Patents by Inventor Robert W. Du

Robert W. Du has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Method and apparatus for photomask image registration
    Patent number: 7260813
    Abstract: 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.
    Type: Grant
    Filed: October 25, 2004
    Date of Patent: August 21, 2007
    Assignee: Synopsys, Inc.
    Inventors: Robert W. Du, Ronald J. Lesnick, Jr., John T. Nogatch