US 12,228,523 B2
Method of evaluating SiC substrate, method of manufacturing SiC epitaxial wafer, and method of manufacturing SiC device
Ling Guo, Chichibu (JP)
Assigned to Resonac Corporation, Tokyo (JP)
Filed by SHOWA DENKO K.K., Tokyo (JP)
Filed on Sep. 1, 2020, as Appl. No. 17/009,130.
Claims priority of application No. 2019-159584 (JP), filed on Sep. 2, 2019.
Prior Publication US 2021/0063321 A1, Mar. 4, 2021
Int. Cl. G01N 21/95 (2006.01); C30B 23/00 (2006.01); C30B 29/36 (2006.01); G01N 21/64 (2006.01); H01L 21/66 (2006.01); H01L 21/78 (2006.01)
CPC G01N 21/9505 (2013.01) [C30B 23/00 (2013.01); C30B 29/36 (2013.01); G01N 21/6489 (2013.01); H01L 22/12 (2013.01); H01L 21/78 (2013.01); H01L 22/20 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A method of evaluating a SiC substrate which is used for forming a SiC epitaxial layer thereon, comprising:
a preparation step of preparing two or more SiC substrates before a SiC epitaxial layer is formed, wherein the SiC substrates are used for forming a SiC epitaxial layer and are obtained from the same SiC ingot grown from the same seed crystal,
a defect position specifying step of specifying positions of defects in the substrates by observing a main surface of each of the two or more SiC substrates before a SiC epitaxial layer is formed, with a confocal differential interference microscope or an optical surface inspection device, and
a comparison step of comparing the positions of the defects of the two or more SiC substrates, wherein,
in the preparation step, a SiC substrate positioned closest to the seed crystal is used as a reference wafer among the two or more SiC substrates, and
the comparison step comprises a sub-step wherein
a first defect of the reference wafer is compared with a second defect of a SiC substrate other than the reference wafer,
it is judged whether a defect distance of the two compared defects in a [11-20] direction is 0.6 mm or more or less than 0.2 mm, and
the two compared defects are determined to be defects not associated with the same threading defect when the defect distance is 0.6 mm or more, and
the two compared defects are determined to be defects associated with the same threading defect when the defect distance is less than 0.2 mm.