The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 01, 2025
Filed:
Jun. 30, 2022
Fuji Electric Co., Ltd., Kawasaki, JP;
Yasuyuki Kawada, Kanagawa, JP;
FUJI ELECTRIC CO., LTD., Kawasaki, JP;
Abstract
After trench etching but before formation of a gate insulating film, a 15-minute to 60-minute heat treatment under a mixed gas atmosphere containing nitric oxide gas and nitrogen gas at a temperature from 1200 degrees C. to 1350 degrees C. and a 30-minute to 75-minute heat treatment under a nitrogen gas atmosphere held at the temperature of the 15-minute to 60-minute heat treatment are successively performed, oxidizing etching damage of inner walls of trenches. The total treatment time of the heat treatments includes a total time of at least 90 minutes when the temperature is a predetermined maximum temperature. The oxide layer of the trench inner walls is removed, exposing a clean face. Emission intensity of band edge emission for SiC obtained by CL analysis of surface areas of the inner walls of the trenches is at least equal to the emission intensity of the band edge emission for SiC obtained by the CL analysis of a surface free of dry etching.