This embodiment comprises: a step for preparing a sample wafer; a step for forming a first oxide film on the sample wafer at a temperature of 700-800° C.; a step for forming a second oxide film on the first oxide film at a temperature of 800-1000° C.; a step for forming a third oxide film on the second oxide film at a temperature of 1000-1100° C.; a step for forming a fourth oxide film on the third oxide film at a temperature of 1100-1200° C.; a step for removing the first to fourth oxide films; a step for forming a haze on the surface of the sample wafer by etching the sample wafer from which the first to fourth oxide films have been removed; and a step for evaluating a defective region of the sample wafer on the basis of the haze.