SiC epitaxial wafer and method for manufacturing SiC epitaxial wafer
A SiC epitaxial wafer according to the present embodiment includes: a SiC substrate; and a SiC epitaxial layer laminated on the SiC substrate, in which a carrier concentration uniformity of the SiC epitaxial layer is less than 3.8%, and the carrier concentration uniformity is a value obtained by dividing, by an average value, a difference between a maximum value and a minimum value of carrier concentrations of the SiC epitaxial layer measured along a straight line passing through a center of the SiC epitaxial layer when seen in a plan view.
1 . A SiC epitaxial wafer comprising:
a SiC substrate; and
a SiC epitaxial layer laminated on the SiC substrate,
wherein a carrier concentration uniformity of the SiC epitaxial layer is less than 3.8%,
the carrier concentration uniformity is a value obtained by dividing, by an average value, a difference between a maximum value and a minimum value of carrier concentrations of the SiC epitaxial layer measured along a straight line passing through a center of the SiC epitaxial layer when seen in a plan view, and
the measurement points for the carrier concentration of the SiC epitaxial layer when determining the carrier concentration uniformity include points 5 mm from the outer periphery.
2 . The SiC epitaxial wafer according to claim 1 , wherein a diameter of the SiC substrate is 149 mm or more.
3 . The SiC epitaxial wafer according to claim 1 , wherein a diameter of the SiC substrate is 199 mm or more.
4 . A method for manufacturing a SiC epitaxial wafer, the method comprising
a film formation step of forming a SiC epitaxial layer on one surface of a SiC substrate,
wherein a growth rate of the SiC epitaxial layer is 61 μm/h or more,
a film formation temperature for an inner region of the SiC epitaxial layer in the film formation step is lower than ±1° C. with respect to an average temperature in the inner region,
a film formation temperature for an outer region of the SiC epitaxial layer in the film formation step is lower than a temperature of an outermost circumference of the inner region by equal to or higher than 2° C. and lower than 10° C.,
the inner region is a region on an inner side of a concentric circle having a center position coinciding with a center of the SiC substrate and having a diameter that is 80% of a diameter of the SiC substrate, and
the outer region is a region on an outer side of the inner region.
5 . The method for manufacturing a SiC epitaxial wafer according to claim 4 , wherein the diameter of the SiC substrate is 149 mm or more.
6 . The method for manufacturing a SiC epitaxial wafer according to claim 4 , wherein the diameter of the SiC substrate is 199 mm or more.
7 . The SiC epitaxial wafer according to claim 1 , wherein a carrier concentration uniformity of the SiC epitaxial layer is 3.0% or less.
8 . The SiC epitaxial wafer according to claim 1 , wherein a carrier concentration uniformity of the SiC epitaxial layer is 2.4% or less.
9 . The SiC epitaxial wafer according to claim 1 , wherein a carrier concentration uniformity of the SiC epitaxial layer is 1.0% or less.
10 . The SiC epitaxial wafer according to claim 1 , wherein the SiC epitaxial layer contain boron or aluminum,
the carrier concentrations of boron and aluminum are each be 1.0×10 14 cm −3 or less at all measurement points as in the case of the carrier concentration.
11 . The method for manufacturing a SiC epitaxial wafer according to claim 4 , wherein the film formation temperature for the outer region of the SiC epitaxial layer in the film formation step is lower than the temperature of an outermost circumference of the inner region by equal to or higher than 4° C.