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).
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Publication number: 20130001638Abstract: 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: ApplicationFiled: October 19, 2011Publication date: January 3, 2013Applicant: FUJI ELECTRIC CO., LTD.Inventor: Koh Yoshikawa
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Patent number: 8334581Abstract: 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: GrantFiled: December 22, 2010Date of Patent: December 18, 2012Assignee: Fuji Electric Co., Ltd.Inventor: Koh Yoshikawa
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Patent number: 8334565Abstract: 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: GrantFiled: July 10, 2008Date of Patent: December 18, 2012Assignee: Fuji Electric Co., Ltd.Inventor: Koh Yoshikawa
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Publication number: 20120286326Abstract: 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: ApplicationFiled: July 25, 2012Publication date: November 15, 2012Applicant: Fuji Electric Device Technology Co., Ltd.Inventor: Koh YOSHIKAWA
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Patent number: 8278682Abstract: 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: GrantFiled: May 26, 2011Date of Patent: October 2, 2012Assignee: Fuji Electric Co., Ltd.Inventors: Koh Yoshikawa, Kenichi Iguchi
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Patent number: 8258032Abstract: 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: GrantFiled: August 11, 2009Date of Patent: September 4, 2012Assignee: Fuji Electric Co., Ltd.Inventor: Koh Yoshikawa
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Publication number: 20120211768Abstract: 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: ApplicationFiled: February 14, 2012Publication date: August 23, 2012Applicant: Fuji Electric Co., Ltd.Inventor: Koh Yoshikawa
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Patent number: 8242556Abstract: 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: GrantFiled: April 26, 2010Date of Patent: August 14, 2012Assignee: Fuji Electric Co., Ltd.Inventors: Koh Yoshikawa, Hiroki Wakimoto, Masahito Otsuki
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Patent number: 8138542Abstract: 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: GrantFiled: April 21, 2009Date of Patent: March 20, 2012Assignee: Fuji Electric Co., Ltd.Inventors: Koh Yoshikawa, Akio Sugi, Kouta Takahashi, Manabu Takei, Haruo Nakazawa, Noriyuki Iwamuro
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Patent number: 8125027Abstract: 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: GrantFiled: April 7, 2011Date of Patent: February 28, 2012Assignee: Fuji Electric Co., Ltd.Inventor: Koh Yoshikawa
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Patent number: 8097901Abstract: 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: GrantFiled: May 25, 2011Date of Patent: January 17, 2012Assignees: Denso Corporation, Fuji Electric Device Technology Co., Ltd.Inventors: Masaki Koyama, Yoshifumi Okabe, Makoto Asai, Takeshi Fujii, Koh Yoshikawa
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Patent number: 8089134Abstract: 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: GrantFiled: January 30, 2009Date of Patent: January 3, 2012Assignee: Fuji Electric Sytems Co., Ltd.Inventors: Koh Yoshikawa, Tomoyuki Yamazaki, Yuichi Onozawa
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Patent number: 8089094Abstract: 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: GrantFiled: May 15, 2009Date of Patent: January 3, 2012Assignee: Fuji Electric Co., Ltd.Inventor: Koh Yoshikawa
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Patent number: 8080846Abstract: 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: GrantFiled: June 15, 2007Date of Patent: December 20, 2011Assignee: Fuji Electric Co., Ltd.Inventors: Koh Yoshikawa, Setsuko Wakimoto, Hitoshi Kuribayashi
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Publication number: 20110291241Abstract: 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: ApplicationFiled: May 26, 2011Publication date: December 1, 2011Applicant: Fuji Electric Co., Ltd.Inventors: Koh YOSHIKAWA, Kenichi Iguchi
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Publication number: 20110220962Abstract: 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: ApplicationFiled: May 25, 2011Publication date: September 15, 2011Applicants: DENSO CORPORATION, Fuji Electric Device Technology Co., Ltd.Inventors: Masaki Koyama, Yoshifumi Okabe, Makoto Asai, Takeshi Fujii, Koh Yoshikawa
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Publication number: 20110215435Abstract: 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: ApplicationFiled: March 1, 2011Publication date: September 8, 2011Applicant: FUJI ELECTRIC HOLDINGS CO., LTD.Inventors: Hiroki WAKIMOTO, Kenichi Iguchi, Koh Yoshikawa, Tsunehiro Nakajima, Shunsuke Tanaka, Masaaki Ogino
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Publication number: 20110180909Abstract: 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: ApplicationFiled: April 7, 2011Publication date: July 28, 2011Applicant: FUJI ELECTRIC CO., LTD.Inventor: Koh YOSHIKAWA
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Patent number: 7977704Abstract: 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: GrantFiled: January 27, 2009Date of Patent: July 12, 2011Assignees: Denso Corporation, Fuji Electric Device Technology Co., Ltd.Inventors: Masaki Koyama, Yoshifumi Okabe, Makoto Asai, Takeshi Fujii, Koh Yoshikawa
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Publication number: 20110156210Abstract: 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: ApplicationFiled: December 22, 2010Publication date: June 30, 2011Applicant: FUJI ELECTRIC HOLDINGS CO., LTD.Inventor: Koh YOSHIKAWA