Patent ID: 7619735
Filing Date: 2009-11-17
Classification: G01N

Abstract:
1. A method, comprising: directing a beam of radiation towards a patterned surface of a sample, said patterned surface having a substantially regular pattern; subjecting said beam to a selected apodization scheme before it impinges on said patterned surface to produce an apodized beam having shape and angle of incidence characteristics determined by the selected apodization scheme, said selected apodization scheme determined by an apodizer and at least in part by a spatial filter, each chosen from among a plurality of available shapes set in respective wheels, wherein the apodizer adjusts an angle of incidence of the beam on the surface; impinging the apodized beam onto the patterned surface so as to produce scattered radiation from the patterned surface, a first portion of said scattered radiation resulting from impingement of the apodized beam on the substantially regular pattern and a second portion resulting from impingement of the apodized beam on defects in the substantially regular pattern; filtering said first portion of said scattered radiation with the spatial filter matched to said selected apodization scheme so as to suppress scattered interference lobes created by impingement of the apodized beam on the substantially regular pattern; and detecting with a detector at least some of said second portion of said scattered radiation.