WAFER INSPECTION METHOD AND APPARATUS USING DIFFRACTED LIGHT

Defects in a processed or partly processed semiconductor wafer, or other similar three-dimensional periodic pattern formed on a substrate surface, are detected by light diffraction. Incident monochromatic light is provided from an elongated and extended source to illuminate the entire wafer surface. By use of automated image processing techniques, wafer macro inspection is thereby automated. The elongated and extended light source allows light at different angles to be incident upon each point of the wafer surface, thereby allowing defect detection for an entire wafer surface in a single field of view and reducing inspection time. The particular wavelength of the incident monochromatic light is predetermined to allow optimum detection of defects in the periodic pattern on the wafer, depending on the width and pitch of the features of the periodic pattern.