Silicon carbide single crystal, silicon carbide single crystal wafer, and method of production of same
View Patent ↗The present invention provides a high resistivity, high quality, large size SiC single crystal, SiC single crystal wafer, and method of production of the same, that is, a silicon carbide single crystal containing uncompensated impurities in an atomic number density of 1×10 15 /cm 3 or more and containing vanadium in an amount less than said uncompensated impurity concentration, silicon carbide single crystal wafer obtained by processing and polishing the silicon carbide single crystal and having an electrical resistivity at room temperature of 5×10 3 Ωcm or more, and a method of production of a silicon carbide single crystal.
1. A method of production of a silicon carbide single crystal, comprising:
sublimation recrystallization of a sublimating material onto a seed crystal comprising silicon carbide in a graphite crucible, thereby growing a single crystal containing an uncompensated impurity in a concentration of at least 1×10 15 /cm 3 and not more than 1×10 17 /cm 3 and containing vanadium in a concentration of less than the concentration of said uncompensated impurity; wherein the difference in concentrations of said uncompensated impurity and said vanadium is such that said single crystal has an electrical resistivity at room temperature of at least 1.19×10 10 Ωcm,
wherein the graphite crucible has a nitrogen concentration of not more than 50 ppm as measured by an inert gas fusion thermal conductivity method, and
the sublimating material comprises a mixture of silicon carbide and vanadium or a mixture of silicon carbide and a vanadium compound.
2. The method of production of a silicon carbide single crystal as set forth in claim 1 , wherein the graphite crucible has a nitrogen concentration of not more than 20 ppm.
3. The method of production of a silicon carbide single crystal as set forth in claim 1 , wherein the graphite crucible has a nitrogen concentration of not more than 10 ppm.
4. The method of production of a silicon carbide single crystal as set forth in claim 1 , further comprising holding the graphite crucible in an inert gas atmosphere at a pressure of not more than 1.3 Pa at a temperature of 1400° C. or more for 10 hours to less than 120 hours.
5. The method of production of a silicon carbide single crystal as set forth in claim 1 , further comprising charging the graphite crucible with a powder comprising silicon carbide and, holding the graphite crucible and silicon carbide powder in an inert gas atmosphere at a pressure of not more than 1.3 Pa at a temperature of 1400 to 1800° C. for 10 hours to less than 120 hours,
placing a seed crystal in the graphite crucible,
adding the sublimating material to the graphite crucible,
heating the graphite crucible, sublimating material, and seed crystal in an inert gas atmosphere at a pressure of 1.3×10 2 to 1.3×10 4 Pa at 2000° C. or more, and then starting crystal growth.
6. The method of production of a silicon carbide single crystal as set forth in claim 4 , wherein the pressure is 1.3×10 −1 Pa or less.
7. The method of production of a silicon carbide single crystal as set forth in claim 4 , wherein the pressure is 6.5×10 −2 Pa or less.
8. The method of production of a silicon carbide single crystal as set forth in claim 4 , wherein after heating the crucible in an inert atmosphere, the graphite crucible is used for crystal growth without being exposed to the atmosphere.