Patent ID: 6486946
Filing Date: 2002-11-26
Classification: G01N

Abstract:
A method for detecting defects on a surface of a film-covered substrate and for discriminating between particles on the film and holes in the film, the method comprising:directing a first beam of light having a predominant P-polarized component onto the substrate at a first incident angle such that the light is scattered by any defect present at or in the film; detecting a first intensity of light back-scattered over one or more regions of space caused by the first beam; directing a second beam of light having a predominant P-polarized component onto the substrate at a second incident angle that is angularly displaced substantially farther from a surface normal than the first beam; detecting a second intensity of light back-scattered over said one or more regions caused by the second beam; and classifying a detected defect as either a particle on the film or a hole in the film based on relative magnitudes of the first and second intensities.