Patents by Inventor Kenji Sawamura

Kenji Sawamura 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).

  • Publication number: 20110228583
    Abstract: According to one embodiment, a semiconductor memory device includes a memory cell array, a first sense amplifier circuit, and a second sense amplifier circuit. The memory cell array includes a plurality of first memory cell units, a plurality of second memory cell units, a plurality of first interconnects, and a plurality of second interconnects. The first sense amplifier circuit is connected to the plurality of first interconnects. The second sense amplifier circuit is connected to the plurality of second interconnects. Heights of upper surfaces of interconnects are equal.
    Type: Application
    Filed: February 25, 2011
    Publication date: September 22, 2011
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Mitsuhiro NOGUCHI, Kenji SAWAMURA, Takeshi KAMIGAICHI, Katsuaki ISOBE
  • Publication number: 20110157997
    Abstract: A control circuit is configured to performs, in a write operation to a memory cell and a verify operation for verifying a threshold voltage of the memory cell, a voltage control to provide the memory cell with threshold voltage distributions. The circuit is configured to apply, in a read operation from the memory cell, to a selected memory cell a read voltage between the lower and upper limits of the threshold voltage distributions, and apply to an unselected memory cell a first read-pass voltage higher than the upper limit of a first threshold voltage distribution that is the maximum distribution of the threshold voltage distributions.
    Type: Application
    Filed: December 28, 2010
    Publication date: June 30, 2011
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Takeshi KAMIGAICHI, Kenji SAWAMURA
  • Publication number: 20110069553
    Abstract: A semiconductor memory device includes a first insulation film, Charge accumulation portions, a second insulation film, and a control gate. The first insulation film is located on an active area (AA). The charge accumulation portions comprise minute crystals arranged on the first insulation film. A density of the charge accumulation portions at an end portion in an AA width direction of the first insulation film is higher than a density of the charge accumulation portions at a central potion in the AA width direction. The second insulation film is located on the first insulation film so as to coat the charge accumulation portions. The control gate is located on the second insulation film.
    Type: Application
    Filed: March 19, 2010
    Publication date: March 24, 2011
    Inventor: Kenji SAWAMURA
  • Publication number: 20100270527
    Abstract: A phase-change memory device has a plurality of first wiring lines; a plurality of memory cells that are provided on the plurality of first wiring lines; a plurality of second wiring lines that are provided on the plurality of memory cells, respectively; and an interlayer insulating film that is formed between the plurality of first wiring lines and the plurality of second wiring lines and insulates the plurality of first wiring lines from the plurality of second wiring lines; wherein each of the memory cells includes a heat source element that is supplied with a current and generates heat and a phase-change element that is changed to an amorphous state or a crystalline state according to a cooling speed after being heated by the heat source element, a resistance value of the phase-change element varying with the change in the state, and wherein a void is formed between the two adjacent memory cells in the interlayer insulating film.
    Type: Application
    Filed: September 14, 2009
    Publication date: October 28, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventor: Kenji Sawamura
  • Publication number: 20100244091
    Abstract: In some embodiments, an insulated gate bipolar transistor includes a drift layer, insulation gates formed at a principle surface portion of the drift layer, base regions formed in a between-gate region, an emitter region formed in the base region so as to be adjacent to the insulation gate, an emitter electrode connected to the emitter region, a collector layer formed at the other side of the principle surface portion of the drift layer, and a collector electrode connected to the collector layer. The conductive type base regions are separated with each other by the drift layers, and the drift layer and the emitter electrode are insulated by an interlayer insulation film.
    Type: Application
    Filed: March 26, 2010
    Publication date: September 30, 2010
    Applicants: SANYO ELECTRIC CO., LTD., SANYO SEMICONDUCTOR CO., LTD.
    Inventors: Shuji Yoneda, Kenji Sawamura
  • Publication number: 20100246256
    Abstract: A nonvolatile semiconductor memory includes: a lower semiconductor layer; a first cell string having a plurality of memory cells formed on the lower semiconductor layer; an upper semiconductor layer formed above the lower semiconductor layer; and a second cell string having a plurality of memory cells formed on the upper semiconductor layer. A memory cell formed on a crystal defect of the upper semiconductor layer among the plurality of memory cells that form the second cell string is operated as a dummy cell.
    Type: Application
    Filed: March 29, 2010
    Publication date: September 30, 2010
    Applicant: Kabushiki Kaisha Toshiba
    Inventor: Kenji SAWAMURA
  • Publication number: 20100001401
    Abstract: A semiconductor device includes an interlayer insulating film, a barrier metal layer, a conductive layer and a first insulating film. The barrier metal layer is formed on a bottom surface and a side face of a trench made in the interlayer insulating film. The conductive layer is formed on the barrier metal layer. The conductive layer has its upper surface lower than an upper surface of an opening of the trench and buries a part of the trench. The first insulating film is formed on the conductive layer and is formed on the barrier metal layer on a side face of the opening of the trench. The first insulating film is made of a material having a dielectric constant higher than that of the interlayer insulating film.
    Type: Application
    Filed: September 16, 2009
    Publication date: January 7, 2010
    Inventor: Kenji SAWAMURA
  • Patent number: 7636256
    Abstract: A semiconductor memory device includes a memory cell string provided on a semiconductor substrate, and a first select transistor including a gate insulation film, which is provided on the semiconductor substrate having a recess structure which is lower, only at a central portion thereof, than the semiconductor substrate on which the memory cell string is provided, and a gate electrode provided on the gate insulation film, the first select transistor selecting the memory cell string.
    Type: Grant
    Filed: October 9, 2007
    Date of Patent: December 22, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kenji Gomikawa, Kenji Sawamura, Mitsuhiro Noguchi
  • Publication number: 20090003070
    Abstract: A semiconductor memory device includes a memory cell string provided on a semiconductor substrate, and a first select transistor including a gate insulation film, which is provided on the semiconductor substrate having a recess structure which is lower, only at a central portion thereof, than the semiconductor substrate on which the memory cell string is provided, and a gate electrode provided on the gate insulation film, the first select transistor selecting the memory cell string.
    Type: Application
    Filed: October 9, 2007
    Publication date: January 1, 2009
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Kenji Gomikawa, Kenji Sawamura, Mitsuhiro Noguchi
  • Patent number: 7465984
    Abstract: A nonvolatile memory element includes a laminated gate provided above a semiconductor substrate with a tunnel insulating film disposed therebetween and having a floating gate electrode, a gate-gate insulating film and a control gate electrode sequentially stacked. The gate-gate insulating film includes a first silicon oxide film, a first aluminum oxide film having hafnium added thereto, a second aluminum oxide film, a third aluminum oxide film having hafnium added thereto and a second silicon oxide film sequentially stacked.
    Type: Grant
    Filed: July 2, 2007
    Date of Patent: December 16, 2008
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Kenji Sawamura
  • Patent number: 7436714
    Abstract: A nonvolatile semiconductor memory according to examples of the present invention includes a NAND string comprised memory cells connected in series, two select gate transistors each of which is connected to each end of the NAND string, and a write control circuit which makes a first write condition for a selected cell different from a second write condition for the selected cell. The first write condition is that the selected cell is one of two memory cells adjacent to the two select gate transistors. The second write condition is that the selected cell is one of the memory cells except for two memory cells adjacent to the two select gate transistors.
    Type: Grant
    Filed: April 30, 2007
    Date of Patent: October 14, 2008
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Toshitake Yaegashi, Kenji Sawamura
  • Publication number: 20080121978
    Abstract: A nonvolatile memory element includes a laminated gate provided above a semiconductor substrate with a tunnel insulating film disposed therebetween and having a floating gate electrode, a gate-gate insulating film and a control gate electrode sequentially stacked. The gate-gate insulating film includes a first silicon oxide film, a first aluminum oxide film having hafnium added thereto, a second aluminum oxide film, a third aluminum oxide film having hafnium added thereto and a second silicon oxide film sequentially stacked.
    Type: Application
    Filed: July 2, 2007
    Publication date: May 29, 2008
    Inventor: Kenji SAWAMURA
  • Publication number: 20070279986
    Abstract: A nonvolatile semiconductor memory according to examples of the present invention includes a NAND string comprised memory cells connected in series, two select gate transistors each of which is connected to each end of the NAND string, and a write control circuit which makes a first write condition for a selected cell different from a second write condition for the selected cell. The first write condition is that the selected cell is one of two memory cells adjacent to the two select gate transistors. The second write condition is that the selected cell is one of the memory cells except for two memory cells adjacent to the two select gate transistors.
    Type: Application
    Filed: April 30, 2007
    Publication date: December 6, 2007
    Inventors: Toshitake YAEGASHI, Kenji Sawamura
  • Publication number: 20070267750
    Abstract: A semiconductor device includes an interlayer insulating film, a barrier metal layer, a conductive layer and a first insulating film. The barrier metal layer is formed on a bottom surface and a side face of a trench made in the interlayer insulating film. The conductive layer is formed on the barrier metal layer. The conductive layer has its upper surface lower than an upper surface of an opening of the trench and buries a part of the trench. The first insulating film is formed on the conductive layer and is formed on the barrier metal layer on a side face of the opening of the trench. The first insulating film is made of a material having a dielectric constant higher than that of the interlayer insulating film.
    Type: Application
    Filed: May 17, 2007
    Publication date: November 22, 2007
    Inventor: Kenji SAWAMURA
  • Patent number: 6939810
    Abstract: A silicon oxide film and a silicon nitride film are formed on a silicon substrate. Then, isotropic etching is performed to the silicon nitride film by the total thickness of the silicon oxide film and a sacrifice oxide film after trenches for element isolation have been formed in the silicon substrate. Subsequently, a high-voltage operation section is covered with a resist film, and isotropic etching is performed to the silicon oxide film in a low-voltage operation section by a thickness of one gate oxide film.
    Type: Grant
    Filed: June 13, 2003
    Date of Patent: September 6, 2005
    Assignee: Fujitsu Limited
    Inventor: Kenji Sawamura
  • Publication number: 20050127471
    Abstract: A dummy active region is formed in which abrading processes are averaged. A semiconductor device is characterized in that an active region for forming an actual device, a device separation region being formed by a trench, and a dummy active region formed substantially in a rectangular shape are included, and the length of the short side of the dummy active region is less than 1 ?m.
    Type: Application
    Filed: January 13, 2005
    Publication date: June 16, 2005
    Inventor: Kenji Sawamura
  • Patent number: 6882024
    Abstract: A dummy active region is formed in which abrading processes are averaged. A semiconductor device is characterized in that an active region for forming an actual device, a device separation region being formed by a trench, and a dummy active region formed substantially in a rectangular shape are included, and the length of the short side of the dummy active region is less than 1 ?m.
    Type: Grant
    Filed: July 9, 2003
    Date of Patent: April 19, 2005
    Assignee: Oki Electric Industry Co., Ltd.
    Inventor: Kenji Sawamura
  • Publication number: 20040007703
    Abstract: A dummy active region is formed in which abrading processes are averaged. A semiconductor device is characterized in that an active region for forming an actual device, a device separation region being formed by a trench, and a dummy active region formed substantially in a rectangular shape are included, and the length of the short side of the dummy active region is less than 1 &mgr;m.
    Type: Application
    Filed: July 9, 2003
    Publication date: January 15, 2004
    Inventor: Kenji Sawamura
  • Publication number: 20040002219
    Abstract: A silicon oxide film and a silicon nitride film are formed on a silicon substrate. Then, isotropic etching is performed to the silicon nitride film by the total thickness of the silicon oxide film and a sacrifice oxide film after trenches for element isolation have been formed in the silicon substrate. Subsequently, a high-voltage operation section is covered with a resist film, and isotropic etching is performed to the silicon oxide film in a low-voltage operation section by a thickness of one gate oxide film.
    Type: Application
    Filed: June 13, 2003
    Publication date: January 1, 2004
    Applicant: FUJITSU LIMITED
    Inventor: Kenji Sawamura
  • Patent number: 6495855
    Abstract: A dummy active region is formed in which abrading processes are averaged. A semiconductor device is characterized in that an active region for forming an actual device, a device separation region being formed by a trench, and a dummy active region formed substantially in a rectangular shape are included, and the length of the short side of the dummy active region is less than 1 &mgr;m.
    Type: Grant
    Filed: March 30, 2000
    Date of Patent: December 17, 2002
    Assignee: Oki Electric Industry Co., Ltd.
    Inventor: Kenji Sawamura