Patents by Inventor Keiji Okumura
Keiji Okumura 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: 20240170558Abstract: A method for producing a semiconductor power device, includes forming a gate trench from a surface of a semiconductor layer toward an inside thereof. A first insulation film is formed on an inner surface of the gate trench. The method also includes removing a part on a bottom surface of the gate trench in the first insulation film. A second insulation film having a dielectric constant higher than SiO2 is formed in such a way as to cover the bottom surface of the gate trench exposed by removing the first insulation film.Type: ApplicationFiled: January 24, 2024Publication date: May 23, 2024Applicant: ROHM CO., LTD.Inventors: Keiji OKUMURA, Mineo MIURA, Yuki NAKANO, Noriaki KAWAMOTO, Hidetoshi ABE
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Publication number: 20240170569Abstract: A semiconductor device includes: a drift layer; a base region provided on the drift layer; a main region provided on the drift layer; a gate electrode provided on the drift layer and buried in a gate trench extending in one direction across both ends of an active part with a gate insulating film interposed; a gate runner provided on an outer circumferential side of the active part so as to be electrically connected to the gate electrode; a gate pad provided on an inner side of the gate runner; and a resistance layer provided on the drift layer and buried in a trench for resistance extending in the one direction across the both ends of the active part with an insulating film interposed so as to be electrically connected between the gate pad and the gate runner.Type: ApplicationFiled: September 25, 2023Publication date: May 23, 2024Applicant: FUJI ELECTRIC CO., LTD.Inventor: Keiji OKUMURA
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Patent number: 11984498Abstract: A semiconductor device includes a current spreading region of the first conductivity type provided on a drift layer and having a higher impurity density than the drift layer; a base region of a second conductivity type provided on the current spreading region; a base contact region of the second conductivity type provided in a top part of the base region and having a higher impurity density than the base region; and an electrode contact region of the first conductivity type provided in a top part of the base region that is laterally in contact with the base contact region, the electrode contact region having a higher impurity density than the drift layer, wherein a density of a second conductivity type impurity element in the base contact region is at least two times as much as a density of a first conductivity type impurity element in the electrode contact region.Type: GrantFiled: September 29, 2020Date of Patent: May 14, 2024Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
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Publication number: 20240145589Abstract: A semiconductor device having an active portion and a gate pad portion on a semiconductor substrate includes: a first semiconductor layer of a first conductivity type; and a second semiconductor layer of a second conductivity type. The active portion has: first semiconductor regions of the first conductivity type; a first electrode provided on the first semiconductor regions; and first trenches. The gate pad portion has: a gate electrode pad provided above the second semiconductor layer; second trenches provided beneath the gate electrode pad; and second semiconductor regions of the second conductivity type, each provided in the first semiconductor layer so as to be in contact with a respective one of bottoms of the second trenches. Each of the second trenches is continuous with a respective one of the first trenches. The second semiconductor layer is continuous from the active portion to the gate pad portion.Type: ApplicationFiled: January 10, 2024Publication date: May 2, 2024Applicant: FUJI ELECTRIC CO., LTD.Inventor: Keiji OKUMURA
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Publication number: 20240120322Abstract: A semiconductor device includes a MOSFET including a PN junction diode. A unipolar device is connected in parallel to the MOSFET and has two terminals. A first wire connects the PN junction diode to one of the two terminals of the unipolar device. A second wire connects the one of the two terminals of the unipolar device to an output line, so that the output line is connected to the MOSFET and the unipolar device via the first wire and the second wire. In one embodiment the connection of the first wire to the diode is with its anode, and in another the connection is with the cathode.Type: ApplicationFiled: December 19, 2023Publication date: April 11, 2024Applicant: ROHM CO., LTD.Inventor: Keiji OKUMURA
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Patent number: 11908929Abstract: A semiconductor device having an active portion and a gate pad portion on a semiconductor substrate includes: a first semiconductor layer of a first conductivity type; and a second semiconductor layer of a second conductivity type. The active portion has: first semiconductor regions of the first conductivity type; a first electrode provided on the first semiconductor regions; and first trenches. The gate pad portion has: a gate electrode pad provided above the second semiconductor layer; second trenches provided beneath the gate electrode pad; and second semiconductor regions of the second conductivity type, each provided in the first semiconductor layer so as to be in contact with a respective one of bottoms of the second trenches. Each of the second trenches is continuous with a respective one of the first trenches. The second semiconductor layer is continuous from the active portion to the gate pad portion.Type: GrantFiled: October 26, 2022Date of Patent: February 20, 2024Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
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Patent number: 11894349Abstract: A semiconductor device includes a MOSFET including a PN junction diode. A unipolar device is connected in parallel to the MOSFET and has two terminals. A first wire connects the PN junction diode to one of the two terminals of the unipolar device. A second wire connects the one of the two terminals of the unipolar device to an output line, so that the output line is connected to the MOSFET and the unipolar device via the first wire and the second wire. In one embodiment the connection of the first wire to the diode is with its anode, and in another the connection is with the cathode.Type: GrantFiled: October 4, 2022Date of Patent: February 6, 2024Assignee: ROHM CO., LTD.Inventor: Keiji Okumura
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Publication number: 20240014270Abstract: An insulated-gate semiconductor device, which has trenches arranged in a chip structure, the trenches defining both sidewalls in a first and second sidewall surface facing each other, includes: a first unit cell including a main-electrode region in contact with a first sidewall surface of a first trench, a base region in contact with a bottom surface of the main-electrode region and the first sidewall surface, a drift layer in contact with a bottom surface of the base region and the first sidewall surface, and a gate protection-region in contact with the second sidewall surface and a bottom surface of the first trench; and a second unit cell including an operation suppression region in contact with a first sidewall surface and a second sidewall surface of a second trench, wherein the second unit cell includes the second trench located at one end of an array of the trenches.Type: ApplicationFiled: September 20, 2023Publication date: January 11, 2024Applicant: FUJI ELECTRIC CO., LTD.Inventor: Keiji OKUMURA
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Patent number: 11798993Abstract: An insulated-gate semiconductor device, which has trenches arranged in a chip structure, the trenches defining both sidewalls in a first and second sidewall surface facing each other, includes: a first unit cell including a main-electrode region in contact with a first sidewall surface of a first trench, a base region in contact with a bottom surface of the main-electrode region and the first sidewall surface, a drift layer in contact with a bottom surface of the base region and the first sidewall surface, and a gate protection-region in contact with the second sidewall surface and a bottom surface of the first trench; and a second unit cell including an operation suppression region in contact with a first sidewall surface and a second sidewall surface of a second trench, wherein the second unit cell includes the second trench located at one end of an array of the trenches.Type: GrantFiled: January 17, 2023Date of Patent: October 24, 2023Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
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Patent number: 11695045Abstract: In a silicon carbide semiconductor device and a silicon carbide semiconductor circuit device equipped with the silicon carbide semiconductor device, a gate leak current that flows when negative voltage with respect to the potential of a source electrode is applied to the gate electrode is limited to less than 2×10?11 A and the gate leak current is limited to less than 3.7×10?6 A/m2.Type: GrantFiled: October 1, 2020Date of Patent: July 4, 2023Assignee: FUJI ELECTRIC CO., LTD.Inventors: Keiji Okumura, Akimasa Kinoshita
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Publication number: 20230154986Abstract: An insulated-gate semiconductor device, which has trenches arranged in a chip structure, the trenches defining both sidewalls in a first and second sidewall surface facing each other, includes: a first unit cell including a main-electrode region in contact with a first sidewall surface of a first trench, a base region in contact with a bottom surface of the main-electrode region and the first sidewall surface, a drift layer in contact with a bottom surface of the base region and the first sidewall surface, and a gate protection-region in contact with the second sidewall surface and a bottom surface of the first trench; and a second unit cell including an operation suppression region in contact with a first sidewall surface and a second sidewall surface of a second trench, wherein the second unit cell includes the second trench located at one end of an array of the trenches.Type: ApplicationFiled: January 17, 2023Publication date: May 18, 2023Applicant: FUJI ELECTRIC CO., LTD.Inventor: Keiji OKUMURA
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Patent number: 11637199Abstract: A semiconductor device, including a first semiconductor layer of the first conductivity type formed on a semiconductor substrate, a first semiconductor region of the first conductivity type, a first base region and a first base region, both of a second conductivity type, selectively provided in the first semiconductor layer, a second semiconductor layer of the second conductivity type provided on the first semiconductor layer, a second semiconductor region of the first conductivity type selectively provided in the second semiconductor layer, a trench penetrating the second semiconductor layer and the second semiconductor region, a gate electrode provided in the trench, an interlayer insulating film provided on the gate electrode, a second base region in contact with a bottom of the trench, a first electrode in contact with the second semiconductor layer and the second semiconductor region, and a second electrode provided on the back of the semiconductor substrate.Type: GrantFiled: January 18, 2022Date of Patent: April 25, 2023Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
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Patent number: 11631668Abstract: An electronic circuit having a first terminal and a second terminal. The electronic circuit includes a plurality of diodes connected in parallel, the plurality of diodes including a first diode and a second diode that respectively have applied thereto a first forward voltage and a second forward voltage, the second forward voltage being higher than the first forward voltage. A first path and a second path are formed from the first terminal, respectively via the first diode and the second diode, to the second terminal. An inductance of the first path is larger than an inductance of the second path.Type: GrantFiled: October 30, 2020Date of Patent: April 18, 2023Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
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Patent number: 11610969Abstract: An insulated-gate semiconductor device, which has trenches arranged in a chip structure, the trenches defining both sidewalls in a first and second sidewall surface facing each other, includes: a first unit cell including a main-electrode region in contact with a first sidewall surface of a first trench, a base region in contact with a bottom surface of the main-electrode region and the first sidewall surface, a drift layer in contact with a bottom surface of the base region and the first sidewall surface, and a gate protection-region in contact with the second sidewall surface and a bottom surface of the first trench; and a second unit cell including an operation suppression region in contact with a first sidewall surface and a second sidewall surface of a second trench, wherein the second unit cell includes the second trench located at one end of an array of the trenches.Type: GrantFiled: September 28, 2021Date of Patent: March 21, 2023Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
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Publication number: 20230049039Abstract: A semiconductor device having an active portion and a gate pad portion on a semiconductor substrate includes: a first semiconductor layer of a first conductivity type; and a second semiconductor layer of a second conductivity type. The active portion has: first semiconductor regions of the first conductivity type; a first electrode provided on the first semiconductor regions; and first trenches. The gate pad portion has: a gate electrode pad provided above the second semiconductor layer; second trenches provided beneath the gate electrode pad; and second semiconductor regions of the second conductivity type, each provided in the first semiconductor layer so as to be in contact with a respective one of bottoms of the second trenches. Each of the second trenches is continuous with a respective one of the first trenches. The second semiconductor layer is continuous from the active portion to the gate pad portion.Type: ApplicationFiled: October 26, 2022Publication date: February 16, 2023Applicant: FUJI ELECTRIC CO., LTD.Inventor: Keiji OKUMURA
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Publication number: 20230025045Abstract: A semiconductor device includes a MOSFET including a PN junction diode. A unipolar device is connected in parallel to the MOSFET and has two terminals. A first wire connects the PN junction diode to one of the two terminals of the unipolar device. A second wire connects the one of the two terminals of the unipolar device to an output line, so that the output line is connected to the MOSFET and the unipolar device via the first wire and the second wire. In one embodiment the connection of the first wire to the diode is with its anode, and in another the connection is with the cathode.Type: ApplicationFiled: October 4, 2022Publication date: January 26, 2023Inventor: Keiji OKUMURA
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Publication number: 20220367294Abstract: A method of manufacturing a silicon carbide semiconductor device. The method includes providing a starting substrate containing silicon carbide, epitaxially growing an epitaxial layer on the starting substrate to thereby form a semiconductor wafer, forming a plurality of scribe lines at a surface of the semiconductor wafer to delineate a plurality of chip regions, forming a mark in the epitaxial layer, the mark being formed in a marking region that is outside the scribe lines, inspecting the epitaxial layer for a crystal defect, forming a device element structure in at least one of the plurality of chip regions, dicing the semiconductor wafer into a plurality of individual semiconductor chips along the plurality of scribe lines, and identifying, as a conforming product candidate, one of the plurality of semiconductor chips that is free of the crystal defect detected during the inspecting.Type: ApplicationFiled: March 25, 2022Publication date: November 17, 2022Applicant: FUJI ELECTRIC CO., LTD.Inventors: Hidetatsu NAKAMURA, Keiji OKUMURA, Yoshikuni FUJIMOTO
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Publication number: 20220367274Abstract: A method of manufacturing a silicon carbide semiconductor device. The method includes epitaxially growing an epitaxial layer on a starting substrate to form a semiconductor wafer, forming a plurality of scribe lines, including a first scribe line, in the epitaxial layer, forming a mark in the first scribe line, inspecting the epitaxial layer for a crystal defect using crystal defect inspection equipment, which recognizes the first scribe line as being a second scribe line, forming a device element structure in the semiconductor wafer, dicing the semiconductor wafer into semiconductor chips along the scribe lines, and identifying, as a conforming product candidate, one of the semiconductor chips that is free of the crystal defect detected during the inspecting. A distance between an edge of the second scribe line and an edge of the mark, when the first and second scribe lines are aligned, is in a range from 10 ?m to 25 ?m.Type: ApplicationFiled: March 29, 2022Publication date: November 17, 2022Applicant: FUJI ELECTRIC CO., LTD.Inventors: Hidetatsu NAKAMURA, Keiji OKUMURA, Yoshikuni FUJIMOTO
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Patent number: 11502063Abstract: A semiconductor device includes a MOSFET including a PN junction diode. A unipolar device is connected in parallel to the MOSFET and has two terminals. A first wire connects the PN junction diode to one of the two terminals of the unipolar device. A second wire connects the one of the two terminals of the unipolar device to an output line, so that the output line is connected to the MOSFET and the unipolar device via the first wire and the second wire. In one embodiment the connection of the first wire to the diode is with its anode, and in another the connection is with the cathode.Type: GrantFiled: December 17, 2020Date of Patent: November 15, 2022Assignee: ROHM CO., LTD.Inventor: Keiji Okumura
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Patent number: 11489071Abstract: A semiconductor device includes a semiconductor substrate of a first conductivity type, having an active portion and a gate pad portion; a first semiconductor layer of the first conductivity type; and a second semiconductor layer of a second conductivity type. The active portion has first semiconductor regions of the first conductivity type, first trenches, gate insulating films, first gate electrodes, an interlayer insulating film, and second semiconductor regions of the second conductivity type. The gate pad portion has at least one second trench, an insulating film 9b, at least one second gate electrode, at least one fourth semiconductor region of the second conductivity type, and a gate electrode pad. Between the gate electrode pad and the semiconductor substrate, a polycrystalline silicon film is provided.Type: GrantFiled: April 19, 2021Date of Patent: November 1, 2022Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura