Patents by Inventor Masao Nagatomo

Masao Nagatomo 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: 5888851
    Abstract: A semiconductor device includes a specific circuit portion having a predetermined function and a spare redundant circuit portion having the same function as the specific circuit portion. The semiconductor device includes a silicon substrate (1), an interlayer insulating film (2), an LT fuse (3), interconnection layers (4), a testing electrode (5) and a protection film (6). The interlayer insulating film (2) has a groove (11) and is formed on the silicon substrate (1). The LT fuse (3) is formed of polysilicon and is located immediately below the bottom wall of the groove (11). The interconnection layers (4) are formed on the interlayer insulating film (2) with the groove (11) therebetween. The testing electrode (5) is spaced from the interconnection layers (4) and is formed on the interlayer insulating film (2). The protection film (6) is formed on the interlayer insulating film to cover surfaces of the interconnection layers (4) and expose a surface of the testing electrode (5).
    Type: Grant
    Filed: June 11, 1993
    Date of Patent: March 30, 1999
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Kaoru Motonami, Masao Nagatomo
  • Patent number: 5323343
    Abstract: A DRAM according to the present invention comprises a memory cell array having memory cells constituted by one transfer gate transistor (10) and a capacitor (11), and a peripheral circuit having a MOS transistor (45a) with the LDD structure. At least the source/drain region (19) connected to the capacitor of the transfer gate transistor is formed of a low concentration impurity region (19a). The low concentration impurity region has an impurity concentration substantially equal to that of the low concentration source/drain region (31) of the LDD MOS transistor of the peripheral circuit. The low concentration/drain region of the transfer gate transistor is formed by masking the surface thereof at the time of the high concentration ion implantation step for high concentration source/drain formation of the MOS transistor of the peripheral circuit.
    Type: Grant
    Filed: June 18, 1993
    Date of Patent: June 21, 1994
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Ikuo Ogoh, Masao Nagatomo
  • Patent number: 5300444
    Abstract: A semiconductor memory device comprising memory cells having stacked capacitors has a stacked structure formed by the selective removal of a polycrystalline silicon film (15; 20) and a silicon oxide film (18a; 18), employing the same mask (14). A field effect transistor connected to a stacked capacitor has a gate electrode (20) formed of the above described polycrystalline silicon film. This polycrystalline silicon film (20) is formed on the major surface of a semiconductor substrate. The above described silicon oxide film (18) as an upper layer insulating film formed on the gate electrode (20) has a residual stress not more than 10.sup.9 dyn/cm.sup.2.
    Type: Grant
    Filed: April 30, 1991
    Date of Patent: April 5, 1994
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Atsushi Hachisuka, Masao Nagatomo, Ikuo Ogoh, Hideki Genjou, Yoshinori Okumura, Takayuki Matsukawa
  • Patent number: 5241212
    Abstract: A semiconductor device includes a specific circuit portion having a predetermined function and a spare redundant circuit portion having the same function as the specific circuit portion. The semiconductor device includes a silicon substrate (1), an interlayer insulating film (2), an LT fuse (3), interconnection layers (4), a testing electrode (5) and a protection film (6). The interlayer insulating film (2) has a groove (11) and is formed on the silicon substrate (1). The LT fuse (3) is formed of polysilicon and is located immediately below the bottom wall of the groove (11). The interconnection layers (4) are formed on the interlayer insulating film (2) with the groove (11) therebetween. The testing electrode (5) is spaced from the interconnection layers (4) and is formed on the interlayer insulating film (2). The protection film (6) is formed on the interlayer insulating film to cover surfaces of the interconnection layers (4) and expose a surface of the testing electrode (5).
    Type: Grant
    Filed: December 21, 1992
    Date of Patent: August 31, 1993
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Kaoru Motonami, Masao Nagatomo
  • Patent number: 5164806
    Abstract: An element isolating structure employed for isolating the elements of a semiconductor substrate has an impurity region having a concentration lower than that of a source/drain and a channel stop region, between the source/drain of an MOS transistor formed in an active region, and the channel stop region formed under an LOCOS film.A field shield isolating structure has a low concentrated impurity region between the source/drain of an MOS transistor formed in the active region and the substrate surface region covered by a field shield electrode layer. The low concentrated impurity region improves its junction breakdown voltage in the boundary region with the element isolating region.An improved LOCOS film is formed into an amorphous region on the surface of the substrate by an oblique rotating ion implanting method, and the amorphous region is formed by thermal oxidation. The method suppresses the emergence of a bird's beak.
    Type: Grant
    Filed: May 13, 1991
    Date of Patent: November 17, 1992
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Masao Nagatomo, Hiroki Shimano, Tomonori Okudaira, Yoshinori Okumura
  • Patent number: 5153689
    Abstract: A memory cell of a semiconductor memory device comprises one MOS transistor (3) and one stacked capacitor (4). One of the source/drain regions (8a, 8b) of the MOS transistor is connected to a bit line (2a, 2b). The bit line is formed from a contact portion to the source/drain regions of the MOS transistor to a portion above the stacked capacitor. The bit line is formed of a metal having high melting point, a silicide of a metal having high melting point or a polycide. Since this material has low reflectance against exposing light, the precision in patterning the interconnection is improved.
    Type: Grant
    Filed: September 8, 1989
    Date of Patent: October 6, 1992
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Yoshinori Okumura, Takayuki Matsukawa, Ikuo Ogoh, Masao Nagatomo, Hideki Genjo, Atsushi Hachisuka
  • Patent number: 5112771
    Abstract: A semiconductor device having a trench (30) comprises a semiconductor substrate (11), a plurality of elements (13) provided on the semiconductor substrate, a trench (30) provided between the elements and an insulating material (12) embedded in the trench for isolating the elements. The trench has its bottom portion region enlarged in both sides.The semiconductor device is manufactured by enlarging the bottom portion region of the trench by etching.
    Type: Grant
    Filed: June 12, 1989
    Date of Patent: May 12, 1992
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Tatsuya Ishii, Yoji Mashiko, Masao Nagatomo, Michihiro Yamada
  • Patent number: 5047359
    Abstract: The present invention relates to a method of manufacturing a semiconductor device. In order to controllably introduce impurities into the side wall of a trench 2a by ion implantation impurity ions are directed at a predetermined angle into the side wall of the trench 2a provided in a wafer 2a and, for implantation thereof, at the same time, the wafer 2 is rotated around an ion implantation axis at a rotational speed related to the ion implantation current.
    Type: Grant
    Filed: April 26, 1989
    Date of Patent: September 10, 1991
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Masao Nagatomo
  • Patent number: 4985368
    Abstract: The semiconductor device in which no stress occurs at the corner portion of the trench comprises a p type semiconductor substrate having a trench and a main surface, a thick insulating film formed on the bottom portion of the trench, a thin insulating film formed on the sidewall portion of the trench and connected to the end portion of the thick insulating film, and an n type impurity region formed in the semiconductor substrate only on the side portion of the thin insulating film.
    Type: Grant
    Filed: October 31, 1989
    Date of Patent: January 15, 1991
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Tatsuya Ishii, Yoshinori Okumura, Masao Nagatomo
  • Patent number: 4984055
    Abstract: A semiconductor device having a plurality of conductive layers is disclosed. The device has first level conductors (9) formed spaced apart on a semiconductor substrate (1). The semiconductor substrate (1) is provided with impurity diffusion regions (11) in its major surface between adjacent first level conductors (9). A triple layer insulation formed of a pair of oxide layers (12, 14) and an silicon oxide layer (13) sandwiched between the oxide layers (12, 14) covers the semiconductor substrate (1) and the first level conductors (9) thereon. At least one contact hole (15) is formed to extend through the triple layer insulation to either the impurity diffusion region (11) in the semiconductor substrate (1) or the first level conductor (9) on the semiconductor substrate (1). A second level conductor (16, 17) is provided on the triple layer insulation and on the inner surrounding wall of the contact hole (15).
    Type: Grant
    Filed: November 7, 1988
    Date of Patent: January 8, 1991
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Yoshinori Okumura, Atsuhiro Fujii, Masao Nagatomo, Hiroji Ozaki, Wataru Wakamiya, Takayuki Matsukawa
  • Patent number: 4956310
    Abstract: A semiconductor memory device in accordance with the present invention comprises: a semiconductor substrate (1) of a first conductivity type; a charge storage region (6) and a bit line region (7) of a second conductivity type formed on a main surface of the substrate; highly doped regions (12a, 12b) of the first conductivity type formed respectively contiguous to only the bottom boundaries of the charge storage region (6) and the bit line region (7).
    Type: Grant
    Filed: October 5, 1988
    Date of Patent: September 11, 1990
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Akira Tokui, Shinichi Sato, Akira Kawai, Masayuki Nakajima, Hiroji Ozaki, Masao Nagatomo
  • Patent number: 4956692
    Abstract: Two trenches are formed at a predetermined distance on a main surface of a semiconductor substrate. An oxide film and a nitride film are successively formed on the main surface of the semiconductor including the inner surfaces of the trenches. After a resist is formed over the whole surface including the inner surfaces of the trenches, the resist is patterned to expose a portion of the nitride film on a side surface of each trench. The exposed portions of the nitride film are removed by using the patterned resist as a mask and thermal oxidation is applied. Then, an isolation oxide film is formed on a region between the trenches and an end of a bird's beak is located on a side surface of each trench and is connected to the oxide film formed in each trench.
    Type: Grant
    Filed: November 3, 1988
    Date of Patent: September 11, 1990
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Hiroji Ozaki, Masahiro Yoneda, Ikuo Ogoh, Yoshinori Okumura, Wataru Wakamiya, Masao Nagatomo
  • Patent number: 4905068
    Abstract: A cell plate (6) is formed on a main surface of a semiconductor substrate (7) with an insulating film (8) interposed therebetween and an interconnection (1) having T-shape cross section is formed on the cell plate (6) with an interlayer insulating film (11) interposed therebetween. An upper insulating film (12) is formed to cover the interconnection (1).
    Type: Grant
    Filed: January 13, 1988
    Date of Patent: February 27, 1990
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Shinichi Satoh, Makoto Hirayama, Masao Nagatomo, Ikuo Ogoh, Yoshikazu Ohno, Masato Fujinaga
  • Patent number: 4894695
    Abstract: The semiconductor device in which no stress occurs at the corner portion of the trench comprises a p type semiconductor substrate having a trench and a main surface, a thick insulating film formed on the bottom portion of the trench, a thin insulating film formed on the sidewall portion of the trench and connected to the end portion of the thick insulating film, and an n type impurity region formed in the semiconductor substrate only on the side portion of the thin insulating film.
    Type: Grant
    Filed: March 17, 1988
    Date of Patent: January 16, 1990
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Tatsuya Ishii, Yoshinori Okumura, Masao Nagatomo
  • Patent number: 4763182
    Abstract: A semiconductor memory device comprises a first conductivity type semiconductor substrate (1) formed thereon with a charge storage region (5) and a second conductivity type region (6) serving as a bit line, and first conductivity type highly concentrated regions (8, 11) higher in concentration than the semiconductor substrate (1) at least by one digit are formed to enclose the charge storage region (5) and the bit line region (6) respectively. Thus, potential barriers against electrons can be defined in interfaces between the highly concentrated region (8) and the charge storage region (5) and between the highly concentrated region (11) and the bit line region (6), thereby to prevent malfunction caused by incidence of radioactive rays such as alpha rays.
    Type: Grant
    Filed: December 12, 1986
    Date of Patent: August 9, 1988
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Hiroji Ozaki, Shinichi Sato, Akira Tokui, Akira Kawai, Masayuki Nakajima, Masao Nagatomo
  • Patent number: 4702796
    Abstract: The present invention is a method for fabricating a semiconductor device, wherein impurity is selectively diffused to surround a region (7) of a second conductivity type as a bit line formed on a semiconductor substrate (1), thereby forming an impurity diffused region (9) of a first conductivity type having high density and, by extending the impurity diffused region (9) in the element separating step to form a high density region of the first conductivity type having high density.
    Type: Grant
    Filed: November 14, 1986
    Date of Patent: October 27, 1987
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Masayuki Nakajima, Shinichi Sato, Akira Tokui, Akira Kawai, Masao Nagatomo, Hiroji Ozaki
  • Patent number: 4341616
    Abstract: A dry etching device is provided in which on at least one portion of the path of etchant movement from the plasma production region to the etching workpiece a resin coating containing atoms or molecules of the same type as the chemically active atoms or molecules which constitute the etchant, is formed.
    Type: Grant
    Filed: December 11, 1980
    Date of Patent: July 27, 1982
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Masao Nagatomo, Haruhiko Abe, Kazuo Mizuguchi
  • Patent number: 4333226
    Abstract: A thin film of a metal which is capable of oxidation and sublimation is formed on a major surface of a semiconductor substrate, and a portion of a major surface of the thin metallic film is irradiated with an oxygen ion beam to convert a portion of the thin metallic film to an oxide, and subsequently the thin metallic film is heat treated to remove the oxide by sublimation, whereby electrodes or wiring for a semiconductor integrated circuit are formed by the remaining thin metallic film.
    Type: Grant
    Filed: November 24, 1980
    Date of Patent: June 8, 1982
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Haruhiko Abe, Masao Nagatomo, Natsuro Tsubouchi, Hiroshi Harada, Junichi Mitsuhashi