IMPROVED DEFECT DETECTION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a detection system capable of distinguishing between micro-scratches and particles. SOLUTION: Scattered light from a sample surface (20a) is collected by means of collectors (38, 52) that collects light substantially symmetrically about a line perpendicular to the surface (20a). The collected light is directed to channels at different azimuthal angles so that information related to relative azimuthal positions of the collected scattered light about the line is preserved. The collected light is converted into respective signals representative of light scattered at different azimuthal angles about the line. The presence and/or characteristics of anomalies are determined from the signals. Alternatively, the light collected by the collectors (38, 52) obtained from the narrow and wide collection channels may be compared to distinguish between micro-scratches and particles. Forward scattered light may be collected from other light and compared to distinguish between micro-scratches and particles. Intensity of scattering is measured when the surface is illuminated sequentially by S- and P-polarized light and compared to distinguish between micro-scratches and particles. COPYRIGHT: (C)2009,JPO&INPIT