Method for manufacturing silicon carbide epitaxial substrate, and silicon carbide epitaxial substrate
A method for manufacturing a silicon carbide epitaxial substrate includes: a step of placing a silicon carbide single crystal substrate within a chamber and reducing a pressure within the chamber; a step of increasing a temperature within the chamber to a first temperature; a step of introducing hydrogen gas into the chamber and adjusting the pressure within the chamber; a step of introducing hydrocarbon gas into the chamber; a substrate reforming step of increasing the temperature within the chamber to a second temperature and holding the temperature at the second temperature for a predetermined time, with the adjusted pressure within the chamber and a flow rate of the hydrogen gas being maintained and the hydrocarbon gas being introduced; and a step of growing an epitaxial layer on the silicon carbide single crystal substrate by introducing silane gas into the chamber with the second temperature being maintained.
1. A silicon carbide epitaxial substrate, comprising:
a silicon carbide single crystal substrate having a main surface inclined relative to a {0001} plane by more than or equal to 1° and less than or equal to 8°; and
an epitaxial layer formed on the silicon carbide single crystal substrate,
trapezoidal defects disposed in a surface of the epitaxial layer, the trapezoidal defects, which are trapezoidal depressions, having a defect density of less than or equal to 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,
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,
the lower base portion including a plurality of step bunchings,
wherein the defect density of the trapezoidal defects is more than zero.
2. 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 100 mm.
3. The silicon carbide epitaxial substrate according to claim 1 , wherein the epitaxial layer has a thickness of more than or equal to 5 μm and less than or equal to 30 μm.
4. A silicon carbide epitaxial substrate, comprising:
a silicon carbide single crystal substrate having a main surface inclined relative to a {0001} plane by more than or equal to 1° and less than or equal to 8° and having a diameter of more than or equal to 100 mm; and
an epitaxial layer formed on the silicon carbide single crystal substrate and having a thickness of more than or equal to 5 μm and less than or equal to 30 μm,
trapezoidal defects disposed in a surface of the epitaxial layer, the trapezoidal defects, which are trapezoidal depressions, having a defect density of less than or equal to 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,
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,
the lower base portion including a plurality of step bunchings,
wherein the defect density of the trapezoidal defects is more than zero.