SCANNING SYSTEM FOR INSPECTING ANOMALIES ON SURFACES

摘要

A high sensitivity and high throughput surface inspection system directs a focused beam of light (38) at a grazing angle towards the surface to be inspected (40). Relative motion is caused between the beam (38) and the surface (40) so that the beam (38) scans a scan path covering substantially the entire surface and light scattered along the path is collected for detecting anomalies. The scan path comprises a plurality of arrays of straight scan path segments. The focused beam of light (38) illuminates an area of the surface between 5-15 microns in width and this system is capable of inspecting in excess of about 40 wafers per hour for 150 millimeter diameter wafers (6-inch wafers), in excess of about 20 wafers per hour for 200 millimeter diameter wafers (8-inch wafers) and in excess of about 10 wafers per hour for 300 millimeter diameter wafers (12-inch wafers).