SMALL DEFECT DETECTION SENSITIVE, LOW COST SPECIMEN INSPECTION SYSTEM

摘要

A method of detecting defects (60) in or on an unpatterned surface (26) of a specimen (28) entails scanning a light beam (20) across the unpatterned surface and collecting with a camera (42) measurement light scattered by defects in or on the unpatterned surface. The camera cooperates with imaging optics (40) and includes an array of light sensitive sensor elements. Portions of the measurement light propagating from the imaging optics and impinging on the light sensitive sensor elements correspond to imaged sensor element (64) areas of different light scattering regions of the unpatterned surface where defects are present. The portions of measurement light are substantially free from contributions of background light scattered by the imaged sensor element areas of neighboring ones of the light scattering regions encompassed within the beam spot area at any instant as the light beam is scanned. The result is a higher degree of defect detection sensitivity.