Patents by Inventor Itaru Gunjishima
Itaru Gunjishima 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: 10236338Abstract: A SiC single crystal seed of the present invention has a main surface with an offset angle of at least 2° but not more than 20° relative to the {0001} plane, and at least one sub-growth surface, wherein the sub-growth surface includes an initial facet formation surface that is on the offset upstream side of the main surface and has an inclination angle ? relative to the {0001} plane with an absolute value of less than 2° in any direction, and the initial facet formation surface has a screw dislocation starting point.Type: GrantFiled: April 20, 2016Date of Patent: March 19, 2019Assignee: SHOWA DENKO K.K.Inventors: Yuuki Furuya, Tomohiro Shonai, Yasushi Urakami, Itaru Gunjishima
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Patent number: 10125435Abstract: A SiC single crystal includes, in a plane substantially parallel to a c-plane thereof, a region (A) in which edge dislocations having a Burgers vector (A) in a specific direction are unevenly distributed, and a region (B) in which basal plane dislocations having a Burgers vector (B) in a specific direction are unevenly distributed. The region (A) is located in a <1-100> direction with respect to a facet portion, while the region (B) is located in a <11-20> direction with respect to the facet portion. A SiC substrate is produced by cutting a SiC wafer from the SiC single crystal in a direction substantially parallel to the c-plane, and cutting the SiC substrate from the SiC wafer such that the SiC substrate mainly contains one of the region (A) and the region (B). A SiC device is fabricated using the SiC substrate.Type: GrantFiled: February 7, 2014Date of Patent: November 13, 2018Assignees: KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO, DENSO CORPORATION, SHOWA DENKO K.K.Inventors: Itaru Gunjishima, Yusuke Kanzawa, Yasushi Urakami, Masakazu Kobayashi
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Publication number: 20180130872Abstract: A SiC single crystal seed of the present invention has a main surface with an offset angle of at least 2° but not more than 20° relative to the {0001} plane, and at least one sub-growth surface, wherein the sub-growth surface includes an initial facet formation surface that is on the offset upstream side of the main surface and has an inclination angle ? relative to the {0001} plane with an absolute value of less than 2° in any direction, and the initial facet formation surface has a screw dislocation starting point.Type: ApplicationFiled: April 20, 2016Publication date: May 10, 2018Applicant: SHOWA DENKO K.K.Inventors: Yuuki FURUYA, Tomohiro SHONAI, Yasushi URAKAMI, Itaru GUNJISHIMA
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Patent number: 9534317Abstract: A seed crystal for SiC single-crystal growth includes a facet formation region containing a {0001}-plane uppermost portion and n (n>=3) planes provided enclosing the periphery of the facet formation region. The seed crystal for SiC single-crystal growth satisfies the relationships represented by formula (a): Bkk-1<=cos?1(sin(2.3 degrees)/sin Ck), formula (b): Bkk<=cos?1(sin(2.3 degrees)/sin Ck), and formula (c): min(Ck)<=20 degrees. In the formulas, Ck is an offset angle of a k-th plane, Bkk-1 is an angle defined by an offset downstream direction of the k-th plane and a (k?1)-th ridge line, and Bkk is an angle defined by the offset downstream direction of the k-th plane and a k-th ridge line.Type: GrantFiled: October 29, 2013Date of Patent: January 3, 2017Assignees: KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO, DENSO CORPORATION, SHOWA DENKO K.K.Inventors: Itaru Gunjishima, Keisuke Shigetoh, Yasushi Urakami, Akihiro Matsuse
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Publication number: 20150308014Abstract: A SiC single crystal includes, in a plane substantially parallel to a c-plane thereof, a region (A) in which edge dislocations having a Burgers vector (A) in a specific direction are unevenly distributed, and a region (B) in which basal plane dislocations having a Burgers vector (B) in a specific direction are unevenly distributed. The region (A) is located in a <1-100> direction with respect to a facet portion, while the region (B) is located in a <11-20> direction with respect to the facet portion. A SiC substrate is produced by cutting a SiC wafer from the SiC single crystal in a direction substantially parallel to the c-plane, and cutting the SiC substrate from the SiC wafer such that the SiC substrate mainly contains one of the region (A) and the region (B). A SiC device is fabricated using the SiC substrate.Type: ApplicationFiled: February 7, 2014Publication date: October 29, 2015Applicants: KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO, DENSO CORPORATION, SHOWA DENKO K.K.Inventors: Itaru GUNJISHIMA, Yusuke KANZAWA, Yasushi URAKAMI, Masakazu KOBAYASHI
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Patent number: 9166008Abstract: An SiC single crystal having at least one orientation region where a basal plane dislocation has a high linearity and is oriented to three crystallographically-equivalent <11-20> directions, and an SiC wafer and a semiconductor device which are manufactured from the SiC single crystal. The SiC single crystal can be manufactured by using a seed crystal in which the offset angle on a {0001} plane uppermost part side is small and the offset angle on an offset direction downstream side is large and growing another crystal on the seed crystal.Type: GrantFiled: May 16, 2012Date of Patent: October 20, 2015Assignees: KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO, TOYOTA JIDOSHA KABUSHIKI KAISHA, DENSO CORPORATIONInventors: Itaru Gunjishima, Yasushi Urakami, Ayumu Adachi
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Publication number: 20150275397Abstract: A seed crystal for SiC single-crystal growth includes a facet formation region containing a {0001}-plane uppermost portion and n (n>=3) planes provided enclosing the periphery of the facet formation region. The seed crystal for SiC single-crystal growth satisfies the relationships represented by formula (a): Bkk-1<=cos?1(sin(2.3 degrees)/sin Ck), formula (b): Bkk<=cos?1(sin(2.3 degrees)/sin Ck), and formula (c): min(Ck)<=20 degrees. In the formulas, Ck is an offset angle of a k-th plane, Bkk-1 is an angle defined by an offset downstream direction of the k-th plane and a (k?1)-th ridge line, and Bkk is an angle defined by the offset downstream direction of the k-th plane and a k-th ridge line.Type: ApplicationFiled: October 29, 2013Publication date: October 1, 2015Applicants: KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO, DENSO CORPORATION, SHOWA DENKO K.K.Inventors: Itaru Gunjishima, Keisuke Shigetoh, Yasushi Urakami, Akihiro Matsuse
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Patent number: 9145622Abstract: In a manufacturing method of a silicon carbide single crystal, a seed crystal made of silicon carbide is prepared. The seed crystal has a growth surface and a stacking fault generation region and includes a threading dislocation that reaches the growth surface. The growth surface is inclined at a predetermined angle from a (0001) plane. The stacking fault generation region is configured to cause a stacking fault in the silicon carbide single crystal when the silicon carbide single crystal is grown. The stacking fault generation region is located at an end portion of the growth surface in an offset direction that is a direction of a vector defined by projecting a normal vector of the (0001) plane onto the growth surface. The seed crystal is joined to a pedestal, and the silicon carbide single crystal is grown on the growth surface of the seed crystal.Type: GrantFiled: September 27, 2011Date of Patent: September 29, 2015Assignee: DENSO CORPORATIONInventors: Yasushi Urakami, Ayumu Adachi, Itaru Gunjishima
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Patent number: 9096947Abstract: When an SiC single crystal having a large diameter of a {0001} plane is produced by repeating a-plane growth, the a-plane growth of the SiC single crystal is carried out so that a ratio Sfacet (=S1×100/S2) of an area (S1) of a Si-plane side facet region to a total area (S2) of the growth plane is maintained at 20% or less.Type: GrantFiled: June 4, 2012Date of Patent: August 4, 2015Assignees: KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO, DENSO CORPORATION, SHOWA DENKO K.K.Inventors: Itaru Gunjishima, Keisuke Shigetoh, Yasushi Urakami, Masanori Yamada, Ayumu Adachi, Masakazu Kobayashi
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Patent number: 9051663Abstract: A manufacturing method of a SiC single crystal includes a first growth process and a re-growth process. In the first growth process, a first seed crystal made of SiC is used to grow a first SiC single crystal. In the re-growth process, a plurality of growth steps is performed for (n?1) times. In a k-th growth step, a k-th seed crystal is cut out from a grown (k?1)-th SiC single crystal, and the k-th seed crystal is used to grow a k-th SiC single crystal (n?2 and 2?k?n). When an offset angle of a growth surface of the k-th seed crystal is defined as ?k, at least in one of the plurality of growth steps, the offset angle ?k is smaller than the offset angle ?k-1.Type: GrantFiled: November 28, 2011Date of Patent: June 9, 2015Assignees: DENSO CORPORATION, TOYOTA JIDOSHA KABUSHIKI KAISHAInventors: Yasushi Urakami, Ayumu Adachi, Itaru Gunjishima
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Patent number: 9048102Abstract: An SiC single crystal includes a low dislocation density region (A) where the density of dislocations each of which has a Burgers vector in a {0001} in-plane direction (mainly a direction parallel to a <11-20> direction) is not more than 3,700 cm/cm3. Such an SiC single crystal is obtained by: cutting out a c-plane growth seed crystal of a high offset angle from an a-plane grown crystal; applying c-plane growth so that the density of screw dislocations introduced into a c-plane facet may fall in a prescribed range; cutting out a c-plane growth crystal of a low offset angle from the obtained c-plane grown crystal; and applying c-plane growth so that the density of screw dislocations introduced into a c-plane facet may fall in a prescribed range. An SiC wafer and a semiconductor device are obtained from such an SiC single crystal.Type: GrantFiled: December 3, 2012Date of Patent: June 2, 2015Assignees: KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO, DENSO CORPORATION, TOYOTA JIDOSHA KABUSHIKI KAISHAInventors: Itaru Gunjishima, Yasushi Urakami, Ayumu Adachi
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Patent number: 8936682Abstract: A manufacturing method of a SiC single crystal includes growing a SiC single crystal on a surface of a SiC seed crystal, which satisfies following conditions: (i) the SiC seed crystal includes a main growth surface composed of a plurality of sub-growth surfaces; (ii) among directions from an uppermost portion of a {0001} plane on the main growth surface to portions on a periphery of the main growth surface, the SiC seed crystal has a main direction in which a plurality of sub-growth surfaces is arranged; and (iii) an offset angle ?k of a k-th sub-growth surface and an offset angle ?k+1 of a (k+1)-th sub-growth surface satisfy a relationship of ?k<?k+1.Type: GrantFiled: August 16, 2011Date of Patent: January 20, 2015Assignee: DENSO CORPORATIONInventors: Yasushi Urakami, Itaru Gunjishima, Ayumu Adachi
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Publication number: 20140291700Abstract: An SiC single crystal includes a low dislocation density region (A) where the density of dislocations each of which has a Burgers vector in a {0001} in-plane direction (mainly a direction parallel to a <11-20> direction) is not more than 3,700 cm/cm3. Such an SiC single crystal is obtained by: cutting out a c-plane growth seed crystal of a high offset angle from an a-plane grown crystal; applying c-plane growth so that the density of screw dislocations introduced into a c-plane facet may fall in a prescribed range; cutting out a c-plane growth crystal of a low offset angle from the obtained c-plane grown crystal; and applying c-plane growth so that the density of screw dislocations introduced into a c-plane facet may fall in a prescribed range. An SiC wafer and a semiconductor device are obtained from such an SiC single crystal.Type: ApplicationFiled: December 3, 2012Publication date: October 2, 2014Inventors: Itaru Gunjishima, Yasushi Urakami, Ayumu Adachi
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Publication number: 20140091325Abstract: When an SiC single crystal having a large diameter of a {0001} plane is produced by repeating a-plane growth, the a-plane growth of the SiC single crystal is carried out so that a ratio Sfacet (=S1×100/S2) of an area (S1) of a Si-plane side facet region to a total area (S2) of the growth plane is maintained at 20% or less.Type: ApplicationFiled: June 4, 2012Publication date: April 3, 2014Applicants: KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO, SHOWA DENKO K.K., DENSO CORPORATIONInventors: Itaru Gunjishima, Keisuke Shigetoh, Yasushi Urakami, Masanori Yamada, Ayumu Adachi, Masakazu Kobayashi
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Publication number: 20140027787Abstract: An SiC single crystal having at least one orientation region where a basal plane dislocation has a high linearity and is oriented to three crystallographically-equivalent <11-20> directions, and an SiC wafer and a semiconductor device which are manufactured from the SiC single crystal. The SiC single crystal can be manufactured by using a seed crystal in which the offset angle on a {0001} plane uppermost part side is small and the offset angle on an offset direction downstream side is large and growing another crystal on the seed crystal.Type: ApplicationFiled: May 16, 2012Publication date: January 30, 2014Applicants: KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO, DENSO CORPORATION, TOYOTA JIDOSHA KABUSHIKI KAISHAInventors: Itaru Gunjishima, Yasushi Urakami, Ayumu Adachi
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Publication number: 20120132132Abstract: A manufacturing method of a SiC single crystal includes a first growth process and a re-growth process. In the first growth process, a first seed crystal made of SiC is used to grow a first SiC single crystal. In the re-growth process, a plurality of growth steps is performed for (n?1) times. In a k-th growth step, a k-th seed crystal is cut out from a grown (k?1)-th SiC single crystal, and the k-th seed crystal is used to grow a k-th SiC single crystal (n?2 and 2?k?n). When an offset angle of a growth surface of the k-th seed crystal is defined as ?k, at least in one of the plurality of growth steps, the offset angle ?k is smaller than the offset angle ?k?1.Type: ApplicationFiled: November 28, 2011Publication date: May 31, 2012Applicants: TOYOTA JIDOSHA KABUSHIKI KAISHA, DENSO CORPORATIONInventors: Yasushi Urakami, Ayumu Adachi, Itaru Gunjishima
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Publication number: 20120073495Abstract: In a manufacturing method of a silicon carbide single crystal, a seed crystal made of silicon carbide is prepared. The seed crystal has a growth surface and a stacking fault generation region and includes a threading dislocation that reaches the growth surface. The growth surface is inclined at a predetermined angle from a (0001) plane. The stacking fault generation region is configured to cause a stacking fault in the silicon carbide single crystal when the silicon carbide single crystal is grown. The stacking fault generation region is located at an end portion of the growth surface in an offset direction that is a direction of a vector defined by projecting a normal vector of the (0001) plane onto the growth surface. The seed crystal is joined to a pedestal, and the silicon carbide single crystal is grown on the growth surface of the seed crystal.Type: ApplicationFiled: September 27, 2011Publication date: March 29, 2012Applicant: DENSO CORPORATIONInventors: Yasushi URAKAMI, Ayumu Adachi, Itaru Gunjishima
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Publication number: 20120060751Abstract: A manufacturing method of a SiC single crystal includes growing a SiC single crystal on a surface of a SiC seed crystal, which satisfies following conditions: (i) the SiC seed crystal includes a main growth surface composed of a plurality of sub-growth surfaces; (ii) among directions from an uppermost portion of a {0001} plane on the main growth surface to portions on a periphery of the main growth surface, the SiC seed crystal has a main direction in which a plurality of sub-growth surfaces is arranged; and (iii) an offset angle ?k of a k-th sub-growth surface and an offset angle ?k+1 of a (k+1)-th sub-growth surface satisfy a relationship of ?k<?k+1.Type: ApplicationFiled: August 16, 2011Publication date: March 15, 2012Applicant: DENSO CORPORATIONInventors: Yasushi URAKAMI, Itaru GUNJISHIMA, Ayumu ADACHI
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Patent number: 7135074Abstract: A method for manufacturing a silicon carbide single crystal includes the steps of: preparing a seed crystal with a screw dislocation generation region; and growing the single crystal on a growth surface of the seed crystal. The generation region occupies equal to or smaller than 50% of the growth surface, which has an offset angle equal to or smaller than 60 degrees. The screw dislocation density in the single crystal generated from the generation region is higher than that in the other region. The single crystal includes a flat C-surface facet disposed on a growing surface of the single crystal. The C-surface facet overlaps at least one of parts of the growing surface provided by projecting the generation region in a direction perpendicular to the growth surface and in a direction parallel to a <0001> axis, respectively.Type: GrantFiled: August 5, 2004Date of Patent: November 14, 2006Assignees: Kabushiki Kaisha Toyota Chuo Kenkyusho, Denso CorporationInventors: Itaru Gunjishima, Daisuke Nakamura, Naohiro Sugiyama, Fusao Hirose
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Publication number: 20050211156Abstract: A method for manufacturing a silicon carbide single crystal includes the steps of: preparing a seed crystal with a screw dislocation generation region; and growing the single crystal on a growth surface of the seed crystal. The generation region occupies equal to or smaller than 50% of the growth surface, which has an offset angle equal to or smaller than 60 degrees. The screw dislocation density in the single crystal generated from the generation region is higher than that in the other region. The single crystal includes a flat C-surface facet disposed on a growing surface of the single crystal. The C-surface facet overlaps at least one of parts of the growing surface provided by projecting the generation region in a direction perpendicular to the growth surface and in a direction parallel to a <0001> axis, respectively.Type: ApplicationFiled: August 5, 2004Publication date: September 29, 2005Inventors: Itaru Gunjishima, Daisuke Nakamura, Naohiro Sugiyama, Fusao Hirose