Epitaxial silicon carbide single crystal wafer and process for producing the same
An epitaxial silicon carbide single crystal wafer and a method for producing the same, wherein the epitaxial silicon carbide single crystal wafer is produced by forming a buffer layer made of a silicon carbide epitaxial film having a thickness of 1 μm or more and 10 μm or less by adjusting the ratio of the number of carbon to that of silicon (C/Si ratio) contained in a silicon-based and carbon-based material gas to 0.5 or more and 1.0 or less, and then by forming a drift layer made of a silicon carbide epitaxial film at a growth rate of 15 μm or more and 100 μm or less per hour, thereby bringing a depth of shallow pits observed on the surface of the drift layer to 30 nm or less.
1. A method for producing an epitaxial silicon carbide single crystal wafer by thermal chemical vapor deposition, said method comprising:
allowing a silicon-based and carbon-based material gas to flow over a silicon carbide single crystal substrate having an off angle of 4° or less, which is an angle tilted in a <11-20> direction with respect to a (0001) plane;
forming a buffer layer, consisting of a silicon carbide epitaxial film having a thickness of 5 μm or more and 10 μm or less, by adjusting a ratio of a number of carbon atoms to that of silicon atoms (C/Si ratio) in the silicon-based and carbon-based material gas to 0.5 or more and 1.0 or less;
forming a drift layer, consisting of a silicon carbide epitaxial film, at a growth rate of more than 50 μm and 100 μm or less per hour; and
bringing a depth of shallow pits observed on a surface of the drift layer to 19 nm or less.
2. The method according to claim 1 , comprising:
growing the buffer layer at a growth rate of 1 μm or more and 10 μm or less per hour; and
growing the drift layer at an atomic ratio (C/Si ratio) of 1.0 or more and 2.0 or less.