Patent ID: 7528942

Claim:
A method for detecting a defect, comprising the steps of: irradiating a slit shaped area on a specimen with a circuit pattern including a repetitive pattern formed thereon which is covered with an optically transparent film with a slit shaped light from an oblique direction; detecting light scattered from the specimen by the irradiation of light in a direction of a first elevation angle with respect to said specimen by blocking light diffracted from said repetitive pattern, among light from the specimen, thereby obtaining a first detection signal; detecting light scattered from the specimen by the irradiation of light in a direction of a second elevation angle which is lower than said direction of the first elevation angle with respect to said specimen by blocking light diffracted from said repetitive pattern, among light from the specimen, thereby obtaining a second detection signal; and processing said first detection signal and said second detection signal to detect a defect including foreign matter on the specimen, wherein in the step of detecting light scattered from the specimen in a direction of the second elevation angle, said second elevation angle is set so as to reduce detection of light scattered from inside the optically transparent film.