SiC substrate evaluation method and method for manufacturing SiC epitaxial wafer
In a SiC substrate evaluation method, a bar-shaped stacking fault is observed by irradiating a surface of a SiC substrate before stacking an epitaxial layer with excitation light and extracting light having a wavelength range from equal to or greater than 405 nm and equal to or less than 445 nm among photoluminescence light beams emitted from the first surface.
1. A SiC substrate evaluation method, comprising:
observing a bar-shaped stacking fault by irradiating a first surface of a SiC substrate before stacking an epitaxial layer with excitation light and extracting light having a wavelength range of equal to or greater than 405 nm and equal to or less than 445 nm among photoluminescence light beams emitted from the first surface,
wherein the first surface of the SiC substrate has an offset angle from a {0001} plane, an irradiation time of the excitation light is equal to or greater than 1 msec and equal to or less than 10 sec, and an intensity of the excitation light is equal to or less than 1 W/cm 2 , and
wherein the bar-shaped stacking fault extends in a bar shape in a direction substantially perpendicular to the offset direction, the bar-shaped stacking fault has a length in a direction substantially perpendicular to the offset direction with respect to a width in the offset direction is long and the bar-shaped stacking fault has an aspect ratio (length/width) is equal to or greater than 2, and
wherein the offset direction is the direction of a vector obtained by projecting a normal vector of a {0001} plane onto the first surface of the SiC substrate.
2. The SiC substrate evaluation method, according to claim 1 , wherein a wavelength of the excitation light is equal to or greater than 200 nm and equal to or less than 390 nm.
3. The SiC substrate evaluation method, according to claim 1 , wherein the bar-shaped stacking fault is a single Shockley-type stacking fault extending in a bar shape in a direction substantially perpendicular to an offset direction.
4. A method for manufacturing a SiC substrate, comprising:
an evaluation step of evaluating the first surface of the SiC substrate using the SiC substrate evaluation method according to claim 1 ;
a determination step of determining whether to stack an epitaxial layer on the basis of results of the evaluation step; and
a growing step of growing an epitaxial layer on the first surface on the basis of results of the determination step.