Patents by Inventor Kiyoshi Tsukuda

Kiyoshi Tsukuda 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: 5672897
    Abstract: An improved arrangement is provided for forming a bipolar transistor on a substrate with CMOS elements. All of the transistors (i.e., the bipolar, P-MOS and N-MOS) are formed in regions having gradually decreasing impurity concentrations from the surface toward the substrate. In addition, a buried layer is provided under each of the regions of decreasing impurity concentration in which the transistors are formed. These buried layers have a significantly higher impurity concentration than the portion of the region of decreasing impurity concentration which they are respectively adjacent to. Using this arrangement, punch-through is prevented and excellent electrical operating characteristics are provided for both the bipolar transistors and the CMOS elements.
    Type: Grant
    Filed: June 5, 1995
    Date of Patent: September 30, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Atsuo Watanabe, Takahide Ikeda, Kiyoshi Tsukuda, Mitsuru Hirao, Touji Mukai, Tatsuya Kamei
  • Patent number: 5508549
    Abstract: An improved arrangement is provided for forming a bipolar transistor on a substrate with CMOS elements. All of the transistors (i.e., the bipolar, P-MOS and N-MOS) are formed in regions having gradually decreasing impurity concentrations from the surface toward the substrate. In addition, a buried layer is provided under each of the regions of decreasing impurity concentration in which the transistors are formed. These buried layers have a significantly higher impurity concentration than the portion of the region of decreasing impurity concentration which they are respectively adjacent to. Using this arrangement, punch-through is prevented and excellent electrical operating characteristics are provided for both the bipolar transistors and the CMOS elements.
    Type: Grant
    Filed: July 25, 1991
    Date of Patent: April 16, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Atsuo Watanabe, Takahide Ikeda, Kiyoshi Tsukuda, Mitsuru Hirao, Touji Mukai, Tatsuya Kamei
  • Patent number: 5049967
    Abstract: An improved arrangement is provided for forming a bipolar transistor on a substrate with CMOS elements. All of the transistors (i.e., the bipolar, P-MOS and N-MOS) are formed in regions having gradually decreasing impurity concentrations from a surface toward the substrate. In addition, a buried layer is provided under each of the regions of decreasing impurity concentration in which the transistors are formed. These buried layers have a significantly higher impurity concentration than the portion of the region of decreasing impurity concentration which they are respectively adjacent to. Using this arrangement, punch-through is prevented and excellent electrical operating characteristics are provided for both the bipolar transistors and the CMOS elements.
    Type: Grant
    Filed: December 21, 1990
    Date of Patent: September 17, 1991
    Assignee: Hitachi, Ltd.
    Inventors: Atsuo Watanabe, Takahide Ikeda, Kiyoshi Tsukuda, Mitsuru Hirao, Touji Mukai, Tatsuya Kamei
  • Patent number: 4980744
    Abstract: An improved arrangement is provided for forming a bipolar transistor on a substrate with CMOS elements. All of the transistors (i.e., the bipolar, P-MOS and N-MOS) are formed in regions having gradually decreasing impurity concentrations from the surface toward the substrate. In addition, a buried layer is provided under each of the regions of decreasing impurity concentration in which the transistors are formed. These buried layers have a significantly higher impurity concentration than the portion of the region of decreasing impurity concentration which they are respectively adjacent to. Using this arrangement, punch-through is prevented and excellent electrical operating characteristics are provided for both the bipolar transistors and the CMOS elements.
    Type: Grant
    Filed: February 24, 1988
    Date of Patent: December 25, 1990
    Assignee: Hitachi, Ltd.
    Inventors: Atsuo Watanabe, Takahide Ikeda, Kiyoshi Tsukuda, Mitsuru Hirao, Touji Mukai, Tatsuya Kamei
  • Patent number: 4921811
    Abstract: An improved arrangement is provided for forming a bipolar transistor on a substrate with CMOS elements. All of the transistors (i.e., the bipolar, P-MOS and N-MOS) are formed in regions having gradually decreasing impurity concentrations from the surface toward the substrate. In addition, a buried layer is provided under each of the regions of decreasing impurity concentration in which the transistors are formed. These buried layers have a significantly higher impurity concentration than the portion of the region of decreasing impurity concentration which they are respectively adjacent to. Using this arrangement, punch-through is prevented and excellent electrical operating characteristics are provided for both the bipolar transistors and the CMOS elements.
    Type: Grant
    Filed: March 31, 1988
    Date of Patent: May 1, 1990
    Assignee: Hitachi, Ltd.
    Inventors: Atsuo Watanabe, Takahide Ikeda, Kiyoshi Tsukuda, Mitsuru Hirao, Touji Mukai, Tatsuya Kamei
  • Patent number: 4361846
    Abstract: Lateral type semiconductor devices are provided which can withstand a high applied reverse voltage and can be effectively employed in semiconductor integrated circuits with an enhanced integration density. These lateral type semiconductor devices include therein an island region formed in a semiconductor supporting region and a diffusion region formed in the island region. The radius of curvature at the pn junction surface of the diffusion region is selected to be at least 1.5 times larger than the depth of the diffusion region. The diffusion region includes electrode mounting portions of large area and the remaining portions having the form of a fine line.
    Type: Grant
    Filed: August 7, 1980
    Date of Patent: November 30, 1982
    Assignee: Hitachi, Ltd.
    Inventor: Kiyoshi Tsukuda
  • Patent number: 4257060
    Abstract: In a semiconductor switch for use in a telephone exchange, interference between separate switching units located on a single chip is frequently a problem. To overcome this, a semiconductor switch is provided with a plurality of islands of silicon monocrystal disposed in a supporting body of silicon polycrystal through a dielectric film having a plurality of switching circuit islands, at least one driving circuit island, and a plurality of protective circuit islands, wherein a region to reduce parasitic capacitance is formed between said switching circuit islands by arranging the switching circuit islands to be isolated from one another through said region.
    Type: Grant
    Filed: December 26, 1978
    Date of Patent: March 17, 1981
    Assignee: Hitachi, Ltd.
    Inventors: Shigeru Kawamata, Kiyoshi Tsukuda