Patent ID: 6347150
Filing Date: 2002-02-12
Classification: G06T

Abstract:
A pattern inspection system comprising:imaging means for imaging an object to be inspected, said object having a plurality of chips thereon and each chip having essentially the same pattern, by scanning a focused electron beam having a diameter of 0.02 to 0.2 &mgr;m on the object and detecting electrons emanated from the object by the scanning; a height detection sensor which detects a height of the object that has the plurality of chips formed thereon; means for adjusting a focal position of the focused electron beam using an output of the height detection sensor; A/D conversion means for converting an image signal of the object to be inspected which has been imaged by said imaging means into digital image signals; first defect candidate extracting means for comparing the digital image signals of a repetitive pattern of a notice point of one of said chips to be inspected with the digital image signals of an adjacent repetitive pattern of comparison points of the chip, corresponding to the notice point, which should be essentially the same as the pattern of the notice point, in order to extract a first defect candidate of the notice point; second defect candidate extracting means for comparing the digital image signals of a non-repetitive pattern in a notice chip on the object to be inspected with the digital image signals of a non-repetitive pattern of comparison points of an adjacent chip, corresponding to the notice chip, which should be essentially the same as the pattern of the nonrepetitive pattern of the notice chip in order to extract a second defect candidate of the notice chip; defect candidate selecting means for receiving the extracted first and second defect candidates, selecting one of the first defect candidate and the second defect candidate, and outputting the selected defect candidate; defect detecting means for detecting a true defect from the selected defect candidate; and output means for outputting therethrough information relating to the true defect thus detected.