Patents by Inventor Yuki Imoto
Yuki Imoto 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: 9196738Abstract: Many of the physical properties of a silicon semiconductor have already been understood, whereas many of the physical properties of an oxide semiconductor have been still unclear. In particular, an adverse effect of an impurity on an oxide semiconductor has been still unclear. In view of the above, a structure is disclosed in which an impurity that influences electrical characteristics of a semiconductor device including an oxide semiconductor layer is prevented or is eliminated. A semiconductor device which includes a gate electrode, an oxide semiconductor layer, and a gate insulating layer provided between the gate electrode and the oxide semiconductor layer and in which the nitrogen concentration in the oxide semiconductor layer is 1×1020 atoms/cm3 or less is provided.Type: GrantFiled: December 10, 2010Date of Patent: November 24, 2015Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Junichiro Sakata, Tetsunori Maruyama, Yuki Imoto
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Patent number: 9171938Abstract: An object is to provide a thin film transistor and a method for manufacturing the thin film transistor including an oxide semiconductor with a controlled threshold voltage, high operation speed, a relatively easy manufacturing process, and sufficient reliability. An impurity having influence on carrier concentration in the oxide semiconductor layer, such as a hydrogen atom or a compound containing a hydrogen atom such as H2O, may be eliminated. An oxide insulating layer containing a large number of defects such as dangling bonds may be formed in contact with the oxide semiconductor layer, such that the impurity diffuses into the oxide insulating layer and the impurity concentration in the oxide semiconductor layer is reduced. The oxide semiconductor layer or the oxide insulating layer in contact with the oxide semiconductor layer may be formed in a deposition chamber which is evacuated with use of a cryopump whereby the impurity concentration is reduced.Type: GrantFiled: September 23, 2010Date of Patent: October 27, 2015Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Junichiro Sakata, Akiharu Miyanaga, Masayuki Sakakura, Junichi Koezuka, Tetsunori Maruyama, Yuki Imoto
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Patent number: 9151414Abstract: A pipe joint coupling apparatus has first and second pipe joint members coupled to each other, a plate-shaped support member with an opening through which the first pipe joint member extends, and an elastic member accommodated in an annular groove formed in the outer surface of the first pipe joint member. The support member is clamped between a shoulder part formed on the outer surface of the first pipe member and a collar member disposed about the first pipe joint member such that the edge of the opening of the support member engages the elastic member. The width of the groove is greater than the width of the support member to allow the first pipe joint member to be radially displaced relative to the support member with the opening edge partially and radially entering into the annular groove while deforming the elastic member.Type: GrantFiled: May 16, 2008Date of Patent: October 6, 2015Assignee: Nitto Kohki Co., Ltd.Inventor: Yuki Imoto
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Publication number: 20150162421Abstract: The amount of water and hydrogen contained in an oxide semiconductor film is reduced, and oxygen is supplied sufficiently from a base film to the oxide semiconductor film in order to reduce oxygen deficiencies. A stacked base film is formed, a first heat treatment is performed, an oxide semiconductor film is formed over and in contact with the stacked base film, and a second heat treatment is performed. In the stacked base film, a first base film and a second base film are stacked in this order. The first base film is an insulating oxide film from which oxygen is released by heating. The second base film is an insulating metal oxide film. An oxygen diffusion coefficient of the second base film is smaller than that of the first base film.Type: ApplicationFiled: December 26, 2014Publication date: June 11, 2015Inventors: Yuki IMOTO, Yuhei SATO
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Publication number: 20150137123Abstract: In the transistor including an oxide semiconductor film, which includes a film for capturing hydrogen from the oxide semiconductor film (a hydrogen capture film) and a film for diffusing hydrogen (a hydrogen permeable film), hydrogen is transferred from the oxide semiconductor film to the hydrogen capture film through the hydrogen permeable film by heat treatment. Specifically, a base film or a protective film of the transistor including an oxide semiconductor film has a stacked-layer structure of the hydrogen capture film and the hydrogen permeable film. At this time, the hydrogen permeable film is formed on a side which is in contact with the oxide semiconductor film. After that, hydrogen released from the oxide semiconductor film is transferred to the hydrogen capture film through the hydrogen permeable film by the heat treatment.Type: ApplicationFiled: January 22, 2015Publication date: May 21, 2015Inventors: Yuki IMOTO, Tetsunori MARUYAMA, Yuta ENDO
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Patent number: 9012904Abstract: In the transistor including an oxide semiconductor film, a gate insulating film of the transistor including an oxide semiconductor film has a stacked-layer structure of the hydrogen capture film and the hydrogen permeable film. At this time, the hydrogen permeable film is formed on a side which is in contact with the oxide semiconductor film, and the hydrogen capture film is formed on a side which is in contact with a gate electrode. After that, hydrogen released from the oxide semiconductor film is transferred to the hydrogen capture film through the hydrogen permeable film by the heat treatment.Type: GrantFiled: March 16, 2012Date of Patent: April 21, 2015Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Yuki Imoto, Tetsunori Maruyama, Yuta Endo
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Patent number: 8969130Abstract: An amorphous region with low density is formed in an oxide insulating film containing zirconium. The amount of oxygen released from such an oxide insulating film containing zirconium by heating is large and a temperature at which oxygen is released is higher in the oxide insulating film than in a conventional oxide film (e.g., a silicon oxide film). When the insulating film is formed using a sputtering target containing zirconium in an oxygen atmosphere, the temperature of a surface on which the insulating film is formed may be controlled to be lower than a temperature at which a film to be formed starts to crystallize.Type: GrantFiled: November 13, 2012Date of Patent: March 3, 2015Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Tetsuhiro Tanaka, Erika Takahashi, Yuki Imoto, Yuhei Sato
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Patent number: 8956944Abstract: In the transistor including an oxide semiconductor film, which includes a film for capturing hydrogen from the oxide semiconductor film (a hydrogen capture film) and a film for diffusing hydrogen (a hydrogen permeable film), hydrogen is transferred from the oxide semiconductor film to the hydrogen capture film through the hydrogen permeable film by heat treatment. Specifically, a base film or a protective film of the transistor including an oxide semiconductor film has a stacked-layer structure of the hydrogen capture film and the hydrogen permeable film. At this time, the hydrogen permeable film is formed on a side which is in contact with the oxide semiconductor film. After that, hydrogen released from the oxide semiconductor film is transferred to the hydrogen capture film through the hydrogen permeable film by the heat treatment.Type: GrantFiled: March 16, 2012Date of Patent: February 17, 2015Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Yuki Imoto, Tetsunori Maruyama, Yuta Endo
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Patent number: 8936965Abstract: A normally-off transistor having an oxide semiconductor layer in a channel formation layer is provided. The transistor comprises: a first oxide semiconductor layer functioning as a channel formation region; a source electrode layer and a drain electrode layer which overlap with the first oxide semiconductor layer; a gate insulating layer which is provided over and in contact with the first oxide semiconductor layer, the source electrode layer, and the drain electrode layer; a second oxide semiconductor layer which is provided over and in contact with the gate insulating layer and overlaps with the first oxide semiconductor layer; and a gate electrode layer provided over the second oxide semiconductor layer. A manufacturing method thereof is also disclosed.Type: GrantFiled: November 14, 2011Date of Patent: January 20, 2015Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Yuki Imoto, Yuji Asano, Tetsunori Maruyama
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Patent number: 8927329Abstract: The amount of water and hydrogen contained in an oxide semiconductor film is reduced, and oxygen is supplied sufficiently from a base film to the oxide semiconductor film in order to reduce oxygen deficiencies. A stacked base film is formed, a first heat treatment is performed, an oxide semiconductor film is formed over and in contact with the stacked base film, and a second heat treatment is performed. In the stacked base film, a first base film and a second base film are stacked in this order. The first base film is an insulating oxide film from which oxygen is released by heating. The second base film is an insulating metal oxide film. An oxygen diffusion coefficient of the second base film is smaller than that of the first base film.Type: GrantFiled: March 20, 2012Date of Patent: January 6, 2015Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Yuki Imoto, Yuhei Sato
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Publication number: 20140357019Abstract: The silicon nitride layer 910 formed by plasma CVD using a gas containing a hydrogen compound such as silane (SiH4) and ammonia (NH3) is provided on and in direct contact with the oxide semiconductor layer 905 used for the resistor 354, and the silicon nitride layer 910 is provided over the oxide semiconductor layer 906 used for the thin film transistor 355 with the silicon oxide layer 909 serving as a barrier layer interposed therebetween. Therefore, a higher concentration of hydrogen is introduced into the oxide semiconductor layer 905 than into the oxide semiconductor layer 906. As a result, the resistance of the oxide semiconductor layer 905 used for the resistor 354 is made lower than that of the oxide semiconductor layer 906 used for the thin film transistor 355.Type: ApplicationFiled: August 18, 2014Publication date: December 4, 2014Inventors: Jun KOYAMA, Junichiro SAKATA, Tetsunori MARUYAMA, Yuki IMOTO, Yuji ASANO, Junichi KOEZUKA
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Patent number: 8889477Abstract: A semiconductor device including a highly reliable transistor formed using an oxide semiconductor is manufactured. An oxide semiconductor film is deposited by a sputtering method, using a sputtering target including an oxide semiconductor having crystallinity, and in which the direction of the c-axis of a crystal is parallel to a normal vector of the top surface of the oxide semiconductor. The target is formed by mixing raw materials so that its composition ratio can obtain a crystal structure.Type: GrantFiled: September 5, 2012Date of Patent: November 18, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Tetsunori Maruyama, Yuki Imoto, Hitomi Sato, Masahiro Watanabe, Mitsuo Mashiyama, Kenichi Okazaki, Motoki Nakashima, Takashi Shimazu
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Publication number: 20140235015Abstract: An object is to provide an oxide semiconductor having stable electric characteristics and a semiconductor device including the oxide semiconductor. A manufacturing method of a semiconductor film by a sputtering method includes the steps of holding a substrate in a treatment chamber which is kept in a reduced-pressure state; heating the substrate at lower than 400° C.; introducing a sputtering gas from which hydrogen and moisture are removed in the state where remaining moisture in the treatment chamber is removed; and forming an oxide semiconductor film over the substrate with use of a metal oxide which is provided in the treatment chamber as a target. When the oxide semiconductor film is formed, remaining moisture in a reaction atmosphere is removed; thus, the concentration of hydrogen and the concentration of hydride in the oxide semiconductor film can be reduced. Thus, the oxide semiconductor film can be stabilized.Type: ApplicationFiled: April 24, 2014Publication date: August 21, 2014Applicant: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei YAMAZAKI, Junichiro SAKATA, Akiharu MIYANAGA, Masayuki SAKAKURA, Junichi KOEZUKA, Tetsunori MARUYAMA, Yuki IMOTO
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Patent number: 8766329Abstract: A transistor in which an electron state at an interface between an oxide semiconductor film and an underlayer film in contact with the oxide semiconductor film is favorable is provided. A value obtained by dividing a difference between nearest neighbor interatomic distance of the underlayer film within the interface and a lattice constant of the semiconductor film by the nearest neighbor interatomic distance of the underlayer film within the interface is less than or equal to 0.15. For example, an oxide semiconductor film is deposited over an underlayer film which contains stabilized zirconia which has a cubic crystal structure and has the (111) plane orientation, whereby the oxide semiconductor film including a crystal region having a high degree of crystallization can be provided directly on the underlayer film.Type: GrantFiled: June 14, 2012Date of Patent: July 1, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Yuta Endo, Yuki Imoto, Yuko Takabayashi, Yasumasa Yamane
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Patent number: 8748223Abstract: An object is to provide an oxide semiconductor having stable electric characteristics and a semiconductor device including the oxide semiconductor. A manufacturing method of a semiconductor film by a sputtering method includes the steps of holding a substrate in a treatment chamber which is kept in a reduced-pressure state; heating the substrate at lower than 400° C.; introducing a sputtering gas from which hydrogen and moisture are removed in the state where remaining moisture in the treatment chamber is removed; and forming an oxide semiconductor film over the substrate with use of a metal oxide which is provided in the treatment chamber as a target. When the oxide semiconductor film is formed, remaining moisture in a reaction atmosphere is removed; thus, the concentration of hydrogen and the concentration of hydride in the oxide semiconductor film can be reduced. Thus, the oxide semiconductor film can be stabilized.Type: GrantFiled: September 23, 2010Date of Patent: June 10, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Junichiro Sakata, Akiharu Miyanaga, Masayuki Sakakura, Junichi Koezuka, Tetsunori Maruyama, Yuki Imoto
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Patent number: 8716061Abstract: In a thin film transistor which uses an oxide semiconductor, buffer layers containing indium, gallium, zinc, oxygen, and nitrogen are provided between the oxide semiconductor layer and the source and drain electrode layers.Type: GrantFiled: December 18, 2012Date of Patent: May 6, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Junichiro Sakata, Tetsunori Maruyama, Yuki Imoto, Yuji Asano, Junichi Koezuka
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Publication number: 20140113407Abstract: An object is to provide a thin film transistor and a method for manufacturing the thin film transistor including an oxide semiconductor with a controlled threshold voltage, high operation speed, a relatively easy manufacturing process, and sufficient reliability. An impurity having influence on carrier concentration in the oxide semiconductor layer, such as a hydrogen atom or a compound containing a hydrogen atom such as H2O, may be eliminated. An oxide insulating layer containing a large number of defects such as dangling bonds may be formed in contact with the oxide semiconductor layer, such that the impurity diffuses into the oxide insulating layer and the impurity concentration in the oxide semiconductor layer is reduced. The oxide semiconductor layer or the oxide insulating layer in contact with the oxide semiconductor layer may be formed in a deposition chamber which is evacuated with use of a cryopump whereby the impurity concentration is reduced.Type: ApplicationFiled: January 2, 2014Publication date: April 24, 2014Applicant: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei YAMAZAKI, Junichiro SAKATA, Akiharu MIYANAGA, Masayuki SAKAKURA, Junichi KOEZUKA, Tetsunori MARUYAMA, Yuki IMOTO
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Patent number: 8597977Abstract: In a thin film transistor which uses an oxide semiconductor, buffer layers containing indium, gallium, zinc, oxygen, and nitrogen are provided between the oxide semiconductor layer and the source and drain electrode layers.Type: GrantFiled: December 18, 2012Date of Patent: December 3, 2013Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Junichiro Sakata, Tetsunori Maruyama, Yuki Imoto, Yuji Asano, Junichi Koezuka
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Patent number: 8546892Abstract: It is an object of an embodiment of the present invention to reduce leakage current between a source and a drain in a transistor including an oxide semiconductor. As a first gate film in contact with a gate insulating film, a compound conductor which includes indium and nitrogen and whose band gap is less than 2.8 eV is used. Since this compound conductor has a work function of greater than or equal to 5 eV, preferably greater than or equal to 5.5 eV, the electron concentration in an oxide semiconductor film can be maintained extremely low. As a result, the leakage current between the source and the drain is reduced.Type: GrantFiled: October 17, 2011Date of Patent: October 1, 2013Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Yuki Imoto, Tetsunori Maruyama, Takatsugu Omata, Yusuke Nonaka, Tatsuya Honda, Akiharu Miyanaga
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Patent number: 8378393Abstract: An electrode formed using a transparent conductive oxide is likely to be crystallized by heat treatment performed in the manufacturing process of a semiconductor device. In the case of a thin film element using an electrode having a significantly uneven surface due to crystallization, a short circuit is likely to occur and thus reliability of the element is degraded. An object is to provide a light-transmitting conductive oxynitride which is not crystallized even if subjected to heat treatment and a manufacturing method thereof. It is found that an oxynitride containing indium, gallium, and zinc, to which hydrogen atoms are added as impurities, is a light-transmitting conductive film which is not crystallized even if heated at 350° C. and the object is achieved.Type: GrantFiled: October 30, 2009Date of Patent: February 19, 2013Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Junichiro Sakata, Tetsunori Maruyama, Yuki Imoto, Yuji Asano, Junichi Koezuka