124] For example, if the thickness T in the Z direction of the retaining member 15 is... 15 The thickness T2 of the SiC seed crystal 2 is set to be 200% or more and 300% or less. The radial width W of the recess 16 is set to be 1% or more and 5% or less of the diameter of the retaining member 15. The thickness T of the graphite member between the SiC seed crystal 2 and the recess 16 is set to be... 17 Assuming the thickness T2 of SiC seed crystal 2 is greater than 50% and less than 70%, and satisfying the above-mentioned film formation conditions, then the lattice plane S1 satisfies (ω1-ω0) / (d / 3) < -2.00×10⁻⁶. -6 .

[0125] For example, if the thickness T in the Z direction of the retaining member 15 is... 15 The thickness T2 of the SiC seed crystal 2 is set to be more than 300% but less than 500%, the radial width W of the recess 16 is set to be more than 5% but less than 10% of the diameter of the retaining member 15, and the thickness T of the graphite member between the SiC seed crystal 2 and the recess 16 is set to be... 17Assuming the thickness T2 of SiC seed crystal 2 is greater than 30% and less than 50%, and the above film formation conditions are met, then the lattice plane S1 satisfies (ω1-ω0) / (d / 3)<-3.00×10⁻⁶. -6 .

[0126] For example, if the thickness T in the Z direction of the retaining member 15 is... 15 The thickness T2 of the SiC seed crystal 2 is set to be more than 500% and less than 800%, the radial width W of the recess 16 is set to be more than 10% and less than 20% of the diameter of the retaining member 15, and the thickness T of the graphite member between the SiC seed crystal 2 and the recess 16 is set to be... 17 Assuming the thickness T2 of SiC seed crystal 2 is greater than 10% and less than 30%, and the above film formation conditions are met, then the lattice plane S1 satisfies (ω1-ω0) / (d / 3) < -4.00 × 10⁻⁶. -6 .

[0127] When a retaining member 15 is used instead of the retaining member 11, the central portion of the retaining member 15 also expands compared to the portion where the recess 16 is formed, achieving the same effect as when the retaining member 11 has an expanded portion 12. That is, by controlling the shape of the crystal growth surface of the SiC single crystal in the early stage of crystal growth, and by controlling the stress generated inside the SiC single crystal 1 through the retaining member 15, the warping (shape) of the lattice surface can be controlled, thus obtaining the SiC single crystal 1 of this embodiment.

[0128] In addition, SiC substrates can be fabricated by processing the produced SiC single crystal 1 into a cylindrical shape and slicing it.

[0129] In this embodiment, the SiC single crystal 1 has a convex shape with lattice plane S1 facing the C plane, and the ratio of the basal plane dislocation density of the C plane 1B to the basal plane dislocation density of the Si plane 1A is small. In other words, the SiC single crystal 1 of this embodiment exhibits a high rate of reduction in basal plane dislocation density due to crystal growth. Therefore, the SiC single crystal 1 of this embodiment has a low basal plane dislocation density near the C plane, and a high-quality SiC substrate can be obtained by cutting the SiC substrate from near the C plane.

[0130] The SiC substrate of this embodiment is obtained by slicing the SiC single crystal 1 described above. The SiC substrate contains a SiC single crystal that satisfies the above conditions. The SiC substrate may also be composed of a SiC single crystal that satisfies the above conditions. Therefore, in the SiC substrate of this embodiment, the lattice planes S1 measured along the first straight line L1, the second straight line L2, the third straight line L3, the fourth straight line L4, the fifth straight line L5, and the sixth straight line L6 are all bent into a convex shape. Among the lattice planes S1 measured along the first straight line L1, the second straight line L2, the third straight line L3, the fourth straight line L4, the fifth straight line L5, and the sixth straight line L6, the center C is located on the C-side of the lattice plane S1 measured along each straight line. That is, the lattice planes S1 measured along each straight line are all bent in a manner with the center convex toward the C-side. Since the SiC substrate of this embodiment satisfies the above conditions, the in-plane dislocation distribution deviation is small. If this SiC substrate is used, the yield when fabricating SiC devices is increased.

[0131] The thickness of the SiC substrate in the Z direction is thinner than the crystal length T in the Z direction of the SiC single crystal 1. The thickness of the SiC substrate in the Z direction can be, for example, less than 600 μm, less than 450 μm, less than 400 μm, less than 375 μm, less than 350 μm, or less than 300 μm. The thickness of the SiC substrate in the Z direction can be more than 200 μm.

[0132] Alternatively, a SiC epitaxial layer may be stacked on one side of the SiC substrate in this embodiment. The SiC epitaxial wafer includes a SiC substrate and a SiC epitaxial layer stacked on one side of the SiC substrate. The SiC epitaxial layer may be stacked on the Si surface of the SiC substrate or on its C surface.

[0133] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to specific embodiments and various modifications and alterations can be made within the scope of the spirit of the present invention as described in the claims.

[0134] [Example]

[0135] Example 1

[0136] A seed crystal with a diameter of 6 inches (150 mm) was prepared. Then, using... Figures 7-9 The manufacturing apparatus 100 shown crystallized and grew a 32.6 mm thick SiC single crystal 1 on a SiC seed crystal 2 with a thickness of 1.2 mm.

[0137] Graphite is used in retaining member 11. The thickness T of retaining member 11 is... 11 The thickness T2 of the SiC seed crystal 2 is 700%. The material of the expansion portion 12 is NbC. The thickness T of the expansion portion 12 is... 12The thickness T2 of the SiC seed crystal 2 is 90%. The diameter d of the expanded portion 12 is... 12 The diameter d2 of the SiC seed crystal 2 is 60%. The thickness T of the retaining member 11 between the expansion portion 12 and the SiC seed crystal 2 is... 13 It is 20% of the thickness T2 of SiC seed crystal 2.

[0138] During the crystal growth of SiC single crystal 1, the lower end of the shielding member 41 is positioned at the same height as the upper end of the holding member 11, and the upper end of the shielding member 42 is positioned at the height of the crystal growth surface of the SiC single crystal 1. As a result, the temperature distribution within the growth space during crystal growth and cooling satisfies conditions 1, 2, and 3. The moving speed of the shielding member 41 is set to 2.0 mm / h or less. If the moving speed is greater than 2.0 mm / h, crystallinity may deteriorate due to rapid temperature changes, resulting in a deterioration of the half-width.

[0139] The fabricated SiC single crystal 1 was taken out and X-ray diffraction measurements were performed along the first straight line L1, the second straight line L2, the third straight line L3, the fourth straight line L4, the fifth straight line L5, and the sixth straight line L6. X-ray diffraction was performed at the center, the first measurement point, and the second measurement point on each straight line. Then, the diffraction peak angle and the half-width of the maximum diffraction peak on the (0004) plane at each measurement point were calculated. Using the measurement results at the first measurement point and the center, (ω1-ω0) / (d / 3) was calculated, and using the measurement results at the second measurement point and the center, (ω2-ω0) / (d / 3) was calculated. These represent the change in diffraction peak angle per unit length (degrees / mm (deg / mm)).

[0140] The X-ray diffraction results of Example 1 are summarized in Table 1 below. Figure 4 As shown, it was confirmed that the change in diffraction peak angle per unit length was negative, and the shape of the lattice plane S1 of the SiC single crystal 1 in Example 1 was a mountain shape with the center protruding towards the C plane.

[0141] Table 1

[0142]

[0143] Next, the defect density (EPD), basal dislocation density (BPD), and through-screw dislocation density (TSD) were measured in the Si plane 1A and C plane 1B of the fabricated SiC single crystal 1. The results are shown in Table 2 below. The type and number of dislocations can be determined using optical microscopy, electron microscopy (SEM), etc., based on the shape of the etch pits revealed by etching with molten KOH.

[0144] Table 2

[0145]

[0146] Comparative Example 1

[0147] Comparative Example 1 used a holding member made solely of graphite, which differs from Example 1. Other conditions were set the same as in Example 1 to grow a SiC single crystal. In Comparative Example 1, a 37.4 mm SiC single crystal was grown.

[0148] In Comparative Example 1, X-ray diffraction measurements were performed along the first line L1, the second line L2, the third line L3, the fourth line L4, the fifth line L5, and the sixth line L6, just as in Example 1. The X-ray diffraction results of Comparative Example 1 are summarized in Table 3 below. Based on the measurement results in Table 3, it was confirmed that the shape of the lattice plane S2 of the SiC single crystal in Comparative Example 1 is as follows: Figure 5 As shown, it is shaped like a potato chip.

[0149] Table 3

[0150]

[0151] In addition, in the SiC single crystal of Comparative Example 1, the defect density (EPD), basal dislocation density (BPD), and through-screw dislocation density (TSD) of the Si and C planes were measured respectively. The results are shown in Table 4 below.

[0152] Table 4

[0153]

[0154] Comparative Example 2

[0155] Comparative Example 2 used a holding member made solely of graphite, and unlike Example 1, temperature control using a shielding member was not implemented during crystal growth. Other conditions were set the same as in Example 1 to grow a SiC single crystal. In Comparative Example 2, a 38.3 mm SiC single crystal was grown.

[0156] In Comparative Example 2, X-ray diffraction measurements were performed along the first line L1, the second line L2, the third line L3, the fourth line L4, the fifth line L5, and the sixth line L6, just as in Example 1. The X-ray diffraction results of Comparative Example 2 are summarized in Table 5 below. Based on the measurement results in Table 5, it was confirmed that the shape of the lattice plane S3 of the SiC single crystal in Comparative Example 2 is as follows: Figure 6 As shown, it is a bowl shape that protrudes from the center away from surface C.

[0157] Table 5

[0158]

[0159] In addition, in the SiC single crystal of Comparative Example 2, the defect density (EPD), basal dislocation density (BPD), and through-screw dislocation density (TSD) of the Si and C planes were measured respectively. The results are shown in Table 6 below.

[0160] Table 6

[0161]

[0162] The SiC single crystal of Example 1 has a lower basal dislocation density in the C-plane compared to Comparative Examples 1 and 2. Furthermore, the SiC single crystal of Example 1 exhibits a greater reduction rate in basal dislocation density during crystal growth compared to Comparative Examples 1 and 2.

[0163] In Examples 1, 1, and 2, SiC single crystals were fabricated using SiC seed crystals with a diameter of 6 inches (150 mm). The same study was conducted using SiC seed crystals with a diameter of 8 inches (200 mm). The same tendency was observed with the 200 mm diameter seed crystal as with the 150 mm diameter seed crystal.

Claims

1. A SiC single crystal, The lattice planes measured along lines 1, 2, 3, 4, 5, and 6 are all curved into a convex shape. In the lattice planes measured along the first, second, third, fourth, fifth, and sixth lines respectively, the center is located closer to the C-plane than the end of the lattice plane measured along each line. The first straight line is a straight line passing through the center when viewed from above in the thickness direction. The second straight line is a straight line that passes through the center and is inclined at 30° relative to the first straight line with the center as a reference. The third straight line is a straight line that passes through the center and is inclined at 60° relative to the first straight line with the center as a reference. The fourth straight line is a straight line that passes through the center and is inclined at 90° relative to the first straight line with the center as a reference. The fifth straight line is a straight line that passes through the center and is inclined at 120° relative to the first straight line with the center as a reference. The sixth line is a line that passes through the center and is inclined at 150° relative to the first line with the center as a reference.

2. The SiC single crystal according to claim 1, The main face has an offset angle relative to the (0001) face. The first straight line is a straight line extending in the direction of <11-20>.

3. The SiC single crystal according to claim 1, Let d be the diameter viewed from the thickness direction, ω0 be the maximum diffraction peak angle of the (0004) plane at the center, and ω1 be the maximum diffraction peak angle of the (0004) plane at the measurement point d / 3 away from the center. In the X-ray diffraction results measured along the first, second, third, fourth, fifth, and sixth straight lines respectively, the following condition is met: (ω1-ω0) / (d / 3) < -2.00 × 10⁻⁶. -6 .

4. The SiC single crystal according to claim 3, In the X-ray diffraction results measured according to the first, second, third, fourth, fifth, and sixth straight lines respectively, (ω1-ω0) / (d / 3) < -3.00 × 10⁻⁶ -6 .

5. The SiC single crystal according to claim 4, In the X-ray diffraction results measured according to the first, second, third, fourth, fifth, and sixth straight lines respectively, (ω1-ω0) / (d / 3) < -4.00 × 10⁻⁶ -6 .

6. The SiC single crystal according to claim 1, When the diameter viewed from above along the thickness direction is denoted as d, in the X-ray diffraction results measured along the first, second, third, fourth, fifth, and sixth straight lines respectively, the half-width of the maximum diffraction peak on the (0004) plane at the measurement point d / 3 away from the center is less than 5.20 × 10⁻⁶. -2 .

7. The SiC single crystal according to claim 6, In the X-ray diffraction results measured according to the first, second, third, fourth, fifth, and sixth straight lines respectively, the half-width of the maximum diffraction peak on the (0004) plane at the measurement point d / 3 away from the center is less than 4.80 × 10⁻⁶. -2 .

8. The SiC single crystal according to claim 1, In the X-ray diffraction results measured according to the first, second, third, fourth, fifth, and sixth straight lines respectively, the half-width of the maximum diffraction peak on the (0004) plane at the measurement point d / 3 away from the center is less than 4.40 × 10⁻⁶. -2 .

9. The SiC single crystal according to claim 1, When the basal dislocation density in the Si plane is denoted as BPD0 and the basal dislocation density in the C plane is denoted as BPD1, the condition (BPD0-BPD1) / BPD0>64% is satisfied.

10. The SiC single crystal according to claim 1, When the density of through screw dislocations in the Si plane is denoted as TSD0 and the density of through screw dislocations in the C plane is denoted as TSD1, the condition (TSD0-TSD1) / TSD0 > 48.2% is satisfied.

11. The SiC single crystal according to claim 1, When the basal dislocation density in the Si plane is denoted as BPD0, the basal dislocation density in the C plane is denoted as BPD1, the through screw dislocation density in the Si plane is denoted as TSD0, the through screw dislocation density in the C plane is denoted as TSD1, and the crystal length in the thickness direction is denoted as T, the following conditions are met: (BPD0-BPD1) / (BPD0×T)>1% / mm, and (TSD0-TSD1) / (TSD0×T)>1% / mm.

12. The SiC single crystal according to claim 11, It satisfies (BPD0-BPD1) / (BPD0×T)>2% / mm and (TSD0-TSD1) / (TSD0×T)>2% / mm.

13. The SiC single crystal according to claim 12, It satisfies (BPD0-BPD1) / (BPD0×T)>3% / mm and (TSD0-TSD1) / (TSD0×T)>3% / mm.

14. The SiC single crystal according to claim 1, The diameter when viewed from above in the thickness direction is over 145mm.

15. The SiC single crystal according to claim 1, The diameter when viewed from above in the thickness direction is over 195mm.

16. The SiC single crystal according to claim 1, The diameter when viewed from above in the thickness direction is over 295mm.

17. The SiC single crystal according to claim 1, The basal dislocation density in plane C is 500 dislocations / cm². 2 the following.

18. The SiC single crystal according to claim 1, The density of through-screw dislocations in the C-plane is 300 dislocations / cm². 2 the following.

19. The SiC single crystal according to claim 1, The defect density in surface C is 4000 defects / cm². 2 the following.

20. A SiC substrate comprising the SiC single crystal of claim 1.

21. A SiC epitaxial wafer comprising the SiC substrate of claim 20 and a SiC epitaxial layer stacked on one side of the SiC substrate.

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