Patent ID: 7397941
Filing Date: 2008-07-08
Classification: G01N,G06K,G06T

Abstract:
1. A method of detecting defects in a microminiature pattern repeated over a particular surface of an object, the method comprising: illuminating a surface of the object with incident electrons; deflecting image electrons mirrored from the surface and the incident electrons in opposite directions using a beam separator; detecting the image electrons from the surface in parallel using a pixel array electron detector capable of resolving intensity data for each pixel of an image projected thereupon; retrieving image data from the detected image electrons from the surface into a data processor; determining a sub-pixel difference between a cell dimension in a first portion of the surface and a nearest integer number of pixels; determining sub-pixel differences between a cell dimension in other portions of the surface and a nearest integer number of pixels; selecting one of the other portions having a sub-pixel difference which is close to the sub-pixel difference in the first portion; and comparing features in the first portion with features in said selected portion to detect said defects.