Patent ID: 6288782
Filing Date: 2001-09-11
Classification: G01N,G01R,G02B,G06T

Abstract:
A method of locating defects on a test surface, wherein the test surface is contained within a test volume represented by a Cartesian coordinate system having x, y, and z axes describing a set of unique x-y-z coordinates, the method comprising the steps of:scanning the test surface in the test volume with a focused beam so that the focal point of the focused beam coincides, in turn, with each unique x-y-z coordinate within the test volume, the test surface being part of a semiconductor wafer;determining, for each column of points specified by a unique x-y coordinate in the test volume, a measured characteristic of the focused beam;storing all the measured characteristics to form an array of test data representing a two-dimensional mapping of the test surface;extracting a set of test primitives from the test data, the test primitives representing boundaries of features on the test surface; andcomparing the set of test primitives with a set of reference primitives to determine whether the set of test primitives is different the set of reference primitives.