Patent ID: 7142294
Filing Date: 2006-11-28
Classification: G01N

Abstract:
1. A method for detecting a defect, comprising the steps of: repeatedly obtaining image signals of a same portion of a sample by imaging said sample through an optical system by changing optical conditions; analyzing said repeatedly obtained image signals and selecting plural optical conditions which decrease a difference of contrast in the image signal among segments corresponding to a plurality of regions on said sample; obtaining image signals of said sample under said selected plural optical conditions by imaging said sample with said optical system; evaluating images obtained under said selected plural optical conditions to adjust optical conditions for inspection; and detecting a defect of said sample by processing image signals of the sample under said adjusted optical conditions; wherein in the step of evaluating, said images are evaluated so as to determine an inspection threshold, which is greater than a maximum contrast difference among false defects detected at the step of obtaining image signals and with which a maximum number of true defects can be detected.