Patents Represented by Attorney, Agent or Law Firm Eric E. Petraske
  • Design verification for asymmetric phase shift mask layouts
    Patent number: 6185727
    Abstract: A checking routine verifies a phase shifted mask (PSM) design based on fundamental principles of PSM and utilizing only basic shape manipulation functions and Boolean operations found in most computer aided design (CAD) systems. The design verification system checks complete chip designs for the two possible design errors that can cause defective masks by eliminating the phase transition; namely, placing a 180° phase region on both sides of a critical feature or completely omitting the phase region adjacent to certain critical features.
    Type: Grant
    Filed: December 12, 1995
    Date of Patent: February 6, 2001
    Assignee: International Business Machines Corporation
    Inventor: Lars Wolfgang Liebmann