A high sensitivity and high throughput surface inspection system directs a
focused beam of light at a grazing angle towards the surface to be
inspected. Relative motion is caused between the beam and the surface so
that the beam scans a scan path covering substantially the entire surface
and light scattered along the path is collected for detecting anamolies.
The scan path comprises a plurality of arrays of straight scan path
segments. The focused beam of light 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).