Method for manufacturing silicon carbide epitaxial substrate, silicon carbide epitaxial substrate, method for manufacturing silicon carbide semiconductor device, and silicon carbide semiconductor device
A method for manufacturing a silicon carbide epitaxial substrate includes epitaxially growing a first layer on a silicon carbide single crystal substrate, and forming a second layer at an outermost surface of the first layer. The second layer has a chemical composition or density different from that of the first layer. A ratio of a thickness of the second layer to a thickness of the first layer is more than 0% and less than or equal to 10%.
1. A silicon carbide epitaxial substrate, comprising:
a silicon carbide single crystal substrate; and
an epitaxial layer formed on the silicon carbide single crystal substrate;
an arithmetic average roughness in a surface of the epitaxial layer being less than or equal to 0.1 nm,
in the surface,
carrot defects having a defect density of less than or equal to 0.1/cm 2 ,
trapezoidal defects, which are trapezoidal depressions, having a defect density of less than or equal to 0.1/cm 2 ,
the trapezoidal defects each including an upper base portion and a lower base portion intersecting with a <11-20> direction when viewed in plan view,
the upper base portion having a width of more than or equal to 0.1 μm and less than or equal to 100 μm, and the lower base portion having a width of more than or equal to 50 μm and less than or equal to 5000 μm,
the upper base portion including a protruding portion, and the lower base portion including a plurality of step bunchings.
2. A method for manufacturing a silicon carbide semiconductor device, comprising:
preparing the silicon carbide epitaxial substrate according to claim 1 ; and
forming a silicon oxide film on the epitaxial layer.
3. The silicon carbide epitaxial substrate according to claim 1 , wherein the silicon carbide single crystal substrate has a diameter of more than or equal to 150 mm and less than or equal to 300 mm.
4. The silicon carbide epitaxial substrate according to claim 1 , wherein the silicon carbide single crystal substrate has a main surface inclined from a (0001) plane or a (000-1) plane by more than or equal to 1° and less than or equal to 8°, and the epitaxial layer formed on the main surface.
5. The silicon carbide epitaxial substrate according to claim 1 , wherein the defect density of the carrot defects is more than zero.
6. The silicon carbide epitaxial substrate according to claim 1 , wherein the defect density of the trapezoidal defects is more than zero.