Patents by Inventor Kenji Kasahara

Kenji Kasahara 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: 20090236629
    Abstract: The present invention provides a substrate and a semiconductor light emitting device. Convexes having a curved surface are formed on the substrate. The semiconductor light emitting device comprises a substrate on which convexes having a curved surface are formed and a semiconductor layer on the substrate.
    Type: Application
    Filed: July 5, 2006
    Publication date: September 24, 2009
    Applicant: SUMITOMO CHEMICAL COMPANY, LIMITED
    Inventors: Naohiro Nishikawa, Kazumasa Ueda, Kenji Kasahara, Yoshihiko Tsuchida
  • Publication number: 20090212878
    Abstract: An oven-controlled crystal oscillator includes a circuit board, a crystal unit surface-mounted on the circuit board, and a temperature control circuit that maintains operating temperature of the crystal unit constant. The temperature control circuit includes a heating resistor, a power transistor that supplies power to a heating resistor, and a temperature sensitive resistor that detects temperature of the crystal unit. The heating resistor is formed, as a film resistor, on a surface of the circuit board in an area thereof in which the crystal unit is located. The temperature sensitive resistor is provided on the circuit board as a film resistor.
    Type: Application
    Filed: February 19, 2009
    Publication date: August 27, 2009
    Inventors: Junichi Arai, Kenji Kasahara
  • Patent number: 7557412
    Abstract: The sizes of crystal masses are made to be a uniform in a crystalline silicon film obtained by a thermal crystallization method in which a metal element is used. An amorphous silicon film to be crystallized is doped with a metal element that accelerates crystallization, and then irradiated with laser light (with an energy which is not large enough to melt the film and which is large enough to allow the metal element to diffuse in the solid silicon film) from the back side of a light-transmissive substrate. Thereafter, heat treatment is performed to obtain a crystalline silicon film. Thus crystal masses in the crystalline silicon film can have a uniform size and the problem of fluctuation between TFTs can be solved.
    Type: Grant
    Filed: April 18, 2007
    Date of Patent: July 7, 2009
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Kenji Kasahara, Shinji Maekawa, Hiroshi Shibata, Hidekazu Miyairi
  • Publication number: 20090114944
    Abstract: The present invention provides a method for fine processing of a substrate, a method for fabrication of a substrate, and a light emitting device. In the method for fine processing of a substrate, after removing a single particle layer from the substrate having the single particle layer, a hole having an inner diameter smaller than a diameter of a particle and centering on a position on the substrate where each particle constructing the single particle layer has been placed is formed by etching.
    Type: Application
    Filed: March 30, 2007
    Publication date: May 7, 2009
    Applicant: Sumitomo Chemical Company , Limited
    Inventors: Yoshinobu Ono, Kenji Kasahara, Kazumasa Ueda
  • Publication number: 20090093122
    Abstract: The present invention provides a method for producing a group III-V nitride semiconductor substrate. The method for producing a group III-V nitride semiconductor substrate comprises the steps of (I-1) to (I-6): (I-1) placing inorganic particles on a template, (I-2) dry-etching the template by using the inorganic particles as an etching mask, to form convexes on the template, (I-3) forming a coating film for an epitaxial growth mask on the template, (I-4) removing the inorganic particles to form an exposed surface of the template, (I-5) growing a group III-V nitride semiconductor on the exposed surface of the template, and (I-6) separating the group III-V nitride semiconductor from the template.
    Type: Application
    Filed: March 8, 2007
    Publication date: April 9, 2009
    Applicant: SUMITOMO CHEMICAL COMPANY LIMITED
    Inventors: Kazumasa Ueda, Naohiro Nishikawa, Kenji Kasahara
  • Patent number: 7514852
    Abstract: A piezooscillator having a piezoelectric vibrator and an oscillation circuit in a space surrounded by a substrate and a cover, which has a smaller size and height, and further, which can be assembled easily and suppress power consumption, is provided.
    Type: Grant
    Filed: June 21, 2006
    Date of Patent: April 7, 2009
    Assignee: Nihon Dempa Kogyo Co., Ltd.
    Inventors: Kenji Kasahara, Takeshi Uchida
  • Patent number: 7510920
    Abstract: Position control of a crystal grain in accordance with an arrangement of a TFT is achieved, and at the same time, a processing speed during a crystallization process is increased. More specifically, there is provided a manufacturing method for a semiconductor device, in which crystal having a large grain size can be continuously formed through super lateral growth that is artificially controlled and substrate processing efficiency during a laser crystallization process can be increased. In the manufacturing method for a semiconductor device, instead of performing laser irradiation on an entire semiconductor film within a substrate surface, a marker as a reference for positioning is formed so as to crystallize at least an indispensable portion at minimum. Thus, a time period required for laser crystallization can be reduced to make it possible to increase a processing speed for a substrate.
    Type: Grant
    Filed: November 23, 2005
    Date of Patent: March 31, 2009
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Akihisa Shimomura, Hisashi Ohtani, Masaaki Hiroki, Koichiro Tanaka, Aiko Shiga, Mai Akiba, Kenji Kasahara
  • Patent number: 7510915
    Abstract: To realize TFT enabling high-speed operation by fabricating a crystalline semiconductor film in which positions and sizes of crystal grains are controlled and using the crystalline semiconductor film in a channel forming region of TFT, a film thickness is stepped by providing a stepped difference in at least one layer of a matrix insulating film among a plurality of matrix insulating films having refractive indices different from each other. By irradiating laser beam from a rear face side of a substrate (or both sides of a surface side and the rear face side of the substrate), there is formed an effective intensity distribution of laser beam with regard to a semiconductor film and there is produced a temperature gradient in correspondence with a shape of the stepped difference and a distribution of the film thickness of the matrix insulating film in the semiconductor film.
    Type: Grant
    Filed: June 19, 2006
    Date of Patent: March 31, 2009
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Kenji Kasahara, Ritsuko Kawasaki, Hisashi Ohtani
  • Patent number: 7503975
    Abstract: In a crystalline silicon film fabricated by a related art method, the orientation planes of its crystal randomly exist and the orientation rate relative to a particular crystal orientation is low. A semiconductor material which contains silicon as its main component and 0.1-10 atomic % of germanium is used as a first layer, and an amorphous silicon film is used as a second layer. Laser light is irradiated to crystallize the amorphous semiconductor films, whereby a good semiconductor film is obtained. In addition, TFTs are fabricated by using such a semiconductor film.
    Type: Grant
    Filed: June 25, 2001
    Date of Patent: March 17, 2009
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Toru Mitsuki, Kenji Kasahara, Taketomi Asami, Tamae Takano, Takeshi Shichi, Chiho Kokubo
  • Patent number: 7485553
    Abstract: A first amorphous semiconductor film is formed on an insulating surface. A catalyst element for promoting crystallization is added thereto. Thereafter, by a first heat treatment in an inert gas, a first crystalline semiconductor film is formed. A barrier layer and a second semiconductor layer are formed on the first crystalline semiconductor film. The second semiconductor layer contains a rare gas element at a concentration of 1×1019 to 2×1022/cm3, preferably 1×1020 to 1×1021/cm3 and oxygen at a concentration of 5×1017 to 1×1021/cm3. Subsequently, by a second treatment in an inert gas, the catalyst element remaining in the first crystalline semiconductor film is moved to the second semiconductor film.
    Type: Grant
    Filed: October 16, 2006
    Date of Patent: February 3, 2009
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Hisashi Ohtani, Toru Mitsuki, Hideto Ohnuma, Tamae Takano, Kenji Kasahara, Koji Dairiki
  • Patent number: 7482627
    Abstract: A crystalline semiconductor film in which the locations and sizes of crystal grains have been controlled, is prepared, and a TFT capable of high speed operation is realized by employing the crystalline semiconductor film as the channel forming region of the TFT. An organic resin film (2 in FIG. 1) having a predetermined shape is provided on a substrate (1), whereupon an inorganic insulating film (3) and an amorphous semiconductor film are formed. Subsequently, the amorphous semiconductor film is crystallized by laser annealing. The material and thickness of the organic resin film (2) in the predetermined shape or those of the inorganic insulating film (3) are properly regulated, whereby the cooling rate of the semiconductor film is lowered to form a first region (4a) in which crystal grain diameters are large.
    Type: Grant
    Filed: January 8, 2003
    Date of Patent: January 27, 2009
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Misako Nakazawa, Kenji Kasahara, Hisashi Ohtani
  • Patent number: 7476937
    Abstract: A crystalline semiconductor film in which the position and size of a crystal grain is controlled is fabricated, and the crystalline semiconductor film is used for a channel formation region of a TFT, so that a high performance TFT is realized. An island-like semiconductor layer is made to have a temperature distribution, and a region where temperature change is gentle is provided to control the nucleus generation speed and nucleus generation density, so that the crystal grain is enlarged. In a region where an island-like semiconductor layer 1003 overlaps with a base film 1002, a thick portion is formed in the base film 1002. The volume of this portion increases and heat capacity becomes large, so that a cycle of temperature change by irradiation of a pulse laser beam to the island-like semiconductor layer becomes gentle (as compared with other thin portion).
    Type: Grant
    Filed: July 24, 2003
    Date of Patent: January 13, 2009
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Ritsuko Kawasaki, Kenji Kasahara, Hisashi Ohtani
  • Publication number: 20090008745
    Abstract: A process for producing a nitride compound semiconductor represented by a general formula, InxGayAlzN (where x+y+Z=1, 0?x?1, 0?y?1, and 0?z?1), characterized in that a non-doped nitride compound semiconductor (A) represented by a general formula, InaGabAlcN (where a+b+c=1, 0?a?1, 0?b?1, and 0?c?1) of a thickness of 500 to 5000 ? is formed between a p-type contact layer and an n-type contact layer at a temperature within a range between 550 and 850° C.
    Type: Application
    Filed: July 28, 2005
    Publication date: January 8, 2009
    Applicant: Sumitomo Chemical Company, Limited
    Inventors: Kenji Kasahara, Makoto Sasaki, Masaya Shimizu
  • Patent number: 7473622
    Abstract: To provide a laser apparatus and a laser annealing method with which a crystalline semiconductor film with a larger crystal grain size is obtained and which are low in their running cost. A solid state laser easy to maintenance and high in durability is used as a laser, and laser light emitted therefrom is linearized to increase the throughput and to reduce the production cost as a whole. Further, both the front side and the back side of an amorphous semiconductor film is irradiated with such laser light to obtain the crystalline semiconductor film with a larger crystal grain size.
    Type: Grant
    Filed: February 16, 2007
    Date of Patent: January 6, 2009
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Hisashi Ohtani, Koichiro Tanaka, Kenji Kasahara, Ritsuko Kawasaki
  • Patent number: 7456371
    Abstract: The present invention provides a laser apparatus including a transmission-variable mirror and a method for forming a semiconductor device using the apparatus. For crystallizing an amorphous semiconductor film by irradiation of laser beams, a top surface and a back surface of the amorphous semiconductor film are irradiated with the laser beams. In this case, the transmission-variable mirror is used for dividing a laser light emitted from a laser source.
    Type: Grant
    Filed: May 3, 2004
    Date of Patent: November 25, 2008
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Kenji Kasahara, Ritsuko Kawasaki, Hisashi Ohtani, Koichiro Tanaka
  • Publication number: 20080149952
    Abstract: The present invention provides a semiconductor light emitting device and a method for manufacturing the same. The semiconductor device comprises (i) a semiconductor layer with convex portions in a shape selected from a cone and a truncated cone and (ii) electrodes, wherein in the case of the convex portions with the shape of the truncated cone, the convex portions has a height of from 0.05 to 5.0 ?m and a bottom base diameter of from 0.05 to 2.0 ?m; in case of the convex portions with the shape of the cone, the convex portions has a height of from 0.05 to 5.0 ?m and a base diameter of from 0.05 to 2.0 ?m. A method for manufacturing a semiconductor light emitting device comprising the steps of (a) growing a semiconductor layer on a substrate, (b) forming on the semiconductor layer a region having particles with an average particle diameter of 0.
    Type: Application
    Filed: February 16, 2006
    Publication date: June 26, 2008
    Applicant: Sumitomo Chemical Comapan, Limited
    Inventors: Kenji Kasahara, Kazumasa Ueda
  • Patent number: 7368335
    Abstract: The orientation ratio of a crystalline semiconductor film obtained by crystallizing an amorphous semiconductor film through heat treatment and irradiation of intense light such as laser light, ultraviolet rays, or infrared rays is enhanced, and a semiconductor device whose active region is formed from the crystalline semiconductor film and a method of manufacturing the semiconductor device are provided. In a semiconductor film containing silicon and germanium as its ingredient and having a crystal structure, the {101} plane reaches 30% or more of all the lattice planes detected by Electron backscatter diffraction.
    Type: Grant
    Filed: April 25, 2006
    Date of Patent: May 6, 2008
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Taketomi Asami, Mitsuhiro Ichijo, Satoshi Toriumi, Takashi Ohtsuki, Toru Mitsuki, Kenji Kasahara, Tamae Takano, Chiho Kokubo, Shunpei Yamazaki, Takeshi Shichi
  • Patent number: 7369005
    Abstract: Oscillation in which unwanted vibration (B mode) is surely suppressed while stable oscillation by principal vibration (C mode) is obtained is obtained. In a Colpitts oscillator including a piezoelectric vibrator, a transistor, and a first and second divided capacitive components, by inserting a feedback circuit formed by connecting a third capacitive component and a first inductor in series between a connection midpoint between the first capacitive component and the second capacitive component and an emitter of the transistor, inserting a second inductor in parallel with the second capacitive component, and setting the parallel resonance frequency of the second capacitive component and the second inductor in the vicinity of the oscillation frequency of the oscillator, the frequency band in which the negative resistance of the circuit side seen from the piezoelectric vibrator appears is set to a narrow band containing only a desired frequency to suppress unwanted vibration of the oscillator.
    Type: Grant
    Filed: June 5, 2006
    Date of Patent: May 6, 2008
    Assignee: Nihon Dempa Kogyo Co., Ltd.
    Inventor: Kenji Kasahara
  • Publication number: 20080055011
    Abstract: Conventional oven controlled crystal oscillators have a problem that heat generated by a heat generator consisting of resistors and a transistor is not transmitted uniformly over a substrate and hence a temperature difference is produced between a temperature sensor and a crystal resonator, so that reliable temperature control cannot be performed, thereby degrading the frequency-temperature characteristics. The present invention is to provide an oven controlled crystal oscillator capable of uniformly transmitting heat from the heat generator to improve the frequency-temperature characteristics. The oven controlled crystal oscillator includes a high thermal conductivity plate having high thermal conductivity and provided on one side of a substrate, where the crystal resonator is provided, in such a manner to contact the resistors, the transistor, the crystal resonator, and the temperature sensor.
    Type: Application
    Filed: August 28, 2007
    Publication date: March 6, 2008
    Inventor: Kenji Kasahara
  • Patent number: 7338913
    Abstract: A laser annealing method for obtaining a crystalline semiconductor film having a large grain size is provided. Laser light is irradiated to the top surface and the bottom surface of an amorphous semiconductor film when crystallizing the amorphous semiconductor film by laser light irradiation. Furthermore, a relationship of 0<(I0?/I0)<1, or 1<(I0?/I0) is achieved for the ratio (I0/I0?) between the effective energy strength of the laser light when irradiated to the top surface (I0) and the effective energy strength of the laser light when irradiated to the bottom surface (I0?).
    Type: Grant
    Filed: April 4, 2003
    Date of Patent: March 4, 2008
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Kenji Kasahara, Ritsuko Kawasaki, Hisashi Ohtani, Shunpei Yamazaki