Method of forming thin film for minimizing increase in defects at interface during high-temperature oxidation process

A method of forming a thin film to minimize an increase in defects at an interface during a high-temperature oxidation process of a SiC substrate, the method comprising:

• depositing a first thin film on the SiC substrate by applying a OH radical gas, wherein the first thin film is composed of an insulating layer of SiO2;
• forming an oxide film on the first thin film by performing the high-temperature oxidation process;
• and
• performing annealing on the oxide film,
• wherein the step of depositing the first thin film is performed before the step of the forming an oxide film and the step of the performing annealing, and
• in the step of depositing the first thin film, the radical gas comprised of OH radicals generates by-products which react with at least some of carbons in the SIC substrate and are vaporized.