Patent ID: 6369888
Filing Date: 2002-04-09
Classification: G01N,G02B,G03F

Abstract:
In the inspection of a patterned article used in the manufacture of semiconductor devices, a method of reducing speckle, said method comprising:effecting relative movement between an illuminating beam and said patterned article, said illuminating beam being obtained by modifying a coherent light beam so as to break, at least partially, its coherence; said modifying of said coherent light beam comprising: disposing a plurality of optical fiber bundles sequentially along a light path between a source of said illuminating beam and the patterned article, each of said plurality of fiber bundles having a predetermined number of fibers, each of said fibers having an input and an output, each of said fibers of a first bundle of said plurality of bundles receiving said coherent light beam through said input and each of said fibers of a last bundle of said plurality of bundles transmitting an output beam through said output, such that an optical path length difference between any two fibers in each bundle is greater than a coherence length of said coherent light beam.