Silicon carbide substrate

Abstract

To provide a silicon carbide substrate having high transmittance in the deep ultraviolet region. [Solution] The silicon carbide substrate has a main surface. At the center of the main surface, the transmittance of light with a wavelength of 300 nm is 40% or more.

Description

Technical Field

[0001] The present disclosure relates to a silicon carbide substrate.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2008-505833 (Patent Document 1) discloses a vanadium-doped silicon carbide crystal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present disclosure is to provide a silicon carbide substrate having a high transmittance in the deep ultraviolet region.

Means for Solving the Problems

[0005] The silicon carbide substrate according to the present disclosure has a main surface. At the center of the main surface, the transmittance of light having a wavelength of 300 nm is 40% or more.

Effects of the Invention

[0006] According to the present disclosure, it is possible to provide a silicon carbide substrate having a high transmittance in the deep ultraviolet region.

Brief Description of the Drawings

[0007] [Figure 1] FIG. 1 is a schematic plan view showing the configuration of the silicon carbide substrate according to the present embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line II-II of FIG. 1. [Figure 3]Figure 3 is a schematic diagram showing the relationship between the transmittance and wavelength of the silicon carbide substrate according to this embodiment. [Figure 4] Figure 4 is a schematic plan view showing the measurement area for surface roughness. [Figure 5] Figure 5 is a schematic flowchart showing the manufacturing method of the silicon carbide substrate according to this embodiment. [Figure 6] Figure 6 is a schematic cross-sectional view showing the firing process. [Figure 7] Figure 7 is a schematic cross-sectional view showing the sublimation process. [Figure 8] Figure 8 is a schematic diagram showing the relationship between the transmittance and wavelength of silicon carbide substrates for samples 1 and 2. [Modes for carrying out the invention]

[0008] [Description of Embodiments in this Disclosure] First, the embodiments of this disclosure will be listed and described.

[0009] (1) The silicon carbide substrate relating to this disclosure has a main surface. At the center of the main surface, the transmittance of light with a wavelength of 300 nm is 40% or more.

[0010] (2) The silicon carbide substrate relating to this disclosure has a main surface. At the center of the main surface, if the transmittance of light with a wavelength of 300 nm is defined as the first transmittance and the transmittance of light with a wavelength of 400 nm is defined as the second transmittance, the value obtained by dividing the first transmittance by the second transmittance is 0.5 or greater.

[0011] (3) In the silicon carbide substrate relating to (1) or (2) above, the diameter of the main surface may be 100 mm or more.

[0012] (4) In the silicon carbide substrate relating to any of (1) to (3) above, the thickness of the silicon carbide substrate may be 350 μm or more and 550 μm or less.

[0013] (5) In the silicon carbide substrate according to any one of (1) to (4) above, the arithmetic mean roughness of the main surface may be 0.02 nm or more and 0.20 nm or less.

[0014] (6) In the silicon carbide substrate according to any one of (1) to (5) above, the concentration of vanadium on the main surface is 8×10

[0019] cm -3 or more and 5×10 17 cm -3 or less.

[0015] (7) In the silicon carbide substrate according to any one of (1) to (6) above, the concentration of nitrogen at the center of the main surface is 5×10 15 cm -3 or more and 5×10 17 cm -3 or less.

[0016] (8) In the silicon carbide substrate according to any one of (1) to (6) above, the concentration of aluminum at the center of the main surface is 1×10 13 cm -3 or more and 5×10 15 cm -3 or less.

[0017] [Details of Embodiments of the Present Disclosure] Next, embodiments of the present disclosure will be described based on the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated. In the crystallographic descriptions in this specification, individual orientations are indicated by [], collective orientations by <>, individual planes by (), and collective planes by {}. Also, for negative exponents, in crystallography, a "-" (bar) is placed above the number, but in this specification, a negative sign is placed before the number.

[0018] First, the configuration of the silicon carbide substrate according to the present embodiment will be described. FIG. 1 is a schematic plan view showing the configuration of a silicon carbide substrate 100 according to the present embodiment.

[0019] As shown in Figure 1, the silicon carbide substrate 100 according to this embodiment has a first main surface 1 and an outer peripheral edge 8. The first main surface 1 is, for example, planar. The first main surface 1 extends along a first direction 101 and a second direction 102, respectively. The outer peripheral edge 8 is connected to the first main surface 1. The outer peripheral edge 8 has an orientation flat portion 6 and an arc-shaped portion 7. The arc-shaped portion 7 is connected to the orientation flat portion 6. The orientation flat portion 6 extends along the first direction 101.

[0020] The first direction 101 is, for example, the <11-20> direction. The first direction 101 may also be, for example, the [11-20] direction. The first direction 101 may also be the direction obtained by projecting the <11-20> direction onto the first principal plane 1. From another point of view, the first direction 101 may also be a direction that includes, for example, the <11-20> direction component.

[0021] The second direction 102 is, for example, the <1-100> direction. The second direction 102 may also be, for example, the [1-100] direction. The second direction 102 may also be, for example, the direction obtained by projecting the <1-100> direction onto the first principal plane 1. From another point of view, the second direction 102 may also be, for example, a direction that includes a component of the <1-100> direction.

[0022] The first principal surface 1 may be, for example, the {0001} plane, or a plane inclined with respect to the {0001} plane. If the first principal surface 1 is inclined with respect to the {0001} plane, the inclination angle (off-angle θ) of the first principal surface 1 with respect to the {0001} plane is, for example, 1° or more and 8° or less. If the first principal surface 1 is inclined with respect to the {0001} plane, the inclination direction (off-direction) of the first principal surface 1 is, for example, the <11-20> direction. The off-angle θ may be 2° or more and 6° or less.

[0023] The diameter W1 of the first main surface 1 is, for example, 100 mm (4 inches) or more. The diameter W1 of the first main surface 1 may be, for example, 150 mm (6 inches) or more, or 200 mm (8 inches) or more. The diameter W1 of the first main surface 1 may be 400 mm (16 inches) or less. When viewed in the direction from the first main surface 1 toward the second main surface 2, the diameter of the first main surface 1 is the longest straight-line distance between two different points on the outer edge 8.

[0024] In this specification, 4 inches means 100 mm or 101.6 mm (4 inches × 25.4 mm / inch). 6 inches means 150 mm or 152.4 mm (6 inches × 25.4 mm / inch). 8 inches means 200 mm or 203.2 mm (8 inches × 25.4 mm / inch). 16 inches means 400 mm or 406.4 mm (16 inches × 25.4 mm / inch).

[0025] Figure 2 is a schematic cross-sectional view along the line II-II in Figure 1. As shown in Figure 2, the silicon carbide substrate 100 has a second main surface 2. The second main surface 2 is opposite to the first main surface 1. The second main surface 2 is connected to the outer edge 8. The thickness B of the silicon carbide substrate 100 is, for example, 350 μm or more and 550 μm or less. The thickness B of the silicon carbide substrate 100 may be, for example, 400 μm or more, or 450 μm or more. The thickness B of the silicon carbide substrate 100 may be, for example, 525 μm or less, or 500 μm or less.

[0026] The third direction 103 is perpendicular to the first direction 101 and the second direction 102, and is the direction from the first principal surface 1 to the second principal surface 2. The third direction 103 is the direction along the thickness of the silicon carbide substrate 100. The silicon carbide substrate 100 is formed of, for example, hexagonal silicon carbide. The polytype of the hexagonal silicon carbide constituting the silicon carbide substrate 100 is, for example, 4H or 6H.

[0027] <Transmittance> Figure 3 is a schematic diagram showing the relationship between the transmittance and wavelength of the silicon carbide substrate 100 according to this embodiment. In Figure 3, the horizontal axis represents the wavelength of light. The unit of the horizontal axis is nm. The vertical axis represents the transmittance of the silicon carbide substrate 100. The unit of the vertical axis is %.

[0028] As shown in Figure 3, the silicon carbide substrate 100 according to this embodiment has a high transmittance of light in the deep ultraviolet region. At the center A of the first main surface 1, the transmittance of light with a wavelength of 300 nm is defined as the first transmittance T1. The first transmittance T1 may be 44% or more, or 48% or more. The first transmittance T1 may be 70% or less, or 60% or less, or 55% or less.

[0029] At the center A of the first main surface 1, the transmittance of light with a wavelength of 400 nm is defined as the second transmittance T2. The second transmittance T2 may be 52% or more, or 56% or more. The second transmittance T2 may be 80% or less, or 70% or less.

[0030] The value obtained by dividing the first transmittance T1 by the second transmittance T2 is 0.5 or greater. The value obtained by dividing the first transmittance T1 by the second transmittance T2 may be 0.6 or greater, 0.7 or greater, or 0.8 or greater. The value obtained by dividing the first transmittance T1 by the second transmittance T2 may be 0.95 or less, 0.9 or less, or 0.85 or less.

[0031] Next, the method for measuring the transmittance of the silicon carbide substrate 100 will be described. The transmittance of the silicon carbide substrate 100 is measured using a transmittance measuring device (model number: SolidSpec-3700) manufactured by Shimadzu Corporation. The measurement wavelength range is, for example, from 240 nm to 800 nm. The measurement wavelength pitch is 0.5 nm. The measurement sample includes the center A of the first main surface 1. The thickness of the measurement sample is, for example, 500 μm. The measurement sample is a square shape of 20 mm × 20 mm. The transmittance was measured at the center A of the first main surface 1.

[0032] <Electrical resistivity> The silicon carbide substrate 100 according to this embodiment has semi-insulating properties. The silicon carbide substrate 100 may have high resistance by, for example, introducing vanadium, or by introducing point defects. The electrical resistivity of the silicon carbide substrate 100 according to this embodiment is, for example, 1 × 10⁻⁶ 10 It is greater than Ωcm. The electrical resistivity of silicon carbide substrate 100 is 5 × 10⁻⁶. 10 It may be greater than Ωcm, or 1 × 10 11 It may be greater than Ωcm, or 5 × 10 11 It may be greater than Ωcm, or 1 × 10 12 It may be greater than Ωcm.

[0033] The electrical resistivity of the silicon carbide substrate 100 is measured using a COREMA-WT electrical resistivity measuring device manufactured by Semilab. The voltage applied to the silicon carbide substrate 100 is, for example, 5.0V. The probe diameter is 1mm. The electrical resistivity of the silicon carbide substrate 100 is measured at room temperature (27°C).

[0034] <Impurity concentration> The silicon carbide substrate 100 may contain, for example, vanadium (V). The vanadium concentration on the first main surface 1 is, for example, 8 × 10⁻⁶. 16 cm -3 The above 5 x 10 17 cm -3 The following applies: The vanadium concentration on the first main surface 1 is, for example, 1.5 × 10⁻⁶. 17 cm -3 It may be more than that, or 2 x 10 17 cm -3 The above may also be the case. The vanadium concentration on the first main surface 1 is, for example, 4.5 × 10⁻⁶. 17 cm -3 The following is also acceptable, or 4 x 10 17 cm -3 The following is also acceptable.

[0035] The conductivity type of the silicon carbide substrate 100 is, for example, n-type. The silicon carbide substrate 100 contains, for example, nitrogen (N). The nitrogen concentration on the first main surface 1 is, for example, 5 × 10⁻⁶. 15 cm -3 The above 5 x 10 17 cm -3 The following applies: The nitrogen concentration on the first main surface 1 is, for example, 8 × 10⁻⁶. 15 cm -3 It may be more than that, or 1 x 10 16 cm -3 The above may also be the case. The nitrogen concentration on the first main surface 1 is, for example, 1 × 10⁻⁶. 17 cm -3 The following is also acceptable, or 5 x 10 16 cm -3 The following is also acceptable.

[0036] The conductivity type of the silicon carbide substrate 100 may be, for example, p-type. The silicon carbide substrate 100 contains, for example, aluminum (Al). The concentration of aluminum on the first main surface 1 is, for example, 1 × 10⁻⁶. 13 cm -3 The above 5 x 10 15 cm -3 The following applies: The concentration of aluminum on the first main surface 1 is, for example, 3 × 10⁻⁶. 13 cm -3 It may be more than that, or 5 x 10 13 cm -3 The above may also be the case. The concentration of aluminum on the first main surface 1 is, for example, 3 × 10⁻⁶. 15 cm -3 The following is also acceptable, or 1 × 10 15 cm -3 The following is also acceptable.

[0037] The concentrations of impurities such as vanadium, nitrogen, and aluminum are measured using a Cameca secondary ion mass spectrometer (model number: IMS7f). In secondary ion mass spectrometry, the primary ion is O2 + It is said that the primary ion energy is 8 keV. The measurement position is said to be center A of the first main surface 1.

[0038] <Surface roughness> The arithmetic mean roughness (Ra) of the first main surface 1 of the silicon carbide substrate 100 is, for example, 0.02 nm or more and 0.20 nm or less. The arithmetic mean roughness (Ra) of the first main surface 1 may be 0.15 nm or less, or 0.1 nm or less. The arithmetic mean roughness (Ra) of the first main surface 1 may be 0.03 nm or more, or 0.04 nm or more.

[0039] Figure 4 is a schematic plan view showing the measurement area for surface roughness. The arithmetic mean roughness Ra can be measured using a white-beam microscope. A white-beam interference microscope (model number: Nikon BW-D507) manufactured by Nikon Corporation may be used as the white-beam microscope. The magnification of the objective lens is, for example, 20x. As shown in Figure 4, the measurement area C for the arithmetic mean roughness Ra is, for example, a square area containing the center A of the first principal surface 1. The length of one side W2 of the measurement area C is, for example, 250 μm.

[0040] <Method for manufacturing silicon carbide substrates> Next, the method for manufacturing the silicon carbide substrate 100 according to this embodiment will be described. Figure 5 is a schematic flowchart showing the method for manufacturing the silicon carbide substrate 100 according to this embodiment. As shown in Figure 5, the method for manufacturing the silicon carbide substrate 100 according to this embodiment includes a preparation step (S1), a firing step (S2), a sublimation step (S3), and a cutting step (S4).

[0041] First, a preparation step (S1) is carried out. In the preparation step (S1), a silicon carbide raw material is prepared. The silicon carbide raw material is a powder of polycrystalline silicon carbide. In the silicon carbide raw material of this embodiment, the nitrogen concentration is significantly reduced. Specifically, the nitrogen concentration in the silicon carbide raw material is 0.2 ppm or less. The nitrogen concentration in the silicon carbide raw material may be 0.15 ppm or less, or 0.1 ppm or less. Furthermore, the concentration of metal impurities in the silicon carbide raw material is significantly reduced. For example, the concentrations of boron (B), aluminum (Al), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), nickel (Ni), and copper (Cu) in the silicon carbide raw material are each 1 ppm or less.

[0042] Next, the firing process (S2) is carried out. Figure 6 is a schematic cross-sectional view showing the firing process. As shown in Figure 6, the silicon carbide crystal manufacturing apparatus 300 mainly consists of a crucible 130 and an insulating material 160. The insulating material 160 is arranged to cover the outer circumference of the crucible 130. An induction heating coil (not shown) is arranged spirally around the outer circumference of the insulating material 160. By applying power to the induction heating coil, the crucible 130 is heated by electromagnetic induction.

[0043] As shown in Figure 6, silicon carbide raw material 153 is placed in crucible 130. Next, crucible 130 is heated. The temperature of crucible 130 is heated from room temperature (27°C) to 2300°C. The pressure of crucible 130 is, for example, 80 Pa. The heating time of crucible 130 is, for example, 3 hours. This causes the silicon carbide raw material 153 to be calcined. In the calcination process (S20), nitrogen contained in the silicon carbide raw material 153 is detached from the silicon carbide raw material 153. As a result, the nitrogen content in the silicon carbide raw material 153 becomes even lower.

[0044] Next, a seed crystal 150 and a vanadium source (not shown) are placed inside the crucible 130. The vanadium source is a raw material that supplies vanadium gas. The vanadium source is, for example, vanadium carbide powder. The vanadium source may be mixed with the silicon carbide raw material 153, or it may be placed inside the crucible 130 separately from the silicon carbide raw material 153.

[0045] The seed crystal 150 is fixed to the crucible 130, for example, using an adhesive (not shown). The seed crystal 150 has a growth surface 151 and a mounting surface 152. The mounting surface 152 is on the opposite side from the growth surface 151. The growth surface 151 faces the silicon carbide raw material 153. The mounting surface 152 is attached to the crucible 130.

[0046] The seed crystal 150 is, for example, a silicon carbide single crystal substrate with a polytype of 4H. The diameter of the growth surface 151 is, for example, 150 mm. The growth surface 151 may also be a surface tilted with respect to the {0001} plane by an off-angle of about 8° or less.

[0047] Next, the sublimation process (S3) is carried out. Figure 7 is a schematic cross-sectional view showing the sublimation process. Specifically, with the temperature of the growth surface 151 of the seed crystal 150 lower than the temperature of the silicon carbide raw material 153, the pressure of the atmospheric gas inside the crucible 130 is reduced to, for example, 1.0 kPa. The atmospheric gas is, for example, argon gas. As a result, the silicon carbide raw material 153 and the vanadium supply source each begin to sublimate.

[0048] The sublimated silicon carbide gas recrystallizes on the growth surface 151. Silicon carbide crystals 200 grow on the growth surface 151. While the silicon carbide crystals 200 are growing, the pressure inside the crucible 130 is maintained at, for example, between 0.1 kPa and 3 kPa. The temperature of the silicon carbide crystals 200 is, for example, between 2100°C and 2300°C. When the silicon carbide crystals 200 grow, they are doped with vanadium. As described above, silicon carbide crystals 200 grow on the seed crystal 150.

[0049] Next, a cutting process (S4) is performed. For example, using a saw wire, the silicon carbide crystal 200 is sliced ​​along a plane perpendicular to the central axis of the silicon carbide crystal 200. This yields a silicon carbide substrate 100 (see Figure 1).

[0050] Next, the effects and benefits of the silicon carbide substrate 100 according to this embodiment will be described. Ultraviolet light-emitting diodes (LEDs), such as deep ultraviolet (DUV) LEDs, are widely used in sterilization and disinfection due to their high photon energy. Gallium nitride (GaN) semiconductors are commonly used as the light-emitting layer in DUV LEDs. Improvements in both luminous efficiency and light extraction efficiency are required for DUV LEDs.

[0051] Flip-chip deep ultraviolet light-emitting diodes (DUVs) have a structure that extracts light from the light-emitting layer through a substrate. Sapphire substrates have a higher transmittance than silicon carbide substrates. For this reason, sapphire substrates are often used as the substrate for flip-chip deep ultraviolet light-emitting diodes.

[0052] However, the difference between the lattice constant of silicon carbide (polytype 4H) (0.308 nm) and the lattice constant of gallium nitride (0.319 nm) is smaller than the difference between the lattice constant of sapphire (0.275 nm) and the lattice constant of gallium nitride (0.319 nm). Therefore, the luminous efficiency of a gallium nitride layer formed on a silicon carbide substrate 100 is higher than that of a gallium nitride layer formed on a sapphire substrate. Furthermore, the silicon carbide substrate 100 is superior to the sapphire substrate in terms of heat dissipation. To take advantage of these benefits, there is a need for a silicon carbide substrate 100 that has high transmittance in the deep ultraviolet region (200 nm to 300 nm).

[0053] The inventors diligently investigated methods for obtaining a silicon carbide substrate 100 with high transmittance in the deep ultraviolet region and obtained the following findings. Specifically, they found that a silicon carbide substrate 100 with high transmittance in the deep ultraviolet region can be obtained by significantly reducing the nitrogen concentration in the silicon carbide raw material.

[0054] According to the silicon carbide substrate 100 of this embodiment, the transmittance of light with a wavelength of 300 nm at the center A of the main surface is 40% or more. Therefore, a silicon carbide substrate 100 with high transmittance in the deep ultraviolet region can be obtained. As a result, the luminous efficiency of the flip-chip type deep ultraviolet light-emitting diode is improved compared to that of a sapphire substrate. Furthermore, the light extraction efficiency is improved in the flip-chip type deep ultraviolet light-emitting diode.

[0055] According to the silicon carbide substrate 100 of this embodiment, if the transmittance of light with a wavelength of 300 nm is defined as the first transmittance T1 and the transmittance of light with a wavelength of 400 nm is defined as the second transmittance T2 at the center A of the main surface, then the value obtained by dividing the first transmittance T1 by the second transmittance T2 is 0.5 or greater. Therefore, a silicon carbide substrate 100 having high transmittance in the deep ultraviolet region can be obtained. As a result, the luminous efficiency of the flip-chip type deep ultraviolet light-emitting diode is improved compared to a sapphire substrate. Furthermore, the light extraction efficiency is improved in the flip-chip type deep ultraviolet light-emitting diode.

[0056] According to the silicon carbide substrate 100 of this embodiment, the diameter of the main surface may be 100 mm or more. This makes it possible to obtain a large-diameter silicon carbide substrate 100.

[0057] According to the silicon carbide substrate 100 of this embodiment, the arithmetic mean roughness of the main surface may be 0.01 nm or more and 0.2 nm or less. This makes it possible to further improve the transmittance in the deep ultraviolet region.

[0058] Normally, when impurities such as vanadium are present in a silicon carbide substrate, the transmittance of the silicon carbide substrate tends to decrease. Therefore, it is difficult to obtain a silicon carbide substrate that is semi-insulating and has high transmittance. According to the silicon carbide substrate 100 of this embodiment, the vanadium concentration at the center of the main surface is 1 × 10⁻⁶ 17 cm -3 The above 5 x 10 17 cm -3 The following is also possible. This makes it possible to obtain a silicon carbide substrate 100 that has semi-insulating properties and high transmittance. [Examples]

[0059] (Sample preparation) Silicon carbide substrates 100 for Samples 1 and 2 were prepared. The silicon carbide substrate 100 for Sample 1 is a comparative example. The silicon carbide substrate 100 for Sample 2 is an example.

[0060] In the manufacturing method of the silicon carbide substrate 100 for Sample 1, silicon carbide crystals 200 were produced using silicon carbide raw material 153 with a nitrogen concentration of 2 ppm. In the manufacturing method of the silicon carbide substrate 100 for Sample 1, the growth process (S30) and the cutting process (S40) were carried out without performing the firing process (S20).

[0061] On the other hand, in the manufacturing method of the silicon carbide substrate 100 for Sample 2, silicon carbide crystals 200 were produced using silicon carbide raw material 153 with a nitrogen concentration of 0.2 ppm. In the manufacturing method of the silicon carbide substrate 100 for Sample 2, a firing process (S20), a growth process (S30), and a cutting process (S40) were carried out.

[0062] (Evaluation results) Figure 8 is a schematic diagram showing the relationship between transmittance and wavelength for silicon carbide substrates 100 for samples 1 and 2. The transmittance of silicon carbide substrates 100 was measured using a transmittance measuring device (model: SolidSpec-3700) manufactured by Shimadzu Corporation. The measurement wavelength range was, for example, from 200 nm to 1120 nm. The measurement wavelength pitch was set to 0.5 nm. The measurement sample was prepared to include center A of the first main surface 1. The thickness of the measurement sample was set to 500 μm.

[0063] As shown in Figure 8, the silicon carbide substrate 100 of Sample 2 exhibits higher light transmittance in the deep ultraviolet region compared to the silicon carbide substrate 100 of Sample 1. At the center A of the first main surface 1 of the silicon carbide substrates 100 of Samples 1 and 2, the transmittance of light with a wavelength of 300 nm was 0% and 50%, respectively. Furthermore, at the center A of the first main surface 1 of the silicon carbide substrates 100 of Samples 1 and 2, the values ​​obtained by dividing the transmittance of light with a wavelength of 300 nm by the transmittance of light with a wavelength of 400 nm were 0 and 0.83, respectively.

[0064] Table 1 shows the impurity concentrations at center A of the first main surface 1 of the silicon carbide substrate 100. The impurity concentrations were measured using a secondary ion mass spectrometer. As shown in Table 1, the concentrations of nitrogen (N), boron (B), aluminum (Al), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), nickel (Ni), and copper (Cu) at center A of the first main surface 1 of the silicon carbide substrate 100 for sample 1 were 1.4 × 10⁻⁶ each. 17 cm -3 , 9.6×10 15 cm -3 , 5.7×10 13 cm -3 , 3.5×10 14 cm -3 , 1.1 × 10 17 cm -3 , 6.0×10 13 cm -3 , 2.9×10 14 cm -3 , 7.8×10 14 cm-3 and 1.5×10 14 cm -3 was the case.

[0065] Regarding the silicon carbide substrate 100 according to Sample 2, at the center A of the first main surface 1, the concentrations of nitrogen (N), boron (B), aluminum (Al), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), nickel (Ni), and copper (Cu) were 1.8×10 16 cm -3 、5.4×10 15 cm -3 、1.1×10 13 cm -3 、8.7×10 14 cm -3 、1.5×10 17 cm -3 、7.5×10 13 cm -3 、6.2×10 14 cm -3 、4.7×10 14 cm -3 、1.8×10 15 cm -3 was the case.

[0066]

Table 1

[0070] 1. First main surface 2. Second main surface 6. Orientation Flat Section 7. Arc-shaped part 8 Outer edge 100 Silicon carbide substrate 101 1st direction 102 Second direction 103 Third direction 130 Crucible 150 seed crystals 151 Growth aspect 152 Mounting surface 153 Silicon carbide raw material 160 Insulation 200 Silicon Carbide Crystals 300 Manufacturing equipment A center B Thickness C measurement area T1 1st transmittance T2 2nd transmittance W1 diameter W2 Length

Claims

1. A silicon carbide substrate having a main surface, A silicon carbide substrate having a transmittance of 40% or more of light with a wavelength of 300 nm at the center of the main surface.

2. A silicon carbide substrate having a main surface, A silicon carbide substrate in which, at the center of the main surface, the transmittance of light with a wavelength of 300 nm is defined as the first transmittance, and the transmittance of light with a wavelength of 400 nm is defined as the second transmittance, and the value obtained by dividing the first transmittance by the second transmittance is 0.5 or more.

3. The silicon carbide substrate according to claim 1 or claim 2, wherein the diameter of the main surface is 100 mm or more.

4. The silicon carbide substrate according to claim 1 or claim 2, wherein the thickness of the silicon carbide substrate is 350 μm or more and 550 μm or less.

5. The silicon carbide substrate according to claim 1 or claim 2, wherein the arithmetic mean roughness of the main surface is 0.02 nm or more and 0.20 nm or less.

6. The vanadium concentration at the center of the main surface is 8 × 10 16 cm -3 The above 5 x 10 17 cm -3 The silicon carbide substrate according to claim 1 or claim 2, which is as follows:

7. The nitrogen concentration at the center of the main surface is 5 × 10 15 cm -3 The above 5 x 10 17 cm -3 The silicon carbide substrate according to claim 1 or claim 2, which is as follows:

8. The concentration of aluminum at the center of the main surface is 1 × 10 13 cm -3 or more and 5 × 10 15 cm -3 or less. The silicon carbide substrate according to claim 1 or claim 2.

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