Patents by Inventor Toru Kaga

Toru Kaga 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: 5115289
    Abstract: A semiconductor device, such as an FET or a charge coupled device, is provided having a channel or a charge coupled portion formed in a thin semiconductor layer which is substantially perpendicular to the substrate. Necessary electrodes, such as the gate electrode, and necessary insulating layers can be added at the thin semiconductor layer, and can maintain the necessary amount of electric current by securing the height of the semiconductor layer. The structure has the advantage that it can have its plane size reduced. Further, the semiconductor memory device using the above semiconductor device is suitable to high integration and has excellent electric characteristics.
    Type: Grant
    Filed: August 5, 1991
    Date of Patent: May 19, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Dai Hisamoto, Toru Kaga, Shinichiro Kimura, Masahiro Moniwa, Haruhiko Tanaka, Atsushi Hiraiwa, Eiji Takeda
  • Patent number: 5106775
    Abstract: A semiconductor memory comprises a switching device and a charge-storage device disposed at the upper and lower sides, respectively, of each of semiconductor islands. The islands are formed on a semiconductor substrate that is completely isolated from the semiconductor substrate by an insulator. The switching device and charge-storage device are substantially the same width. The memory cell structure is extremely small. The cell structure is highly resistant to alpha-particles and is formed self-aligned. During manufacture, the SiO.sub.2 island is oxidized adjacent its lower end to insulate the island from the substrate.
    Type: Grant
    Filed: July 30, 1990
    Date of Patent: April 21, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Toru Kaga, Yoshifumi Kawamoto, Hideo Sunami
  • Patent number: 5012310
    Abstract: A megabit dynamic random access memory realizing high integration and high reliability is disclosed. The need for an allowance for photomask alignment which is carried out to produce a stacked capacitor memory cell is eliminated. The plate electrode of each memory cell is isolated from the corresponding data line in a memory array by means of an insulating film which is self-alignedly provided around the plate electrode.
    Type: Grant
    Filed: August 13, 1990
    Date of Patent: April 30, 1991
    Assignee: Hitachi, Ltd.
    Inventors: Shinichiro Kimura, Yoshifumi Kawamoto, Toru Kaga, Hideo Sunami
  • Patent number: 4967247
    Abstract: A semiconductor memory comprises a switching device and a charge-storage device disposed at the upper and lower sides, respectively, of each of semiconductor islands. The islands are formed on a semiconductor substrate that is completely isolated from the semiconductor substrate by an insulator. The switching device and charge-storage device are substantially the same width. The memory cell structure is extremely small. The cell structure is highly resistant to alpha-particles and is formed self-aligned. During manufacture, the SiO.sub.2 island is oxidized adjacent its lower end to insulate the island from the substrate.
    Type: Grant
    Filed: December 2, 1988
    Date of Patent: October 30, 1990
    Assignee: Hitachi, Ltd
    Inventors: Toru Kaga, Yoshifumi Kawamoto, Hideo Sunami
  • Patent number: 4918502
    Abstract: The present invention relates to a highly packaged semiconductor memory, and more particularly to a memory cell having a trench capacitor for use in a CMOS memory. The present invention discloses a semiconductor memory employing memory cells each constructed of a trench type charge storage capacitor formed within a substrate, and a switching transistor; one electrode of the capacitor having a sheath-shaped structure which is electrically continuous with the Si substrate at a bottom of a groove and whose sideward periphery is covered with an insulator, the other electrode of the capacitor having a part which is buried inside the sheath electrode and another part which is electrically connected with an impurity diffused layer to function as a source region of the transistor. Further, a structure in which a voltage of 1/2 V.sub.cc can be applied to a plate electrode of a memory cell having a trench capacitor is disclosed.
    Type: Grant
    Filed: November 20, 1987
    Date of Patent: April 17, 1990
    Assignee: Hitachi, Ltd.
    Inventors: Toru Kaga, Shinichiro Kimura, Hideo Sunami
  • Patent number: 4882289
    Abstract: A semiconductor memory wherein a memory cell region having a plurality of memory cells and has higher altitude from the surface of semiconductor substrate is formed in the recessed part of semiconductor substrate having the recessed part and projected part and a peripheral circuit region which is comparatively low from the surface of semiconductor substrate is formed to the projected part of semiconductor substrate.
    Type: Grant
    Filed: April 22, 1988
    Date of Patent: November 21, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Noboru Moriuchi, Yoshiki Yamaguchi, Toshihiko Tanaka, Norio Hasegawa, Yoshifumi Kawamoto, Shin-ichiro Kimura, Toru Kaga, Tokuo Kure
  • Patent number: 4873560
    Abstract: This invention relates to a very large scale dynamic random access memory, and discloses a memory cell having a reduced step on the device surface portion and being hardly affected by incident radioactive rays. In a semiconductor memory consisting of a deep hole bored in a semiconductor substrate, a capacitor formed on the sidewall portion at the lower half of the deep hole and a switching transistor formed immediately above the capacitor, at least the half of a word line constituting the gate of the switching transistor is buried in an elongated recess formed at the surface portion of the semiconductor substrate.
    Type: Grant
    Filed: February 16, 1988
    Date of Patent: October 10, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Hideo Sunami, Shinichiro Kimura, Toru Kaga
  • Patent number: 4873203
    Abstract: An insulation film on silicon buried in a trench is prepared by forming a field oxide film by using a first Si.sub.3 N.sub.4 mask formed on a silicon substrate, forming a second Si.sub.3 N.sub.4 mask for formation of a trench, forming a trench in the silicon substrate by using the second Si.sub.3 N.sub.4 mask, burying polycrystalline silicon in the trench, removing the second Si.sub.3 N.sub.4 mask while leaving the first Si.sub.3 N.sub.4 mask and oxidizing the surface of the polycrystalline silicon buried in the trench by thermal oxidation. The so-formed insulation film on silicon buried in the trench has a uniform thickness and a high dielectric strength. The surface of the substrate at a part where an active element will be formed in the future is not oxidized.
    Type: Grant
    Filed: July 19, 1988
    Date of Patent: October 10, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Toru Kaga, Shinichiro Kimura, Tokuo Kure, Yoshifumi Kawamoto, Hideo Sunami
  • Patent number: 4668970
    Abstract: In a semiconductor device which includes an insulation film through which a charge can tunnel, a gate insulation film of a material different from the material of said insulation film or having a thickness different from that of said insulation film, and a floating gate extending over said tunnelable insulation film, the improvement wherein at least two sides of said tunnelable region are bounded by a device separation oxide film.
    Type: Grant
    Filed: December 2, 1985
    Date of Patent: May 26, 1987
    Assignee: Hitachi, Ltd.
    Inventors: Yuji Yatsuda, Takaaki Hagiwara, Masatada Horiuchi, Shinichi Minami, Toru Kaga
  • Patent number: 4656607
    Abstract: In a semiconductor memory made up of semiconductor memory elements, each consisting of a transistor of an MOS structure which has a charge-storage layer and which is formed on a semiconductor substrate, the improvement wherein a switching element is provided so that positive or negative charge can be stored or discharged from the charge-storage layer in a mode for writing data, and the charge-storage layer can be allowed to float electrically when in a mode for reading data.
    Type: Grant
    Filed: July 19, 1984
    Date of Patent: April 7, 1987
    Assignee: Hitachi, Ltd.
    Inventors: Takaaki Hagiwara, Toru Kaga, Hiroo Masuda
  • Patent number: 4633438
    Abstract: In a 3-transistor random access memory for dynamic operation, the invention discloses a structure in which one of the transistors is stacked on the other transistor. A transistor for writing is disposed on a transistor for reading, and one of its terminals is used in common with the gate electrode of a transistor for judging data. The other terminal is connected to one of the terminals of the transistor for reading.A memory cell capable of extremely large scale integration can be obtained.
    Type: Grant
    Filed: December 13, 1984
    Date of Patent: December 30, 1986
    Assignees: Hitachi, Ltd., Hitachi Micro Computer Engineering Ltd.
    Inventors: Hitoshi Kume, Takaaki Hagiwara, Masatada Horiuchi, Toru Kaga, Yasuo Igura, Akihiro Shimizu