Patents by Inventor Akihiro Tomozawa

Akihiro Tomozawa 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: 4782037
    Abstract: Herein disclosed is a process of fabricating a semiconductor integrated circuit device, in which there is formed between a conductive layer prepared by covering a polycrystalline silicon layer with either a layer containing a refractory metal of high melting point, i.e., a refractory metal layer or a silicide layer of the refractory metal and a first insulating film made of phosphosilicate glass flowing over said conductive layer containing the refractory metal, a second insulating film preventing the layer containing a refractory metal from peeling from the polycrystalline silicon layer by the glass flow. The second insulating film is formed by deposition to have a thickness not smaller than a predetermined value.
    Type: Grant
    Filed: October 30, 1986
    Date of Patent: November 1, 1988
    Assignees: Hatachi, Ltd, Hitachi Microcomputer Engineering Ltd.
    Inventors: Akihiro Tomozawa, Yoku Kaino, Shigeru Shimada, Nozomi Horino, Yoshiaki Yoshiura, Osamu Tsuchiya, Shozo Hosoda
  • Patent number: 4377819
    Abstract: A semiconductor device including at least a resistance element formed of polycrystalline silicon having a high resistivity. An electrode is provided on the high resistance polycrystalline silicon region with a silicon dioxide film and a silicon nitride film being interposed therebetween. The electrode is coupled to the ground potential. In this manner, high stability is obtained in the behavior of the resistance element inasmuch as the formation of a parasitic MOS device under said high resistance region is suppressed, and the threshold voltage of any such MOS device is made raised.
    Type: Grant
    Filed: April 20, 1979
    Date of Patent: March 22, 1983
    Assignee: Hitachi, Ltd.
    Inventors: Yoshio Sakai, Toshiaki Masuhara, Osamu Minato, Toshio Sasaki, Hisao Katto, Norikazu Hashimoto, Shin-ichi Muramatsu, Akihiro Tomozawa
  • Patent number: 4014718
    Abstract: In order to prevent the formation of a parasitic PNPN thyristor in an integrated circuit having at least one NPN transistor, a layer of semiconductor material of a conductivity type opposite that of the substrate is formed on the substrate. An isolation region of the same conductivity type as the substrate is formed on this layer and a further layer of the same conductivity type as the isolation region, but of a higher impurity concentration, is formed on the back surface of the substrate. A diffusion layer of the same conductivity type as the substrate, which serves as the base region of the NPN transistor, is formed on the layer having the conductivity type opposite to that of the substrate. A further layer of the same conductivity type and a higher impurity concentration than the isolation region is formed on the back surface of the substrate and an insolation layer is formed on the back surface of the substrate and on the substrate.
    Type: Grant
    Filed: September 2, 1975
    Date of Patent: March 29, 1977
    Assignee: Hitachi, Ltd.
    Inventors: Akihiro Tomozawa, Takanori Nishimura, Takashi Yamaguchi
  • Patent number: 3972756
    Abstract: A method of producing an MIS structure having self-alignment construction, wherein an insulating film is formed on the surface of a semiconductor substrate, a semiconductor layer is formed on a selected area of the insulating film, parts of the insulating film are etched using the semiconductor layer as a mask, and the surface of the semiconductor layer is etched in such manner that the underlying insulating film may not be etched, whereby the marginal portion of the semiconductor layer which otherwise projects laterally beyond the underlying insulating film is caused to recede.
    Type: Grant
    Filed: September 26, 1973
    Date of Patent: August 3, 1976
    Assignee: Hitachi, Ltd.
    Inventors: Akira Nagase, Masayasu Tsunematsu, Norio Anzai, Akihiro Tomozawa
  • Patent number: 3935083
    Abstract: A method for forming an insulating film on an interconnection layer for an integrated circuit, or the like, includes the steps of forming an aluminum layer on the surface of a substrate, oxidizing a thin portion of the upper surface of the aluminum layer in order to convert the thin parts into a porous alumina film, applying a photoresist film having a predetermined pattern on the upper surface of the porous alumina film, and etching those portions of the porous alumina film, together with the aluminum layer which are not covered with the photoresist film. Then, the photoresist film is removed and an aluminum film is formed on the entire surface of the resulting substrate; the aluminum film is oxidized, to form a porous alumina film, and the surface of the remaining aluminum layer is anodized, in order to form a non-porous alumina film. Finally, unnecessary portions of the remaining porous alumina film are removed, and a film is formed by chemical vapor deposition on the resulting structure.
    Type: Grant
    Filed: January 7, 1974
    Date of Patent: January 27, 1976
    Assignee: Hitachi, Ltd.
    Inventors: Akihiro Tomozawa, Kensuke Nakata, Akira Kikuchi, Takashi Agastuma