Patents by Inventor Wataru Saito
Wataru Saito 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: 20120187413Abstract: According to one embodiment, a nitride semiconductor device includes a first semiconductor, a second semiconductor layer, a third semiconductor layer, a fourth semiconductor layer, a first electrode, a second electrode and a third electrode. The first, second and fourth semiconductor layers include a nitride semiconductor. The second semiconductor layer is provided on the first semiconductor layer, has a band gap not less than that of the first semiconductor layer. The third semiconductor layer is provided on the second semiconductor layer. The third semiconductor layer is GaN. The fourth semiconductor layer is provided on the third semiconductor layer to have an interspace on a part of the third semiconductor layer, has a band gap not less than that of the second semiconductor layer. The first electrode is provided on a portion of the third semiconductor layer. The fourth semiconductor layer is not provided on the portion.Type: ApplicationFiled: September 21, 2011Publication date: July 26, 2012Applicant: Kabushiki Kaisha ToshibaInventors: Yasunobu SAITO, Hidetoshi FUJIMOTO, Tetsuya OHNO, Akira YOSHIOKA, Wataru SAITO
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Patent number: 8227854Abstract: A semiconductor device includes: a drift layer having a superjunction structure; a semiconductor base layer selectively formed in a part of one surface of the drift layer; a first RESURF layer formed around a region having the semiconductor base layer formed thereon; a second semiconductor RESURF layer of a conductivity type which is opposite to a conductivity type of the first semiconductor RESURF layer; a first main electrode connected to a first surface of the drift layer; and a second main electrode connected to a second surface of the drift layer. The first RESURF layer is connected to the semiconductor base layer. The second semiconductor RESURF layer is in contact with the first semiconductor RESURF layer.Type: GrantFiled: November 7, 2007Date of Patent: July 24, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Syotaro Ono, Wataru Saito, Masakatsu Takashita, Yasuto Sumi, Masaru Izumisawa, Hiroshi Ohta
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Patent number: 8227834Abstract: A semiconductor device includes: a first semiconductor layer including AlXGa1-XN (0?X?1); a second semiconductor layer provided on the first semiconductor layer, including AlYGa1-YN (0?Y?1, X<Y), and having a larger bandgap than the first semiconductor layer; a source electrode provided on the second semiconductor layer; a drain electrode provided on the second semiconductor layer; and a gate electrode provided on the second semiconductor layer between the source electrode and the drain electrode. A region of the second semiconductor layer below the gate electrode at a depth short of the first semiconductor layer is doped with atoms to be negatively charged in the second semiconductor layer.Type: GrantFiled: August 26, 2011Date of Patent: July 24, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Yasunobu Saito, Wataru Saito, Yorito Kakiuchi, Tomohiro Nitta, Akira Yoshioka, Tetsuya Ohno, Hidetoshi Fujimoto, Takao Noda
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Patent number: 8203172Abstract: A nitride semiconductor device includes: a first layer made of a first nitride semiconductor; a second layer provided on the first layer and made of a second nitride semiconductor having a larger band gap than the first nitride semiconductor; a first electrode electrically connected to the second layer; a second electrode provided on the second layer and juxtaposed to the first electrode in a first direction; and a floating electrode provided on the second layer, the floating electrode including: a portion sandwiched by the second electrode in a second direction orthogonal to the first direction; and a portion protruding from the second electrode toward the first electrode.Type: GrantFiled: April 9, 2010Date of Patent: June 19, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Wataru Saito, Yasunobu Saito, Takao Noda, Hidetoshi Fujimoto, Tetsuya Ohno
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Patent number: 8188521Abstract: A power semiconductor device has semiconductor layers, including: first layer of first type; second and third layers respectively of first and second types alternately on the first layer; fourth layers of second type on the third layers; fifth layers of first type on the fourth layer; sixth and seventh layers respectively of second and first types alternately on the second and third layers; a first electrode connected to the first layer; an insulation film on fourth, sixth, and seventh layers; a second electrode on fourth, sixth, and seventh layers via the insulation film; and a third electrode joined to fourth and fifth layers, wherein the sixth layers are connected to the fourth layers and one of the third layers between two fourth layers, and an impurity concentration of the third layers below the sixth layers is higher than that of the third layers under the fourth layers.Type: GrantFiled: March 22, 2010Date of Patent: May 29, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Wataru Saito, Syotaro Ono, Munehisa Yabuzaki, Nana Hatano, Miho Watanabe
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Patent number: 8159023Abstract: A semiconductor device includes a semiconductor substrate of a first conductivity type, a first semiconductor region of the first conductivity type on the semiconductor substrate, and a plurality of second semiconductor regions of a second conductivity type disposed separately in the first semiconductor region. A difference between a charge quantity expressed by an integral value of a net activated doping concentration in the second semiconductor regions in the surface direction of the semiconductor substrate and a charge quantity expressed by an integral value of a net activated doping concentration in the first semiconductor region in the surface direction of the semiconductor substrate is always a positive quantity and becomes larger from the depth of the first junction plane to a depth of a second junction plane on an opposite side from the first junction plane.Type: GrantFiled: January 22, 2010Date of Patent: April 17, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Syotaro Ono, Wataru Saito, Nana Hatano, Hiroshi Ohta, Miho Watanabe
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Publication number: 20120074491Abstract: In general, according to one embodiment, a power semiconductor device includes a first pillar region, a second pillar region, and an epitaxial layer of a first conductivity type on a first semiconductor layer. The first pillar region is composed of a plurality of first pillar layers of a second conductivity type and a plurality of second pillar layers of the first conductivity type alternately arranged along a first direction. The second pillar region is adjacent to the first pillar region along the first direction and includes a third pillar layer of the second conductivity type, a fourth pillar layer of the first conductivity type, and a fifth pillar layer of the second conductivity type in this order along the first direction. A plurality of second base layers of the second conductivity type electrically connected, respectively, onto the third pillar layer and the fifth pillar layer and spaced from each other.Type: ApplicationFiled: September 16, 2011Publication date: March 29, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Hiroshi OHTA, Yasuto SUMI, Kiyoshi KIMURA, Junji SUZUKI, Hiroyuki IRIFUNE, Wataru SAITO, Syotaro ONO
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Publication number: 20120074461Abstract: According to an embodiment, a semiconductor device includes a second semiconductor layer provided on a first semiconductor layer and including first pillars and second pillars. A first control electrode is provided in a trench of the second semiconductor layer and a second control electrode is provided on the second semiconductor layer and connected to the first control electrode. A first semiconductor region is provided on a surface of the second semiconductor layer except for a portion under the second control electrode. A second semiconductor region is provided on a surface of the first semiconductor region, the second semiconductor region being apart from the portion under the second control electrode and a third semiconductor region is provided on the first semiconductor region. A first major electrode is connected electrically to the first semiconductor layer and a second major electrode is connected electrically to the second and the third semiconductor region.Type: ApplicationFiled: September 16, 2011Publication date: March 29, 2012Applicant: Kabushiki Kaisha ToshibaInventors: Syotaro ONO, Wataru Saito, Shunji Taniuchi, Miho Watanabe, Hiroaki Yamashita
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Publication number: 20120068258Abstract: According to one embodiment, a semiconductor device includes a first main electrode, a control electrode, an extraction electrode, a second insulating film, a plurality of contact electrodes, and a control terminal. The first main electrode is electrically connected to a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type selectively provided on a surface of the first semiconductor region. The control electrode is provided on the first semiconductor region via a first insulating film. The extraction electrode is electrically connected to the control electrode. The second insulating film is provided on the first main electrode and the extraction electrode. The plurality of contact electrodes are provided in an inside of a plurality of first contact holes formed in the second insulating film and are electrically connected to the extraction electrode.Type: ApplicationFiled: March 21, 2011Publication date: March 22, 2012Applicant: Kabushiki Kaisha ToshibaInventors: Syotaro ONO, Wataru Saito, Shunji Taniuchi, Miho Watanabe, Hiroaki Yamashita
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Publication number: 20120056262Abstract: According to one embodiment, a semiconductor device includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, a third semiconductor layer of the first conductivity type, an embedded electrode, a control electrode, a fourth semiconductor layer of the second conductivity type, a first main electrode, and a second main electrode. The second semiconductor layer is provided on the first semiconductor layer. The third semiconductor layer is provided on the second semiconductor layer. The embedded electrode is provided in a first trench via a first insulating film. The first trench penetrates through the second semiconductor layer from a surface of the third semiconductor layer to reach the first semiconductor layer. The control electrode is provided above the embedded electrode via a second insulating film in the first trench.Type: ApplicationFiled: March 18, 2011Publication date: March 8, 2012Applicant: Kabushiki Kaisha ToshibaInventors: Wataru SAITO, Syotaro Ono, Shunji Taniuchi, Miho Watanabe, Hiroaki Yamashita
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Patent number: 8125023Abstract: In a vertical power semiconductor device having the super junction structure both in a device section and a terminal section, an n-type impurity layer is formed on the outer peripheral surface in the super junction structure. This allows an electric field on the outer peripheral surface of the super junction structure region to be reduced. Accordingly, a reliable vertical power semiconductor device of a high withstand voltage can be provided.Type: GrantFiled: November 17, 2009Date of Patent: February 28, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Hiroshi Ohta, Wataru Saito, Syotaro Ono, Munehisa Yabuzaki, Nana Hatano, Miho Watanabe
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Patent number: 8120517Abstract: A digital-analog conversion circuit includes a correction unit that adds a correction bit to a lower-order bit of externally input first digital input data and outputs second digital input data, and a conversion unit that receives the second digital input data and outputs an analog value, and the correction unit generates the second digital input data by manipulating data of a lower-order bit of the second digital input data around a point at which an error between the analog value and an expected value set for the first digital input data becomes larger than a preset value.Type: GrantFiled: September 14, 2009Date of Patent: February 21, 2012Assignee: Renesas Electronics CorporationInventor: Wataru Saito
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Publication number: 20120012929Abstract: According to one embodiment, a semiconductor device includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of the first conductivity type, a third semiconductor layer of a second conductivity type, a fourth semiconductor layer of the second conductivity type, a fifth semiconductor layer of the first conductivity type, a control electrode, a first main electrode, a second main electrode, and a sixth semiconductor layer of the first conductivity type. The second semiconductor layer and the third semiconductor layer are alternately provided on the first semiconductor layer in a direction substantially parallel to a major surface of the first semiconductor layer. The fourth semiconductor layer is provided on the second semiconductor layer and the third semiconductor layer. The fifth semiconductor layer is selectively provided on a surface of the fourth semiconductor layer. The control electrode is provided in a trench via an insulating film.Type: ApplicationFiled: March 18, 2011Publication date: January 19, 2012Applicant: Kabushiki Kaisha ToshibaInventors: Wataru SAITO, Syotaro Ono, Shunji Taniuchi, Miho Watanabe, Hiroaki Yamashita
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Publication number: 20110309413Abstract: A semiconductor device includes: a first semiconductor layer including AlXGa1-XN (0?X?1); a second semiconductor layer provided on the first semiconductor layer, including AlYGa1-YN (0?Y?1, X<Y), and having a larger bandgap than the first semiconductor layer; a source electrode provided on the second semiconductor layer; a drain electrode provided on the second semiconductor layer; and a gate electrode provided on the second semiconductor layer between the source electrode and the drain electrode. A region of the second semiconductor layer below the gate electrode at a depth short of the first semiconductor layer is doped with atoms to be negatively charged in the second semiconductor layer.Type: ApplicationFiled: August 26, 2011Publication date: December 22, 2011Applicant: Kabushiki Kaisha ToshibaInventors: Yasunobu SAITO, Wataru SAITO, Yorito KAKIUCHI, Tomohiro NITTA, Akira YOSHIOKA, Totsuya OHNO, Hidetoshi FUJIMOTO, Takao NODA
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Patent number: 8058688Abstract: A semiconductor device includes: a semiconductor substrate; a first semiconductor layer of a first conductivity type provided on a major surface of the semiconductor substrate and having lower doping concentration than the semiconductor substrate; a plurality of first semiconductor column regions of the first conductivity type provided on the first semiconductor layer; a plurality of second semiconductor column regions of a second conductivity type provided on the first semiconductor layer, the second semiconductor column regions being adjacent to the first semiconductor column regions; a first semiconductor region; a second semiconductor region; a gate insulating film; a first main electrode; a second main electrode; and a control electrode. Doping concentrations in both the first and second semiconductor column region are low on the near side of the first semiconductor layer and high on the second main electrode side.Type: GrantFiled: September 28, 2007Date of Patent: November 15, 2011Assignee: Kabushiki Kaisha ToshibaInventors: Syotaro Ono, Wataru Saito
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Publication number: 20110272708Abstract: According to one embodiment, a nitride semiconductor device includes a first, a second and a third semiconductor layer, a first and a second main electrode and a control electrode. The first layer made of a nitride semiconductor of a first conductivity type is provided on a substrate. The second layer made of a nitride semiconductor of a second conductivity type is provided on the first layer. The third layer made of a nitride semiconductor is provided on the second layer. The first electrode is electrically connected with the second layer. The second electrode is provided at a distance from the first electrode and electrically connected with the second layer. The control electrode is provided within a first trench via an insulating film. The first trench is disposed between the first and the second main electrodes, penetrates the third and the second layers, and reaches the first layer.Type: ApplicationFiled: March 21, 2011Publication date: November 10, 2011Applicant: Kabushiki Kaisha ToshibaInventors: Akira Yoshioka, Wataru Saito, Yasunobu Saito, Hidetoshi Fujimoto, Tetsuya Ohno
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Publication number: 20110260243Abstract: According to one embodiment, a power semiconductor device includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of the first conductivity type and a third semiconductor layer of a second conductivity type, a fourth semiconductor layer, a fifth semiconductor layer, a first and second main electrode, a first and second insulating film and a control electrode. The second and third layers are provided periodically on the first layer. The fourth layer is provided on the third layer. The fifth layer is selectively provided on the fourth layer. The first film is provided on sidewalls of a trench that reaches from a surface of the fifth layer to the second layer. The second film is provided closer to a bottom side of the trench than the first film and has a higher permittivity than the first film. The control electrode is embedded in the trench.Type: ApplicationFiled: March 21, 2011Publication date: October 27, 2011Applicant: Kabushiki Kaisha ToshibaInventors: Wataru Saito, Syotaro Ono, Munehisa Yabuzaki, Shunji Taniuchi, Miho Watanabe
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Patent number: 8030660Abstract: A semiconductor device includes: a first semiconductor layer including AlXGa1-XN (0?X?1); a second semiconductor layer provided on the first semiconductor layer, including AlYGa1-YN (0?Y?1, X<Y), and having a larger bandgap than the first semiconductor layer; a source electrode provided on the second semiconductor layer; a drain electrode provided on the second semiconductor layer; and a gate electrode provided on the second semiconductor layer between the source electrode and the drain electrode. A region of the second semiconductor layer below the gate electrode at a depth short of the first semiconductor layer is doped with atoms to be negatively charged in the second semiconductor layer.Type: GrantFiled: February 13, 2009Date of Patent: October 4, 2011Assignee: Kabushiki Kaisha ToshibaInventors: Yasunobu Saito, Wataru Saito, Yorito Kakiuchi, Tomohiro Nitta, Akira Yoshioka, Tetsuya Ohno, Hidetoshi Fujimoto, Takao Noda
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Patent number: 8030706Abstract: A semiconductor device according to an embodiment of the present invention includes a device part and a terminal part.Type: GrantFiled: August 12, 2009Date of Patent: October 4, 2011Assignee: Kabushiki Kaisha ToshibaInventors: Miho Watanabe, Masaru Izumisawa, Yasuto Sumi, Hiroshi Ohta, Wataru Sekine, Wataru Saito, Syotaro Ono, Nana Hatano
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Publication number: 20110227154Abstract: A semiconductor device comprising: a first semiconductor layer of a first conductivity type; a second semiconductor layer of the first conductivity type formed on the first semiconductor layer; a first buried layer of the first conductivity type selectively formed in the second semiconductor layer and having a first peak impurity concentration at a first depth; a second buried layer of a second conductivity type selectively formed in the second semiconductor layer and having a second peak impurity concentration at a second depth; a base layer of the second conductivity type selectively formed in the second semiconductor layer and overlapping with an upper portion of the second buried layer; a source layer of the first conductivity type selectively formed in the base layer; and a gate electrode formed on the base layer and on the second semiconductor layer above the first buried layer with a gate insulating film being interposed therebetween.Type: ApplicationFiled: March 18, 2011Publication date: September 22, 2011Applicant: Kabushiki Kaisha ToshibaInventors: Syotaro ONO, Wataru Saito, Munehisa Yabuzaki, Shunji Taniuchi, Miho Watanabe