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).

  • Patent number: 10553726
    Abstract: 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: Grant
    Filed: August 8, 2017
    Date of Patent: February 4, 2020
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Masashi Tsubuku, Kosei Noda, Kouhei Toyotaka, Kazunori Watanabe, Hikaru Harada
  • Publication number: 20200006393
    Abstract: 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: Application
    Filed: September 12, 2019
    Publication date: January 2, 2020
    Inventors: Shunpei YAMAZAKI, Toshinari SASAKI, Junichiro SAKATA, Masashi TSUBUKU
  • Patent number: 10522347
    Abstract: 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: Grant
    Filed: March 7, 2017
    Date of Patent: December 31, 2019
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Masashi Tsubuku, Masashi Oota, Yoichi Kurosawa, Noritaka Ishihara
  • Publication number: 20190386141
    Abstract: 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, leadind 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: Application
    Filed: August 29, 2019
    Publication date: December 19, 2019
    Inventors: Shunpei YAMAZAKI, Jun KOYAMA, Masashi TSUBUKU, Kosei NODA
  • Patent number: 10490671
    Abstract: 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: Grant
    Filed: November 9, 2015
    Date of Patent: November 26, 2019
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Jun Koyama, Masashi Tsubuku, Kosei Noda
  • Publication number: 20190355592
    Abstract: An object is to provide a display device with excellent display characteristics, where a pixel circuit and a driver circuit provided over one substrate are formed using transistors which have different structures corresponding to characteristics of the respective circuits. The driver circuit portion includes a driver circuit transistor in which a gate electrode layer, a source electrode layer, and a drain electrode layer are formed using a metal film, and a channel layer is formed using an oxide semiconductor. The pixel portion includes a pixel transistor in which a gate electrode layer, a source electrode layer, and a drain electrode layer are formed using an oxide conductor, and a semiconductor layer is formed using an oxide semiconductor. The pixel transistor is formed using a light-transmitting material, and thus, a display device with higher aperture ratio can be manufactured.
    Type: Application
    Filed: July 30, 2019
    Publication date: November 21, 2019
    Inventors: Shunpei YAMAZAKI, Junichiro SAKATA, Masashi TSUBUKU, Kengo AKIMOTO, Miyuki HOSOBA, Masayuki SAKAKURA, Yoshiaki OIKAWA
  • Patent number: 10468506
    Abstract: The on-state characteristics of a transistor are improved and thus, a semiconductor device capable of high-speed response and high-speed operation is provided. A highly reliable semiconductor device showing stable electric characteristics is made. The semiconductor device includes a transistor including a first oxide layer; an oxide semiconductor layer over the first oxide layer; a source electrode layer and a drain electrode layer in contact with the oxide semiconductor layer; a second oxide layer over the oxide semiconductor layer; a gate insulating layer over the second oxide layer; and a gate electrode layer over the gate insulating layer. An end portion of the second oxide layer and an end portion of the gate insulating layer overlap with the source electrode layer and the drain electrode layer.
    Type: Grant
    Filed: November 19, 2018
    Date of Patent: November 5, 2019
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Hideomi Suzawa, Shinya Sasagawa, Motomu Kurata, Masashi Tsubuku
  • Patent number: 10468536
    Abstract: A semiconductor device includes a gate electrode, a gate insulating film which includes oxidized material containing silicon and covers the gate electrode, an oxide semiconductor film provided to be in contact with the gate 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 gate 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. At least the first region includes a crystal portion.
    Type: Grant
    Filed: April 11, 2019
    Date of Patent: November 5, 2019
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Tatsuya Honda, Masashi Tsubuku, Yusuke Nonaka, Takashi Shimazu, Shunpei Yamazaki
  • Patent number: 10461099
    Abstract: A metal oxide film including a crystal part and having highly stable physical properties is provided. The size of the crystal part is less than or equal to 10 nm, which allows the observation of circumferentially arranged spots in a nanobeam electron diffraction pattern of the cross section of the metal oxide film when the measurement area is greater than or equal to 5 nm? and less than or equal to 10 nm?.
    Type: Grant
    Filed: January 25, 2018
    Date of Patent: October 29, 2019
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Masahiro Takahashi, Takuya Hirohashi, Masashi Tsubuku, Noritaka Ishihara, Masashi Oota
  • Publication number: 20190312063
    Abstract: 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: Application
    Filed: June 10, 2019
    Publication date: October 10, 2019
    Inventors: Shunpei YAMAZAKI, Jun KOYAMA, Atsushi HIROSE, Masashi TSUBUKU, Kosei NODA
  • Publication number: 20190312062
    Abstract: One embodiment of the invention is characterized as follows. A display device comprising: a display area including a plurality of pixels, each of the pixels has a first TFT and a second TFT, the first TFT and the second TFT comprise an oxide semiconductor, the first TFT and the second TFT are covered by an interlayer insulating film, a first through hole is formed in the in the interlayer insulating film to connect a drain of the first TFT, wherein a distance d1 between a center of the first through hole and an edge of a channel of the first TFT is shorter than a distance d2 between a center of the first through hole and an edge of a channel of the second TFT, a channel length of the first TFT is shorter than a channel length of the second TFT.
    Type: Application
    Filed: March 28, 2019
    Publication date: October 10, 2019
    Applicant: Japan Display Inc.
    Inventors: Miyuki ISHIKAWA, Masashi TSUBUKU
  • Patent number: 10439074
    Abstract: A semiconductor device with improved electrical characteristics is provided. A semiconductor device with improved field effect mobility is provided. A semiconductor device in which the field-effect mobility is not lowered even at high temperatures is provided. A semiconductor device which can be formed at low temperatures is provided. A semiconductor device with improved productivity can be provided. In the semiconductor device, there is a range of a gate voltage where the field-effect mobility increases as the temperature increases within a range of the gate voltage from 0 V to 10 V. For example, such a range of a gate voltage exists at temperatures ranging from a room temperature (25° C.) to 120° C. In the semiconductor device, the off-state current is kept extremely low (lower than or equal to the detection limit of a measurement device) within the above temperature range.
    Type: Grant
    Filed: July 13, 2018
    Date of Patent: October 8, 2019
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Kenichi Okazaki, Masashi Tsubuku, Satoru Saito, Noritaka Ishihara
  • Patent number: 10418384
    Abstract: 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: Grant
    Filed: April 19, 2018
    Date of Patent: September 17, 2019
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Toshinari Sasaki, Junichiro Sakata, Masashi Tsubuku
  • Patent number: 10373843
    Abstract: An object is to provide a display device with excellent display characteristics, where a pixel circuit and a driver circuit provided over one substrate are formed using transistors which have different structures corresponding to characteristics of the respective circuits. The driver circuit portion includes a driver circuit transistor in which a gate electrode layer, a source electrode layer, and a drain electrode layer are formed using a metal film, and a channel layer is formed using an oxide semiconductor. The pixel portion includes a pixel transistor in which a gate electrode layer, a source electrode layer, and a drain electrode layer are formed using an oxide conductor, and a semiconductor layer is formed using an oxide semiconductor. The pixel transistor is formed using a light-transmitting material, and thus, a display device with higher aperture ratio can be manufactured.
    Type: Grant
    Filed: July 2, 2015
    Date of Patent: August 6, 2019
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Junichiro Sakata, Masashi Tsubuku, Kengo Akimoto, Miyuki Hosoba, Masayuki Sakakura, Yoshiaki Oikawa
  • Patent number: 10374030
    Abstract: 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: Grant
    Filed: August 25, 2017
    Date of Patent: August 6, 2019
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Masahiro Takahashi, Takuya Hirohashi, Masashi Tsubuku, Masashi Oota
  • Publication number: 20190237585
    Abstract: A semiconductor device includes a gate electrode, a gate insulating film which includes oxidized material containing silicon and covers the gate electrode, an oxide semiconductor film provided to be in contact with the gate 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 gate 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. At least the first region includes a crystal portion.
    Type: Application
    Filed: April 11, 2019
    Publication date: August 1, 2019
    Inventors: Tatsuya HONDA, Masashi TSUBUKU, Yusuke NONAKA, Takashi SHIMAZU, Shunpei YAMAZAKI
  • Patent number: 10319744
    Abstract: 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: Grant
    Filed: September 18, 2018
    Date of Patent: June 11, 2019
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Jun Koyama, Atsushi Hirose, Masashi Tsubuku, Kosei Noda
  • Patent number: 10310348
    Abstract: A liquid crystal display device includes: a driver circuit portion; a pixel portion; a signal generation circuit for generating a control signal for driving the driver circuit portion and an image signal which is supplied to the pixel portion; a memory circuit; a comparison circuit for detecting a difference of image signals for a series of frame periods among image signals stored for respective frame periods in the memory circuit; a selection circuit which selects and outputs the image signals for the series of frame periods when the difference is detected in the comparison circuit; and a display control circuit which supplies the control signal and the image signals output from the selection circuit, to the driver circuit portion when the difference is detected in the comparison circuit, and stops supplying the control signal to the driver circuit portion when the difference is not detected in the comparison circuit.
    Type: Grant
    Filed: August 23, 2018
    Date of Patent: June 4, 2019
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Jun Koyama, Hiroyuki Miyake, Masashi Tsubuku, Kosei Noda
  • Patent number: 10290744
    Abstract: A semiconductor device includes a gate electrode, a gate insulating film which includes oxidized material containing silicon and covers the gate electrode, an oxide semiconductor film provided to be in contact with the gate 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 gate 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. At least the first region includes a crystal portion.
    Type: Grant
    Filed: February 2, 2017
    Date of Patent: May 14, 2019
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Tatsuya Honda, Masashi Tsubuku, Yusuke Nonaka, Takashi Shimazu, Shunpei Yamazaki
  • Publication number: 20190103478
    Abstract: The on-state characteristics of a transistor are improved and thus, a semiconductor device capable of high-speed response and high-speed operation is provided. A highly reliable semiconductor device showing stable electric characteristics is made. The semiconductor device includes a transistor including a first oxide layer; an oxide semiconductor layer over the first oxide layer; a source electrode layer and a drain electrode layer in contact with the oxide semiconductor layer; a second oxide layer over the oxide semiconductor layer; a gate insulating layer over the second oxide layer; and a gate electrode layer over the gate insulating layer. An end portion of the second oxide layer and an end portion of the gate insulating layer overlap with the source electrode layer and the drain electrode layer.
    Type: Application
    Filed: November 19, 2018
    Publication date: April 4, 2019
    Inventors: Shunpei YAMAZAKI, Hideomi SUZAWA, Shinya SASAGAWA, Motomu KURATA, Masashi TSUBUKU