Patents by Inventor Shigehisa Yamamoto

Shigehisa Yamamoto 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).

  • Publication number: 20240055306
    Abstract: The following steps (a) to (d) are provided. The step (a) is to form a drift layer of an n type on a silicon carbide semiconductor substrate of the n type through epitaxial growth. The step (b) is to measure impurity concentration of the drift layer. The step (c) is to form an ion implantation mask on the drift layer, the ion implantation mask including a plurality of first openings being periodically provided. The step (d) is to implant impurity ions of a p type through the plurality of first openings, form a plurality of second pillar regions of the p type in the drift layer, and turn the drift layer between the plurality of second pillar regions into a first pillar region. The step (d) includes performing feedforward control on an ion implantation amount so that there is a positive correlation with measurement results of the step (b).
    Type: Application
    Filed: June 6, 2023
    Publication date: February 15, 2024
    Applicant: Mitsubishi Electric Corporation
    Inventors: Yuichi NAGAHISA, Shigeto HONDA, Shinya AKAO, Shigehisa YAMAMOTO
  • Patent number: 10858757
    Abstract: An epitaxial substrate includes a single-crystal substrate of silicon carbide, and an epitaxial layer of silicon carbide disposed on the single-crystal substrate. The epitaxial layer includes a first epitaxial layer disposed on the single-crystal substrate, a second epitaxial layer disposed on the first epitaxial layer, and a third epitaxial layer disposed on the second epitaxial layer. The first epitaxial layer has a basal-plane-dislocation conversion rate of less than 95%. The second epitaxial layer has a basal-plane-dislocation conversion rate of more than 98%.
    Type: Grant
    Filed: May 9, 2017
    Date of Patent: December 8, 2020
    Assignee: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Takanori Tanaka, Shigehisa Yamamoto, Yu Nakamura, Yasuhiro Kimura, Shuhei Nakata, Yoichiro Mitani
  • Publication number: 20190145021
    Abstract: An epitaxial substrate includes a single-crystal substrate of silicon carbide, and an epitaxial layer of silicon carbide disposed on the single-crystal substrate. The epitaxial layer includes a first epitaxial layer disposed on the single-crystal substrate, a second epitaxial layer disposed on the first epitaxial layer, and a third epitaxial layer disposed on the second epitaxial layer. The first epitaxial layer has a basal-plane-dislocation conversion rate of less than 95%. The second epitaxial layer has a basal-plane-dislocation conversion rate of more than 98%.
    Type: Application
    Filed: May 9, 2017
    Publication date: May 16, 2019
    Applicant: Mitsubishi Electric Corporation
    Inventors: Takanori TANAKA, Shigehisa YAMAMOTO, Yu NAKAMURA, Yasuhiro KIMURA, Shuhei NAKATA, Yoichiro MITANI
  • Patent number: 9874596
    Abstract: The present invention provides a method for manufacturing silicon carbide semiconductor apparatus including a testing step of testing a PN diode for the presence or absence of stacking faults in a relatively short time and an energization test apparatus. The present invention sets the temperature of a bipolar semiconductor element at 150° C. or higher and 230° C. or lower, causes a forward current having a current density of 120 [A/cm2] or more and 400 [A/cm2] or less to continuously flow through the bipolar semiconductor element, calculates, in a case where a forward resistance of the bipolar semiconductor element through which the forward current flows reaches a saturation state, the degree of change in the forward resistance, and determines whether the calculated degree of change is smaller than a threshold value.
    Type: Grant
    Filed: March 10, 2014
    Date of Patent: January 23, 2018
    Assignee: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Shoyu Watanabe, Akihiro Koyama, Shigehisa Yamamoto, Yukiyasu Nakao, Kazuya Konishi
  • Publication number: 20160003889
    Abstract: The present invention provides a method for manufacturing silicon carbide semiconductor apparatus including a testing step of testing a PN diode for the presence or absence of stacking faults in a relatively short time and an energization test apparatus. The present invention sets the temperature of a bipolar semiconductor element at 150° C. or higher and 230° C. or lower, causes a forward current having a current density of 120 [A/cm2] or more and 400 [A/cm2] or less to continuously flow through the bipolar semiconductor element, calculates, in a case where a forward resistance of the bipolar semiconductor element through which the forward current flows reaches a saturation state, the degree of change in the forward resistance, and determines whether the calculated degree of change is smaller than a threshold value.
    Type: Application
    Filed: March 10, 2014
    Publication date: January 7, 2016
    Applicant: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Shoyu WATANABE, Akihiro KOYAMA, Shigehisa YAMAMOTO, Yukiyasu NAKAO, Kazuya KONISHI
  • Publication number: 20100193972
    Abstract: A resin composition for semiconductor encapsulation having good moldability, of which the cured product has effective electromagnetic wave shieldability, is provided. A resin composition for semiconductor encapsulation, containing spherical sintered ferrite particles having the following properties (a) to (c) : (a) the soluble ion content of the particles is at most 5 ppm; (b) the mean particle size of the particles is from 10 to 50 ?m; (c) the crystal structure of the particles by X-ray diffractiometry is a spinel structure.
    Type: Application
    Filed: June 6, 2006
    Publication date: August 5, 2010
    Applicants: NITTO DENKO CORPORATION, TODA KOGYO CORP.
    Inventors: Kazumi Yamamoto, Masaharu Abe, Shigehisa Yamamoto, Kazushi Nishimoto, Tomohiro Dote, Kazumasa Igarashi, Kazuhiro Ikemura, Takuya Eto, Masataka Tada, Katsumi Okayama, Kaoru Kato
  • Patent number: 6470479
    Abstract: A method of verifying semiconductor integrated circuit reliability allows reliability verification of a large-scale semiconductor integrated circuit without any omission. Step S12 is to obtain a sum total (Cio) of inner-cell input/output load capacities in a selected cell on the basis of input and output load capacities registered in a cell library database (1A), and step S13 is to obtain wiring capacitance (Cic) between cells. In step S14, the sum total (Cio) of inner-cell input/output load capacities and the wiring capacitance (Cic) between cells are added to obtain output-terminal load capacity (COUT). On the basis of the output-terminal load capacity (COUT), a failure rate (FOUT) of an intercellular interconnect line is obtained in step S15, and a failure rate (Fcell) of inner-cell interconnect lines is obtained in step S16 from an equation registered in the cell library database (1A). Then, those failure rates (Fcell, FOUT) are added to obtain a total failure rate (Ftotal) in step S17.
    Type: Grant
    Filed: April 13, 2000
    Date of Patent: October 22, 2002
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Shigehisa Yamamoto
  • Patent number: 6404219
    Abstract: A burn-in test method and apparatus and a semiconductor chip to be used in a burn-in test method that allow current stress to be imposed on every circuit node by varying a power supply voltage in pulse form, and thereby enables an efficient burn-in test. A burn-in test is performed efficiently by imposing current stress to every internal circuit by supplying the internal circuits of a semiconductor chip with a pulse Vcc voltage that varies from 0 V to a burn-in voltage Vbi. The burn-in test time can further be shortened by varying the Vcc voltage in pulse form in a range from a voltage that is higher than or equal to the threshold voltage Vth to the burn-in voltage Vbi or by setting the pulse waveform of the Vcc voltage in such a manner that a high-voltage period TH is longer than a low-voltage period TL.
    Type: Grant
    Filed: May 11, 1999
    Date of Patent: June 11, 2002
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Shigehisa Yamamoto
  • Publication number: 20020050813
    Abstract: A burn-in test method and apparatus and a semiconductor chip to be used in a burn-in test method that allow current stress to be imposed on every circuit node by varying a power supply voltage in pulse form, and thereby enables an efficient burn-in test. A burn-in test is performed efficiently by imposing current stress to every internal circuit by supplying the internal circuits of a semiconductor chip with a pulse Vcc voltage that varies from 0 V to a burn-in voltage Vbi. The burn-in test time can further be shortened by varying the Vcc voltage in pulse form in a range from a voltage that is higher than or equal to the threshold voltage Vth to the burn-in voltage Vbi or by setting the pulse waveform of the Vcc voltage in such a manner that a high-voltage period TH is longer than a low-voltage period TL.
    Type: Application
    Filed: May 11, 1999
    Publication date: May 2, 2002
    Inventor: SHIGEHISA YAMAMOTO
  • Patent number: 6372528
    Abstract: To provide a burn-in method and device capable of accelerating burn-in also in a peripheral circuit portion and a logic circuit portion as well as a memory cell array portion. A high temperature stress is applied to a wafer to be an evaluation object (Step SP11). Next, a low temperature stress and an electric stress are applied to the wafer (Step SP12). Then, it is decided whether a predetermined stress is applied to the wafer or not (Step SP13). If a result of the decision at the Step SP13 is “YES”, it is decided whether a defective portion is generated in each chip of the wafer or not (Step SP14). Referring to a chip decided to have a failure generated thereon as a result of the decision at the Step SP14, it is decided whether repair is executed for the defective portion or not (Step SP15). If a result of the decision at the Step SP15 is “YES”, the repair is executed for the defective portion (Step SP16).
    Type: Grant
    Filed: March 22, 2001
    Date of Patent: April 16, 2002
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Shigehisa Yamamoto
  • Publication number: 20020039800
    Abstract: To provide a burn-in method and device capable of accelerating burn-in also in a peripheral circuit portion and a logic circuit portion as well as a memory cell array portion. A high temperature stress is applied to a wafer to be an evaluation object (Step SP11). Next, a low temperature stress and an electric stress are applied to the wafer (Step SP12). Then, it is decided whether a predetermined stress is applied to the wafer or not (Step SP13). If a result of the decision at the Step SP13 is “YES”, it is decided whether a defective portion is generated in each chip of the wafer or not (Step SP14). Referring to a chip decided to have a failure generated thereon as a result of the decision at the Step SP14, it is decided whether repair is executed for the defective portion or not (Step SP15). If a result of the decision at the Step SP15 is “YES”, the repair is executed for the defective portion (Step SP16).
    Type: Application
    Filed: March 22, 2001
    Publication date: April 4, 2002
    Applicant: MITSUBISHI DENKI KABUSHIKI KAISHA
    Inventor: Shigehisa Yamamoto
  • Publication number: 20020009120
    Abstract: An object is to obtain a burn-in system which can speed up the burn-in not only in memory cell array portions but also in peripheral circuit and logic circuit portions. First, a wafer (3) to be evaluated is put in a constant temperature chamber (1a) and subjected to high temperature stress. The wafer (3) is then put in a constant temperature chamber (1b) and subjected to low temperature stress. The applications of the temperature stresses in the constant temperature chambers (1a) and (1b) may be repeatedly performed. When given temperature stresses have been applied to the wafer (3), the wafer (3) is conveyed to an evaluation unit (5). The evaluation unit (5) then checks whether failure exists in chips (30). If the evaluation determines that a chip (30) has a failure, whether to apply repair to the failure portion is decided and repair is applied if possible.
    Type: Application
    Filed: January 9, 2001
    Publication date: January 24, 2002
    Applicant: MITSUBISHI DENKI KABUSHIKI KAISHA
    Inventors: Hiromitsu Sugimoto, Shigehisa Yamamoto
  • Patent number: 6127837
    Abstract: A semiconductor device testing method using a semiconductor device testing apparatus that can improve the contact characteristic between probe needles and power-supply terminals and signal terminals while ensuring efficiency of product utilization of a tested wafer. Provided on a probe wafer (4) are bumps (5) formed in the same positions in mirror symmetry as the positions of pads (3) formed in individual chips (2) on a tested wafer (1), a common interconnection (6) for interconnecting bumps (5) to be supplied with the same power supplies and signals, and terminals (7) connected to the common interconnection (6) to supply power supplies and signals to the common interconnection (6) from the outside. The bumps (5) come in contact with the pads (3) in the chips (2) when the probe wafer (4) and the tested wafer (1) are put together. The common interconnection (6) supplies the power supplies and signals for a burn-in test to the pads (3) in the chips (2).
    Type: Grant
    Filed: December 20, 1999
    Date of Patent: October 3, 2000
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Shigehisa Yamamoto, Katsuya Shiga
  • Patent number: 6099957
    Abstract: The present invention relates to plate-like ferrite particles with magnetoplumbite structure having a composition represented by the general formula of AO.multidot.n{(Fe.sub.1-(a+b) Bi.sub.a M.sub.b).sub.2 O.sub.3 } wherein A is Ba, Sr or Ba--Sr; M is Zn--Nb, Zn--Ta or Zn--Sn; n is from 5.5 to 6.1; a is from 0.001 to 0.005; b is from 0.050 to 0.120; and the ratio of b/a is from 20 to 50. The plate-like ferrite particles with magnetoplumbite structure have an appropriate particle size, a low coercive force, a large saturation magnetization, a small switching field distribution (S.F.D.) and an excellent temperature stability, and a magnetic card containing the plate-like ferrite particles with magnetoplumbite structure.
    Type: Grant
    Filed: November 10, 1999
    Date of Patent: August 8, 2000
    Assignee: Toda Kogyo Corporation
    Inventors: Akinori Yamamoto, Kazutoshi Sanada, Shigehisa Yamamoto
  • Patent number: 6037794
    Abstract: An object is to obtain a semiconductor device testing apparatus that can improve the contact characteristic between probe needles and power-supply terminals and signal terminals while ensuring efficiency of product utilization of a tested wafer. Provided on a probe wafer (4) are bumps (5) formed in the same positions in mirror symmetry as the positions of pads (3) formed in individual chips (2) on a tested wafer (1), a common interconnection (6) for interconnecting bumps (5) to be supplied with the same power supplies and signals, and terminals (7) connected to the common interconnection (6) to supply power supplies and signals to the common interconnection (6) from the outside. The bumps (5) come in contact with the pads (3) in the chips (2) when the probe wafer (4) and the tested wafer (1) are put together. The common interconnection (6) supplies the power supplies and signals for a burn-in test to the pads (3) in the chips (2).
    Type: Grant
    Filed: August 5, 1998
    Date of Patent: March 14, 2000
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Shigehisa Yamamoto, Katsuya Shiga
  • Patent number: 6024478
    Abstract: An electric work station calculates an output load of a selected cell based on information from at least one of a design cell information library, a logic circuit information library and a layout information library. The work station further calculates a hot carrier dependent lifetime of a transistor in the cell by using the computed output load and information from a reliability information library, and verifies reliability of the cell by comparing the calculated lifetime with a reference value.
    Type: Grant
    Filed: December 9, 1996
    Date of Patent: February 15, 2000
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Shigehisa Yamamoto
  • Patent number: 6017631
    Abstract: The present invention relates to plate-like ferrite particles with magnetoplumbite structure having a composition represented by the general formula of AO.multidot.n{(Fe.sub.1-(a+b) Bi.sub.a M.sub.b).sub.2 O.sub.3 } wherein A is Ba, Sr or Ba--Sr; M is Zn--Nb, Zn--Ta or Zn--Sn; n is from 5.5 to 6.1; a is from 0.001 to 0.005; b is from 0.050 to 0.120; and the ratio of b/a is from 20 to 50. The plate-like ferrite particles with magnetoplumbite structure have an appropriate particle size, a low coercive force, a large saturation magnetization, a small switching field distribution (S.F.D.) and an excellent temperature stability, and a magnetic card containing the plate-like ferrite particles with magnetoplumbite structure.
    Type: Grant
    Filed: March 3, 1998
    Date of Patent: January 25, 2000
    Assignee: Toda Kogyo Corporation
    Inventors: Akinori Yamamoto, Kazutoshi Sanada, Shigehisa Yamamoto
  • Patent number: 5968248
    Abstract: A heat-resistant inorganic pigment of the present invention comprises a composite metal oxide containing Ti and two divalent metals selected from the group consisting of Mg, Fe, Ni and Co, the content of said two divalent metals in said composite metal oxide being 0.95 to 1.05, in an atomic ratio, based on Ti, and the composition ratio of said two divalent metals being 95/5 to 5/95 in an atomic ratio. The pigment of the present invention is useful as a pigment for a heat-resistant coating material and is a novel heat-resistant inorganic pigment which does not pollute the environment.
    Type: Grant
    Filed: February 13, 1997
    Date of Patent: October 19, 1999
    Assignees: General of Agency of Industrial Science, Toda Kogyo Corporation
    Inventors: Yasuo Shibasaki, Kiichi Oda, Saburo Sano, Shigehisa Yamamoto, Nanao Horiishi
  • Patent number: 5900735
    Abstract: Center-to-center spacings (L.sub.1, L.sub.2, L.sub.3, L.sub.4, . . . ) of adjacent holes (5) in a hole chain (6) are set to values not less than five times a Blech length. This setting causes two parameters (MTF and .sigma.) of a logarithmic normal distribution used as a failure distribution for EM lifetime prediction to be constant independently of the center-to-center spacings, permitting stable EM lifetime prediction of the hole chain. Further, setting the length of each of extension interconnect wires (2) to a value not greater than the Blech length prevents voids from being created in the extension interconnect wires (2).
    Type: Grant
    Filed: February 27, 1997
    Date of Patent: May 4, 1999
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Shigehisa Yamamoto
  • Patent number: 5876819
    Abstract: A semiconductor substrate with no reduction in the effective usage area and mechanical strength, and non-uniformity of the resist film thickness, and method of manufacturing and using the same are obtained. A detection mark for detecting the crystal orientation of a silicon wafer having an outer perimeter entirely of a circular contour is formed at a predetermined region of the silicon wafer. The crystal orientation of the semiconductor wafer can easily be detected with the outer perimeter still taking a circular contour. Therefore, various problems encountered in a conventional semiconductor substrate having an orientation flat or notch such as reduction in mechanical strength and effective usage area, and non-uniformity of the resist film can be circumvented.
    Type: Grant
    Filed: November 7, 1995
    Date of Patent: March 2, 1999
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Yasuhiro Kimura, Keiji Yamauchi, Hidekazu Yamamoto, Shigehisa Yamamoto, Masafumi Katsumata, Yasukazu Mukogawa, Hajime Watanabe