SiC SUBSTRATE AND SiC EPITAXIAL WAFER

Abstract

To provide a SiC substrate and a SiC epitaxial wafer that are large in diameter and have few micropipes.SOLUTION: A SiC substrate according to the present embodiment has a diameter of 195 mm or more and a micropipe density of 0.01 / cm2 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a SiC substrate and a SiC epitaxial wafer. [Background technology]

[0002] Silicon carbide (SiC) has an electric breakdown field one order of magnitude larger than silicon (Si) and a band gap three times larger. Silicon carbide (SiC) also has properties such as a thermal conductivity about three times higher than silicon (Si). For this reason, silicon carbide (SiC) is expected to be applied to power devices, high-frequency devices, high-temperature operating devices, and the like. For this reason, SiC epitaxial wafers have come to be used in the above-mentioned semiconductor devices in recent years.

[0003] SiC epitaxial wafers are obtained by stacking a SiC epitaxial layer on the surface of a SiC substrate. Hereinafter, the substrate before the SiC epitaxial layer is stacked is referred to as the SiC substrate, and the substrate after the SiC epitaxial layer is stacked is referred to as the SiC epitaxial wafer. SiC substrates are produced by slicing from SiC ingots. SiC devices such as power devices, high frequency devices, and high temperature operating devices are obtained by forming devices in the SiC epitaxial layer of the SiC epitaxial wafer and then chipping the SiC epitaxial wafer.

[0004] In order to increase the number of SiC devices that can be obtained from one SiC epitaxial wafer, there is a demand for larger diameter SiC substrates and SiC epitaxial wafers. However, it is not easy to increase the diameter of SiC substrates and SiC epitaxial wafers. For example, Non-Patent Document 1 describes that the number of defects increases significantly as the diameter of SiC substrates and SiC epitaxial wafers increases.

[0005] Furthermore, one of the defects contained in SiC substrates is a micropipe (for example, Patent Document 1). A micropipe is one of the killer defects that adversely affect subsequent processes and SiC devices. For example, a micropipe causes a breakdown voltage defect in SiC devices. A micropipe is a hollow crystal defect with a diameter of sub-μm to several μm that propagates in the c-axis direction of hexagonal silicon carbide. It is believed that a micropipe is formed when a screw dislocation with a large Burgers vector relaxes strain energy. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2016-127201 A [Non-patent literature]

[0007] [Non-Patent Document 1] N. Piluso, E. Carria, R. Anzalone, A Severino. Microelectronic Engineering 273 (2023) 111962. Summary of the Invention [Problem to be solved by the invention]

[0008] As described in Patent Document 1, micropipes are a defect that is difficult to completely eliminate. Furthermore, this tendency becomes more pronounced when the diameter of the SiC substrate becomes large.

[0009] The present invention has been made in consideration of the above problems, and has an object to provide a SiC substrate and a SiC epitaxial wafer that are large in diameter and have few micropipes. [Means for solving the problem]

[0010] The present inventors have produced SiC substrates and SiC epitaxial wafers that have few micropipes even when they are large in diameter.

[0011] (1) The SiC substrate according to the first aspect has a diameter of 195 mm or more and a micropipe density of 0.01 pc / cm 2 The following is the result.

[0012] (2) In the SiC substrate according to the above aspect, the number of micropipes in the effective area excluding the edge exclusion area within 3 mm from the outer periphery may be 3 or less.

[0013] (3) The SiC substrate according to the above aspect may have one or less micropipes in the effective area excluding the edge exclusion area within 3 mm from the outer periphery.

[0014] (4) The SiC substrate according to the above aspect has a surface area of ​​4 mm 2 Of the plurality of first regions divided into squares, 7209 or more of the first regions may have no micropipes.

[0015] (5) The SiC substrate according to the above aspect has a surface area of ​​9 mm 2 Of the plurality of second regions divided by squares, 3168 or more of the second regions may have no micropipes.

[0016] (6) The SiC substrate according to the above aspect has a surface area of ​​16 mm 2 Of the plurality of third regions divided by squares, 1764 or more of the third regions may have no micropipes.

[0017] (7) The SiC substrate according to the above aspect has a surface area of ​​25 mm 2 Of the plurality of fourth regions divided by squares, 1116 or more of the fourth regions may have no micropipes.

[0018] (8) The SiC substrate according to the above aspect has a surface area of ​​36 mm 2Of the plurality of fifth regions divided by squares, 764 or more of the fifth regions may have no micropipes.

[0019] (9) The SiC substrate according to the above aspect has a surface area of ​​49 mm 2 Of the plurality of sixth regions divided by squares, 556 or more of the sixth regions may have no micropipes.

[0020] (10) The SiC substrate according to the above aspect has a surface area of ​​64 mm 2 Of the plurality of seventh regions divided by squares, 421 or more of the seventh regions may have no micropipes.

[0021] (11) The SiC substrate according to the above aspect has a surface area of ​​81 mm 2 Of the plurality of eighth regions divided by squares, 329 or more of the eighth regions may have no micropipes.

[0022] (12) The SiC substrate according to the above aspect has a surface area of ​​100 mm 2 Of the plurality of ninth regions divided by squares, 262 or more of the ninth regions may have no micropipes.

[0023] (13) The SiC substrate according to the above aspect has a surface area of ​​225 mm 2 Of the plurality of tenth regions divided by squares, 112 or more of the tenth regions may have no micropipes.

[0024] (14) The SiC substrate according to the above aspect has a surface area of ​​400 mm 2 Of the plurality of eleventh regions divided by squares, 58 or more of the eleventh regions may have no micropipes.

[0025] (15) The SiC substrate according to the above aspect may have a diameter of 205 mm or less.

[0026] (16) A SiC epitaxial wafer according to a second aspect includes the SiC substrate according to the above aspect and a SiC epitaxial layer stacked on the SiC substrate. Effect of the Invention

[0027] The SiC substrate and SiC epitaxial wafer according to the above aspects have a large diameter and few micropipes. [Brief description of the drawings]

[0028] [Figure 1] FIG. 2 is a plan view of the SiC substrate according to the embodiment. [Diagram 2] FIG. 2 is an enlarged view of the vicinity of the center of the SiC substrate according to the embodiment. [Diagram 3] 2A to 2C are diagrams for explaining a method for manufacturing a SiC substrate according to the present embodiment. [Figure 4] FIG. 2 is a cross-sectional view of the SiC epitaxial wafer according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] The SiC substrate and SiC epitaxial wafer according to the present embodiment will be described in detail below with reference to the drawings. The drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the characteristics of the present embodiment easier to understand, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and may be modified as appropriate within the scope of the present invention.

[0030] In this specification, individual orientations are indicated by [] and collective orientations by <>. For negative indices, a "-" (bar) is placed above the number in crystallography, but in this specification, a negative sign is placed before the number.

[0031] FIG. 1 is a plan view of a SiC substrate 10 according to this embodiment. <0001> The figure is a view seen from the direction. The SiC substrate 10 is made of, for example, n-type SiC. The polytype of the SiC substrate 10 is not particularly limited and may be any of 2H, 3C, 4H, and 6H. The SiC substrate 10 is, for example, 4H—SiC.

[0032] The SiC substrate 10 has a substantially circular shape in plan view. The SiC substrate 10 may have a notch 3 for grasping the direction of the crystal axis. Instead of the notch 3, the SiC substrate 10 may have an orientation flat.

[0033] The diameter of the SiC substrate 10 is, for example, 195 mm or more, and preferably 199 mm or more. The diameter of the SiC substrate 10 is preferably 205 mm or less, and more preferably 201 mm or less.

[0034] The SiC substrate 10 has an effective area 1 and an edge exclusion area 2. The effective area 1 is an area used for obtaining devices, and is the area of ​​the SiC substrate 10 excluding the edge exclusion area 2. The edge exclusion area 2 is an area within 3 mm from the outer periphery. The edge exclusion area 2 is an area that is generally not used for device fabrication.

[0035] The SiC substrate 10 according to this embodiment has a micropipe density of 0.01 pieces / cm 2 or less. Furthermore, in the SiC substrate 10 according to this embodiment, the number of micropipes is 3 or less, preferably 1 or less, and more preferably 0. Furthermore, the number of micropipes in the effective region 1 is, for example, 3 or less, preferably 1 or less, and more preferably 0.

[0036] A micropipe is a hollow defect exposed on the surface of the SiC substrate 10 and having a diameter of more than 1 μm. The micropipe can be confirmed by transmission X-ray topography. The micropipe has a strong distortion and a dark dot-like contrast. Therefore, in transmission X-ray topography, the micropipe can be distinguished by utilizing the difference in contrast from other defects. For example, when a micropipe is confirmed by transmission X-ray topography, the contrast of a dot-like defect caused by the distortion of the micropipe is three times or more the contrast of a dot-like defect caused by a threading dislocation.

[0037] Micropipes may also be evaluated using optical microscopy and photoluminescence in addition to transmission X-ray topography. Micropipes are identified as irregularities using an optical microscope. Micropipes are identified as dark spots accompanied by bright spots using photoluminescence. Observing micropipes using multiple evaluation methods can further increase the accuracy of identifying micropipes.

[0038] After distinguishing between micropipes and other defects using the above procedure, the number of micropipes can be counted to determine the micropipe density and number of micropipes in the SiC substrate 10. The position coordinates of the micropipes can be calculated from the position coordinates of the full-surface photograph of the transmission X-ray topography image. In addition, the micropipe density can be calculated by dividing the number of micropipes by the area of ​​the substrate.

[0039] When obtaining devices, the SiC substrate 10 is cut into a plurality of chips. For example, the SiC substrate 10 is divided into a plurality of regions according to the size of the chips. FIG. 2 is an enlarged view of the vicinity of the center C of the SiC substrate 10 according to this embodiment. For example, the surface of the SiC substrate 10 is divided into a plurality of regions A. Each of the regions A is a square with a side length of a. The regions A are laid out without gaps on the surface of the SiC substrate 10. The center of one of the plurality of regions A coincides with the center C of the SiC substrate 10. Each of the regions A corresponds to each of the chips to be diced, and each becomes a SiC device.

[0040] The size of region A varies depending on the size required for the device. The area of ​​region A varies depending on the length a of one side. Length a is 2 mm and area is 4 mm 2 The square area is called the first area. Length a is 3 mm and area is 9 mm 2 The square region is called the second region. Length a is 4 mm and area is 16 mm 2 The square area is called the third area. Length a is 5 mm and area is 25 mm 2 The square area is called the fourth area. Length a is 6 mm and area is 36 mm 2 The square area is called the fifth area. Length a is 7mm and area is 49mm 2 The square area is called the sixth area. Length a is 8 mm and area is 64 mm 2 The square area is called the seventh area. Length a is 9mm and area is 81mm 2 The square area is called the 8th area. Length a is 10 mm and area is 100 mm 2 The square area is called the 9th area. Length a is 15 mm and area is 225 mm 2 The square area is called the 10th area. Length a is 20 mm and area is 400 mm 2 The square area is called the 11th area.

[0041] Here, an example of the area A is shown, but the size of the area is not limited to this. For example, the length of one side may be 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, or 19 mm, and the length of one side is not limited to an integer.

[0042] When region A is the first region, it is preferable that 7209 or more of the first regions included in SiC substrate 10 do not have micropipes. The number of first regions belonging to effective region 1 is 7209, and if all of these regions do not have micropipes, the maximum number of SiC devices can be obtained from one SiC substrate 10.

[0043] When region A is a second region, it is preferable that 3168 or more of the second regions among the plurality of second regions included in SiC substrate 10 do not have micropipes. The number of second regions belonging to effective region 1 is 3168.

[0044] When region A is a third region, it is preferable that 1764 or more of the third regions among the plurality of third regions included in SiC substrate 10 do not have micropipes. The number of third regions belonging to effective region 1 is 1764.

[0045] When region A is a fourth region, it is preferable that 1116 or more of the fourth regions among the plurality of fourth regions included in SiC substrate 10 do not have micropipes. The number of fourth regions belonging to effective region 1 is 1116.

[0046] When region A is a fifth region, it is preferable that 764 or more of the fifth regions among the plurality of fifth regions included in SiC substrate 10 do not have micropipes. The number of fifth regions belonging to effective region 1 is 764.

[0047] When region A is a sixth region, it is preferable that 556 or more sixth regions among the plurality of sixth regions included in SiC substrate 10 do not have micropipes. The number of sixth regions belonging to effective region 1 is 556.

[0048] When region A is a seventh region, it is preferable that 421 or more of the seventh regions among the multiple seventh regions included in SiC substrate 10 do not have micropipes. The number of seventh regions belonging to effective region 1 is 421.

[0049] When region A is an eighth region, it is preferable that 329 or more of the eighth regions included in SiC substrate 10 do not have micropipes. The number of eighth regions belonging to effective region 1 is 329.

[0050] When region A is a ninth region, it is preferable that 262 or more of the ninth regions among the multiple ninth regions included in SiC substrate 10 do not have micropipes. The number of ninth regions belonging to effective region 1 is 262.

[0051] When region A is a 10th region, it is preferable that 112 or more of the multiple 10th regions included in SiC substrate 10 do not have micropipes. The number of 10th regions belonging to effective region 1 is 112.

[0052] When region A is an eleventh region, it is preferable that 58 or more second regions among the multiple eleventh regions included in SiC substrate 10 do not have micropipes. The number of eleventh regions belonging to effective region 1 is 58.

[0053] Next, a method for manufacturing the SiC substrate 10 according to this embodiment will be described. Fig. 3 is a diagram for explaining the method for manufacturing the SiC substrate 10 according to this embodiment. The method for manufacturing the SiC substrate 10 includes a seed crystal preparation step, a crucible preparation step, a seed crystal installation step, a raw material installation step, a crystal growth step, and a slicing step.

[0054] First, in the seed crystal preparation step, a seed crystal 11 is prepared. A crystal not including micropipes is prepared as the seed crystal 11. The seed crystal 11 not including micropipes can be produced by using, for example, the RAF (Repeated a-face) method.

[0055] Next, in the crucible preparation step, crucible 12 to be used for crystal growth is prepared. Crucible 12 is prepared from graphite, with a portion of its inner wall surface 12A covered with coating film 13. Coating film 13 is made of TaC. Coating film 13 covers 10% to 50% of the area of ​​inner wall surface 12A of crucible 12. Here, inner wall surface 12A refers to the surface of the inner surface of the crucible that is not filled with raw material 15 and is exposed to the growth space.

[0056] If the coverage area of ​​the coating film 13 is too small, carbon dust emitted from the inner wall surface 12A of the crucible 12 is easily incorporated into the growing crystal. Carbon inclusions incorporated into the crystal cause the generation of micropipes. If the coverage area of ​​the coating film 13 is too large, the supply of carbon gas from the inner wall surface 12A of the crucible 12 is reduced, and different polytypes of SiC are easily generated in the growing crystal. Different polytypes of SiC are also a cause of micropipes. Covering a predetermined area of ​​the inner wall surface 12A of the crucible 12 with the coating film 13 is one factor in preventing the generation of micropipes in the SiC substrate 10.

[0057] The coating film 13 is placed on the inner wall surface 12A at a position close to the seed crystal. For example, when the crucible 12 has a guide member 16, a part of the guide member 16 is coated with the coating film 13. Specifically, the surface of the guide member 16 is coated with the coating film 13 from a position 5 mm away from the first end 16a of the guide member 16 to a position 100 mm away. Here, the first end 16a is the end of the guide member 16 on the seed crystal 11 side. By partially covering the guide member 16 with the coating film 13, it is possible to suppress the generation of different polytypes while suppressing dust generation. The state of occurrence of micropipes in the SiC substrate 10 also changes depending on the installation position of the coating film 13.

[0058] Next, in the seed crystal installation step, the seed crystal 11 is installed in the crucible 12. The seed crystal 11 may be installed on the inner wall surface 12A of the crucible 12, or on a pedestal installed on the inner wall surface 12A. The pedestal is made of the same material as the crucible 12, for example.

[0059] The seed crystal 11 is placed in the crucible 12 with, for example, an adhesive 14. At this time, the crucible 12 is placed on the seed crystal 11 so that the shortest distance D between the back surface of the seed crystal 11 and the installation surface of the seed crystal 11 is 30 μm or less at any position in the in-plane direction of the seed crystal 11. The installation surface is the inner wall surface 12A of the crucible 12 when the seed crystal 11 is directly installed in the crucible 12, and is the exposed surface of the pedestal when the seed crystal 11 is installed on a pedestal. The in-plane of the seed crystal 11 is the plane in which the seed crystal 11 spreads, and coincides with the direction in which the plane perpendicular to the straight line connecting the seed crystal 11 and the raw material 15 at the shortest distance spreads. The shortest distance D between the back surface of the seed crystal 11 and the installation surface of the seed crystal 11 does not change significantly before and after heating during crystal growth, so it may be measured before or after heating. The adhesive 14 is carbonized when heated. A gap may occur between the carbonized surface of adhesive 14 and seed crystal 11. The thickness of this gap (the shortest distance between the carbonized surface of adhesive 14 and seed crystal 11) is set to 10 μm or less.

[0060] When the distance between the seed crystal 11 and the installation surface increases, the seed crystal 11 is relatively closer to the raw material 15. The temperature is higher at a position closer to the raw material 15, and the seed crystal 11 is more likely to be etched in a high-temperature environment. When the seed crystal 11 is etched, the adhesive 14 or the installation surface is exposed. SiC polycrystals are likely to grow in the area where the adhesive 14 or the installation surface is exposed. Micropipes are likely to occur in the SiC polycrystal. By appropriately controlling the distance between the seed crystal 11 and the installation surface, the occurrence of micropipes in the SiC substrate 10 can be suppressed. In addition, the gap between the carbonized surface of the adhesive 14 and the seed crystal 11 disrupts the temperature uniformity in the surface during crystal growth, causing a temperature rise. In the area where the temperature is locally increased, etching is accelerated and the adhesive 14 or the installation surface is exposed. Therefore, by not generating a gap between the surface of the adhesive 14 and the seed crystal 11 or by making the gap sufficiently narrow, the occurrence of micropipes in the SiC substrate 10 can be further suppressed.

[0061] Next, in the raw material setting step, raw material 15 is set in the lower part of crucible 12. Raw material 15 is, for example, SiC powder. In the raw material setting step, raw material 15 is set so that the shortest distance between the outermost surface of raw material 15 and seed crystal 11 is 150 mm or more. By increasing the distance between the raw material and the seed crystal, it is possible to reduce the risk that the seed crystal will become hot and be etched.

[0062] Next, the crystal growth step is performed by sublimation. In the sublimation method, the crucible 12 is heated to supply sublimation gas sublimated from the raw material 15 in the crucible 12 to the seed crystal 11, which grows into a larger SiC ingot. The SiC ingot grows on the seed crystal 11.

[0063] In the crystal growth process, the SiC ingot is grown to 10 mm or more. The diameter expansion amount of the SiC ingot relative to the seed crystal 11 is set to 5 mm or more and 10 mm or less. The diameter expansion amount is a value obtained by subtracting the diameter of the seed crystal 11 from the maximum diameter of the SiC ingot. The diameter expansion amount of the SiC ingot can be increased to a predetermined amount by adjusting the shape of the guide member 16 that expands the flow of the sublimation gas. The diameter expansion amount is set to 5 mm or more and 10 mm or less by adjusting the growth amount of the SiC ingot according to the shape of the guide member 16. If the diameter expansion amount is 5 mm or less, it is necessary to repeat the diameter expansion multiple times to obtain a large-diameter crystal, making it difficult to produce a large-diameter crystal.

[0064] On the other hand, if the diameter of the crystal is expanded too much during crystal growth, stress is generated within the crystal. If the expansion amount during crystal growth is too large, stress concentration occurs, and cracks may occur within the crystal. These cracks are the cause of micropipe defects. By controlling the expansion of the crystal diameter to 10 mm or less during the crystal growth process, the generation of micropipes in the SiC substrate 10 can be suppressed.

[0065] Next, in the slicing step, the SiC substrate 10 is cut out from the SiC ingot. For example, the SiC ingot is hollowed out into a cylinder of a predetermined diameter, and the cylinder is sliced ​​to produce the SiC substrate 10. The slicing may be performed using a laser, a wire saw, or the like.

[0066] As described above, by controlling each of the steps of seed crystal preparation, crucible preparation, seed crystal installation, raw material installation, crystal growth, and slicing, a SiC substrate 10 with few micropipes can be produced even if it is large in diameter.

[0067] The SiC substrate 10 according to this embodiment has few micropipes despite its large diameter. Therefore, many good SiC devices can be obtained from the SiC substrate 10 according to this embodiment. The SiC devices are obtained by chipping the SiC epitaxial wafer for each region A. FIG. 4 is a cross-sectional view of the SiC epitaxial wafer 100 according to this embodiment. The SiC epitaxial wafer 100 has the SiC substrate 10 and the SiC epitaxial layer 20. The device is formed in the SiC epitaxial layer 20.

[0068] Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims. EXAMPLES

[0069] "Example 1" First, a seed crystal was prepared. A 4H-SiC single crystal with a diameter of 197 mm was prepared as the seed crystal.

[0070] Next, a crucible was prepared. The crucible used had 39% of the inner wall surface covered with TaC. A coating film made of TaC was formed on a part of the inner surface of the guide member near the seed crystal of the crucible. Specifically, the guide member was covered with TaC from a position 5 mm away from the first end on the seed crystal side to a position 100 mm away.

[0071] Next, a seed crystal was placed on the inner wall of the crucible. The seed crystal was placed on the inner wall using an adhesive. A 20 μm thick carbon adhesive was used as the adhesive. After the seed crystal was placed, the distance between the back surface of the seed crystal and the surface on which the seed crystal was placed remained at 20 μm because the adhesive did not peel off, and no gap was formed between the carbonized adhesive and the seed crystal.

[0072] Next, the bottom of the crucible was filled with raw material. The raw material was SiC powder. The distance between the outermost surface of the raw material and the surface of the seed crystal was set to 200 mm.

[0073] Next, a SiC ingot was grown on the seed crystal by sublimation. The crystal growth amount (thickness of the SiC ingot) was 25 mm. The diameter expansion amount of the SiC ingot relative to the seed crystal was 8 mm.

[0074] Next, the fabricated SiC ingot was sliced, and the (0001) surface of the sliced ​​substrate was polished by grinding, mechanical polishing (MP), and chemical mechanical polishing (CMP) in that order to obtain a SiC substrate. The surface of the SiC substrate was measured by transmission X-ray topography to determine the number of micropipes contained in the SiC substrate.

[0075] The number of micropipes contained in the SiC substrate of Example 1 was one. The one micropipe was within the effective area, but was in the vicinity of the edge exclusion area. Therefore, the micropipe was removed from the area for acquiring devices, and the device acquisition area could be divided.

[0076] Therefore, regions without micropipes could be obtained depending on the size of the regions from the SiC substrate of Example 1. The number of these regions corresponds to the number of devices obtained. 1st area: 7209 pieces 2nd area: 3168 pieces Third area: 1764 pieces 4th area: 1116 pieces 5th area: 764 pieces 6th area: 556 pieces 7th area: 421 pieces 8th area: 329 pieces 9th area: 262 pieces 10th area: 112 pieces Area 11: 58 pieces

[0077] As described above, in Example 1, even in the case of a large-diameter substrate of 8 inches, a SiC substrate with few micropipes was obtained. In Example 1, reproducibility was obtained even in multiple experiments. Note that, as the seed crystal in Example 1, a crystal with few micropipes that had been subjected to multiple diameter expansions in the same manner as in Example 1 was used. [Explanation of symbols]

[0078] 1...effective area, 2...edge exclusion area, 3...notch, 10...SiC substrate, A...area, C...center, 11...seed crystal, 12...crucible, 12A...inner wall surface, 14...adhesive, 15...raw material, 20...SiC epitaxial layer, 100...SiC epitaxial wafer

Claims

1. The diameter is 195 mm or more, Micropipe density is 0.01 pieces / cm ２ The following is a SiC substrate.

2. 2. The SiC substrate according to claim 1, wherein the number of micropipes in an effective area excluding an edge exclusion area within 3 mm from the outer periphery is 3 or less.

3. 2. The SiC substrate according to claim 1, wherein the number of micropipes in an effective area excluding an edge exclusion area within 3 mm from the outer periphery is one or less.

4. The surface area is 4 mm ２ 2. The SiC substrate of claim 1 , wherein 7209 or more of the first regions divided into squares have no micropipes.

5. The surface area is 9 mm ２ 2. The SiC substrate of claim 1, wherein 3168 or more of the second regions divided into squares have no micropipes.

6. The surface area is 16 mm ２ 2. The SiC substrate of claim 1, wherein at least 1764 of the third regions divided into a plurality of squares have no micropipes.

7. The surface area is 25 mm ２ 2. The SiC substrate of claim 1, wherein at least 1,116 of the plurality of fourth regions divided into squares have no micropipes.

8. The surface area is 36 mm ２ 2. The SiC substrate of claim 1, wherein 764 or more of the plurality of fifth regions divided into squares have no micropipes.

9. The surface area is 49 mm ２ 2. The SiC substrate of claim 1, wherein at least 556 of the sixth regions divided into squares have no micropipes.

10. The surface area is 64 mm ２ 2. The SiC substrate of claim 1, wherein at least 421 of the plurality of seventh regions divided into squares have no micropipes.

11. The surface area is 81 mm ２ 2. The SiC substrate of claim 1, wherein 329 or more of the eighth regions divided into squares have no micropipes.

12. The surface area is 100 mm ２ 2. The SiC substrate of claim 1, wherein at least 262 of the plurality of ninth regions divided into squares have no micropipes.

13. The surface area is 225 mm ２ 2. The SiC substrate of claim 1, wherein at least 112 of the plurality of tenth regions divided into squares have no micropipes.

14. The surface area is 400 mm ２ 2. The SiC substrate of claim 1, wherein 58 or more of the plurality of 11 regions divided into squares have no micropipes.

15. The SiC substrate of claim 1 having a diameter of 205 mm or less.

16. A SiC epitaxial wafer comprising: the SiC substrate according to claim 1; and a SiC epitaxial layer laminated on the SiC substrate.

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