Patents by Inventor Digh Hisamoto

Digh Hisamoto 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: 20170062440
    Abstract: A property of a semiconductor device having a non-volatile memory is improved. A semiconductor device, which has a control gate electrode part and a memory gate electrode part placed above a semiconductor substrate of a non-volatile memory, is configured as follows. A thick film portion is formed in an end portion of the control gate insulating film on the memory gate electrode part side, below the control gate electrode part. According to this configuration, even when holes are efficiently injected to a corner portion of the memory gate electrode part by an FN tunnel erasing method, electrons can be efficiently injected to the corner portion of the memory gate electrode part by an SSI injection method. Thus, a mismatch of the electron/hole distribution can be moderated, so that the retention property of the memory cell can be improved.
    Type: Application
    Filed: August 26, 2016
    Publication date: March 2, 2017
    Inventors: Tsuyoshi ARIGANE, Digh HISAMOTO
  • Patent number: 9558826
    Abstract: A first potential and a second potential lower than the first potential are applied to a first end of a memory gate electrode part of the nonvolatile memory and to a second end of the memory gate electrode part, respectively, so that a current is caused to flow in a direction in which the memory gate electrode part extends, then, a hole is injected from the memory gate electrode part into a charge accumulating part below it, therefore, an electron accumulated in the charge accumulating part is eliminated. By causing the current to flow through the memory gate electrode part of a memory cell region as described above, Joule heat can be generated to heat the memory cell. Consequently, in the erasing by a FN tunneling method in which the erasing characteristics degrade at a low temperature, the erasing speed can be improved by heating the memory gate electrode part.
    Type: Grant
    Filed: May 11, 2016
    Date of Patent: January 31, 2017
    Assignee: Renesas Electronics Corporation
    Inventors: Tsuyoshi Arigane, Daisuke Okada, Digh Hisamoto
  • Publication number: 20160379713
    Abstract: A first potential and a second potential lower than the first potential are applied to a first end of a memory gate electrode part of the nonvolatile memory and to a second end of the memory gate electrode part, respectively, so that a current is caused to flow in a direction in which the memory gate electrode part extends, then, a hole is injected from the memory gate electrode part into a charge accumulating part below it, therefore, an electron accumulated in the charge accumulating part is eliminated. By causing the current to flow through the memory gate electrode part of a memory cell region as described above, Joule heat can be generated to heat the memory cell. Consequently, in the erasing by a FN tunneling method in which the erasing characteristics degrade at a low temperature, the erasing speed can be improved by heating the memory gate electrode part.
    Type: Application
    Filed: May 11, 2016
    Publication date: December 29, 2016
    Inventors: Tsuyoshi ARIGANE, Daisuke Okada, Digh Hisamoto
  • Patent number: 9515082
    Abstract: A memory gate is formed of a first memory gate including a second gate insulating film made of a second insulating film and a first memory gate electrode, and a second memory gate including a third gate insulating film made of a third insulating film and a second memory gate electrode. In addition, the lower surface of the second memory gate electrode is located lower in level than the lower surface of the first memory gate electrode. As a result, during an erase operation, an electric field is concentrated on the corner portion of the first memory gate electrode which is located closer to a selection gate and a semiconductor substrate and on the corner portion of the second memory gate electrode which is located closer to the first memory gate and the semiconductor substrate. This allows easy injection of holes into each of the second and third insulating films.
    Type: Grant
    Filed: March 20, 2015
    Date of Patent: December 6, 2016
    Assignee: Renesas Electronics Corporation
    Inventors: Tsuyoshi Arigane, Digh Hisamoto, Daisuke Okada
  • Patent number: 9508837
    Abstract: To provide a semiconductor device having a nonvolatile memory improved in characteristics. In the semiconductor device, a nonvolatile memory has a high-k insulating film (high dielectric constant film) between a control gate electrode portion and a memory gate electrode portion and a transistor of a peripheral circuit region has a high-k/metal configuration. The high-k insulating film arranged between the control gate electrode portion and the memory gate electrode portion relaxes an electric field intensity at the end portion (corner portion) of the memory gate electrode portion on the side of the control gate electrode portion. This results in reduction in uneven distribution of charges in a charge accumulation portion (silicon nitride film) and improvement in erase accuracy.
    Type: Grant
    Filed: January 24, 2016
    Date of Patent: November 29, 2016
    Assignee: Renesas Electronics Corporation
    Inventors: Tsuyoshi Arigane, Daisuke Okada, Digh Hisamoto
  • Patent number: 9490247
    Abstract: An IGBT (50) includes a p+ collector region (3) and an n?? drift region (1), in which a first transistor (TR1) and a second transistor (TR2) are formed on the n?? drift region (1). In the n?? drift region (1), a p-type hole extraction region (14) is formed in contact with the second transistor (TR2). When the IGBT (50) is in an on-state, electrons and holes flow through the first transistor (TR1), but a current does not flow through the second transistor (TR2). On the other hand, when the IGBT (50) is switched from the on-state to an off-state, holes flow through the first transistor (TR1), and holes flow through the hole extraction region (14) and the second transistor (TR2).
    Type: Grant
    Filed: August 29, 2013
    Date of Patent: November 8, 2016
    Assignee: Hitachi, Ltd.
    Inventors: Hiroyuki Yoshimoto, Akio Shima, Digh Hisamoto
  • Publication number: 20160284690
    Abstract: An IGBT (50) includes a p+ collector region (3) and an n?? drift region (1), in which a first transistor (TR1) and a second transistor (TR2) are formed on the n?? drift region (1). In the n?? drift region (1), a p-type hole extraction region (14) is formed in contact with the second transistor (TR2). When the IGBT (50) is in an on-state, electrons and holes flow through the first transistor (TR1), but a current does not flow through the second transistor (TR2). On the other hand, when the IGBT (50) is switched from the on-state to an off-state, holes flow through the first transistor (TR1), and holes flow through the hole extraction region (14) and the second transistor (TR2).
    Type: Application
    Filed: August 29, 2013
    Publication date: September 29, 2016
    Inventors: Hiroyuki YOSHIMOTO, Akio SHIMA, Digh HISAMOTO
  • Patent number: 9412750
    Abstract: A non-volatile semiconductor memory device with good write/erase characteristics is provided. A selection gate is formed on a p-type well of a semiconductor substrate via a gate insulator, and a memory gate is formed on the p-type well via a laminated film composed of a silicon oxide film, a silicon nitride film, and a silicon oxide film. The memory gate is adjacent to the selection gate via the laminated film. In the regions on both sides of the selection gate and the memory gate in the p-type well, n-type impurity diffusion layers serving as the source and drain are formed. The region controlled by the selection gate and the region controlled by the memory gate located in the channel region between said impurity diffusion layers have the different charge densities of the impurity from each other.
    Type: Grant
    Filed: March 11, 2016
    Date of Patent: August 9, 2016
    Assignee: RENESAS ELECTRONICS CORPORATION
    Inventors: Digh Hisamoto, Shinichiro Kimura, Kan Yasui, Nozomu Matsuzaki
  • Publication number: 20160197091
    Abstract: A non-volatile semiconductor memory device with good write/erase characteristics is provided. A selection gate is formed on a p-type well of a semiconductor substrate via a gate insulator, and a memory gate is formed on the p-type well via a laminated film composed of a silicon oxide film, a silicon nitride film, and a silicon oxide film. The memory gate is adjacent to the selection gate via the laminated film. In the regions on both sides of the selection gate and the memory gate in the p-type well, n-type impurity diffusion layers serving as the source and drain are formed. The region controlled by the selection gate and the region controlled by the memory gate located in the channel region between said impurity diffusion layers have the different charge densities of the impurity from each other.
    Type: Application
    Filed: March 11, 2016
    Publication date: July 7, 2016
    Inventors: Digh HISAMOTO, Shinichiro KIMURA, Kan YASUI, Nozomu MATSUZAKI
  • Publication number: 20160141396
    Abstract: To provide a semiconductor device having a nonvolatile memory improved in characteristics. In the semiconductor device, a nonvolatile memory has a high-k insulating film (high dielectric constant film) between a control gate electrode portion and a memory gate electrode portion and a transistor of a peripheral circuit region has a high-k/metal configuration. The high-k insulating film arranged between the control gate electrode portion and the memory gate electrode portion relaxes an electric field intensity at the end portion (corner portion) of the memory gate electrode portion on the side of the control gate electrode portion. This results in reduction in uneven distribution of charges in a charge accumulation portion (silicon nitride film) and improvement in erase accuracy.
    Type: Application
    Filed: January 24, 2016
    Publication date: May 19, 2016
    Inventors: Tsuyoshi Arigane, Daisuke Okada, Digh Hisamoto
  • Publication number: 20160111499
    Abstract: A MOSFET using a SiC substrate has a problem that a carbon-excess layer is formed on a surface by the application of mechanical stress due to thermal oxidation and the carbon-excess layer degrades mobility of channel carriers. In the invention, (1) a layer containing carbon-carbon bonds is removed; (2) a gate insulating film is formed by a deposition method; and (3) an interface between a crystal surface and the insulating film is subjected to an interface treatment at a low temperature for a short time. Due to this, the carbon-excess layer causing characteristic degradation is effectively eliminated, and at the same time, dangling bonds can be effectively eliminated by subjecting an oxide film and an oxynitride film to an interface treatment.
    Type: Application
    Filed: March 29, 2013
    Publication date: April 21, 2016
    Inventors: Digh HISAMOTO, Keisuke KOBAYASHI, Naoki TEGA, Toshiyuki OHNO, Hirotaka HAMAMURA, Mieko MATSUMURA
  • Patent number: 9299715
    Abstract: A non-volatile semiconductor memory device with good write/erase characteristics is provided. A selection gate is formed on a p-type well of a semiconductor substrate via a gate insulator, and a memory gate is formed on the p-type well via a laminated film composed of a silicon oxide film, a silicon nitride film, and a silicon oxide film. The memory gate is adjacent to the selection gate via the laminated film. In the regions on both sides of the selection gate and the memory gate in the p-type well, n-type impurity diffusion layers serving as the source and drain are formed. The region controlled by the selection gate and the region controlled by the memory gate located in the channel region between said impurity diffusion layers have the different charge densities of the impurity from each other.
    Type: Grant
    Filed: April 13, 2015
    Date of Patent: March 29, 2016
    Assignee: Renesas Electronics Corporation
    Inventors: Digh Hisamoto, Shinichiro Kimura, Kan Yasui, Nozomu Matsuzaki
  • Publication number: 20160071882
    Abstract: Provided is a semiconductor element having, while maintaining the same integratability as a conventional MOSFET, excellent switch characteristics compared with the MOSFET, that is, having the S-value less than 60 mV/order at room temperature. Combining the MOSFET and a tunnel bipolar transistor having a tunnel junction configures a semiconductor element that shows an abrupt change in the drain current with respect to a change in the gate voltage (an S-value of less than 60 mV/order) even at a low voltage.
    Type: Application
    Filed: November 5, 2015
    Publication date: March 10, 2016
    Inventors: Digh Hisamoto, Shinichi Saito, Akio Shima, Hiroyuki Yoshimoto
  • Patent number: 9263571
    Abstract: When a gate length is reduced for the purpose of reducing on-resistance in a SiC DOMSFET, it is difficult to achieve both of the reduction of on-resistance by the reduction of gate length and the high element withstand voltage at the same time. In the present invention, a body layer is formed after the source diffusion layer region is formed and then a portion of the source diffusion layer region is recessed. Because of the presence of the body layer, the distances between the source diffusion region and respective end portions can be increased, a depletion layer is effectively expanded, and electric field concentration at the end portions can be suppressed, thereby improving withstand voltage characteristics. Consequently, the present invention can provide a silicon carbide semiconductor device that achieves both of the reduction of channel resistance by the reduction of gate length and the high element withstand voltage at the same time.
    Type: Grant
    Filed: December 28, 2012
    Date of Patent: February 16, 2016
    Assignee: Hitachi, Ltd.
    Inventors: Ryuta Tsuchiya, Hiroyuki Matsushima, Naoki Tega, Digh Hisamoto
  • Patent number: 9257446
    Abstract: To provide a semiconductor device having a nonvolatile memory improved in characteristics. In the semiconductor device, a nonvolatile memory has a high-k insulating film (high dielectric constant film) between a control gate electrode portion and a memory gate electrode portion and a transistor of a peripheral circuit region has a high-k/metal configuration. The high-k insulating film arranged between the control gate electrode portion and the memory gate electrode portion relaxes an electric field intensity at the end portion (corner portion) of the memory gate electrode portion on the side of the control gate electrode portion. This results in reduction in uneven distribution of charges in a charge accumulation portion (silicon nitride film) and improvement in erase accuracy.
    Type: Grant
    Filed: November 20, 2014
    Date of Patent: February 9, 2016
    Assignee: Renesas Electronics Corporation
    Inventors: Tsuyoshi Arigane, Daisuke Okada, Digh Hisamoto
  • Publication number: 20150372151
    Abstract: In a non-volatile memory in which writing/erasing is performed by changing a total charge amount by injecting electrons and holes into a silicon nitride film serving as a charge accumulation layer, in order to realize a high efficiency of a hole injection from a gate electrode, the gate electrode of a memory cell comprises a laminated structure made of a plurality of polysilicon films with different impurity concentrations, for example, a two-layered structure comprising a p-type polysilicon film with a low impurity concentration and a p?-type polysilicon film with a high impurity concentration deposited thereon.
    Type: Application
    Filed: August 28, 2015
    Publication date: December 24, 2015
    Inventors: Itaru YANAGI, Toshiyuki MINE, Hirotaka HAMAMURA, Digh HISAMOTO, Yasuhiro SHIMAMOTO
  • Patent number: 9209171
    Abstract: Provided is a semiconductor element having, while maintaining the same integratability as a conventional MOSFET, excellent switch characteristics compared with the MOSFET, that is, having the S-value less than 60 mV/order at room temperature. Combining the MOSFET and a tunnel bipolar transistor having a tunnel junction configures a semiconductor element that shows an abrupt change in the drain current with respect to a change in the gate voltage (an S-value of less than 60 mV/order) even at a low voltage.
    Type: Grant
    Filed: June 20, 2011
    Date of Patent: December 8, 2015
    Assignee: Hitachi, Ltd.
    Inventors: Digh Hisamoto, Shinichi Saito, Akio Shima, Hiroyuki Yoshimoto
  • Publication number: 20150349115
    Abstract: Disclosed herein is a technique for realizing a high-performance and high-reliability silicon carbide semiconductor device. A trenched MISFET with a trench formed into the drift through a p-type body layer 105 includes an n-type resistance relaxation layer 109 covering the bottom portion of the trench, and a p-type field relaxation layer 108. The p-type field relaxation layer 108 is separated from the trench bottom portion via the resistance relaxation layer 109, and is wider than the resistance relaxation layer 109. This achieves a low ON resistance, high reliability, and high voltage resistance at the same time. By forming the field relaxation layer beneath the trench, feedback capacitance can be controlled to achieve a high switching rate and high reliability.
    Type: Application
    Filed: January 23, 2013
    Publication date: December 3, 2015
    Inventors: Naoki TEGA, Digh HISAMOTO, Satoru AKIYAMA, Takashi TAKAHAMA, Tadao MORIMOTO, Ryuta TSUCHIYA
  • Publication number: 20150318389
    Abstract: When a gate length is reduced for the purpose of reducing on-resistance in a SiC DOMSFET, it is difficult to achieve both of the reduction of on-resistance by the reduction of gate length and the high element withstand voltage at the same time. In the present invention, a body layer is formed after the source diffusion layer region is formed and then a portion of the source diffusion layer region is recessed. Because of the presence of the body layer, the distances between the source diffusion region and respective end portions can be increased, a depletion layer is effectively expanded, and electric field concentration at the end portions can be suppressed, thereby improving withstand voltage characteristics. Consequently, the present invention can provide a silicon carbide semiconductor device that achieves both of the reduction of channel resistance by the reduction of gate length and the high element withstand voltage at the same time.
    Type: Application
    Filed: December 28, 2012
    Publication date: November 5, 2015
    Inventors: Ryuta TSUCHIYA, Hiroyuki MATSUSHIMA, Naoki TEGA, Digh HISAMOTO
  • Publication number: 20150270279
    Abstract: A memory gate is formed of a first memory gate including a second gate insulating film made of a second insulating film and a first memory gate electrode, and a second memory gate including a third gate insulating film made of a third insulating film and a second memory gate electrode. In addition, the lower surface of the second memory gate electrode is located lower in level than the lower surface of the first memory gate electrode. As a result, during an erase operation, an electric field is concentrated on the corner portion of the first memory gate electrode which is located closer to a selection gate and a semiconductor substrate and on the corner portion of the second memory gate electrode which is located closer to the first memory gate and the semiconductor substrate. This allows easy injection of holes into each of the second and third insulating films.
    Type: Application
    Filed: March 20, 2015
    Publication date: September 24, 2015
    Inventors: Tsuyoshi ARIGANE, Digh HISAMOTO, Daisuke OKADA