Patent ID: 7764367

Claim:
A surface inspection method for detecting contaminant particles and defects present on a surface of an object to be inspected or in the interior of the object to be inspected in the vicinity of the surface by irradiating a region of a predetermined size on the surface of the object to be inspected with an irradiation beam, comprising: a photodetection step of detecting light that derives from the irradiation beam and is scattered, diffracted or reflected on the surface of the object to be inspected or in the vicinity of the surface by use of a plurality of photodetectors in a plurality of directions; and a contaminant particle detection step that involves performing weighted addition processing or weighted averaging processing by linear combination for signals detected by the plurality of photodetectors and detecting a contaminant particle and a defect from results of the weighted addition processing or weighted averaging processing; wherein the weighted addition processing or the weighted averaging processing in the contaminant particle detection step is performed so that among output signals from the plurality of photodetectors, the contribution rate of an output signal with a high noise level decreases; a signal processing step that involves dividing a plurality of detection signals detected by the plurality of photodetectors into signals for two systems each, and taking out a first signal component generated by deriving from roughness of the surface of the object to be inspected, which belongs to the light scattered, diffracted or reflected from the surface of the object to be inspected or in the vicinity of the surface, and a second signal component generated by deriving from a contaminant particle or a defect on the surface of the object to be inspected or in the vicinity of the surface, which belongs to the light scattered, diffracted or reflected from the surface of the object to be inspected or in the vicinity of the surface, wherein in the contaminant particle detection step, a weighting factor for the weighted addition processing or the weighted averaging processing is determined by using the first signal component and the weighted addition processing or the weighted averaging processing of the second signal component is performed.