Patents by Inventor Masashi Tsubuku
Masashi Tsubuku 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: 9331208Abstract: An oxide semiconductor film which has more stable electric conductivity is provided. The oxide semiconductor film comprises a crystalline region. The oxide semiconductor film has a first peak of electron diffraction intensity with a full width at half maximum of greater than or equal to 0.4 nm?1 and less than or equal to 0.7 nm?1 in a region where a magnitude of a scattering vector is greater than or equal to 3.3 nm?1 and less than or equal to 4.1 nm?1. The oxide semiconductor film has a second peak of electron diffraction intensity with a full width at half maximum of greater than or equal to 0.45 nm?1 and less than or equal to 1.4 nm?1 in a region where a magnitude of a scattering vector is greater than or equal to 5.5 nm?1 and less than or equal to 7.1 nm?1.Type: GrantFiled: March 2, 2015Date of Patent: May 3, 2016Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Masashi Tsubuku, Kengo Akimoto, Hiroki Ohara, Tatsuya Honda, Takatsugu Omata, Yusuke Nonaka, Masahiro Takahashi, Akiharu Miyanaga
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Publication number: 20160118418Abstract: An object is to provide a memory device including a memory element that can be operated without problems by a thin film transistor with a low off-state current. Provided is a memory device in which a memory element including at least one thin film transistor that includes an oxide semiconductor layer is arranged as a matrix. The thin film transistor including an oxide semiconductor layer has a high field effect mobility and low off-state current, and thus can be operated favorably without problems. In addition, the power consumption can be reduced. Such a memory device is particularly effective in the case where the thin film transistor including an oxide semiconductor layer is provided in a pixel of a display device because the memory device and the pixel can be formed over one substrate.Type: ApplicationFiled: January 7, 2016Publication date: April 28, 2016Inventors: Shunpei YAMAZAKI, Masashi TSUBUKU, Kosei NODA, Kouhei TOYOTAKA, Kazunori WATANABE, Hikaru HARADA
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Patent number: 9299855Abstract: A semiconductor device includes a semiconductor layer, a gate electrode overlapping with the semiconductor layer, a first gate insulating layer between the semiconductor layer and the gate electrode, and a second gate insulating layer between the first gate insulating layer and the gate electrode. The first gate insulating layer includes an oxide in which the nitrogen content is lower than or equal to 5 at. %, and the second gate insulating layer includes charge trap states.Type: GrantFiled: July 31, 2014Date of Patent: March 29, 2016Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Takuya Hirohashi, Masahiro Takahashi, Motoki Nakashima, Ryosuke Watanabe, Masashi Tsubuku
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Patent number: 9299724Abstract: An object is to obtain a semiconductor device having a high sensitivity in detecting signals and a wide dynamic range, using a thin film transistor in which an oxide semiconductor layer is used. An analog circuit is formed with the use of a thin film transistor including an oxide semiconductor which has a function as a channel formation layer, has a hydrogen concentration of 5×1019 atoms/cm3 or lower, and substantially functions as an insulator in the state where no electric field is generated. Thus, a semiconductor device having a high sensitivity in detecting signals and a wide dynamic range can be obtained.Type: GrantFiled: July 24, 2014Date of Patent: March 29, 2016Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Jun Koyama, Atsushi Hirose, Masashi Tsubuku, Kosei Noda
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Patent number: 9293541Abstract: A highly reliable semiconductor device including an oxide semiconductor is provided. Provided is a semiconductor device including an oxide semiconductor layer, an insulating layer in contact with the oxide semiconductor layer, a gate electrode layer overlapping with the oxide semiconductor layer, and a source electrode layer and a drain electrode layer electrically connected to the oxide semiconductor layer. The oxide semiconductor layer includes a first region having a crystal whose size is less than or equal to 10 nm and a second region which overlaps with the insulating layer with the first region provided therebetween and which includes a crystal part whose c-axis is aligned in a direction parallel to a normal vector of the surface of the oxide semiconductor layer.Type: GrantFiled: June 9, 2015Date of Patent: March 22, 2016Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Masahiro Takahashi, Takuya Hirohashi, Masashi Tsubuku, Masashi Oota
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Patent number: 9281407Abstract: Reducing hydrogen concentration in a channel formation region of an oxide semiconductor is important in stabilizing threshold voltage of a transistor including an oxide semiconductor and improving reliability. Hence, hydrogen is attracted from the oxide semiconductor and trapped in a region of an insulating film which overlaps with a source region and a drain region of the oxide semiconductor. Impurities such as argon, nitrogen, carbon, phosphorus, or boron are added to the region of the insulating film which overlaps with the source region and the drain region of the oxide semiconductor, thereby generating a defect. Hydrogen in the oxide semiconductor is attracted to the defect in the insulating film. The defect in the insulating film is stabilized by the presence of hydrogen.Type: GrantFiled: April 30, 2015Date of Patent: March 8, 2016Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Masashi Tsubuku, Yusuke Nonaka, Noritaka Ishihara, Masashi Oota, Hideyuki Kishida
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Publication number: 20160064570Abstract: A logic circuit includes a thin film transistor having a channel formation region formed using an oxide semiconductor, and a capacitor having terminals one of which is brought into a floating state by turning off the thin film transistor. The oxide semiconductor has a hydrogen concentration of 5×1019 (atoms/cm3) or less and thus substantially serves as an insulator in a state where an electric field is not generated. Therefore, off-state current of a thin film transistor can be reduced, leading to suppressing the leakage of electric charge stored in a capacitor, through the thin film transistor. Accordingly, a malfunction of the logic circuit can be prevented. Further, the excessive amount of current which flows in the logic circuit can be reduced through the reduction of off-state current of the thin film transistor, resulting in low power consumption of the logic circuit.Type: ApplicationFiled: November 9, 2015Publication date: March 3, 2016Inventors: Shunpei YAMAZAKI, Jun KOYAMA, Masashi TSUBUKU, Kosei NODA
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Publication number: 20160054362Abstract: A current measurement method with which an extremely low current can be measured is provided. In the method, a charge written to a first terminal of a capacitor through a transistor under test is retained, data on the correspondence between a potential V of the first terminal of the capacitor and Time t is generated, and a stretched exponential function represented by Formula (a1) is fitted to the data to determine parameters of Formula (a1). The derivative of Formula (a1) with respect to time gives a stretched exponential function describing an off-state current of the transistor under test. The potential of the first terminal of the capacitor is measured using an on-state current of a transistor whose gate is connected to the first terminal of the capacitor.Type: ApplicationFiled: August 20, 2015Publication date: February 25, 2016Inventors: Masashi TSUBUKU, Shunpei YAMAZAKI, Hidetomo KOBAYASHI, Kazuaki OHSHIMA, Masashi FUJITA, Toshihiko TAKEUCHI
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Publication number: 20160056299Abstract: A decrease in on-state current in a semiconductor device including an oxide semiconductor film is suppressed. A transistor including an oxide semiconductor film, an insulating film which includes oxygen and silicon, a gate electrode adjacent to the oxide semiconductor film, the oxide semiconductor film provided to be in contact with the insulating film and overlap with at least the gate electrode, and a source electrode and a drain electrode electrically connected to the oxide semiconductor film. In the oxide semiconductor film, a first region which is provided to be in contact with the interface with the insulating film and have a thickness less than or equal to 5 nm has a silicon concentration lower than or equal to 1.0 at. %, and a region in the oxide semiconductor film other than the first region has lower silicon concentration than the first region.Type: ApplicationFiled: November 3, 2015Publication date: February 25, 2016Inventors: Tatsuya HONDA, Masashi TSUBUKU, Yusuke NONAKA, Takashi SHIMAZU, Shunpei YAMAZAKI
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Patent number: 9267199Abstract: A method for manufacturing a sputtering target with which an oxide semiconductor film with a small amount of defects can be formed is provided. Alternatively, an oxide semiconductor film with a small amount of defects is formed. A method for manufacturing a sputtering target is provided, which includes the steps of: forming a polycrystalline In-M-Zn oxide (M represents a metal chosen among aluminum, titanium, gallium, yttrium, zirconium, lanthanum, cesium, neodymium, and hafnium) powder by mixing, sintering, and grinding indium oxide, an oxide of the metal, and zinc oxide; forming a mixture by mixing the polycrystalline In-M-Zn oxide powder and a zinc oxide powder; forming a compact by compacting the mixture; and sintering the compact.Type: GrantFiled: February 24, 2014Date of Patent: February 23, 2016Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Masashi Tsubuku, Masashi Oota, Yoichi Kurosawa, Noritaka Ishihara
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Patent number: 9257082Abstract: A display device including a pixel having a memory. The pixel includes at least a display element, a capacitor, an inverter, and a switch. The switch is controlled with a signal held in the capacitor and a signal output from the inverter so that voltage is supplied to the display element. The inverter and the switch can be constituted by transistors with the same polarity. A semiconductor layer included in the pixel may be formed using a light-transmitting material. Moreover, a gate electrode, a drain electrode, and a capacitor electrode may be formed using a light-transmitting conductive layer. The pixel is formed using a light-transmitting material in such a manner, whereby the display device can be a transmissive display device while including a pixel having a memory.Type: GrantFiled: August 31, 2010Date of Patent: February 9, 2016Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Hajime Kimura, Kengo Akimoto, Masashi Tsubuku, Toshinari Sasaki
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Publication number: 20160035902Abstract: It is an object to manufacture a highly reliable display device using a thin film transistor having favorable electric characteristics and high reliability as a switching element. In a bottom gate thin film transistor including an amorphous oxide semiconductor, an oxide conductive layer having a crystal region is formed between an oxide semiconductor layer which has been dehydrated or dehydrogenated by heat treatment and each of a source electrode layer and a drain electrode layer which are formed using a metal material. Accordingly, contact resistance between the oxide semiconductor layer and each of the source electrode layer and the drain electrode layer can be reduced; thus, a thin film transistor having favorable electric characteristics and a highly reliable display device using the thin film transistor can be provided.Type: ApplicationFiled: August 6, 2015Publication date: February 4, 2016Inventors: Shunpei YAMAZAKI, Toshinari SASAKI, Junichiro SAKATA, Masashi TSUBUKU
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Patent number: 9236489Abstract: A logic circuit includes a thin film transistor having a channel formation region formed using an oxide semiconductor, and a capacitor having terminals one of which is brought into a floating state by turning off the thin film transistor. The oxide semiconductor has a hydrogen concentration of 5×1019 (atoms/cm3) or less and thus substantially serves as an insulator in a state where an electric field is not generated. Therefore, off-state current of a thin film transistor can be reduced, leading to suppressing the leakage of electric charge stored in a capacitor, through the thin film transistor. Accordingly, a malfunction of the logic circuit can be prevented. Further, the excessive amount of current which flows in the logic circuit can be reduced through the reduction of off-state current of the thin film transistor, resulting in low power consumption of the logic circuit.Type: GrantFiled: March 18, 2013Date of Patent: January 12, 2016Assignee: SEMICONDUCTOR ENERGY LABORATORY CO., LTD.Inventors: Shunpei Yamazaki, Jun Koyama, Masashi Tsubuku, Kosei Noda
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Patent number: 9236402Abstract: A voltage regulator circuit includes a transistor and a capacitor. The transistor includes a gate, a source, and a drain, a first signal is inputted to one of the source and the drain, a second signal which is a clock signal is inputted to the gate, an oxide semiconductor layer is used for a channel formation layer, and an off-state current is less than or equal to 10 aA/?m. The capacitor includes a first electrode and a second electrode, the first electrode is electrically connected to the other of the source and the drain of the transistor, and a high power source voltage and a low power source voltage are alternately applied to the second electrode.Type: GrantFiled: June 3, 2014Date of Patent: January 12, 2016Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Jun Koyama, Kei Takahashi, Masashi Tsubuku, Kosei Noda
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Patent number: 9236385Abstract: An object is to provide a memory device including a memory element that can be operated without problems by a thin film transistor with a low off-state current. Provided is a memory device in which a memory element including at least one thin film transistor that includes an oxide semiconductor layer is arranged as a matrix. The thin film transistor including an oxide semiconductor layer has a high field effect mobility and low off-state current, and thus can be operated favorably without problems. In addition, the power consumption can be reduced. Such a memory device is particularly effective in the case where the thin film transistor including an oxide semiconductor layer is provided in a pixel of a display device because the memory device and the pixel can be formed over one substrate.Type: GrantFiled: July 21, 2014Date of Patent: January 12, 2016Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Masashi Tsubuku, Kosei Noda, Kouhei Toyotaka, Kazunori Watanabe, Hikaru Harada
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Patent number: 9224839Abstract: To provide a method for manufacturing a thin film transistor in which contact resistance between an oxide semiconductor layer and source and drain electrode layers is small, the surfaces of the source and drain electrode layers are subjected to sputtering treatment with plasma and an oxide semiconductor layer containing In, Ga, and Zn is formed successively over the source and drain electrode layers without exposure of the source and drain electrode layers to air.Type: GrantFiled: August 14, 2014Date of Patent: December 29, 2015Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Kengo Akimoto, Masashi Tsubuku
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Patent number: 9219160Abstract: A decrease in on-state current in a semiconductor device including an oxide semiconductor film is suppressed. A transistor including an oxide semiconductor film, an insulating film which includes oxygen and silicon, a gate electrode adjacent to the oxide semiconductor film, the oxide semiconductor film provided to be in contact with the insulating film and overlap with at least the gate electrode, and a source electrode and a drain electrode electrically connected to the oxide semiconductor film. In the oxide semiconductor film, a first region which is provided to be in contact with the interface with the insulating film and have a thickness less than or equal to 5 nm has a silicon concentration lower than or equal to 1.0 at. %, and a region in the oxide semiconductor film other than the first region has lower silicon concentration than the first region.Type: GrantFiled: September 25, 2012Date of Patent: December 22, 2015Assignee: SEMICONDUCTOR ENERGY LABORATORY CO., LTD.Inventors: Tatsuya Honda, Masashi Tsubuku, Yusuke Nonaka, Takashi Shimazu, Shunpei Yamazaki
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Patent number: 9218966Abstract: To suppress a decrease in on-state current in a semiconductor device including an oxide semiconductor. Provided is a semiconductor device including the following: an oxide semiconductor film which serves as a semiconductor layer; a gate insulating film including an oxide containing silicon, over the oxide semiconductor film; a gate electrode which overlaps with at least the oxide semiconductor film, over the gate insulating film; and a source electrode and a drain electrode which are electrically connected to the oxide semiconductor film. In the semiconductor device, the oxide semiconductor film overlapping with at least the gate electrode includes a region in which a concentration of silicon distributed from the interface with the gate insulating film toward the inside of the oxide semiconductor film is lower than or equal to 1.1 at. %.Type: GrantFiled: October 11, 2012Date of Patent: December 22, 2015Assignee: SEMICONDUCTOR ENERGY LABORATORY CO., LTD.Inventors: Tatsuya Honda, Masashi Tsubuku, Yusuke Nonaka, Shunpei Yamazaki
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Publication number: 20150364502Abstract: An object is to improve reliability of a semiconductor device. A semiconductor device including a driver circuit portion and a display portion (also referred to as a pixel portion) over the same substrate is provided. The driver circuit portion and the display portion include thin film transistors in which a semiconductor layer includes an oxide semiconductor; a first wiring; and a second wiring. The thin film transistors each include a source electrode layer and a drain electrode layer. In the thin film transistor in the driver circuit portion, the semiconductor layer is sandwiched between a gate electrode layer and a conductive layer. The first wiring and the second wiring are electrically connected to each other in an opening provided in a gate insulating film through an oxide conductive layer.Type: ApplicationFiled: August 25, 2015Publication date: December 17, 2015Inventors: Shunpei YAMAZAKI, Junichiro SAKATA, Masayuki SAKAKURA, Yoshiaki OIKAWA, Kenichi OKAZAKI, Hotaka MARUYAMA, Masashi TSUBUKU
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Publication number: 20150364610Abstract: A semiconductor device includes a first oxide semiconductor film, a second oxide semiconductor film over the first oxide semiconductor film, a source electrode in contact with the second oxide semiconductor film, a drain electrode in contact with the second oxide semiconductor film, a metal oxide film over the second oxide semiconductor film, the source electrode, and the drain electrode, a gate insulating film over the metal oxide film, and a gate electrode over the gate insulating film. The metal oxide film contains M (M represents Ti, Ga, Y, Zr, La, Ce, Nd, or Hf) and Zn. The metal oxide film includes a portion where x/(x+y) is greater than 0.67 and less than or equal to 0.99 when a target has an atomic ratio of M:Zn=x:y.Type: ApplicationFiled: June 8, 2015Publication date: December 17, 2015Inventors: Masashi TSUBUKU, Toshihiko TAKEUCHI, Yasumasa YAMANE, Masashi OOTA
