Patents by Inventor Riichiro Shirota

Riichiro Shirota 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: 7952934
    Abstract: A memory structure includes a first memory cell and a second memory cell located at an identical bit line and adjacent to the first memory cell. Each memory cell includes a substrate, a source, a drain, a charge storage device, and a gate. A method for programming the memory structure includes respectively providing a first gate biasing voltage and a second gate biasing voltage to the gates of the first memory cell and the second memory cell, boosting an absolute value of a channel voltage of the first memory cell to generate electron and hole pairs at the drain of the second memory cell through gate-induced drain leakage or band-to-band tunneling, and injecting the hole of the generated electron and hole pairs into the charge storage device of the first memory cell to program the first memory cell.
    Type: Grant
    Filed: November 11, 2010
    Date of Patent: May 31, 2011
    Assignee: Powerflash Technology Corporation
    Inventors: Riichiro Shirota, Ching-Hsiang Hsu, Cheng-Jye Liu
  • Publication number: 20110108905
    Abstract: A nonvolatile semiconductor memory includes first and second memory cells having a floating gate and a control gate. The floating gate of the first and second memory cells is comprised a first part, and a second part arranged on the first part, and a width of the second part in an extending direction of the control gate is narrower than that of the first part. A first space between the first parts of the first and second memory cells is filled with one kind of an insulator. The control gate is arranged at a second space between the second parts of the first and second memory cells.
    Type: Application
    Filed: January 14, 2011
    Publication date: May 12, 2011
    Inventors: Masayuki ICHIGE, Fumitaka Arai, Riichiro Shirota, Toshitake Yaegashi, Yoshio Ozawa, Akihito Yamamoto, Ichiro Mizushima, Yoshihiko Saito
  • Patent number: 7939406
    Abstract: Disclosure is semiconductor device of a selective gate region, comprising a semiconductor layer, a first insulating film formed on the semiconductor layer, a first electrode layer formed on the first insulating layer, an element isolating region comprising an element isolating insulating film formed to extend through the first electrode layer and the first insulating film to reach an inner region of the semiconductor layer, the element isolating region isolating a element region and being self-aligned with the first electrode layer, a second insulating film formed on the first electrode layer and the element isolating region, an open portion exposing a surface of the first electrode layer being formed in the second insulating film, and a second electrode layer formed on the second insulating film and the exposed surface of the first electrode layer, the second electrode layer being electronically connected to the first electrode layer via the open portion.
    Type: Grant
    Filed: May 5, 2009
    Date of Patent: May 10, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Michiharu Matsui, Seiichi Mori, Riichiro Shirota, Yuji Takeuchi, Takeshi Kamigaichi
  • Publication number: 20110092033
    Abstract: A nonvolatile semiconductor memory of an aspect of the present invention comprises a semiconductor substrate, a pillar-shaped semiconductor layer extending in the vertical direction with respect to the surface of the semiconductor substrate, a plurality of memory cells arranged in the vertical direction on the side surface of the semiconductor layer and having a charge storage layer and a control gate electrode, a first select gate transistor arranged on the semiconductor layer at an end of the memory cells on the side of the semiconductor substrate, and a second select gate transistor arranged on the semiconductor layer on the other end of the memory cells opposite to the side of the semiconductor substrate, wherein the first select gate transistor includes a diffusion layer in the semiconductor substrate and is electrically connected to the pillar-shaped semiconductor layer by way of the diffusion layer that serves as the drain region.
    Type: Application
    Filed: December 21, 2010
    Publication date: April 21, 2011
    Inventors: Fumitaka Arai, Riichiro Shirota
  • Publication number: 20110051526
    Abstract: A memory structure includes a first memory cell and a second memory cell located at an identical bit line and adjacent to the first memory cell. Each memory cell includes a substrate, a source, a drain, a charge storage device, and a gate. A method for programming the memory structure includes respectively providing a first gate biasing voltage and a second gate biasing voltage to the gates of the first memory cell and the second memory cell, boosting an absolute value of a channel voltage of the first memory cell to generate electron and hole pairs at the drain of the second memory cell through gate-induced drain leakage or band-to-band tunneling, and injecting the hole of the generated electron and hole pairs into the charge storage device of the first memory cell to program the first memory cell.
    Type: Application
    Filed: November 11, 2010
    Publication date: March 3, 2011
    Inventors: Riichiro Shirota, Ching-Hsiang Hsu, Cheng-Jye Liu
  • Patent number: 7888730
    Abstract: A nonvolatile semiconductor memory includes first and second memory cells having a floating gate and a control gate. The floating gate of the first and second memory cells is comprised a first part, and a second part arranged on the first part, and a width of the second part in an extending direction of the control gate is narrower than that of the first part. A first space between the first parts of the first and second memory cells is filled with one kind of an insulator. The control gate is arranged at a second space between the second parts of the first and second memory cells.
    Type: Grant
    Filed: March 19, 2007
    Date of Patent: February 15, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masayuki Ichige, Fumitaka Arai, Riichiro Shirota, Toshitake Yaegashi, Yoshio Ozawa, Akihito Yamamoto, Ichiro Mizushima, Yoshihiko Saito
  • Patent number: 7884422
    Abstract: A semiconductor memory including a plurality of cell units arranged in a row direction, each of the cell units includes: a semiconductor region; a first buried insulating film provided on the semiconductor region; a second buried insulating film provided on the first buried insulating film, which has higher dielectric constant than the first buried insulating film; a semiconductor layer provided on the second buried insulating film; and a plurality of memory cell transistors arranged in a column direction, each of the memory cell transistors having a source region, a drain region and a channel region defined in the semiconductor layer.
    Type: Grant
    Filed: August 20, 2007
    Date of Patent: February 8, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Makoto Mizukami, Riichiro Shirota, Fumitaka Arai
  • Patent number: 7875922
    Abstract: A nonvolatile semiconductor memory of an aspect of the present invention comprises a semiconductor substrate, a pillar-shaped semiconductor layer extending in the vertical direction with respect to the surface of the semiconductor substrate, a plurality of memory cells arranged in the vertical direction on the side surface of the semiconductor layer and having a charge storage layer and a control gate electrode, a first select gate transistor arranged on the semiconductor layer at an end of the memory cells on the side of the semiconductor substrate, and a second select gate transistor arranged on the semiconductor layer on the other end of the memory cells opposite to the side of the semiconductor substrate, wherein the first select gate transistor includes a diffusion layer in the semiconductor substrate and is electrically connected to the pillar-shaped semiconductor layer by way of the diffusion layer that serves as the drain region.
    Type: Grant
    Filed: December 20, 2007
    Date of Patent: January 25, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Fumitaka Arai, Riichiro Shirota
  • Patent number: 7855918
    Abstract: A memory structure includes a first memory cell and a second memory cell located at an identical bit line and adjacent to the first memory cell. Each memory cell includes a substrate, a source, a drain, a charge storage device, and a gate. A method for programming the memory structure includes respectively providing a first gate biasing voltage and a second gate biasing voltage to the first memory cell and the second memory cell, boosting the absolute value of a channel voltage of the first memory cell to generate electron and hole pairs at the drain of the second memory cell through gate-induced drain leakage or band-to-band tunneling, and injecting the electron of the generated electron and hole pairs into the charge storage device of the first memory cell to program the first memory cell.
    Type: Grant
    Filed: June 24, 2008
    Date of Patent: December 21, 2010
    Assignee: Powerflash Technology Corporation
    Inventors: Riichiro Shirota, Ching-Hsiang Hsu, Cheng-Jye Liu
  • Publication number: 20100252875
    Abstract: A structure of a non-volatile memory is described, including a substrate, isolation structures disposed in and protrudent over the substrate, floating gates as conductive spacers on the sidewalls of the isolation structures protrudent over the substrate, and a tunneling layer between each floating gate and the substrate. A process for fabricating a non-volatile memory is also described. Isolation structures are formed in a substrate protrudent over the same, a tunneling layer is formed over the substrate, and then floating gates are formed as conductive spacers on the sidewalls of the first isolation structures protrudent over the substrate.
    Type: Application
    Filed: April 3, 2009
    Publication date: October 7, 2010
    Applicant: POWERCHIP SEMICONDUCTOR CORP.
    Inventor: Riichiro Shirota
  • Publication number: 20100226173
    Abstract: A NAND cell unit includes memory cells which are connected in series. An erase operation is effected on all memory cells. Then, a soft-program voltage, which is opposite in polarity to the erase voltage applied in an erase operation, is applied to all memory cells, thereby setting all memory cells out of an over-erased state. Thereafter, a program voltage of 20V is applied to the control gate of a selected memory cell, 0V is applied to the control gates of the two memory cells provided adjacent to the selected memory cell, and 11V is applied to the control gates of the remaining memory cells. Data is thereby programmed into the selected memory cell. The time for which the program voltage is applied to the selected memory cell is adjusted in accordance with the data to be programmed into the selected memory cell. Hence, data “0” can be correctly programmed into the selected memory cell, multi-value data can be read from any selected memory cell at high speed.
    Type: Application
    Filed: May 17, 2010
    Publication date: September 9, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Tomoharu Tanaka, Hiroshi Nakamura, Ken Takeuchi, Riichiro Shirota, Fumitaka Arai, Susumu Fujimura
  • Patent number: 7791948
    Abstract: A semiconductor memory device includes: a semiconductor layer provided on an insulating substrate or an insulating layer; active areas each defined in the semiconductor layer with a device insulating film buried therein; and NAND cell units formed on the active areas, each NAND cell unit including a plurality of electrically rewritable and non-volatile memory cells connected in series, both ends of each NAND cell unit being coupled to a source line and a bit line, wherein the device has such a carrier discharging mode as to discharge channel carriers in the NAND cell unit to at least one of the source line and the bit line.
    Type: Grant
    Filed: June 30, 2008
    Date of Patent: September 7, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Riichiro Shirota, Fumitaka Arai
  • Patent number: 7755134
    Abstract: A nonvolatile semiconductor memory device includes: a semiconductor region; device isolation regions placed in the semiconductor region and extending in a column direction; a semiconductor layer placed on the semiconductor region and between the device isolation regions, and having a convex shape in cross section along a row direction; source/drain regions placed in the semiconductor layer and spaced from each other; a gate insulating film placed on the semiconductor layer between the source/drain regions; a floating gate electrode layer placed on the gate insulating film; an intergate insulating film placed on the floating gate electrode layer and upper surfaces of the device isolation regions; and a control gate electrode layer placed on the intergate insulating film and extending in the row direction.
    Type: Grant
    Filed: June 20, 2007
    Date of Patent: July 13, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masaru Kito, Nobutoshi Aoki, Masaru Kidoh, Ryota Katsumata, Masaki Kondo, Naoki Kusunoki, Toshiyuki Enda, Sanae Ito, Hiroyoshi Tanimoto, Hideaki Aochi, Akihiro Nitayama, Riichiro Shirota
  • Patent number: 7746707
    Abstract: A NAND cell unit includes memory cells which are connected in series. An erase operation is effected on all memory cells. Then, a soft-program voltage, which is opposite in polarity to the erase voltage applied in an erase operation, is applied to all memory cells, thereby setting all memory cells out of an over-erased state. Thereafter, a program voltage of 20V is applied to the control gate of a selected memory cell, 0V is applied to the control gates of the two memory cells provided adjacent to the selected memory cell, and 11V is applied to the control gates of the remaining memory cells. Data is thereby programmed into the selected memory cell. The time for which the program voltage is applied to the selected memory cell is adjusted in accordance with the data to be programmed into the selected memory cell. Hence, data “0” can be correctly programmed into the selected memory cell, multi-value data can be read from any selected memory cell at high speed.
    Type: Grant
    Filed: October 30, 2007
    Date of Patent: June 29, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tomoharu Tanaka, Hiroshi Nakamura, Ken Takeuchi, Riichiro Shirota, Fumitaka Arai, Susumu Fujimura
  • Publication number: 20100159657
    Abstract: A semiconductor memory device includes: a semiconductor substrate, on which an impurity diffusion layer is formed in a cell array area; a gate wiring stack body formed on the cell array area, in which multiple gate wirings are stacked and separated from each other with insulating films; a gate insulating film formed on the side surface of the gate wiring stack body, in which an insulating charge storage layer is contained; pillar-shaped semiconductor layers arranged along the gate wiring stack body, one side surfaces of which are opposed to the gate wiring stack body via the gate insulating film, each pillar-shaped semiconductor layer having the same conductivity type as the impurity diffusion layer; and data lines formed to be in contact with the upper surfaces of the pillar-shaped semiconductor layers and intersect the gate wirings.
    Type: Application
    Filed: March 2, 2010
    Publication date: June 24, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Fumitaka ARAI, Riichiro Shirota, Makoto Mizukami
  • Publication number: 20100149870
    Abstract: A non-volatile semiconductor memory and a writing method thereof are provided for preventing miswriting induced by gate-induced-drain leakage (GIDL). The non-volatile semiconductor memory comprises a non-volatile memory cell array 10 for recording multiple values by setting a plurality of different thresholds to each memory cell transistor that is connected in series between selection transistors Qs1 and Qs2 on two terminals of a selected bit line; and a control circuit 11 for controlling writing of the data from the memory cell array 10. The control circuit 11 records two values for at least a plurality of first memory cell transistors Q0, Q1, Q32 and Q33 respectively adjacent to the selection transistors Qs1 and Qs2 on two terminals of the bit line, and records more than three values for a plurality of second transistors Q2˜Q31 other than the first memory cell transistors.
    Type: Application
    Filed: December 3, 2009
    Publication date: June 17, 2010
    Inventor: Riichiro SHIROTA
  • Patent number: 7696559
    Abstract: A semiconductor memory device includes: a semiconductor substrate, on which an impurity diffusion layer is formed in a cell array area; a gate wiring stack body formed on the cell array area, in which multiple gate wirings are stacked and separated from each other with insulating films; a gate insulating film formed on the side surface of the gate wiring stack body, in which an insulating charge storage layer is contained, pillar-shaped semiconductor layers arranged along the gate wiring stack body, one side surfaces of which are opposed to the gate wiring stack body via the gate insulating film, each pillar-shaped semiconductor layer having the same conductivity type as the impurity diffusion layer; and data lines formed to be in contact with the upper surfaces of the pillar-shaped semiconductor layers and intersect the gate wirings.
    Type: Grant
    Filed: December 27, 2006
    Date of Patent: April 13, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Fumitaka Arai, Riichiro Shirota, Makoto Mizukami
  • Patent number: 7616491
    Abstract: A bit line is shared by first and second NAND units. First and second selection transistors are connected in series between the bit line and the first NAND unit. Third and fourth selection transistors are connected in series between the bit line and the second NAND unit. A control unit changes a first and second signals and a potential of the bit line from a first level to a second level higher than a first level, and changes the potential of the bit line from the second level to the first level after changing the first signal from the second level to the first level.
    Type: Grant
    Filed: April 23, 2007
    Date of Patent: November 10, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Takeshi Kamigaichi, Riichiro Shirota
  • Publication number: 20090221128
    Abstract: Disclosure is semiconductor device of a selective gate region, comprising a semiconductor layer, a first insulating film formed on the semiconductor layer, a first electrode layer formed on the first insulating layer, an element isolating region comprising an element isolating insulating film formed to extend through the first electrode layer and the first insulating film to reach an inner region of the semiconductor layer, the element isolating region isolating a element region and being self-aligned with the first electrode layer, a second insulating film formed on the first electrode layer and the element isolating region, an open portion exposing a surface of the first electrode layer being formed in the second insulating film, and a second electrode layer formed on the second insulating film and the exposed surface of the first electrode layer, the second electrode layer being electronically connected to the first electrode layer via the open portion.
    Type: Application
    Filed: May 5, 2009
    Publication date: September 3, 2009
    Inventors: Michiharu MATSUI, Seiichi MORI, Riichiro SHIROTA, Yuji TAKEUCHI, Takeshi KAMIGAICHI
  • Patent number: 7573092
    Abstract: Disclosure is semiconductor device of a selective gate region, comprising a semiconductor layer, a first insulating film formed on the semiconductor layer, a first electrode layer formed on the first insulating layer, an element isolating region comprising an element isolating insulating film formed to extend through the first electrode layer and the first insulating film to reach an inner region of the semiconductor layer, the element isolating region isolating a element region and being self-aligned with the first electrode layer, a second insulating film formed on the first electrode layer and the element isolating region, an open portion exposing a surface of the first electrode layer being formed in the second insulating film, and a second electrode layer formed on the second insulating film and the exposed surface of the first electrode layer, the second electrode layer being electronically connected to the first electrode layer via the open portion.
    Type: Grant
    Filed: November 2, 2006
    Date of Patent: August 11, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Michiharu Matsui, Seiichi Mori, Riichiro Shirota, Yuji Takeuchi, Takeshi Kamigaichi