JP2002274994A - Method and apparatus of manufacturing silicon carbide single crystal and silicon carbide single crystal ingot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single crystal silicon carbide ingot of high purity, a less defect and large bore, and a method of manufacturing the same. SOLUTION: A graphite crucible 3 packed with Si crystal lumps 2 is closed with a cap 4 and after the crucible is covered with graphite felt 7, the crucible is placed on a graphite supporting rod 6 and is installed within a double pipe quartz tube 5. The inside of the quartz tube is evacuated to a vacuum and thereafter the raw material temperature is raised up to 2,000 deg.C. Gaseous Ar and gaseous hydrogen carbide C3 H8 are respectively admitted as gaseous atmospheres through purifying devices 11 and 14 and while the pressure in the quartz tube is kept at about 80 kPa, the raw material temperature is raised up to 2,400 deg.C which is a target temperature and thereafter the pressure is reduced down to 1.3 kPa by spending about 30 minutes, following which growth is continued for about 20 hours. The resultant crystal is confirmed to be the single crystal of a hexagonal system having a bore of 51 mm and height of about 6 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon carbide single crystal and a method for manufacturing the same, and more particularly, to a high-quality large-sized single crystal ingot to be used as a substrate wafer for a blue light emitting diode or an electronic device, and a method for manufacturing the same. is there.

[0002]

2. Description of the Related Art Silicon carbide (SiC) has attracted attention as an environment-resistant semiconductor material due to its physical and chemical properties such as excellent heat resistance and mechanical strength and resistance to radiation. Further, in recent years, demand for a SiC single crystal wafer has been increasing as a substrate wafer for a short wavelength optical device from blue to ultraviolet, a high frequency high withstand voltage electronic device, and the like. However, a crystal growth technique capable of stably supplying a high-quality SiC single crystal having a large area on an industrial scale has not yet been established. Therefore, despite its many advantages and possibilities as described above, SiC has been hampered from practical use.

Conventionally, on a laboratory scale, a SiC single crystal has been grown by, for example, a sublimation recrystallization method (Rayleigh method) to obtain a SiC single crystal having a size capable of manufacturing a semiconductor device.
However, in this method, the area of the obtained single crystal is small, and it is difficult to control the size and shape with high precision. Further, it is not easy to control the polymorphism and impurity carrier concentration of SiC. In addition, chemical vapor deposition
A cubic silicon carbide single crystal is also grown by heteroepitaxial growth on a heterogeneous substrate such as silicon (Si) using (CVD method). With this method, a single crystal with a large area can be obtained, but many defects (~ 10 ⁷ cm ^-2 ) due to about 20% lattice mismatch with the substrate
Can only grow SiC single crystals containing Si, and it is not easy to obtain high quality SiC single crystals. To solve these problems, an improved Rayleigh method for sublimation recrystallization using a SiC single crystal wafer as a seed crystal has been proposed (Yu.M. Tairov and VF Tsvetkov, Journal o.
f Crystal Growth, vol.52 (1981) pp.146-150). In this method, since a seed crystal is used, the nucleation process of the crystal can be controlled.
By controlling from a to about 15 kPa, the crystal growth rate and the like can be controlled with good reproducibility. The principle of the improved Rayleigh method will be described with reference to FIG. The SiC single crystal serving as a seed crystal and the SiC polycrystalline powder serving as a raw material are housed in a crucible (usually graphite) and placed in an inert gas atmosphere such as argon (133 Pa to 13.3
kPa), heated to 2000-2400 degrees Celsius. At this time, the temperature gradient is set so that the seed crystal is slightly lower in temperature than the raw material powder. After sublimation, the raw material is diffused and transported in the direction of the seed crystal by a concentration gradient (formed by a temperature gradient). Single crystal growth is realized by recrystallization of the source gas that has reached the seed crystal on the seed crystal. At this time, the resistivity of the crystal can be controlled by adding an impurity gas into an atmosphere composed of an inert gas, or by mixing an impurity element or its compound into SiC raw material powder. Si
A typical example of a substitutional impurity in a C single crystal is nitrogen.
(n-type), boron and aluminum (p-type). Using the improved Rayleigh method, the polymorphs of SiC single crystal (6H type, 4H type, 15
(R type etc.) and shape, while controlling the carrier type and concentration,
A SiC single crystal can be grown.

At present, Si prepared by the above-mentioned improved Rayleigh method is used.
SiC from 2 inch (50mm) to 3 inch (75mm) diameter from C single crystal
Single crystal wafer is cut out, epitaxial thin film growth,
Used for device fabrication. However, these
SiC single crystal wafers can be electrically active, such as nitrogen, boron, aluminum, etc., without intentional addition of impurities.
Impurities (which greatly change the resistivity of the crystal) and metal impurities such as iron and titanium (which degrade the device characteristics as a deep bandgap middle level) were contained at about 1 ppma to 10 ppma.

[0005]

As described above, the SiC single crystal produced by the conventional technique contains impurities such as nitrogen, boron, aluminum, iron, and titanium in the range of about 1 ppma to 10 ppma. Almost all of these are raw materials, SiC
It is taken from crystal powder. SiC crystal powder is industrially artificially synthesized by a method generally called the Acheson method. This method uses silica and a carbon source of 2000 Celsius.
This is a method of producing a SiC crystal powder by heating and reacting at a high temperature of a degree or more. The above-mentioned impurities are taken in from the raw materials, the atmosphere, and the like during these processes, and are also brought in by a pulverizing step and the like when the produced SiC polycrystalline mass is refined into a powder. These impurities can be removed to some extent by pretreatment (cleaning, etching) of the SiC crystal powder, but it is basically difficult to remove it after the powder has been formed. In addition, the above-mentioned SiC polycrystalline lump manufacturing process and the highly refined polycrystalline powder are also commercially available, but the purity is not sufficient, and the price is usually low. It is 100 times to 1000 times more expensive than that of

If electrically active impurities are present in the SiC single crystal, it becomes difficult to control the electrical characteristics of the crystal over a wide range. In particular, it becomes difficult to obtain useful high-resistance crystals in high-frequency devices and the like. In the case of a crystal containing metal impurities, the characteristics of the manufactured device deteriorate. Furthermore, the presence of impurities during crystal growth often causes defects, and the crystal growth process and the high purity of the crystal are important technologies for improving the quality of the crystal.

The present invention has been made in view of the above circumstances, and provides a large-diameter ingot of high purity and high quality with a small amount of impurities, and a method and apparatus for producing a SiC single crystal capable of producing the same with good reproducibility. Is what you do.

[0008]

[Means for Solving the Problems] The method for producing a SiC single crystal according to the present invention is (1) a method for producing a single crystal comprising a step of growing a single crystal on a seed crystal. S
After inserting the raw material and attaching a seed crystal of SiC single crystal to the center of the inner surface of the graphite crucible lid, cover the upper end opening of the crucible so that the seed crystal faces the Si raw material, and inactive. Heating and holding the crucible in a gas atmosphere at 2000 to 2400 degrees Celsius, and keeping the seed crystal and the crucible lid at a lower temperature than the crucible,
By reacting Si vapor with graphite, SiC
A method for producing a SiC single crystal, characterized by growing a single crystal, (2) A method for producing a SiC single crystal including a step of growing a single crystal on a seed crystal, wherein a Si material is inserted into a crucible. After attaching a seed crystal of SiC single crystal to the center of the inner surface of the crucible lid, cover the upper end opening of the crucible so that the seed crystal faces the Si raw material, and set the crucible in an inert gas atmosphere to a temperature of Celsius. While heating and holding at 2000 to 2400 degrees, and keeping the seed crystal and the crucible lid at a lower temperature than the crucible, introducing hydrocarbon gas, and reacting the Si vapor with the hydrocarbon gas, A method for producing a SiC single crystal, characterized by growing a SiC single crystal, (3) a method for producing a SiC single crystal including a step of growing a single crystal on a seed crystal, wherein a Si raw material is placed in a graphite crucible. Insert a seed crystal of SiC single crystal in the center of the inner surface of the graphite crucible lid. Et al., Covering the top opening of the crucible as the seed crystal faces the Si material, Celsius crucible in an inert gas atmosphere 2000-24
While heating and holding at 00 degrees, and keeping the seed crystal and the crucible lid lower than the crucible, introducing hydrocarbon gas, Si
By reacting steam with hydrocarbon gas and graphite,
SiC characterized by growing SiC single crystal on seed crystal
Single crystal production method, (4) Hydrocarbon gas partial pressure 1.33Pa
(2) or (3) is a method for producing a SiC single crystal according to (5), wherein the partial pressure of the inert gas is 133 Pa to 13.3 kPa (1).
To (4) the method for producing a SiC single crystal according to any one of (6) S
a crucible for storing the raw material, a crucible lid covering an upper end opening of the crucible having a seed crystal mounting portion in the center part on the inner surface side, a heating furnace having heating means for heating the crucible, A system for introducing an inert gas and a hydrocarbon gas into the heating furnace, and a vacuum system for controlling an atmosphere in the heating furnace, at least having an SiC single crystal production apparatus,
SiC single crystal ingot, wherein the unavoidable impurity concentration in the SiC single crystal is less than 1 ppma, (8) (1) to (5)
The SiC single crystal ingot obtained by any of the manufacturing method described in the above, wherein the inevitable impurity concentration of the ingot
SiC single crystal ingot characterized by being less than 1 ppma, (9) SiC single crystal ingot according to (7) or (8), wherein the diameter of the ingot is 50 mm or more, (10) (7) ~ (9 (11) An SiC single crystal substrate obtained by cutting and polishing the SiC single crystal ingot according to any of (1) and (11), and an SiC epitaxial wafer formed by epitaxial growth on the SiC single crystal substrate according to (10).

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the production method of the present invention, high-purity Si is used as a Si raw material, and high-purity hydrocarbon gas or a high-purity hydrocarbon gas and high-purity graphite are used as a C raw material. Thus, a high-purity, high-quality, large-diameter SiC single crystal wafer can be obtained.

The effect of the present invention will be described with reference to FIG.
The seed crystal SiC single crystal and the raw material high-purity Si crystal (purity excluding carbon element is 99.99999% (7N) or more.Usually, lump or granular) are crucible (usually graphite (purity 99.9995% (5N5) or more). ) Or high melting point metal such as tantalum (purity 99.999% (5N)
Above). In the ordinary modified Rayleigh method, an inert gas such as argon (133 Pa to
Although 13.3 kPa) is used, in the present invention, in addition to these inert gases (purity 99.9999% (6N) or more), a hydrocarbon gas (purity 99.9999% (6N) or more) is introduced (in the present invention). The pressure during the growth is controlled so that the total pressure of the inert gas and the hydrocarbon gas is 133 Pa to 13.3 kPa). Heating is performed slowly, and the Si crystal contained in the crucible gradually melts, and has a vapor pressure of about 10 to several hundred Pa at the growth temperature (2000 to 2400 degrees Celsius). At this time, the temperature gradient is set so that the temperature of the seed crystal is slightly lower than that of the raw material melt.

The hydrocarbon gas to be introduced can basically be used in the present invention as long as it contains a carbon element and a hydrogen element in its chemical formula and can be introduced into the vacuum chamber in a gaseous state. High purity gas of 99.9999% (6N) or more can be obtained at relatively low cost, and methane (CH ₄ ) and ethane (C
₂ H _6), propane (C ₃ H _8), butane (C ₄ H _10), ethylene (C
₂ H _4), propylene (C ₃ H _6), acetylene (C ₂ H ₂₎ such as saturated hydrocarbons, unsaturated hydrocarbon gas are suitable.

The hydrocarbon gas introduced into the atmosphere reacts with the Si vapor on the seed crystal growth surface to grow a SiC single crystal on the seed crystal. The hydrocarbon gas also reacts with the Si vapor on the surface of the Si melt and in the gas phase to form molecules such as Si ₂ C or SiC ₂ and contributes to the growth. Furthermore, if the crucible material is graphite, Si vapor reacts with the graphite wall to generate a gas such as Si ₂ C or SiC ₂ , which contributes to the growth of the SiC single crystal. Here, if the Si source (Si crystal) and the carbon source (hydrocarbon gas, graphite) contributing to all of these reactions have high purity, they have the same or higher purity as these, and extremely few impurities It is possible to obtain a SiC single crystal (a crystal with a higher purity (lower impurity content) than the raw material is obtained because the impurity incorporation rate (the ratio of the impurity amount in the grown crystal to the impurity amount in the raw material, Is usually smaller than 1.0). Further, it is desirable that almost no impurities are present in these growth element processes from the viewpoint of suppressing generation of defects. Impurities often cause polytype mixing and crystal defect generation during SiC single crystal growth, and crystal growth with few impurities is also important in the production of high quality crystals. Raw materials used in the present invention (Si crystal,
(Hydrocarbon gas, graphite) can all be produced industrially at a low cost, and in this sense, the present invention is a method suitable for industrial production of high-purity and high-quality SiC single crystals.

Here, the partial pressure of the hydrocarbon gas introduced into the inert gas atmosphere is desirably in the range of 1.33 Pa to 13.3 kPa. When the partial pressure of the hydrocarbon gas is less than 1.33 Pa, a sufficient amount of carbon is not supplied to the growth element process.
The growth rate of SiC single crystal cannot be obtained. On the other hand, if it exceeds 13.3 kPa, diffusion of Si vapor from the Si melt into the seed crystal is hindered, and a sufficient growth rate cannot be obtained.

The impurity to be controlled to less than 1 ppma in the present invention is an impurity unavoidably introduced into a grown crystal, and is intentionally introduced for the purpose of controlling the conductivity type and resistivity of the crystal. Impurities (for example, donor impurities such as nitrogen, and acceptor impurities such as boron and aluminum) do not correspond to the impurities described in the present invention.
Here, ppma is an abbreviation for atomic parts per million and represents one millionth in atomic number density. The atomic density of SiC is 4.8x10 ²² c
Since it is m ^-3 (there is 2.4 × 10 ²² Si and C each per cm ³ ), 1 ppma is equivalent to 4.8 × 10 ¹⁶ cm ^-3 .

The SiC single crystal ingot produced by the production method of the present invention has a large diameter of 50 mm or more, has an unavoidable impurity concentration of less than 1 ppma, and further has a crystal defect caused by unavoidable impurity contamination. It has the feature of being small.
The diameter of the ingot is not particularly limited as long as it is 50 mm or more, but is preferably in the range of 50 to 200 mm.

Since the SiC single crystal wafer obtained by cutting and polishing the SiC single crystal ingot manufactured as described above has a diameter of 50 mm or more, when manufacturing various devices using this wafer, the Conventionally established production lines for semiconductor (Si, GaAs, etc.) wafers can be used and are suitable for mass production. In addition, since the unavoidable impurity concentration in this wafer is less than 1 ppma, the resistivity of the wafer is controlled in a high range (10 ^-3 to 10 ¹⁰ Ωcm) by intentionally adjusting the amount of impurities added. Is possible. Furthermore, the SiC single crystal epitaxial wafer produced by growing an epitaxial thin film on this SiC single crystal wafer by a CVD method or the like has very few crystal defects due to unavoidable impurities in the SiC single crystal wafer serving as the substrate. for,
Good properties (surface morphology of epitaxial thin film,
Electrical characteristics).

[0017]

An embodiment of the present invention will be described below with reference to FIG. First, the single crystal growth apparatus will be briefly described. The crystal growth is performed by melting and evaporating the Si crystal mass 2 and reacting it with a hydrocarbon gas on the SiC single crystal 1 used as a seed crystal. The seed crystal SiC single crystal 1 is attached to the inner surface of the lid 4 of the graphite crucible 3. Raw material Si grains
2 is filled in the graphite crucible 3. Such a graphite crucible 3 contains a graphite support rod 6 inside a double quartz tube 5.
Installed by Around the graphite crucible 3, a graphite felt 7 for heat shielding is provided. The double quartz tube 5 is evacuated to a high vacuum (10 ^-3 Pa or less) by a vacuum exhaust device
And the internal atmosphere can be pressure-controlled by a mixed gas of Ar gas and hydrocarbon gas. A work coil 8 is provided around the outer periphery of the double quartz tube 5, and the graphite crucible 3 can be heated by flowing a high-frequency current to heat the raw material and the seed crystal to desired temperatures. The temperature of the crucible is measured by providing an optical path having a diameter of 2 to 4 mm at the center of the felt covering the upper and lower portions of the crucible, extracting light from the upper and lower portions of the crucible, and using a two-color thermometer. The temperature at the bottom of the crucible is the raw material temperature, and the temperature at the top of the crucible is the seed temperature.

Next, a single bond of SiC using this crystal growth apparatus
Examples of the production of crystals will be described. First, the seed crystal
Hexagonal SiC single crystal with a (0001) plane of 50 mm in diameter
A crystal wafer was prepared. Next, the seed crystal 1 is placed on the lid of the graphite crucible 3.
4 attached to the inner surface. Graphite crucible 3 (graphite purity 99.9995%
The inside of (5N5)) was filled with Si crystal lump 2. Si crystal mass 2
Purity is 99.99999% (7N) excluding carbon element impurities.
Was. Next, the graphite crucible 3 filled with the raw material is closed with the lid 4.
After covering with graphite felt 7, the graphite support rod 6
And placed inside the double quartz tube 5. And quartz
After evacuating the inside of the tube, apply current to the work coil.
Then, the raw material temperature was increased to 2000 degrees Celsius. Then the atmosphere
Ar gas and hydrocarbon gas (C_ThreeH₈)
Through the vessels 11 and 14 to reduce the pressure inside the quartz tube to about 80 kPa.
Keep the raw material temperature up to the target temperature of 2400 degrees Celsius while maintaining
Raised. The mixing ratio of the mixed gas is C_ThreeH₈/ Ar = 1/140
And Ar, C _ThreeH₈Use gas with purity of 99.9999% (6N)
Was. At the growth pressure of 1.3 kPa (hydrocarbon gas partial pressure 9 Pa)
Decompress for about 30 minutes and then grow for about 20 hours
Was. At this time, the temperature gradient in the crucible was 15 degrees Celsius / cm,
The speed was about 0.3 mm / hour. The diameter of the obtained crystal is 51mm
And the height was about 6 mm.

The silicon carbide single crystal thus obtained was analyzed by X-ray diffraction and Raman scattering.
It was confirmed that the C single crystal grew. For the purpose of evaluating the purity of the crystal, a part of the grown single crystal ingot was cut out and examined by secondary ion mass spectrometry, glow discharge mass spectrometry, and activation analysis, and found that nitrogen, boron, aluminum, iron, titanium Unavoidable impurity concentration is 1p
It was found to be less than pma.

Next, the SiC single crystal ingot produced in this manner is cut and polished to a thickness of 300 μm and a diameter of 51 mm.
A SiC single crystal wafer was fabricated. The wafer orientation is (000
1) 3.5 degrees off from the surface in the <11-20> direction. When the resistivity of this wafer was measured, it was 10 ⁵ Ωcm or more. Also,
The wafer was very transparent, and as far as observed with an optical microscope, almost no crystal defects caused by the incorporation of unavoidable impurities were observed.

Further, SiC was epitaxially grown using the 51 mm-diameter SiC single crystal wafer as a substrate. The growth conditions for the SiC epitaxial thin film were a growth temperature of 1500 degrees Celsius, a flow rate of silane (SiH ₄ ), propane (C ₃ H ₈ ), and hydrogen (H ₂ ) of 5.0 × 10 ⁻⁹ m ^{3 /} sec and 3.3 ×, respectively. 10 ^-9 m ³ / sec,
5.0 × 10 ⁻⁵ m ³ / sec. The growth pressure was atmospheric pressure.
The growth time was 2 hours, and the film was grown to a thickness of about 5 μm.

After the epitaxial thin film was grown, the surface morphology of the obtained epitaxial thin film was observed with a Nomarski optical microscope. It was found that a SiC epitaxial thin film having the same was grown.

[0023]

As described above, according to the present invention, a high-quality silicon carbide single crystal having high purity and few crystal defects can be grown with good reproducibility and uniformity by the vapor phase growth method. By using such a silicon carbide single crystal wafer, a blue light emitting element having excellent optical characteristics and a high withstand voltage / environmentally resistant electronic device having excellent electrical characteristics can be manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the improved Rayleigh method.

FIG. 2 is a configuration diagram showing an example of a single crystal growth apparatus used in the manufacturing method of the present invention.

[Explanation of symbols]

 1 ... Seed crystal (SiC single crystal) 2 ... High-purity Si crystal lump (melted during growth) 3 ... Crucible (high melting point metal such as graphite or tantalum) 4 ... Graphic crucible lid 5 ... Double quartz tube 6 ... Support rod 7 ... Graphite felt 8 ... Work coil 9 ... Ar gas pipe 10 ... Mass flow controller for Ar gas 11 ... Ar gas purifier 12 ... Hydrocarbon gas pipe 13 ... Mass flow controller for hydrocarbon gas 14 ... Hydrocarbon gas purifier 15 ... Vacuum exhaust device

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Tatsuo Fujimoto 20-1 Shintomi, Futtsu City, Chiba Prefecture Nippon Steel Corporation Technology Development Division (72) Inventor Tatsu Aigo 20-1 Shintomi, Futtsu City, Chiba Prefecture New Japan (72) Inventor Hirokatsu Yashiro 20-1 Shintomi, Futtsu-shi, Chiba F-term (Reference) 4G077 AA02 BE08 DA18 EA02 EA04 SA01 SA07

Claims (11)

[Claims] 1. A method for producing a silicon carbide single crystal, comprising the step of growing a single crystal on a seed crystal, comprising inserting a silicon raw material into a graphite crucible, and placing a carbon material in the center of the inner surface of the graphite crucible lid. After attaching a silicon single crystal seed crystal, cover the upper end opening of the crucible so that the seed crystal faces the silicon raw material, and heat and hold the crucible at 2000 to 2400 degrees Celsius in an inert gas atmosphere, And by keeping the seed crystal and the crucible lid at a lower temperature than the crucible, and reacting silicon vapor with graphite,
A method for producing a silicon carbide single crystal, comprising growing a silicon carbide single crystal on a seed crystal. 2. A method for producing a silicon carbide single crystal, comprising a step of growing a single crystal on a seed crystal, wherein a silicon raw material is inserted into a crucible, and the silicon carbide single crystal is After attaching the seed crystal, cover the upper end opening of the crucible so that the seed crystal faces the silicon raw material, heat and hold the crucible at 2,000 to 2,400 degrees Celsius in an inert gas atmosphere, and While maintaining the crystal and the crucible lid at a lower temperature than the crucible, introducing a hydrocarbon gas, and reacting silicon vapor with the hydrocarbon gas, a silicon carbide single crystal is grown on the seed crystal. A method for producing a silicon single crystal. 3. A method for producing a silicon carbide single crystal, comprising a step of growing a single crystal on a seed crystal, wherein a silicon raw material is inserted into a graphite crucible and carbonized at the center of the inner surface of the graphite crucible lid. After attaching a silicon single crystal seed crystal, cover the upper end opening of the crucible so that the seed crystal faces the silicon raw material, and heat and hold the crucible at 2000 to 2400 degrees Celsius in an inert gas atmosphere, In addition, while keeping the seed crystal and the crucible lid at a lower temperature than the crucible, introducing a hydrocarbon gas, and reacting silicon vapor with the hydrocarbon gas and graphite, a silicon carbide single crystal is grown on the seed crystal. A method for producing a silicon carbide single crystal, comprising: 4. The partial pressure of a hydrocarbon gas is 1.33 Pa to 13.3 kPa.
4. The method for producing a silicon carbide single crystal according to claim 2, wherein 5. The method for producing a silicon carbide single crystal according to claim 1, wherein the partial pressure of the inert gas is 133 Pa to 13.3 kPa. 6. A crucible for accommodating a silicon material, a crucible lid covering an upper end opening of the crucible having a seed crystal mounting portion at an inner central portion, and a heating furnace having heating means for heating the crucible. An apparatus for introducing an inert gas and a hydrocarbon gas into the heating furnace; and a vacuum system for controlling an atmosphere in the heating furnace. 7. A silicon carbide single crystal ingot, wherein the unavoidable impurity concentration in the silicon carbide single crystal is less than 1 ppma. 8. A silicon carbide single crystal ingot obtained by any one of the manufacturing methods according to claim 1, wherein the ingot has an unavoidable impurity concentration of less than 1 ppma. Single crystal ingot. 9. The silicon carbide single crystal ingot according to claim 7, wherein the diameter of the ingot is 50 mm or more. 10. A silicon carbide single crystal substrate obtained by cutting and polishing the silicon carbide single crystal ingot according to claim 7. 11. A silicon carbide epitaxial wafer epitaxially grown on the silicon carbide single crystal substrate according to claim 10.