Silicon carbide epitaxial substrate having grooves extending along main surface and method of manufacturing silicon carbide semiconductor device
A silicon carbide epitaxial substrate has a silicon carbide single-crystal substrate and a silicon carbide layer. An average value of carrier concentration in the silicon carbide layer is not less than 1×10 15 cm −3 and not more than 5×10 16 cm −3 . In-plane uniformity of the carrier concentration is not more than 2%. The second main surface has: a groove 80 extending in one direction along the second main surface, a width of the groove in the one direction being twice or more as large as a width thereof in a direction perpendicular to the one direction, and a maximum depth of the groove from the second main surface being not more than 10 nm; and a carrot defect. A value obtained by dividing a number of the carrot defects by a number of the grooves is not more than 1/500.
1. A silicon carbide epitaxial substrate comprising:
a silicon carbide single-crystal substrate including a first main surface; and
a silicon carbide layer on the first main surface,
the silicon carbide layer including a second main surface opposite to a surface thereof in contact with the silicon carbide single-crystal substrate,
an average value of carrier concentration in the silicon carbide layer being not less than 1×10 15 cm −3 and not more than 5×10 16 cm −3 ,
in-plane uniformity of the carrier concentration being not more than 2%,
the second main surface having
grooves extending in one direction along the second main surface, a width of each of the grooves in the one direction being twice or more as large as a width thereof in a direction perpendicular to the one direction, and a maximum depth of each of the grooves from the second main surface being not more than 10 nm, and
one or more carrot defects,
a value obtained by dividing a number of the one or more carrot defects by a number of the grooves being not more than 1/500,
the silicon carbide single-crystal substrate having a diameter of not less than 150 mm.
2. The silicon carbide epitaxial substrate according to claim 1 , wherein
each of the grooves includes a first groove portion and a second groove portion provided continuously with the first groove portion,
the first groove portion is at one end portion of each of the grooves in the one direction, and
the second groove portion extends from the first groove portion along the one direction to the other end portion opposite to the one end portion, and has a depth from the second main surface which is smaller than a maximum depth of the first groove portion.
3. The silicon carbide epitaxial substrate according to claim 1 , wherein
the value is not more than 1/1000.
4. The silicon carbide epitaxial substrate according to claim 3 , wherein
the value is not more than 1/5000.
5. The silicon carbide epitaxial substrate according to claim 1 , wherein
a density of the carrot defects in the second main surface is not more than 1 cm −2 .
6. The silicon carbide epitaxial substrate according to claim 5 , wherein
the density is not more than 0.5 cm −2 .
7. The silicon carbide epitaxial substrate according to claim 6 , wherein
the density is not more than 0.1 cm −2 .
8. A method of manufacturing a silicon carbide semiconductor device, comprising:
preparing the silicon carbide epitaxial substrate according to claim 1 ; and
processing the silicon carbide epitaxial substrate.
9. The silicon carbide epitaxial substrate according to claim 1 , wherein the first main surface is a plane tilted in a <11-20> direction at an angle of not more than 4° from a {0001} plane.