Silicon carbide epitaxial substrate and method of manufacturing silicon carbide semiconductor device

A silicon carbide epitaxial substrate comprising:

• a silicon carbide single-crystal substrate having a first main surface;
• and
• a silicon carbide layer on the first main surface,
• the silicon carbide layer having a second main surface opposite to a surface thereof in contact with the silicon carbide single-crystal substrate,
• the second main surface having a maximum diameter of not less than 100 mm,
• the second main surface having a peripheral region within 5 mm from an outer edge of the second main surface, and a central region surrounded by the peripheral region,
• the silicon carbide layer having a central surface layer including the central region,
• an average value of a carrier concentration in the central surface layer being not less than 1×1014 cm−3 and not more than 5×1016 cm−3,
• circumferential uniformity of the carrier concentration being not more than 2%, and in-plane uniformity of the carrier concentration being not more than 10%,
• an average value of a thickness of a portion of the silicon carbide layer sandwiched between the central region and the silicon carbide single-crystal substrate being not less than 5 μm,
• circumferential uniformity of the thickness being not more than 1%, and in-plane uniformity of the thickness being not more than 4%,
• the circumferential uniformity of the carrier concentration being a ratio of an absolute value of a difference between a maximum value and a minimum value of the carrier concentration in the central surface layer in a circumferential direction, to an average value of the carrier concentration in the central surface layer in the circumferential direction,
• the in-plane uniformity of the carrier concentration being a ratio of an absolute value of a difference between a maximum value and a minimum value of the carrier concentration in the central surface layer in the entire central region, to an average value of the carrier concentration in the central surface layer in the entire central region,
• the circumferential uniformity of the thickness being a ratio of an absolute value of a difference between a maximum value and a minimum value of the thickness of the portion in the circumferential direction, to an average value of the thickness of the portion in the circumferential direction,
• the in-plane uniformity of the thickness being a ratio of an absolute value of a difference between a maximum value and a minimum value of the thickness of the portion in the entire central region, to an average value of the thickness of the portion in the entire central region.