Patents by Inventor Koh Yoshikawa

Koh Yoshikawa 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: 20130001638
    Abstract: Plural gate trenches are formed in the surface of an n-type drift region. A gate electrode is formed across a gate oxide film on the inner walls of the gate trenches. P-type base regions are selectively formed so as to neighbor each other in the gate trench longitudinal direction between neighboring gate trenches. An n-type emitter region is formed in contact with the gate trench in a surface layer of the p-type base regions. Also, a p-type contact region with a concentration higher than that of the p-type base region is formed in the surface layer of the p-type base region so as to be in contact with the gate trench side of the n-type emitter region. An edge portion on the gate trench side of the n-type emitter region terminates inside the p-type contact region.
    Type: Application
    Filed: October 19, 2011
    Publication date: January 3, 2013
    Applicant: FUJI ELECTRIC CO., LTD.
    Inventor: Koh Yoshikawa
  • Patent number: 8334581
    Abstract: A semiconductor device according to embodiments of the invention includes an n?-type drift region; a p-type base region formed selectively in the surface portion of the drift region; an n+-type emitter region and a p+-type body region, both formed selectively in the surface portion of base region; and an n-type shell region between the drift region and the base region, a shell region surrounding the entire region below base region. The shell region is doped more heavily than the drift region. The shell region contains an n-type impurity at an effective impurity amount of 8.0×1011 cm ?2 or smaller. A drift region exhibits a resistivity low enough to prevent the depletion layer expanding from collector region, formed on the back surface of the drift region, toward a shell region from reaching the shell region.
    Type: Grant
    Filed: December 22, 2010
    Date of Patent: December 18, 2012
    Assignee: Fuji Electric Co., Ltd.
    Inventor: Koh Yoshikawa
  • Patent number: 8334565
    Abstract: A vertical and trench type insulated gate MOS semiconductor device includes a plurality of regions each being provided between adjacent ones of a plurality of the straight-line-like trenches arranged in parallel and forming a surface pattern of a plurality of straight lines. A plurality of first inter-trench surface regions are provided, each with an n+-type emitter region and a p+-type body region formed thereon, and the surfaces of regions are alternately arranged along the trench in the longitudinal direction thereof with an emitter electrode being in common contact with both of the surfaces of the n+-type emitter region and the p+-type body region. A plurality of second inter-trench surface regions are provided each of which is formed along the trench in the longitudinal direction thereof with one of the surface of the p base region and the surface of the n-type semiconductor substrate.
    Type: Grant
    Filed: July 10, 2008
    Date of Patent: December 18, 2012
    Assignee: Fuji Electric Co., Ltd.
    Inventor: Koh Yoshikawa
  • Publication number: 20120286326
    Abstract: A power semiconductor device that realizes high-speed turnoff and soft switching at the same time has an n-type main semiconductor layer that includes lightly doped n-type semiconductor layers and extremely lightly doped n-type semiconductor layers arranged alternately and repeatedly between a p-type channel layer and an n+-type field stop layer, in a direction parallel to the first major surface of the n-type main semiconductor layer. A substrate used for manufacturing the semiconductor device is fabricated by forming trenches in an n-type main semiconductor layer 1 and performing ion implantation and subsequent heat treatment to form an n+-type field stop layer in the bottom of the trenches. The trenches are then filled with a semiconductor doped more lightly than the n-type main semiconductor layer for forming extremely lightly doped n-type semiconductor layers. The manufacturing method is applicable with variations to various power semiconductor devices such as IGBT's, MOSFET's and PIN diodes.
    Type: Application
    Filed: July 25, 2012
    Publication date: November 15, 2012
    Applicant: Fuji Electric Device Technology Co., Ltd.
    Inventor: Koh YOSHIKAWA
  • Patent number: 8278682
    Abstract: A semiconductor device that has a reduced size and exhibits a superior blocking voltage capability. A semiconductor device includes an edge termination structure between an active region and an isolation region, the edge termination structure being composed of an edge termination structure for a forward bias section and an edge termination structure for a reverse bias section. A plurality of field limiting rings (FLRs) and a plurality of field plates (FPs) are provided in the edge termination structure for the forward bias section and the edge termination structure for the reverse bias section. A first forward FP that is the nearest of the plurality of FPs to the edge termination structure for the reverse bias section is formed to extend towards the isolation region side. A first reverse FP that is the nearest of the plurality of FPs to the edge termination structure for the forward bias section is formed to extend towards the active region side.
    Type: Grant
    Filed: May 26, 2011
    Date of Patent: October 2, 2012
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Koh Yoshikawa, Kenichi Iguchi
  • Patent number: 8258032
    Abstract: A power semiconductor device that realizes high-speed turnoff and soft switching at the same time has an n-type main semiconductor layer that includes lightly doped n-type semiconductor layers and extremely lightly doped n-type semiconductor layers arranged alternately and repeatedly between a p-type channel layer and an n+-type field stop layer, in a direction parallel to the first major surface of the n-type main semiconductor layer. A substrate used for manufacturing the semiconductor device is fabricated by forming trenches in an n-type main semiconductor layer 1 and performing ion implantation and subsequent heat treatment to form an n+-type field stop layer in the bottom of the trenches. The trenches are then filled with a semiconductor doped more lightly than the n-type main semiconductor layer for forming extremely lightly doped n-type semiconductor layers. The manufacturing method is applicable with variations to various power semiconductor devices such as IGBT's, MOSFET's and PIN diodes.
    Type: Grant
    Filed: August 11, 2009
    Date of Patent: September 4, 2012
    Assignee: Fuji Electric Co., Ltd.
    Inventor: Koh Yoshikawa
  • Publication number: 20120211768
    Abstract: A wide-band-gap reverse-blocking MOS-type semiconductor device includes a SiC n?-type drift layer; a p+-type substrate on the first major surface side of the drift layer; a trench extending through a p+-type substrate into the drift layer; a titanium electrode in the trench bottom that forms a Schottky junction with the SiC n?-type drift layer; an active section including a MOS-gate structure on the second major surface side of the drift layer facing to the area, in which the Schottky junctions are formed; a breakdown withstanding section surrounding the active section; and a trench isolation layer surrounding the breakdown withstanding section, the trench isolation layer extending from the second major surface of the drift layer into p+-type substrate and including insulator film buried therein. The device facilitates making a high current flow with a low ON-voltage and exhibits a very reliable reverse blocking capability.
    Type: Application
    Filed: February 14, 2012
    Publication date: August 23, 2012
    Applicant: Fuji Electric Co., Ltd.
    Inventor: Koh Yoshikawa
  • Patent number: 8242556
    Abstract: A vertical and trench type insulated gate MOS semiconductor device is provided in which the surfaces of p-type channel regions and the surfaces of portions of an n-type semiconductor substrate alternate in the longitudinal direction of the trench between the trenches arranged in parallel, and an n+-type emitter region selectively formed on the surface of the p-type channel region is wide by the side of the trench and becomes narrow toward the center point between the trenches. This enables the device to achieve low on-resistance and enhanced turn-off capability.
    Type: Grant
    Filed: April 26, 2010
    Date of Patent: August 14, 2012
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Koh Yoshikawa, Hiroki Wakimoto, Masahito Otsuki
  • Patent number: 8138542
    Abstract: A semiconductor device including an n-type semiconductor substrate, a p-type channel region and a junction layer provided between the n-type semiconductor substrate and the p-type channel region is disclosed. The junction layer has n-type drift regions and p-type partition regions alternately arranged in the direction in parallel with the principal surface of the n-type semiconductor substrate. The p-type partition region forming the junction layer is made to have a higher impurity concentration than the n-type drift region. This enables the semiconductor device to have an enhanced breakdown voltage and, at the same time, have a reduced on-resistance.
    Type: Grant
    Filed: April 21, 2009
    Date of Patent: March 20, 2012
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Koh Yoshikawa, Akio Sugi, Kouta Takahashi, Manabu Takei, Haruo Nakazawa, Noriyuki Iwamuro
  • Patent number: 8125027
    Abstract: A semiconductor device includes an n-type semiconductor substrate, an alternating conductivity type layer on semiconductor substrate, the alternating conductivity type layer including n-type drift regions and p-type partition regions arranged alternately, p-type channel regions on the alternating conductivity type layer, and trenches formed from the surfaces of the p-type channel regions down to respective n-type drift regions or both the n-type drift regions and the p-type partition regions. The bottom of each trench is near or over the pn-junction between the p-type partition region and the n-type drift region. The semiconductor device facilitates preventing the on-resistance from increasing, obtaining a higher breakdown voltage, and reducing the variations caused in the characteristics thereof.
    Type: Grant
    Filed: April 7, 2011
    Date of Patent: February 28, 2012
    Assignee: Fuji Electric Co., Ltd.
    Inventor: Koh Yoshikawa
  • Patent number: 8097901
    Abstract: A semiconductor device having an IGBT includes: a substrate; a drift layer and a base layer on the substrate; trenches penetrating the base layer to divide the base layer into base parts; an emitter region in one base part; a gate element in the trenches; an emitter electrode; and a collector electrode. The one base part provides a channel layer, and another base part provides a float layer having no emitter region. The gate element includes a gate electrode next to the channel layer and a dummy gate electrode next to the float layer. The float layer includes a first float layer adjacent to the channel layer and a second float layer apart from the channel layer. The dummy gate electrode and the first float layer are coupled with a first float wiring on the base layer. The dummy gate electrode is isolated from the second float layer.
    Type: Grant
    Filed: May 25, 2011
    Date of Patent: January 17, 2012
    Assignees: Denso Corporation, Fuji Electric Device Technology Co., Ltd.
    Inventors: Masaki Koyama, Yoshifumi Okabe, Makoto Asai, Takeshi Fujii, Koh Yoshikawa
  • Patent number: 8089134
    Abstract: A semiconductor device equipped with a primary semiconductor element and a temperature detecting element for detecting a temperature of the primary semiconductor element. The device includes a first semiconductor layer of a first conductivity type that forms the primary semiconductor element. A second semiconductor region of a second conductivity type is provided in the first semiconductor layer. A third semiconductor region of the first conductivity type is provided in the second semiconductor region. The temperature detecting element is provided in the third semiconductor region and is separated from the first semiconductor layer by a PN junction.
    Type: Grant
    Filed: January 30, 2009
    Date of Patent: January 3, 2012
    Assignee: Fuji Electric Sytems Co., Ltd.
    Inventors: Koh Yoshikawa, Tomoyuki Yamazaki, Yuichi Onozawa
  • Patent number: 8089094
    Abstract: A power semiconductor device is provided, that realizes high-speed turnoff and soft switching at the same time, includes n-type main semiconductor layer including lightly doped n-type semiconductor layer and extremely lightly doped n-type semiconductor layer arranged alternately and repeatedly between p-type channel layer and field stop layer and in parallel to the first major surface of n-type main semiconductor layer. Extremely lightly doped n-type semiconductor layer is doped more lightly than lightly doped n-type semiconductor layer. Lightly doped n-type semiconductor layer prevents a space charge region from expanding at the time of turnoff. Extremely lightly doped n-type semiconductor layer expands the space charge region at the time of turnoff to eject electrons and holes quickly further to realize high-speed turnoff.
    Type: Grant
    Filed: May 15, 2009
    Date of Patent: January 3, 2012
    Assignee: Fuji Electric Co., Ltd.
    Inventor: Koh Yoshikawa
  • Patent number: 8080846
    Abstract: A semiconductor device is disclosed which improves the breakdown voltage of a planar-type junction edge terminating structure. The device includes an n-type semiconductor substrate layer common to an active section and an edge terminating section. An n-type drift region is formed selectively on the n-type semiconductor substrate layer in the active section and a p-type partition region is formed selectively on the n-type semiconductor substrate layer in the active section. A p-type base/body region is formed on the n-type drift region and the partition region. A source electrode is connected electrically to the p-type base/body region. A p-type partition region is formed in the edge terminating section between the p-type base/body region and the scribe plane of the semiconductor device such that the p-type partition region in the edge terminating section surrounds the p-type base/body region. A drain electrode is connected electrically to the n-type semiconductor substrate layer.
    Type: Grant
    Filed: June 15, 2007
    Date of Patent: December 20, 2011
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Koh Yoshikawa, Setsuko Wakimoto, Hitoshi Kuribayashi
  • Publication number: 20110291241
    Abstract: A semiconductor device that has a reduced size and exhibits a superior blocking voltage capability. A semiconductor device includes an edge termination structure between an active region and an isolation region, the edge termination structure being composed of an edge termination structure for a forward bias section and an edge termination structure for a reverse bias section. A plurality of field limiting rings (FLRs) and a plurality of field plates (FPs) are provided in the edge termination structure for the forward bias section and the edge termination structure for the reverse bias section. A first forward FP that is the nearest of the plurality of FPs to the edge termination structure for the reverse bias section is formed to extend towards the isolation region side. A first reverse FP that is the nearest of the plurality of FPs to the edge termination structure for the forward bias section is formed to extend towards the active region side.
    Type: Application
    Filed: May 26, 2011
    Publication date: December 1, 2011
    Applicant: Fuji Electric Co., Ltd.
    Inventors: Koh YOSHIKAWA, Kenichi Iguchi
  • Publication number: 20110220962
    Abstract: A semiconductor device having an IGBT includes: a substrate; a drift layer and a base layer on the substrate; trenches penetrating the base layer to divide the base layer into base parts; an emitter region in one base part; a gate element in the trenches; an emitter electrode; and a collector electrode. The one base part provides a channel layer, and another base part provides a float layer having no emitter region. The gate element includes a gate electrode next to the channel layer and a dummy gate electrode next to the float layer. The float layer includes a first float layer adjacent to the channel layer and a second float layer apart from the channel layer. The dummy gate electrode and the first float layer are coupled with a first float wiring on the base layer. The dummy gate electrode is isolated from the second float layer.
    Type: Application
    Filed: May 25, 2011
    Publication date: September 15, 2011
    Applicants: DENSO CORPORATION, Fuji Electric Device Technology Co., Ltd.
    Inventors: Masaki Koyama, Yoshifumi Okabe, Makoto Asai, Takeshi Fujii, Koh Yoshikawa
  • Publication number: 20110215435
    Abstract: Some embodiments of the present invention relate to a semiconductor device and a method of manufacturing a semiconductor device capable of preventing the deterioration of electrical characteristics. A p-type collector region is provided on a surface layer of a backside surface of an n-type drift region. A p+-type isolation layer for obtaining reverse blocking capability is provided at the end of an element. In addition, a concave portion is provided so as to extend from the backside surface of the n-type drift region to the p+-type isolation layer. A p-type region is provided and is electrically connected to the p+-type isolation layer. The p+-type isolation layer is provided so as to include a cleavage plane having the boundary between the bottom and the side wall of the concave portion as one side.
    Type: Application
    Filed: March 1, 2011
    Publication date: September 8, 2011
    Applicant: FUJI ELECTRIC HOLDINGS CO., LTD.
    Inventors: Hiroki WAKIMOTO, Kenichi Iguchi, Koh Yoshikawa, Tsunehiro Nakajima, Shunsuke Tanaka, Masaaki Ogino
  • Publication number: 20110180909
    Abstract: A semiconductor device includes an n-type semiconductor substrate, an alternating conductivity type layer on semiconductor substrate, the alternating conductivity type layer including n-type drift regions and p-type partition regions arranged alternately, p-type channel regions on the alternating conductivity type layer, and trenches formed from the surfaces of the p-type channel regions down to respective n-type drift regions or both the n-type drift regions and the p-type partition regions. The bottom of each trench is near or over the pn-junction between the p-type partition region and the n-type drift region. The semiconductor device facilitates preventing the on-resistance from increasing, obtaining a higher breakdown voltage, and reducing the variations caused in the characteristics thereof.
    Type: Application
    Filed: April 7, 2011
    Publication date: July 28, 2011
    Applicant: FUJI ELECTRIC CO., LTD.
    Inventor: Koh YOSHIKAWA
  • Patent number: 7977704
    Abstract: A semiconductor device having an IGBT includes: a substrate; a drift layer and a base layer on the substrate; trenches penetrating the base layer to divide the base layer into base parts; an emitter region in one base part; a gate element in the trenches; an emitter electrode; and a collector electrode. The one base part provides a channel layer, and another base part provides a float layer having no emitter region. The gate element includes a gate electrode next to the channel layer and a dummy gate electrode next to the float layer. The float layer includes a first float layer adjacent to the channel layer and a second float layer apart from the channel layer. The dummy gate electrode and the first float layer are coupled with a first float wiring on the base layer. The dummy gate electrode is isolated from the second float layer.
    Type: Grant
    Filed: January 27, 2009
    Date of Patent: July 12, 2011
    Assignees: Denso Corporation, Fuji Electric Device Technology Co., Ltd.
    Inventors: Masaki Koyama, Yoshifumi Okabe, Makoto Asai, Takeshi Fujii, Koh Yoshikawa
  • Publication number: 20110156210
    Abstract: A semiconductor device according to embodiments of the invention includes an n?-type drift region; a p-type base region formed selectively in the surface portion of the drift region; an n+-type emitter region and a p+-type body region, both formed selectively in the surface portion of base region; and an n-type shell region between the drift region and the base region, a shell region surrounding the entire region below base region. The shell region is doped more heavily than the drift region. The shell region contains an n-type impurity at an effective impurity amount of 8.0×1011 cm?2 or smaller. A drift region exhibits a resistivity low enough to prevent the depletion layer expanding from collector region, formed on the back surface of the drift region, toward a shell region from reaching the shell region.
    Type: Application
    Filed: December 22, 2010
    Publication date: June 30, 2011
    Applicant: FUJI ELECTRIC HOLDINGS CO., LTD.
    Inventor: Koh YOSHIKAWA