Patents Examined by Leigh Garbowsk
  • Patent number: 6449748
    Abstract: Provided is a non-destructive method of detecting die crack problems in an integrated circuit. The method provides for testing for die crack problems in all chips and in many production chips without adding any extra circuitry or pads. In a preferred embodiment, the method takes advantage of an existing NAND gate tree structure at the perimeter of many conventional dies, although the invention is also applicable to other logic gate structures that may exist or may be formed at the perimeter of dies. The invention recognizes that this NAND gate tree structure may be used in order to identify and localize die cracks in finished chips, thereby providing a faster, more accurate and nondestructive way to test for die cracks in production chips. A typical NAND gate tree structure has the form of a cascade inverter chain. Since one end of the first NAND gate is tied to VDD, the output of each gate will alternate between low and high.
    Type: Grant
    Filed: August 9, 1999
    Date of Patent: September 10, 2002
    Assignee: LSI Logic Corporation
    Inventors: Edward Jewjing Jeng, Lamberto Beleno, Steve Kehchien Hsuing