Patents by Inventor Naotaka Sumihiro

Naotaka Sumihiro 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).

  • Electronically programmable and erasable memory device having floating gate electrode with a unique distribution of impurity concentration
    Patent number: 4812898
    Abstract: An electrically programmable and erasable memory device is disclosed, in which carriers such as electrons transfer between a floating gate electrode made of polycrystalline silicon and a drain region through a thin insulating film portion provided on a part of the drain region by an electric field induced in the thin insulating film portion. The floating gate electrode has such an impurity concentration distribution that the concentration of a portion adjacent to the thin insulating film portion is lower than the concentration of the remaining portion.
    Type: Grant
    Filed: June 20, 1986
    Date of Patent: March 14, 1989
    Assignee: NEC Corporation
    Inventor: Naotaka Sumihiro