Patent ID: 6429931
Filing Date: 2002-08-06
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 reduce, at least partially, its coherence; said modifying of said coherent light beam comprising: disposing an integrating sphere in a light path between a source of said inspection beam and said inspected article, said integrating sphere comprising a first sphere of a predetermined diameter and having an inner surface made of a highly reflective material, said integrating sphere further having a first, entrance aperture of a predetermined first diameter and a second, exit aperture of a predetermined second diameter, said coherent light beam entering said integrating sphere through said first aperture and exiting said integrating sphere through said second aperture after being reflected off said inner surface within said integrating sphere, such that beams output from said integrating sphere have optical path length differences greater than a coherence length of said coherent light beam.