Patent ID: 6879390
Filing Date: 2005-04-12
Classification: G01N

Abstract:
1. An optical inspection system for inspecting the surface of a reticle, mask, or semiconductor wafer for defects along a linear scan path, the optical inspection system comprising: a light source for emitting an incident light beam along an optical axis; a first set of optical elements arranged for separating the incident light beam into a plurality of light beams, directing the plurality of light beams to intersect with the surface of the reticle, mask, or semiconductor wafer, focusing the plurality of light beams to a plurality of scanning spots on the surface of the reticle, mask, or semiconductor wafer, and sweeping the plurality of light beams so as to move the plurality of scanning spots along the surface of the reticle, mask, or semiconductor wafer in a direction that traverses the direction of the linear scan path, the plurality of light beams working together to increase the speed of inspection, the first set of optical elements being arranged for separating the incident light beam into a plurality of spatially distinct light beams, which are offset and staggered relative to one another, the plurality of spatially distinct light beams consist of a first light beam, a second light beam and a third light beam, all of which have about the same light intensity, the first light beam having about a same angular scan rate as the incident light beam and the second and third light beams having a different and non-linear scan rate relative to the incident light beam; and a light detector arrangement including individual light detectors that correspond to individual ones of a plurality of reflected or transmitted light beams caused by the intersection of the plurality of light beams with the surface of the reticle mask, or semiconductor wafer, the light detectors being arranged for sensing the light intensity of either the reflected or transmitted light.