Silicon carbide wafer and silicon carbide semiconductor device including the same
View Patent ↗A silicon carbide wafer includes a substrate made of silicon carbide and an epitaxial layer made of silicon carbide and disposed on the substrate. A concentration of carbon vacancies in the substrate and the epitaxial layer continuously decreases from the substrate toward the epitaxial layer. The concentration of the carbon vacancies in the substrate is 3.0×10 15 cm −3 or more.
1 . A silicon carbide wafer comprising:
a substrate made of silicon carbide; and
an epitaxial layer made of silicon carbide and disposed on the substrate, wherein
a concentration of carbon vacancies in the substrate and the epitaxial layer continuously decreases from the substrate toward the epitaxial layer,
the concentration of the carbon vacancies in the substrate is 3.0×10 15 cm −3 or more, and
the substrate has a specific resistance of 30 mΩ·cm or less.
2 . The silicon carbide wafer according to claim 1 , wherein
the substrate contains impurities including at least one element selected from a group consisting of boron, aluminum, titanium, vanadium, sulfur, iron, niobium, and tantalum.
3 . The silicon carbide wafer according to claim 1 , wherein
the epitaxial layer has a thickness of 4 to 40 μm and includes a portion having an impurity concentration of 1.0×10 15 to 1.0×10 19 cm −3 .
4 . The silicon carbide wafer according to claim 3 , wherein
the epitaxial layer includes a buffer layer disposed on the substrate and a drift layer disposed on the buffer layer,
the buffer layer has an impurity concentration of 1.0×10 18 to 1.0×10 19 cm −3 , and
the drift layer has an impurity concentration of 1.0×10 15 to 5.0×10 16 cm −3 .
5 . A silicon carbide semiconductor device comprising:
a silicon carbide wafer including:
a substrate made of silicon carbide and having a first conductivity type; and
an epitaxial layer made of silicon carbide and disposed on the substrate, the epitaxial layer including a drift layer and a base layer, the drift layer having the first conductivity type and disposed close to the substrate, the base layer disposed on the drift layer; and
a source region of the first conductivity type disposed in a surface layer portion of the base layer, wherein
a concentration of carbon vacancies in the substrate and the epitaxial layer continuously decreases from the substrate toward the epitaxial layer,
the concentration of the carbon vacancies in the substrate is 3.0×10 15 cm −3 or more,
the substrate has a specific resistance of 30 mΩ·cm or less.
6 . A silicon carbide semiconductor device comprising:
a silicon carbide wafer including:
a substrate made of silicon carbide and having a first conductivity type; and
an epitaxial layer made of silicon carbide and disposed on the substrate, wherein
the substrate constitutes a part of a diode,
a concentration of carbon vacancies in the substrate and the epitaxial layer continuously decreases from the substrate toward the epitaxial layer,
the concentration of the carbon vacancies in the substrate is 3.0×10 15 cm −3 or more,
the substrate has a specific resistance of 30 mΩ·cm or less.
7 . A silicon carbide wafer comprising:
a substrate made of silicon carbide; and
an epitaxial layer made of silicon carbide and disposed on the substrate,
wherein a concentration of carbon vacancies in the substrate and the epitaxial layer continuously decreases from the substrate toward the epitaxial layer,
the concentration of the carbon vacancies in the substrate is 3.0×10 15 cm −3 or more, and
the epitaxial layer has a thickness of 4 to 40 μm and includes a portion having an impurity concentration of 1.0×10 15 to 1.0×10 19 cm −3 .
8 . The silicon carbide wafer according to claim 7 , wherein
the substrate contains impurities including at least one element selected from a group consisting of boron, aluminum, titanium, vanadium, sulfur, iron, niobium, and tantalum.
9 . The silicon carbide wafer according to claim 7 , wherein
the epitaxial layer includes a buffer layer disposed on the substrate and a drift layer disposed on the buffer layer,
the buffer layer has an impurity concentration of 1.0×10 18 to 1.0×10 19 cm −3 , and
the drift layer has an impurity concentration of 1.0×10 15 to 5.0×10 16 cm −3 .