Patent ID: 6636302
Filing Date: 2003-10-21
Classification: G01N

Abstract:
A method for detecting anomalies on a surface of a semiconductor wafer; comprising:directing a focused beam of radiation towards said surface to illuminate an area of the surface defining a spot having a spot size whose minimum width is in the range of about 5 to 15 microns; causing relative motion between the beam and the wafer by an acousto-optic deflector so that the beam scans a path covering substantially the entire surface; and collecting radiation scattered along said path at one or more detectors positioned away from any specular reflection direction of the beam from the surface for detecting anomalies; wherein the spot size and said directing and causing are such that the beam substantially inspects the entire surface of the wafer at a throughput in excess of about 40 wafers per hour for 150 mm diameter wafers, at a throughput in excess of about 20 wafers per hour for 200 mm diameter wafers, or at a throughput in excess of about 10 wafers per hour for 300 mm diameter wafers.