Patent ID: 8681328

Claim:
A dark-field defect inspecting method of obtaining, by a first sensor of a detection system, a signal of scattered light occurring due to illumination light illuminating a surface of an inspection subject, from the surface of the inspection subject and detecting a foreign substance or a defect on the inspection subject based on the signal obtained by the first sensor, the method comprising: an illumination light monitoring step of measuring either one or both of an intensity distribution and a polarization state distribution of the illumination light; a detection system monitoring step of detecting an imaging characteristic of a detection lens and a state of operation of a stage on which the inspection subject is placed, by detecting light input to the detection system by a second sensor; and a feedback control step of comparing detection results in the illumination light monitoring step and the detection system monitoring step and predetermined values and adjusting either one or both of the illumination light and the detection system so that differences between the detection results and the predetermined values are each equal to or smaller than an allowable value.