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: 8890159Abstract: An oxide semiconductor stacked film which does not easily cause a variation in electrical characteristics of a transistor and has high stability is provided. Further, a transistor which includes the oxide semiconductor stacked film in its channel formation region and has stable electrical characteristics is provided. An oxide semiconductor stacked film includes a first oxide semiconductor layer, a second oxide semiconductor layer, and a third oxide semiconductor layer which are sequentially stacked and each of which contains indium, gallium, and zinc. The content percentage of indium in the second oxide semiconductor layer is higher than that in the first oxide semiconductor layer and the third oxide semiconductor layer, and the absorption coefficient of the oxide semiconductor stacked film, which is measured by the CPM, is lower than or equal to 3×10?3/cm in an energy range of 1.5 eV to 2.3 eV.Type: GrantFiled: July 29, 2013Date of Patent: November 18, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Masashi Tsubuku, Ryosuke Watanabe, Masashi Oota, Noritaka Ishihara, Koki Inoue
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Patent number: 8890166Abstract: An object of the present invention is to provide a light-emitting device in which plural kinds of circuits are formed over the same substrate, and plural kinds of thin film transistors are provided in accordance with characteristics of the plural kinds of circuits. An inverted-coplanar thin film transistor, an oxide semiconductor layer of which overlaps with a source and drain electrode layers, and a channel-etched thin film transistor are used as a thin film transistor for a pixel and a thin film transistor for a driver circuit, respectively. Between the thin film transistor for a pixel and a light-emitting element, a color filter layer is provided so as to overlap with the light-emitting element which is electrically connected to the thin film transistor for a pixel.Type: GrantFiled: August 30, 2010Date of Patent: November 18, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Masayuki Sakakura, Yoshiaki Oikawa, Shunpei Yamazaki, Junichiro Sakata, Masashi Tsubuku, Kengo Akimoto, Miyuki Hosoba
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Publication number: 20140337603Abstract: 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: July 21, 2014Publication date: November 13, 2014Inventors: Shunpei Yamazaki, Masashi Tsubuku, Kosei Noda, Kouhei Toyotaka, Kazunori Watanabe, Hikaru Harada
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Publication number: 20140332804Abstract: 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: ApplicationFiled: July 24, 2014Publication date: November 13, 2014Inventors: Shunpei Yamazaki, Jun Koyama, Atsushi Hirose, Masashi Tsubuku, Kosei Noda
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Patent number: 8885115Abstract: 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: GrantFiled: January 27, 2014Date of Patent: November 11, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Junichiro Sakata, Masayuki Sakakura, Yoshiaki Oikawa, Kenichi Okazaki, Hotaka Maruyama, Masashi Tsubuku
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Patent number: 8884651Abstract: To reduce a leakage current of a transistor so that malfunction of a logic circuit can be suppressed. The logic circuit includes a transistor which includes an oxide semiconductor layer having a function of a channel formation layer and in which an off current is 1×10?13 A or less per micrometer in channel width. A first signal, a second signal, and a third signal that is a clock signal are input as input signals. A fourth signal and a fifth signal whose voltage states are set in accordance with the first to third signals which have been input are output as output signals.Type: GrantFiled: November 7, 2013Date of Patent: November 11, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Jun Koyama, Masashi Tsubuku, Kosei Noda
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Publication number: 20140327007Abstract: When a transistor having bottom gate bottom contact structure is manufactured, for example, a conductive layer constituting a source and a drain has a three-layer structure and two-step etching is performed. In the first etching process, an etching method in which the etching rates for at least the second film and the third film are high is employed, and the first etching process is performed until at least the first film is exposed. In the second etching process, an etching method in which the etching rate for the first film is higher than that in the first etching process and the etching rate for a “layer provided below and in contact with the first film” is lower than that in the first etching process is employed. The side wall of the second film is slightly etched when a resist mask is removed after the second etching process.Type: ApplicationFiled: July 17, 2014Publication date: November 6, 2014Inventors: Shinya SASAGAWA, Hitoshi NAKAYAMA, Masashi TSUBUKU, Daigo SHIMADA
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Patent number: 8879011Abstract: 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: GrantFiled: March 4, 2014Date of Patent: November 4, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Junichiro Sakata, Masashi Tsubuku, Kengo Akimoto, Miyuki Hosoba, Masayuki Sakakura, Yoshiaki Oikawa
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Publication number: 20140319519Abstract: An oxide semiconductor layer in which “safe” traps exist exhibits two kinds of modes in photoresponse characteristics. By using the oxide semiconductor layer, a transistor in which light deterioration is suppressed to the minimum and the electric characteristics are stable can be achieved. The oxide semiconductor layer exhibiting two kinds of modes in photoresponse characteristics has a photoelectric current value of 1 pA to 10 nA inclusive. When the average time ?1 until which carriers are captured by the “safe” traps is large enough, there are two kinds of modes in photoresponse characteristics, that is, a region where the current value falls rapidly and a region where the current value falls gradually, in the result of a change in photoelectric current over time.Type: ApplicationFiled: July 14, 2014Publication date: October 30, 2014Inventors: Takayuki Inoue, Masashi Tsubuku, Suzunosuke Hiraishi, Junichiro Sakata, Erumu Kikuchi, Hiromichi Godo, Akiharu Miyanaga, Shunpei Yamazaki
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Patent number: 8871565Abstract: An object is to manufacture a semiconductor device including an oxide semiconductor film, which has stable electric characteristics and high reliability. A crystalline oxide semiconductor film is formed, without performing a plurality of steps, as follows: by utilizing a difference in atomic weight of plural kinds of atoms included in an oxide semiconductor target, zinc with low atomic weight is preferentially deposited on an oxide insulating film to form a seed crystal including zinc; and tin, indium, or the like with high atomic weight is deposited on the seed crystal while causing crystal growth. Further, a crystalline oxide semiconductor film is formed by causing crystal growth using a seed crystal with a hexagonal crystal structure including zinc as a nucleus, whereby a single crystal oxide semiconductor film or a substantially single crystal oxide semiconductor film is formed.Type: GrantFiled: August 31, 2011Date of Patent: October 28, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Yusuke Nonaka, Takayuki Inoue, Masashi Tsubuku, Kengo Akimoto, Akiharu Miyanaga
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Patent number: 8872179Abstract: To improve switching characteristics of a transistor in which a channel is formed in an oxide semiconductor layer. A parasitic channel is formed at an end portion of the oxide semiconductor layer because a source and a drain of the transistor are electrically connected to the end portion. That is, when at least one of the source and the drain of the transistor is not electrically connected to the end portion, the parasitic channel is not formed at the end portion. In view of this, a transistor having a structure in which at least one of a source and a drain of the transistor is not or less likely to be electrically connected to an end portion of an oxide semiconductor layer is provided.Type: GrantFiled: November 28, 2012Date of Patent: October 28, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventor: Masashi Tsubuku
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Patent number: 8860023Abstract: 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 25, 2013Date of Patent: October 14, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Masashi Tsubuku, Yusuke Nonaka, Noritaka Ishihara, Masashi Oota, Hideyuki Kishida
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Patent number: 8854286Abstract: In a liquid crystal display device including a plurality of pixels in a display portion and configured to performed display in a plurality of frame periods, each of the frame periods includes a writing period and a holding period, and after an image signal is input to each of the plurality of pixels in the writing period, a transistor included in each of the plurality of pixels is turned off and the image signal is held for at least 30 seconds in the holding period. The pixel includes a semiconductor layer including an oxide semiconductor layer, and the oxide semiconductor layer has a carrier concentration of less than 1×1014/cm3.Type: GrantFiled: October 8, 2010Date of Patent: October 7, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Ryo Arasawa, Jun Koyama, Masashi Tsubuku, Kosei Noda
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Patent number: 8841661Abstract: A method for forming a thin film transistor includes steps of forming a first wiring layer over a first electrode layer and forming a second wiring layer over a second electrode layer, wherein the first electrode layer extends beyond an end portion of the first wiring layer, the second electrode layer extends beyond an end portion of the second wiring layer, and a semiconductor layer is formed so as to be electrically connected to a side face and a top face of the first electrode layer and a side face and a top face of the second electrode layer.Type: GrantFiled: February 5, 2010Date of Patent: September 23, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Kengo Akimoto, Masashi Tsubuku
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Publication number: 20140266115Abstract: 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: ApplicationFiled: June 3, 2014Publication date: September 18, 2014Applicant: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Jun Koyama, Kei Takahashi, Masashi Tsubuku, Kosei Noda
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Publication number: 20140252345Abstract: An oxide semiconductor film having high stability with respect to light irradiation or a semiconductor device having high stability with respect to light irradiation is provided. One embodiment of the present invention is a semiconductor film including an oxide in which light absorption is observed by a constant photocurrent method (CPM) in a wavelength range of 400 nm to 800 nm, and in which an absorption coefficient of a defect level, which is obtained by removing light absorption due to a band tail from the light absorption, is lower than or equal to 5×10?2/cm. Alternatively, a semiconductor device is manufactured using the semiconductor film.Type: ApplicationFiled: March 4, 2014Publication date: September 11, 2014Applicant: Semiconductor Energy Laboratory Co., Ltd.Inventors: Masashi TSUBUKU, Ryosuke WATANABE
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Publication number: 20140246674Abstract: An object is to provide a semiconductor device including an oxide semiconductor film, which has stable electrical characteristics and high reliability. A stack of first and second material films is formed by forming the first material film (a film having a hexagonal crystal structure) having a thickness of 1 nm to 10 nm over an insulating surface and forming the second material film having a hexagonal crystal structure (a crystalline oxide semiconductor film) using the first material film as a nucleus. As the first material film, a material film having a wurtzite crystal structure (e.g., gallium nitride or aluminum nitride) or a material film having a corundum crystal structure (?-Al2O3, ?-Ga2O3, In2O3, Ti2O3, V2O3, Cr2O3, or ?-Fe2O3) is used.Type: ApplicationFiled: May 15, 2014Publication date: September 4, 2014Applicant: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei YAMAZAKI, Yusuke NONAKA, Takayuki INOUE, Masashi TSUBUKU, Kengo AKIMOTO, Akiharu MIYANAGA
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Publication number: 20140241978Abstract: 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: ApplicationFiled: February 24, 2014Publication date: August 28, 2014Applicant: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei YAMAZAKI, Masashi TSUBUKU, Masashi OOTA, Yoichi KUROSAWA, Noritaka ISHIHARA
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Publication number: 20140231802Abstract: The semiconductor device includes a driver circuit portion including a driver circuit and a pixel portion including a pixel. The pixel includes a gate electrode layer having a light-transmitting property, a gate insulating layer, a source electrode layer and a drain electrode layer each having a light-transmitting property provided over the gate insulating layer, an oxide semiconductor layer covering top surfaces and side surfaces of the source electrode layer and the drain electrode layer and provided over the gate electrode layer with the gate insulating layer therebetween, a conductive layer provided over part of the oxide semiconductor layer and having a lower resistance than the source electrode layer and the drain electrode layer, and an oxide insulating layer in contact with part of the oxide semiconductor layer.Type: ApplicationFiled: April 29, 2014Publication date: August 21, 2014Applicant: Semiconductor Energy Laboratory Co., Ltd.Inventors: Masayuki SAKAKURA, Yoshiaki OIKAWA, Shunpei YAMAZAKI, Junichiro SAKATA, Masashi TSUBUKU, Kengo AKIMOTO, Miyuki HOSOBA
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Patent number: 8809115Abstract: 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 11, 2011Date of Patent: August 19, 2014Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Kengo Akimoto, Masashi Tsubuku
