Patents by Inventor Akinori Seki
Akinori Seki 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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Patent number: 11522055Abstract: A stack including at least a semiconductor drift layer stacked on a single-crystal diamond substrate having a coalescence boundary, wherein the coalescence boundary of the single-crystal diamond substrate is a region that exhibits, in a Raman spectrum at a laser excitation wavelength of 785 nm, a full width at half maximum of a peak near 1332 cm?1 due to diamond that is observed to be broader than a full width at half maximum of the peak exhibited by a region different from the coalescence boundary, the coalescence boundary has a width of 200 ?m or more, and the semiconductor drift layer is stacked on at least the coalescence boundary.Type: GrantFiled: January 11, 2019Date of Patent: December 6, 2022Assignee: NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGYInventors: Shinya Ohmagari, Hideaki Yamada, Hitoshi Umezawa, Nobuteru Tsubouchi, Akiyoshi Chayahara, Yoshiaki Mokuno, Akinori Seki, Fumiaki Kawai, Hiroaki Saitoh
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Publication number: 20210066078Abstract: There is provided a novel stack that includes a single-crystal diamond substrate having a coalescence boundary, yet effectively uses the coalescence boundary. A stack comprising at least a semiconductor drift layer stacked on a single-crystal diamond substrate having a coalescence boundary, wherein the coalescence boundary of the single-crystal diamond substrate is a region that exhibits, in a Raman spectrum at a laser excitation wavelength of 785 nm, a full width at half maximum of a peak near 1332 cm?1 due to diamond that is observed to be broader than a full width at half maximum of the peak exhibited by a region different from the coalescence boundary, the coalescence boundary has a width of 200 ?m or more, and the semiconductor drift layer is stacked on at least the coalescence boundary.Type: ApplicationFiled: January 11, 2019Publication date: March 4, 2021Inventors: Shinya OHMAGARI, Hideaki YAMADA, Hitoshi UMEZAWA, Nobuteru TSUBOUCHI, Akiyoshi CHAYAHARA, Yoshiaki MOKUNO, Akinori SEKI, Fumiaki KAWAI, Hiroaki SAITOH
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Patent number: 9903047Abstract: A method for producing an SiC crystal, comprising supplying a raw material gas containing Si, C and N to vapor-grow an N-doped SiC crystal on an SiC substrate, wherein the SiC substrate is an SiC substrate on which La, Ce or Ti is deposited in part or whole of the surface or an SiC substrate in which La, Ce or Ti ion is implanted into part or whole of the surface.Type: GrantFiled: June 17, 2016Date of Patent: February 27, 2018Assignees: TOYOTA JIDOSHA KABUSHIKI KAISHA, JAPAN FINE CERAMICS CENTERInventors: Akinori Seki, Yukari Ishikawa
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Patent number: 9873955Abstract: A method for producing a SiC single crystal substrate that can remove Cr impurity from the surface of a SiC single crystal that contains Cr as an impurity, is provided. This is achieved by a method for producing a SiC single crystal substrate, wherein the method includes a step of immersing a SiC single crystal substrate containing Cr as an impurity in hydrochloric acid at 50° C. to 80° C.Type: GrantFiled: February 23, 2015Date of Patent: January 23, 2018Assignee: TOYOTA JIDOSHA KABUSHIKI KAISHAInventor: Akinori Seki
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Patent number: 9587327Abstract: A method of production of a SiC single crystal uses the solution method to prevent the formation of defects due to seed touch, i.e., causing a seed crystal to touch the melt, and thereby cause growth of a SiC single crystal reduced in defect density. According to the method, a SiC seed crystal touches a melt containing Si in a graphite crucible to thereby cause growth of the SiC single crystal on the SiC seed crystal. The method includes making the SiC seed crystal touch the melt, and then making the melt rise in temperature once to a temperature higher than the temperature at the time of touch and also higher than the temperature for causing growth.Type: GrantFiled: July 17, 2009Date of Patent: March 7, 2017Assignee: Toyota Jidosha Kabushiki KaishaInventors: Katsunori Danno, Akinori Seki, Hiroaki Saitoh, Yoichiro Kawai
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Publication number: 20160369424Abstract: A method for producing an SiC crystal, comprising supplying a raw material gas containing Si, C and N to vapor-grow an N-doped SiC crystal on an SiC substrate, wherein the SiC substrate is an SiC substrate on which La, Ce or Ti is deposited in part or whole of the surface or an SiC substrate in which La, Ce or Ti ion is implanted into part or whole of the surface.Type: ApplicationFiled: June 17, 2016Publication date: December 22, 2016Applicants: TOYOTA JIDOSHA KABUSHIKI KAISHA, JAPAN FINE CERAMICS CENTERInventors: Akinori SEKI, Yukari ISHIKAWA
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Patent number: 9508802Abstract: A process for producing a semiconductor device includes: forming an SiC epitaxial layer on an SiC substrate; implanting the epitaxial layer with ions; forming a gettering layer having a higher defect density than a defect density of the SiC substrate; and carrying out a heat treatment on the epitaxial layer. The semiconductor device includes an SiC substrate, an SiC epitaxial layer formed on the SiC substrate, and a gettering layer having a higher defect density than a defect density of the SiC substrate.Type: GrantFiled: May 4, 2012Date of Patent: November 29, 2016Assignees: Toyota Jidosha Kabushiki Kaisha, Kyoto UniversityInventors: Katsunori Danno, Hiroaki Saitoh, Akinori Seki, Tsunenobu Kimoto
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Patent number: 9157171Abstract: A method for producing n-type SiC single crystal, including: adding gallium and nitrogen, which is a donor element, for obtaining an n-type semiconductor during crystal growth of SiC single crystal, such that the amount of nitrogen as represented in atm unit is greater than the amount of gallium as represented in atm unit; an n-type SiC single crystal obtained according to this production method; and, a semiconductor device that includes the n-type SiC single crystal.Type: GrantFiled: February 18, 2010Date of Patent: October 13, 2015Assignee: TOYOTA JIDOSHA KABUSHIKI KAISHAInventors: Akinori Seki, Yasuyuki Fujiwara
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Publication number: 20150259829Abstract: A method for producing a SiC single crystal substrate that can remove Cr impurity from the surface of a SiC single crystal that contains Cr as an impurity, is provided. This is achieved by a method for producing a SiC single crystal substrate, wherein the method includes a step of immersing a SiC single crystal substrate containing Cr as an impurity in hydrochloric acid at 50° C. to 80° C.Type: ApplicationFiled: February 23, 2015Publication date: September 17, 2015Inventor: Akinori SEKI
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Publication number: 20150064882Abstract: A process for producing a semiconductor device includes: forming an SiC epitaxial layer on an SiC substrate; implanting the epitaxial layer with ions; forming a gettering layer having a higher defect density than a defect density of the SiC substrate; and carrying out a heat treatment on the epitaxial layer. The semiconductor device includes an SiC substrate, an SiC epitaxial layer formed on the SiC substrate, and a gettering layer having a higher defect density than a defect density of the SiC substrate.Type: ApplicationFiled: May 4, 2012Publication date: March 5, 2015Inventors: Katsunori Danno, Hiroaki Saitoh, Akinori Seki, Tsunenobu Kimoto
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Patent number: 8716121Abstract: An ohmic electrode for a p-type SiC semiconductor, and a method of forming the ohmic electrode. The ohmic electrode has an ohmic electrode layer, which has an amorphous structure and which is made of a Ti(1-x-y)Si(x)C(y) ternary film of which a composition ratio is within a composition range that is surrounded by two lines and two curves expressed by an expression x=0 (0.35?y?0.5), an expression y=?1.120x+0.5200 (0.1667?x?0.375), an expression y=1.778(x?0.375)2+0.1 (0?x?0.375) and an expression y=?2.504x2?0.5828x+0.5 (0?x?0.1667) and that excludes the line expressed by the expression x=0. The ohmic layer is directly laminated on a surface of a p-type SiC semiconductor.Type: GrantFiled: August 4, 2010Date of Patent: May 6, 2014Assignee: Toyota Jidosha Kabushiki KaishaInventors: Akinori Seki, Masahiro Sugimoto, Akira Kawahashi, Yasuo Takahashi, Masakatsu Maeda
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Patent number: 8633101Abstract: A manufacturing method of a semiconductor device including an electrode having low contact resistivity to a nitride semiconductor is provided. The manufacturing method includes a carbon containing layer forming step of forming a carbon containing layer containing carbon on a nitride semiconductor layer, and a titanium containing layer forming step of forming a titanium containing layer containing titanium on the carbon containing layer. A complete solid solution Ti (C, N) layer of TiN and TiC is formed between the titanium containing layer and the nitride semiconductor layer. As a result, the titanium containing layer comes to be in ohmic contact with the nitride semiconductor layer throughout the border therebetween.Type: GrantFiled: September 2, 2010Date of Patent: January 21, 2014Assignee: Toyota Jidosha Kabushiki KaishaInventors: Masahiro Sugimoto, Akinori Seki, Akira Kawahashi, Yasuo Takahashi, Masakatsu Maeda
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Patent number: 8470698Abstract: In a method for growing a p-type SiC semiconductor single crystal on a SiC single crystal substrate, using a first solution in which C is dissolved in a melt of Si, a second solution is prepared by adding Al and N to the first solution such that an amount of Al added is larger than that of N added, and the p-type SiC semiconductor single crystal is grown on the SiC single crystal substrate from the second solution. A p-type SiC semiconductor single crystal is provided which is grown by the method as described above, and which contains 1×1020 cm?3 of Al and 2×1018 to 7×1018 cm?3 of N as impurities.Type: GrantFiled: January 28, 2009Date of Patent: June 25, 2013Assignee: Toyota Jidosha Kabushiki KaishaInventors: Akinori Seki, Yasuyuki Fujiwara
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Patent number: 8399888Abstract: A p-type SiC semiconductor includes a SiC crystal that contains Al and Ti as impurities, wherein the atom number concentration of Ti is equal to or less than the atom number concentration of Al. It is preferable that the concentration of Al and the concentration of Ti satisfy the following relations: (Concentration of Al)?5×1018/cm3; and 0.01%?(Concentration of Ti)/(Concentration of Al)?20%. It is more preferable that the concentration of Al and the concentration of Ti satisfy the following relations: (Concentration of Al)?5×1018/cm3; and 1×1017/cm3?(Concentration of Ti)?1×1018/cm3.Type: GrantFiled: November 19, 2009Date of Patent: March 19, 2013Assignee: Toyota Jidosha Kabushiki KaishaInventors: Hiroaki Saitoh, Akinori Seki, Tsunenobu Kimoto
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Publication number: 20130042802Abstract: The present invention provides a method of production of SiC single crystal using the solution method which prevents the formation of defects due to causing a seed crystal to touch the melt for seed touch, and thereby causes growth of an Si single crystal reduced in defect density. The method of the present invention is a method of production of an SiC single crystal which causes an SiC seed crystal to touch a melt containing Si in a graphite crucible to thereby cause growth of the SiC single crystal on the SiC seed crystal, characterized by making the SiC seed crystal touch the melt in the state where the C is not yet saturated.Type: ApplicationFiled: July 17, 2009Publication date: February 21, 2013Inventors: Katsunori Danno, Akinori Seki, Hiroaki Saitoh, Kawai Yoichiro
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Patent number: 8338833Abstract: The present invention provides a method of producing a silicon carbide semiconductor substrate in which a silicon carbide buffer layer doped with germanium and a semiconductor device layer are sequentially laminated on the buffer layer, a silicon carbide semiconductor substrate obtained by the method and a silicon carbide semiconductor in which electrodes are disposed on the silicon carbide semiconductor substrate.Type: GrantFiled: October 16, 2006Date of Patent: December 25, 2012Assignees: Toyota Jidosha Kabushiki Kaisha, Japan Fine Ceramics CenterInventors: Akinori Seki, Yukari Tani, Noriyoshi Shibata
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Publication number: 20120217639Abstract: A manufacturing method of a semiconductor device including an electrode having low contact resistivity to a nitride semiconductor is provided. The manufacturing method includes a carbon containing layer forming step of forming a carbon containing layer containing carbon on a nitride semiconductor layer, and a titanium containing layer forming step of forming a titanium containing layer containing titanium on the carbon containing layer. A complete solid solution Ti (C, N) layer of TiN and TiC is formed between the titanium containing layer and the nitride semiconductor layer. As a result, the titanium containing layer comes to be in ohmic contact with the nitride semiconductor layer throughout the border therebetween.Type: ApplicationFiled: September 2, 2010Publication date: August 30, 2012Applicant: TOYOTA JIDOSHA KABUSHIKI KAIHSAInventors: Masahiro Sugimoto, Akinori Seki, Akira Kawahashi, Yasuo Takahashi, Masakatsu Maeda
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Publication number: 20120132927Abstract: An ohmic electrode for a p-type SiC semiconductor, and a method of forming the ohmic electrode. The ohmic electrode has an ohmic electrode layer, which has an amorphous structure and which is made of a Ti(1?x?y)Si(s)C(y) ternary film of which a composition ratio is within a composition range that is surrounded by two lines and two curves expressed by an expression x=0 (0.35?y?0.5), an expression y=?1.120x+0.5200 (0.1667?x?0.375), an expression y=1.778(x?0.375)2+0.1 (0?x?0.375) and an expression y=?2.504x2?0.5828x+0.5 (0?x?0.1667) and that excludes the line expressed by the expression x=0. The ohmic layer is directly laminated on a surface of a p-type SiC semiconductor.Type: ApplicationFiled: August 4, 2010Publication date: May 31, 2012Applicant: TOYOTA JIDOSHA KABUSHIKI KAISHAInventors: Akinori Seki, Masahiro Sugimoto, Akira Kawahashi, Yasuo Takahashi, Masakatsu Maeda
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Publication number: 20120118221Abstract: The present invention provides a method of production of an SiC single crystal using the solution method which prevents the formation of defects due to seed tough, i.e., causing a seed crystal to touch the melt, and thereby causes growth of an Si single crystal reduced in defect density. The method of the present invention is a method of production of an SiC single crystal by causing an SiC seed crystal to touch a melt containing Si in a graphite crucible to thereby cause growth of the SiC single crystal on the SiC seed crystal, characterized by making the SiC seed crystal touch the melt, then making the melt rise in temperature once to a temperature higher than the temperature at the time of touch and also higher than the temperature for causing growth.Type: ApplicationFiled: July 17, 2009Publication date: May 17, 2012Inventors: Katsunori Danno, Akinori Seki, Hiroaki Saitoh, Yoichiro Kawai
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Publication number: 20110297893Abstract: A method for producing n-type SiC single crystal, including: adding gallium and nitrogen, which is a donor element, for obtaining an n-type semiconductor during crystal growth of SiC single crystal, such that the amount of nitrogen as represented in atm unit is greater than the amount of gallium as represented in atm unit; an n-type SiC single crystal obtained according to this production method; and, a semiconductor device that includes the n-type SiC single crystal.Type: ApplicationFiled: February 18, 2010Publication date: December 8, 2011Applicant: TOYOTA JIDOSHA KABUSHIKI KAISHAInventors: Akinori Seki, Yasuyuki Fujiwara