Patent ID: 6072897
Filing Date: 2000-06-06
Classification: G06T

Abstract:
In a system for real-time inspection of patterns formed on a base, the pattern including surfaces and edges,a detector comprising:at least two input channels for receiving respective streams of data elements representing said patterns, each data element representing at least a surface and/or edge of said pattern in high resolution;at least two line width measurement devices responsive to at least said respective streams of data elements, each said line width measurement device being for successively processing, in real time, said data elements in a manner that corresponds to a given direction in said patterns, so as to measure, in high resolution, line width data between two edges by executing at least the following steps: (i) detecting an opening edge, (ii) successively updating line width, and (iii) providing a line width measurement in response to detecting a closing edge; and for generating a measurement quality grading according to the geometric characteristics of the line width measurement;at least one comparator responsive to at least the line width data delivered from said at least two line width measurement devices, for comparing said line width data and obtaining a difference therebetween, so as to generate a defect/no defect indication depending upon at least whether said difference is above or below a threshold, the threshold being determined in accordance with said measurement quality grading.