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).
-
Publication number: 20220216335Abstract: A semiconductor device has an active area in which a main current flows and an outer-edge area surrounding the active area. The semiconductor device includes: an n-type semiconductor layer made of a wide bandgap semiconductor; a plurality of p-type guard rings provided inside the semiconductor layer in the outer-edge area to surround the active area; and a separation region provided in a concentric ring shape in the outer-edge area to be in contact with both of the adjacent guard rings, wherein the separation region contains both n-type first impurities and p-type second impurities.Type: ApplicationFiled: November 23, 2021Publication date: July 7, 2022Applicant: FUJI ELECTRIC CO., LTD.Inventor: Keiji OKUMURA
-
Publication number: 20220216199Abstract: An electronic circuit having a first terminal and a second terminal. The electronic circuit includes a first diode having a PN junction where a forward voltage is a first voltage, a second diode having a Schottky junction where the forward voltage is a second voltage that is smaller than the first voltage, a first wiring member coupling the first terminal to the second terminal via the first diode, and a second wiring member coupling the first terminal to the second terminal via the second diode. The second wiring member has an inductance larger than an inductance of the first wiring member.Type: ApplicationFiled: March 24, 2022Publication date: July 7, 2022Applicant: FUJI ELECTRIC CO., LTD.Inventor: Keiji OKUMURA
-
Patent number: 11329151Abstract: An insulated-gate semiconductor device includes: an n+-type current spreading layer disposed on an n?-type drift layer; a p-type base region disposed on the current spreading layer; a n+-type main-electrode region arranged in an upper portion of the base region; an insulated-gate electrode structure provided in a trench; and a p+-type gate-bottom protection-region being in contact with a bottom of the trench, including a plurality of openings through which a part of the current spreading layer penetrates, being selectively buried in the current spreading layer, wherein positions of the openings cut on both sides of a central line of the trench are shifted from each other about the central line in a longitudinal direction of the trench in a planar pattern.Type: GrantFiled: September 26, 2018Date of Patent: May 10, 2022Assignee: FUJI ELECTRIC CO., LTD.Inventors: Akimasa Kinoshita, Yasuhiko Oonishi, Keiji Okumura
-
Publication number: 20220140136Abstract: 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: ApplicationFiled: January 18, 2022Publication date: May 5, 2022Applicant: FUJI ELECTRIC CO., LTD.Inventor: Keiji OKUMURA
-
Patent number: 11276757Abstract: A silicon carbide semiconductor device includes an insulated-gate electrode structure that is formed inside a gate trench that goes through a base region and reaches a upper portion of a current transport layer to control a primary current flowing through the base region; a current suppression layer of the second conductivity type embedded within an upper portion of the current transport layer; a control electrode isolation insulating film filled into a control electrode isolation trench that goes through the base region and reaches an upper portion of the current suppression layer; and a control electrode pad disposed on the control electrode isolation insulating film, wherein an upper portion of the current suppression layer abuts a sidewall of the control electrode isolation insulating film, and a lower portion of the current suppression layer covers at least bottom corners of the control electrode isolation insulating film.Type: GrantFiled: November 6, 2018Date of Patent: March 15, 2022Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
-
Patent number: 11257945Abstract: 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 of a second conductivity type and a first base region of a second conductivity type that are respectively 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 that penetrates the second semiconductor layer and the second semiconductor region, a gate electrode provided in the trench via a gate insulating film, an interlayer insulating film provided on the gate electrode, a first electrode in contact with the second semiconductor layer and the second semiconductor region, and a second electrode provided on a back surface of the semiconductor substrate.Type: GrantFiled: December 24, 2019Date of Patent: February 22, 2022Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
-
Publication number: 20220013637Abstract: 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 28, 2021Publication date: January 13, 2022Applicant: FUJI ELECTRIC CO., LTD.Inventor: Keiji OKUMURA
-
Publication number: 20210408278Abstract: 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: ApplicationFiled: April 19, 2021Publication date: December 30, 2021Applicant: FUJI ELECTRIC CO., LTD.Inventor: Keiji OKUMURA
-
Patent number: 11177350Abstract: 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: April 9, 2020Date of Patent: November 16, 2021Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
-
Patent number: 11164859Abstract: A gate pad is includes a first portion disposed in a gate pad region and a second portion disposed in a gate resistance region and connected to the first portion, the gate pad has a planar shape in which the second portion protrudes from the first portion. A gate polysilicon layer disposed on a front surface of a semiconductor substrate via a gate insulating film, between the semiconductor substrate and an interlayer insulating film, has a surface area at least equal to that of the gate pad and opposes an entire surface of the gate pad in a depth direction. ESD capability of a first region where the gate pad is provided is greater than ESD capability of a second region where a gate resistance is provided and is greater than ESD capability of a third region where a MOS structure of an active region is provided.Type: GrantFiled: January 27, 2020Date of Patent: November 2, 2021Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
-
Patent number: 11139376Abstract: A trench gate MOSFET has at an n-type current spreading region between an n?-type drift region and a p-type base region, a first p+-type region facing a bottom of a trench, and a second p+-type region disposed between adjacent trenches. The first and the second p+-type regions extend parallel to a first direction in which the trench extends and are partially connected by a p+-type connecting portion and thus, disposed in a ladder shape when viewed from the front surface of a semiconductor substrate. The second p+-type region has at a portion of a surface on a drain side, a recessed portion that is recessed toward a source side. One or more recessed portions is provided between connection sites in the second p+-type region for connection with the p+-type connecting portions that are adjacent to each other in the first direction X.Type: GrantFiled: August 23, 2019Date of Patent: October 5, 2021Assignee: FUJI ELECTRIC CO., LTD.Inventors: Akimasa Kinoshita, Keiji Okumura
-
Patent number: 11139377Abstract: On a front surface of a silicon carbide semiconductor substrate of a first conductivity type, a first semiconductor layer of the first conductivity type having an impurity concentration lower than an impurity concentration of the silicon carbide semiconductor substrate is formed. A base region of a second conductivity type is selectively formed in the first semiconductor layer. A second semiconductor layer of the second conductivity type is formed on a surface of the first semiconductor layer. A first semiconductor region of the first conductivity type is selectively formed in a surface layer of the second semiconductor layer. The base region is formed by implanting an impurity of the second conductivity type from an angle that relative to a perpendicular to the silicon carbide semiconductor substrate, is three degrees or more.Type: GrantFiled: January 28, 2020Date of Patent: October 5, 2021Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
-
Patent number: 11114560Abstract: A silicon carbide semiconductor device includes a silicon carbide semiconductor substrate, a first semiconductor layer and a first semiconductor region each of a first conductivity type, and a first base region, a second semiconductor layer and a second semiconductor region each of a second conductivity type. The first base region opposes the second semiconductor region in a depth direction. A distribution of point defects in a depth direction from a first surface of the second semiconductor region, opposite a second surface of the second semiconductor region facing toward a front surface of the silicon carbide semiconductor substrate has two peaks at positions deeper than an interface between the first semiconductor layer and the first base region, where a first peak at a deeper position of the two peaks has a greater quantity of the point defects than does a second peak at a shallower position of the two peaks.Type: GrantFiled: March 2, 2020Date of Patent: September 7, 2021Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
-
Patent number: 11063123Abstract: At an upper surface of a gate electrode, a recess occurs due to etching back of poly-silicon for forming the gate electrode. At an upper surface of an interlayer insulating film, a recess occurs in a portion that opposes in a depth direction, the recess of the upper surface of the gate electrode. A barrier metal includes sequentially stacked first to fourth metal films. The first metal film is a titanium nitride film that covers the surface of the interlayer insulating film and has an opening that exposes the recess of the upper surface of the interlayer insulating film. The second metal film is a titanium film that covers the first metal film and the source electrode, and is in contact with the interlayer insulating film, in the opening of the first metal film. The third and fourth metal films are a titanium nitride film and a titanium film, respectively.Type: GrantFiled: July 24, 2019Date of Patent: July 13, 2021Assignee: FUJI ELECTRIC CO., LTD.Inventors: Shin'ichi Nakamata, Masanobu Iwaya, Keiji Okumura
-
Publication number: 20210193651Abstract: 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: ApplicationFiled: October 30, 2020Publication date: June 24, 2021Applicant: FUJI ELECTRIC CO., LTD.Inventor: Keiji OKUMURA
-
Patent number: 10998410Abstract: In a trench-gate MOSFET, between a channel and an n+-type source region, an n-type shunt resistance region is provided in contact with the n+-type source region and the channel. The n+-type source region is disposed at a position separated from a gate insulating film at a side wall of a trench, in a direction parallel to a front surface of a semiconductor substrate. The n-type shunt resistance region is disposed, positioned deeper toward a drain electrode than is a front surface of the semiconductor substrate and shallower toward a source electrode than is the channel, and reaches a position deeper toward the drain electrode from the front surface of the semiconductor substrate than is the n+-type source region. The n-type shunt resistance region is a resistor for reducing current between the drain and the source when a large current exceeding a rated current flows during a short circuit.Type: GrantFiled: September 23, 2019Date of Patent: May 4, 2021Assignee: FUJI ELECTRIC CO., LTD.Inventor: Keiji Okumura
-
Publication number: 20210104500Abstract: 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 17, 2020Publication date: April 8, 2021Inventor: Keiji OKUMURA
-
Publication number: 20210020751Abstract: 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: ApplicationFiled: October 1, 2020Publication date: January 21, 2021Applicant: FUJI ELECTRIC CO., LTD.Inventors: Keiji OKUMURA, Akimasa KINOSHITA
-
Patent number: 10896896Abstract: 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: January 8, 2020Date of Patent: January 19, 2021Assignee: ROHM CO., LTD.Inventor: Keiji Okumura
-
Publication number: 20210013128Abstract: In an inactive region of an active region, a gate pad, a gate poly-silicon layer, and a gate finger are provided at a front surface of a semiconductor substrate, via an insulating film. The gate poly-silicon layer is provided beneath the gate pad, sandwiching the insulating film therebetween. The gate pad, the gate poly-silicon layer, a gate finger, gate electrodes of a trench gate structure, a gate finger, and a second measurement pad are electrically connected in the order stated. As a result, the gate electrodes where parasitic resistance occurs and the gate poly-silicon layer where built-in resistance occurs are connected in series between the second measurement pad and the gate pad. A resistance value of the overall gate resistance that is a combined resistance of the built-in resistance and the parasitic resistance may be measured by the second measurement pad.Type: ApplicationFiled: September 28, 2020Publication date: January 14, 2021Applicant: FUJI ELECTRIC CO., LTD.Inventor: Keiji OKUMURA