Guardbands for pattern inspector
First Claim
1. A computerized method of reducing the incident of false error reporting for an optical pattern inspection system, comprising the steps of:
- identifying the pattern boundaries of a database representation of an ideal pattern, wherein the ideal pattern is comprised of one or more reference polygons, and the data description of each reference polygon is contained within a frame of data, and each side of a polygon is a line segment completely contained within a single frame;
constructing data representations of guardbands around said boundaries and constructing a guardband polygon surrounding each line segment of each side of each reference polygon, wherein each guardband polygon is completely contained within the frame of data containing the polygon whose side it surrounds;
constructing a dummy reference polygon in a frame adjacent to a frame having a side of an actual reference polygon a distance less than epsilon away from the common frame boundary of the two adjacent frames;
constructing a guardband around the dummy reference polygon a distance at least as great as epsilon from the side of the actual reference polygon which is a distance less that epsilon away from the common frame boundary;
comparing data generated from an optically detected pattern on a target with the database representations of the ideal pattern, to detect miscompares; and
identifying as errors only those miscompares which do not occur within the guardbands.
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Accused Products
Abstract
A laser pattern inspection and/or writing system which writes or inspects a pattern on a target on a stage, by raster scanning the target pixels. Inspection can also be done by substage illumination with non-laser light. A database, organized into frames and strips, represents an ideal pattern as one or more polygons. Each polygon'"'"'s data description is contained within a single data frame. The database is transformed into a turnpoint polygon representation, then a left and right vector representation, then an addressed pixel representation, then a bit-mapped representation of the entire target. Most of the transformations are carried out in parallel pipelines. Guardbands around polygon sides are used for error filtering during inspection. Guardbands are polygons, and frames containing only guardband information are sent down dedicated pipelines. Error filtering also is done at the time of pixel comparisons of ideal with real patterns, and subsequently during defect area consolidation. Defect areas are viewed as color overlays of ideal and actual target areas, from data generated during real time. Defect areas can be de-zoomed to allow larger target areas to be viewed. An autofocus keeps the scanning laser beam in focus on the target. The inspection system is used to find fiducial marks to orient the target prior to raster scanning. IC bars are provided with alignment marks for locating each IC bar. Interferometers or glass scale encoders allow the stage position to be known.
92 Citations
3 Claims
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1. A computerized method of reducing the incident of false error reporting for an optical pattern inspection system, comprising the steps of:
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identifying the pattern boundaries of a database representation of an ideal pattern, wherein the ideal pattern is comprised of one or more reference polygons, and the data description of each reference polygon is contained within a frame of data, and each side of a polygon is a line segment completely contained within a single frame; constructing data representations of guardbands around said boundaries and constructing a guardband polygon surrounding each line segment of each side of each reference polygon, wherein each guardband polygon is completely contained within the frame of data containing the polygon whose side it surrounds; constructing a dummy reference polygon in a frame adjacent to a frame having a side of an actual reference polygon a distance less than epsilon away from the common frame boundary of the two adjacent frames; constructing a guardband around the dummy reference polygon a distance at least as great as epsilon from the side of the actual reference polygon which is a distance less that epsilon away from the common frame boundary; comparing data generated from an optically detected pattern on a target with the database representations of the ideal pattern, to detect miscompares; and identifying as errors only those miscompares which do not occur within the guardbands. - View Dependent Claims (2, 3)
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Specification