Synopsys, Inc.

John T Nogatch

Robert Weixiu Du

Chee Peng Yeap

Ronald J Lesnick, Jr

One embodiment of the present invention provides a system that detects an occurrence of a given shape which has been fractured into a configuration of primitive shapes which is different from a desired configuration. The system selects a fractured-shape instantiation of the given shape, to which other fractured-shape instantiations for the given shape are compared. As a part of the comparison process, the system generates a filtered mask-pattern-description which includes primitive shapes in the mask-pattern-description that match at least one primitive shape in the selected fractured-shape instantiation. Next, the system identifies a first set of shape occurrences from the filtered mask-pattern-description which match the given shape, and identifies a second set of shape occurrences from the mask-pattern-description which match the given shape. The system then generates a third set of shape occurrences by performing an exclusive-OR comparison between the first and second sets of shape occurrences.

Method and apparatus for detecting non-uniform fracturing of a photomask shape

One embodiment of the present invention provides a system that computes translational differentials between a database-image and a scanned-image of a photomask. During operation, the system receives a noise-free database-image and a scanned-image that is generated by an imaging process. Next, the system determines whether the database-image has complex geometry and whether the database-image is a line-and-space pattern. If the database-image is a line-and-space pattern, the system first converts the scanned-image into a polarity-enhanced-image. The system then computes translational differentials by performing a correlation using the database-image and the polarity-enhanced-image. On the other hand, if the database-image is not a line-and-space pattern, the system computes translational differentials by performing a correlation using the database-image and the scanned-image. Note that the accuracy of the computed translational differentials is significantly increased because the system chooses a technique for computing the translational differentials which is suitable for the type of pattern present in the database-image.

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Boulder Creek, CA, United States of America

John T Nogatch