Patents by Inventor Walther Rehwald

Walther Rehwald 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 for determining structural defects in semiconductor wafers by ultrasonic microscopy
    Patent number: 4741212
    Abstract: A method and apparatus for determining the location and size of structural defects in a body of solid material, particularly regions of thermoplastic deformation in semiconductor wafers. An acoustical focused beam generated by an ultrasonic transducer, having a pulsed frequency of at least 75 MHZ, is transmitted through the body to provide an attenuated signal pattern which manifests structural defects, such as slip planes which can result in wafer warp, as well as cracks, bubbles, foreign particles or segregation zones and internal interfaces.
    Type: Grant
    Filed: July 31, 1986
    Date of Patent: May 3, 1988
    Assignee: General Electric Company
    Inventor: Walther Rehwald