Patents by Inventor Stephen A. Sefick

Stephen A. Sefick 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).

  • Patent number: 4145233
    Abstract: A method for making an FET comprising as many as three parallel channels having different threshold voltages. The two outer channels can have very low W/L ratios and resulting low drain-to-source currents. In one embodiment, the FET has a central enhancement channel flanked by low W/L ratio, low current, depletion channels. This FET is fabricated by (1) forming on the field oxide a photoresist mask having a relatively narrow aperture; (2) overetching the field oxide beneath the photoresist mask aperture to form a relatively wide aperture in the field oxide, leaving a photoresist overhang; (3) implanting the substrate through the relatively narrow photoresist mask aperture to provide an enhancement section of the channel region; (4) removing the photoresist mask; and (5) depletion implanting the substrate through the relatively wide field oxide aperture. The gate structure is formed over the combined enhancement and depletion channels and a source and a drain span the ends of the channels.
    Type: Grant
    Filed: May 26, 1978
    Date of Patent: March 20, 1979
    Assignee: NCR Corporation
    Inventors: Stephen A. Sefick, Robert K. Jones