Patents by Inventor Akio Nakagawa

Akio Nakagawa 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: 20060138535
    Abstract: A vertical MOSFET includes a base region formed on a drain region and a source region formed in the base region. A trench is formed to extend from the surface of the source region and penetrate the source region and has depth to reach a portion near the drain region. A gate insulating film is formed on the side walls and bottom portion of the trench and the gate electrode is formed in the trench. The impurity concentration profile of the base region has a first peak in a portion near the interface between the source region and the base region and a second peak which is formed in a portion near the interface between the base region and the drain region and is lower than the first peak. The threshold voltage is determined based on the first peak and the dose amount is determined based on the second peak.
    Type: Application
    Filed: February 27, 2006
    Publication date: June 29, 2006
    Inventors: Syotaro Ono, Yusuke Kawaguchi, Akio Nakagawa
  • Patent number: 7061060
    Abstract: A semiconductor device includes a first semiconductor region having a first conductivity type, a second semiconductor region formed on the first semiconductor region and having the first conductivity type, a third semiconductor region formed in a surface of the second semiconductor region and having a second conductivity type, a fourth semiconductor region formed in the surface of the second semiconductor region and having the second conductivity type, and a gate structure formed on the second and fourth semiconductor region. The semiconductor device further includes a conductive member arranged in the trench extending from a surface of the fourth semiconductor region to the first semiconductor region, the trench having one sidewall surface flush with a sidewall surface of the gate structure.
    Type: Grant
    Filed: March 17, 2003
    Date of Patent: June 13, 2006
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Norio Yasuhara, Syotaro Ono, Kazutoshi Nakamura, Yusuke Kawaguchi, Shinichi Hodama, Akio Nakagawa
  • Patent number: 7061047
    Abstract: A vertical MOSFET includes a base region formed on a drain region and a source region formed in the base region. A trench is formed to extend from the surface of the source region and penetrate the source region and has depth to reach a portion near the drain region. A gate insulating film is formed on the side walls and bottom portion of the trench and the gate electrode is formed in the trench. The impurity concentration profile of the base region has a first peak in a portion near the interface between the source region and the base region and a second peak which is formed in a portion near the interface between the base region and the drain region and is lower than the first peak. The threshold voltage is determined based on the first peak and the dose amount is determined based on the second peak.
    Type: Grant
    Filed: October 10, 2003
    Date of Patent: June 13, 2006
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Syotaro Ono, Yusuke Kawaguchi, Akio Nakagawa
  • Patent number: 7061048
    Abstract: A power MOSFET device comprising a low resistance substrate of the first conductivity type, a high resistance epitaxial layer of the first conductivity type formed on the low resistance substrate, a base layer of the second conductivity type formed in a surface region of the high resistance epitaxial layer, a source region of the first conductivity type formed in a surface region of the base layer, a gate insulating film formed on the surface of the base layer so as to contact the source region, a gate electrode formed on the gate insulating film, and an LDD layer of the first conductivity type formed on the surface of the high resistance epitaxial layer oppositely relative to the source region and the gate electrode, wherein the LDD layer and the low resistance substrate are connected to each other by the high resistance epitaxial layer.
    Type: Grant
    Filed: March 2, 2004
    Date of Patent: June 13, 2006
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yusuke Kawaguchi, Norio Yasuhara, Syotaro Ono, Shinichi Hodama, Akio Nakagawa
  • Patent number: 7034357
    Abstract: An insulated gate semiconductor device includes a first base layer of a first conduction type; a second base layer of a second conduction type formed on a first surface of the first base layer; a source layer of the first conduction type selectively formed in a surface region of the second base layer; a drain layer of the second conduction type formed on a second surface of the first base layer opposite from said first surface; and a gate electrode insulated from the source layer, the first base layer and the second base layer and forming in the second base layer a channel electrically connecting between the source layer and the first base layer, wherein the voltage transiently applied to the device is larger than the static breakdown voltage between the source and the drain when a rated current is turned off under a condition, in which condition the device is connected to an inductance load without using a protective circuit.
    Type: Grant
    Filed: December 2, 2003
    Date of Patent: April 25, 2006
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tomoko Matsudai, Akio Nakagawa
  • Patent number: 7026214
    Abstract: A semiconductor device includes a first semiconductor region having a first conductivity type, a second semiconductor region formed on the first semiconductor region and having the first conductivity type, a third semiconductor region formed in a surface of the second semiconductor region and having a second conductivity type, a fourth semiconductor region formed in the surface of the second semiconductor region and having the second conductivity type, and a gate structure formed on the second and fourth semiconductor region. The semiconductor device further includes a conductive member arranged in the trench extending from a surface of the fourth semiconductor region to the first semiconductor region, the trench having one sidewall surface flush with a sidewall surface of the gate structure.
    Type: Grant
    Filed: October 5, 2004
    Date of Patent: April 11, 2006
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Norio Yasuhara, Syotaro Ono, Kazutoshi Nakamura, Yusuke Kawaguchi, Shinichi Hodama, Akio Nakagawa
  • Publication number: 20060055432
    Abstract: A semiconductor module comprises a mounting board. A plurality of power switching device chips are mounted on the mounting board by flip-chip bonding. The chip has an upper surface and a lower surface and is configured to face the upper surface toward the mounting board. A drive IC chip is mounted on the mounting board by flip-chip bonding. The drive IC chip is operative to drive gates of transistors formed in the plurality of power switching device chips. A plurality of heat sink members are located on the lower surfaces of the plurality of power switching device chips, respectively. A resinous member is provided to seal the plurality of power switching device chips and the drive IC chip in a single package.
    Type: Application
    Filed: August 31, 2005
    Publication date: March 16, 2006
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Kazuo Shimokawa, Takashi Koyanagawa, Masako Ooishi, Tatsuya Yamada, Osamu Usuda, Yoshiki Endo, Taiki Miura, Masaki Toyoshima, Ichiro Omura, Akio Nakagawa, Kenichi Matsushita, Yusuke Kawaguchi, Haruki Arai, Hiroshi Takei, Tomohiro Kawano, Noriaki Yoshikawa, Morio Takahashi, Yasuhito Saito, Masahiro Urase
  • Publication number: 20050287744
    Abstract: A semiconductor device has a plurality of pillars formed by filling a poly-silicon via an insulating layer in a plurality of trenches arranged substantially in parallel at certain intervals, n+-semiconductor regions and p+-semiconductor regions which are formed between partial pillars among the plurality of pillars and alternately formed along a direction where the pillars extend, n?-semiconductor regions arranged between the other partial neighboring pillars among the plurality of pillars and a first metal layer which makes a schottky contact on an upper face of the n?-semiconductor regions.
    Type: Application
    Filed: June 22, 2005
    Publication date: December 29, 2005
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Syotaro Ono, Yusuke Kawaguchi, Akio Nakagawa
  • Patent number: 6977414
    Abstract: A semiconductor device comprises: a semiconductor layer of a first conductivity type; a pair of base regions of a second conductivity type selectively provided on a surface of the semiconductor layer; and source regions of a first conductivity type, each of the source regions being selectively provided on a surface of each of the base regions. The semiconductor device further comprises an electrical field reducing region of a second conductivity type selectively provided on the surface of the semiconductor layer between the pair of the base regions; a gate insulating film provided on the surface of the base regions; a pair of gate electrodes provided on the gate insulating film, each of the gate electrodes being provided on the surface of the base regions between the source region and the electrical field reducing region; and a source electrode connected to the source regions. The electrical field reducing region is isolated from both of the gate electrode and the source electrode.
    Type: Grant
    Filed: June 13, 2003
    Date of Patent: December 20, 2005
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kazutoshi Nakamura, Yoshihiro Yamaguchi, Yusuke Kawaguchi, Syotaro Ono, Akio Nakagawa
  • Publication number: 20050258479
    Abstract: Disclosed is a trench MOSFET, including: a trench gate structure having a gate electrode and a gate insulating film; an n-type diffusion layer formed to face the gate electrode via the gate insulating film at an upper portion of the trench; a p-type base layer formed to face the gate electrode via the gate insulating film at a lower portion than the upper portion; an n-type epitaxial layer locating to face the gate electrode via the gate insulating film at a further lower portion than the lower portion; a metal layer formed departing from the trench in parallel with a depth direction of the trench, penetrating the n-type diffusion layer and the p-type base layer, to reach the n-type epitaxial layer; and a p-type layer with higher impurity concentration than the p-type base layer, locating to be in contact with the p-type base layer and the metal layer.
    Type: Application
    Filed: May 12, 2005
    Publication date: November 24, 2005
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Syotaro Ono, Akio Nakagawa, Yusuke Kawaguchi, Yoshihiro Yamaguchi
  • Publication number: 20050179472
    Abstract: A semiconductor device comprises a high side switching element, a driver circuit, and a low side switching element. The high side switching element is formed on a first semiconductor substrate, has a current path to one end of which an input voltage is supplied, and the other end of the current path is connected to an inductance. The driver circuit is formed on the first semiconductor substrate, on which the high side switching element is formed, and drives the high side switching element. The low side switching element is formed on a second semiconductor substrate separate from the first semiconductor substrate, and has a drain connected to the inductance and a source supplied with a reference potential.
    Type: Application
    Filed: December 9, 2004
    Publication date: August 18, 2005
    Inventors: Kazutoshi Nakamura, Norio Yasuhara, Tomoko Matsudai, Kenichi Matsushita, Akio Nakagawa
  • Patent number: 6914294
    Abstract: A semiconductor device comprises a semiconductor substrate having a main surface; a semiconductor layer of a first conduction type provided on the main surface of said semiconductor substrate; a first buried layer of the first conduction type provided between said semiconductor layer and said semiconductor substrate; a first connection region of the first conduction type provided around said first buried layer, said first connection region extending from the surface of said semiconductor layer to said first buried layer; a switching element provided in the surface region of said semiconductor layer on said first buried layer; and a low breakdown-voltage element provided in a surface region of said semiconductor layer, said low breakdown-voltage element being closer to said first connection region than said switching element and having lower breakdown voltage than that of said switching element.
    Type: Grant
    Filed: May 15, 2003
    Date of Patent: July 5, 2005
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kazutoshi Nakamura, Tomoko Matsudai, Yusuke Kawaguchi, Akio Nakagawa
  • Publication number: 20050127440
    Abstract: A semiconductor substrate includes a first principal plane and a second principal plane opposite this first principal plane. A first semiconductor region is formed on the first principal plane of the semiconductor substrate. Second and third semiconductor regions are formed separately from each other on the first semiconductor region. A gate electrode is formed, via a gate insulator, on the first semiconductor region between the second semiconductor region and the third semiconductor region. An electric conductor is formed up to the semiconductor substrate from the second semiconductor region and electrically connects the second semiconductor region with the semiconductor substrate. A first main electrode is formed on the second principal plane of the semiconductor substrate and is electrically connected to the semiconductor substrate. A second main electrode is formed on the first semiconductor region via insulators and is electrically connected to the third semiconductor region.
    Type: Application
    Filed: January 12, 2005
    Publication date: June 16, 2005
    Inventors: Norio Yasuhara, Akio Nakagawa, Yusuke Kawaguchi, Kazutoshi Nakamura
  • Publication number: 20050098845
    Abstract: A MOS field-effect transistor includes a semiconductor substrate of a first-conductivity type, a semiconductor layer of the first-conductivity type, a source region of a second-conductivity type, a first drain region of the second-conductivity type, a resurf layer of the second-conductivity type provided in the surface of the semiconductor layer between the source region and the first drain region in contact with the first drain region, and having a lower impurity concentration than the first drain region, a gate insulation film, and a gate electrode provided on the gate insulation film between the source region and resurf layer. A Schottky barrier diode includes a second drain region of the second-conductivity type provided in the surface of the semiconductor layer separate from the first drain region in a direction away from the gate electrode, and a Schottky electrode provided on the semiconductor layer between the first and second drain regions.
    Type: Application
    Filed: October 7, 2004
    Publication date: May 12, 2005
    Inventors: Tomoko Matsudai, Kazutoshi Nakamura, Akio Nakagawa
  • Patent number: 6879005
    Abstract: A high withstand voltage semiconductor device, comprises: a substrate, a semiconductor layer formed on an upper surface of the substrate, a lateral semiconductor device formed in a surface region of the semiconductor layer and having a first principal electrode in its inner location and a second principal electrode in its outer location so as to let primary current flow between the first and second principal electrodes, a field insulation film formed inside from the second principal electrode in an upper surface of the semiconductor layer to surround the first principal electrode, a resistive field plate formed on an upper surface of the field insulation film to surround the first principal electrode and sectioned in a plurality of circular field plates in an approximate circular arrangement orbiting gradually from the vicinity of the first principal electrode toward the second principal electrode, the innermost one of the circular field plates being electrically connected to the first principal electrode whi
    Type: Grant
    Filed: March 2, 2004
    Date of Patent: April 12, 2005
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yoshihiro Yamaguchi, Akio Nakagawa
  • Patent number: 6878992
    Abstract: A power MOSFET comprises, between source and drain electrodes, a low resistive semiconductor substrate of a first conductivity type, a drift layer of the first conductivity type formed on the semiconductor substrate, a high resistive epitaxial layer of the first conductivity type formed on the drift layer, trenches formed to extend from a surface of the epitaxial layer into the drift layer, gate electrodes buried in the trenches with gate insulating films interposed between the gate electrodes and walls of the trenches, low resistive source layers of the first conductivity type formed in a surface region of the epitaxial layer adjacent to the gate insulating films, and a base layer of a second conductivity type formed in the surface region of the epitaxial layer, wherein the epitaxial layer intervening between the trenches is depleted in a case where 0 volt is applied between the source electrode and the gate electrodes.
    Type: Grant
    Filed: March 7, 2002
    Date of Patent: April 12, 2005
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yusuke Kawaguchi, Norio Yasuhara, Kazutoshi Nakamura, Akio Nakagawa, Syotaro Ono
  • Publication number: 20050056890
    Abstract: A semiconductor device includes a first semiconductor region having a first conductivity type, a second semiconductor region formed on the first semiconductor region and having the first conductivity type, a third semiconductor region formed in a surface of the second semiconductor region and having a second conductivity type, a fourth semiconductor region formed in the surface of the second semiconductor region and having the second conductivity type, and a gate structure formed on the second and fourth semiconductor region. The semiconductor device further includes a conductive member arranged in the trench extending from a surface of the fourth semiconductor region to the first semiconductor region, the trench having one sidewall surface flush with a sidewall surface of the gate structure.
    Type: Application
    Filed: October 5, 2004
    Publication date: March 17, 2005
    Inventors: Norio Yasuhara, Syotaro Ono, Kazutoshi Nakamura, Yusuke Kawaguchi, Shinichi Hodama, Akio Nakagawa
  • Patent number: 6864533
    Abstract: A semiconductor substrate includes a first principal plane and a second principal plane opposite this first principal plane. A first semiconductor region is formed on the first principal plane of the semiconductor substrate. Second and third semiconductor regions are formed separately from each other on the first semiconductor region. A gate electrode is formed, via a gate insulator, on the first semiconductor region between the second semiconductor region and the third semiconductor region. An electric conductor is formed up to the semiconductor substrate from the second semiconductor region and electrically connects the second semiconductor region with the semiconductor substrate. A first main electrode is formed on the second principal plane of the semiconductor substrate and is electrically connected to the semiconductor substrate. A second main electrode is formed on the first semiconductor region via insulators and is electrically connected to the third semiconductor region.
    Type: Grant
    Filed: September 12, 2001
    Date of Patent: March 8, 2005
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Norio Yasuhara, Akio Nakagawa, Yusuke Kawaguchi, Kazutoshi Nakamura
  • Publication number: 20050029586
    Abstract: A vertical MOSFET includes a base region formed on a drain region and a source region formed in the base region. A trench is formed to extend from the surface of the source region and penetrate the source region and has depth to reach a portion near the drain region. A gate insulating film is formed on the side walls and bottom portion of the trench and the gate electrode is formed in the trench. The impurity concentration profile of the base region has a first peak in a portion near the interface between the source region and the base region and a second peak which is formed in a portion near the interface between the base region and the drain region and is lower than the first peak. The threshold voltage is determined based on the first peak and the dose amount is determined based on the second peak.
    Type: Application
    Filed: October 10, 2003
    Publication date: February 10, 2005
    Inventors: Syotaro Ono, Yusuke Kawaguchi, Akio Nakagawa
  • Patent number: RE38907
    Abstract: The differential amplifier of a comparator circuit includes first and second n-type MOSFETs for receiving an input signal, first and second p-type MOSFETs of a current mirror circuit, and a third n-type MOSFET of a current source circuit. The output stage includes a third p-type MOSFET for transmitting a signal, and a fourth n-type MOSFET of the current source circuit. The differential amplifier further includes fifth and sixth n-type MOSFETs respectively series-connected to the first and second n-type MOSFETs. The output stage further includes a seventh n-type MOSFET series-connected to the fourth n-type MOSFET. The gates of the fifth, sixth, and seventh n-type MOSFETs are connected to voltage bias circuits. The fifth, sixth, and seventh n-type MOSFETs suppress variations in voltage at an output node caused by poor saturation characteristics of the first, second, and fourth main n-type MOSFETs.
    Type: Grant
    Filed: June 2, 2003
    Date of Patent: December 6, 2005
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tomoko Matsudai, Tsutomu Kojima, Akio Nakagawa