Patents by Inventor Chiho Kokubo

Chiho Kokubo 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: 6933527
    Abstract: It is a problem to provide a semiconductor device production system using a laser crystallization method capable of preventing grain boundaries from forming in a TFT channel region and further preventing conspicuous lowering in TFT mobility due to grain boundaries, on-current decrease or off-current increase. An insulation film is formed on a substrate, and a semiconductor film is formed on the insulation film. Due to this, preferentially formed is a region in the semiconductor film to be concentratedly applied by stress during crystallization with laser light. Specifically, a stripe-formed or rectangular concavo-convex is formed on the semiconductor film. Continuous-oscillation laser light is irradiated along the striped concavo-convex or along a direction of a longer or shorter axis of rectangle.
    Type: Grant
    Filed: December 27, 2002
    Date of Patent: August 23, 2005
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Atsuo Isobe, Koji Dairiki, Hiroshi Shibata, Chiho Kokubo, Tatsuya Arao, Masahiko Hayakawa, Hidekazu Miyairi, Akihisa Shimomura, Koichiro Tanaka, Shunpei Yamazaki, Mai Akiba
  • Publication number: 20050161742
    Abstract: It is a problem to provide a semiconductor device production system using a laser crystallization method capable of preventing grain boundaries from forming in a TFT channel region and further preventing conspicuous lowering in TFT mobility due to grain boundaries, on-current decrease or off-current increase. An insulation film is formed on a substrate, and a semiconductor film is formed on the insulation film. Due to this, preferentially formed is a region in the semiconductor film to be concentratedly applied by stress during crystallization with laser light. Specifically, a stripe-formed or rectangular concavo-convex is formed on the semiconductor film. Continuous-oscillation laser light is irradiated along the striped concavo-convex or along a direction of a longer or shorter axis of rectangle.
    Type: Application
    Filed: March 24, 2005
    Publication date: July 28, 2005
    Applicant: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Atsuo Isobe, Koji Dairiki, Hiroshi Shibata, Chiho Kokubo, Tatsuya Arao, Masahiko Hayakawa, Hidekazu Miyairi, Akihisa Shimomura, Koichiro Tanaka, Shunpei Yamazaki, Mai Akiba
  • Patent number: 6916693
    Abstract: In a crystallization process of an amorphous semiconductor film, a first crystalline semiconductor film having crystalline regions, and dotted with amorphous regions within the crystalline regions, is obtained by performing heat treatment processing after introducing a metallic element which promotes crystallization on the amorphous semiconductor film. The amorphous regions are kept within a predetermined range by regulating the heat treatment conditions at this point. Laser annealing is performed on the first crystalline semiconductor film, to form a second crystalline semiconductor film. Electrical characteristics for a TFT manufactured based on the second crystalline semiconductor film can be obtained having less dispersion.
    Type: Grant
    Filed: March 5, 2001
    Date of Patent: July 12, 2005
    Assignees: Semiconductor Energy Laboratory Co., Ltd., Sharp Kabushiki Kaisha
    Inventors: Hideto Ohnuma, Chiho Kokubo, Koichiro Tanaka, Naoki Makita, Shuhei Tsuchimoto
  • Patent number: 6911358
    Abstract: A method for manufacturing a semiconductor device having steps of forming an amorphous semiconductor on a substrate having an insulating surface; patterning the amorphous semiconductor to form plural first island-like semiconductors; irradiating a linearly condensed laser beam on the plural first island-like semiconductors while relatively scanning the substrate, thus crystallizing the plural first island-like semiconductors; patterning the plural first island-like semiconductors that have been crystallized to form plural second island-like semiconductors; forming plural transistors using the plural second island-like semiconductors; and forming a unit circuit using a predetermined number of the transistors, where the second island-like semiconductors used for the predetermined number of the transistors are formed from the first island-like semiconductors that are different from each other.
    Type: Grant
    Filed: December 27, 2002
    Date of Patent: June 28, 2005
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Munehiro Azami, Chiho Kokubo, Aiko Shiga, Atsuo Isobe, Hiroshi Shibata, Shunpei Yamazaki
  • Patent number: 6909115
    Abstract: There is disclosed a semiconductor device and a method of fabricating the semiconductor device in which a heat treatment time required for crystal growth is shortened and a process is simplified. Two catalytic element introduction regions are arranged at both sides of one active layer and crystallization is made. A boundary portion where crystal growth from one catalytic element introduction region meets crystal growth from the other catalytic element introduction region is formed in a region which becomes a source region or drain region.
    Type: Grant
    Filed: March 14, 2003
    Date of Patent: June 21, 2005
    Assignee: Semiconductor Energy Laboratory Co. Ltd.
    Inventors: Chiho Kokubo, Hirokazu Yamagata, Shunpei Yamazaki
  • Publication number: 20050098784
    Abstract: A semiconductor device production system using a laser crystallization method is provided which can avoid forming grain boundaries in a channel formation region of a TFT, thereby preventing grain boundaries from lowering the mobility of the TFT greatly, from lowering ON current, and from increasing OFF current. Rectangular or stripe pattern depression and projection portions are formed on an insulating film. A semiconductor film is formed on the insulating film. The semiconductor film is irradiated with continuous wave laser light by running the laser light along the stripe pattern depression and projection portions of the insulating film or along the major or minor axis direction of the rectangle. Although continuous wave laser light is most preferred among laser light, it is also possible to use pulse oscillation laser light in irradiating the semiconductor film.
    Type: Application
    Filed: December 17, 2004
    Publication date: May 12, 2005
    Applicant: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Atsuo Isobe, Shunpei Yamazaki, Koji Dairiki, Hiroshi Shibata, Chiho Kokubo, Tatsuya Arao, Masahiko Hayakawa, Hidekazu Miyairi, Akihisa Shimomura, Koichiro Tanaka, Mai Akiba
  • Publication number: 20050040412
    Abstract: To provide a method of efficiently configuring a circuit requiring high inter-device consistency by using thin-film transistors. A semiconductor layer is formed on a substrate and is patterned into desired shapes to form first semiconductor islands. The first semiconductor islands are uniformly crystallized by laser irradiation within the surface areas thereof. Thereafter, the semiconductor layers are patterned into desired shapes to become active layers of the thin-film transistors layer. Active layers of all of thin-film transistors constituting one unitary circuit are formed of one of the first semiconductor islands in this case. Thus, the TFTs mutually realize high consistency.
    Type: Application
    Filed: September 16, 2004
    Publication date: February 24, 2005
    Applicant: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Chiho Kokubo, Aiko Shiga, Yoshifumi Tanada, Shunpei Yamazaki
  • Patent number: 6841797
    Abstract: A semiconductor device production system using a laser crystallization method is provided which can avoid forming grain boundaries in a channel formation region of a TFT, thereby preventing grain boundaries from lowering the mobility of the TFT greatly, from lowering ON current, and from increasing OFF current. Rectangular or stripe pattern depression and projection portions are formed on an insulating film. A semiconductor film is formed on the insulating film. The semiconductor film is irradiated with continuous wave laser light by running the laser light along the stripe pattern depression and projection portions of the insulating film or along the major or minor axis direction of the rectangle. Although continuous wave laser light is most preferred among laser light, it is also possible to use pulse oscillation laser light in irradiating the semiconductor film.
    Type: Grant
    Filed: January 8, 2003
    Date of Patent: January 11, 2005
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Atsuo Isobe, Shunpei Yamazaki, Koji Dairiki, Hiroshi Shibata, Chiho Kokubo, Tatsuya Arao, Masahiko Hayakawa, Hidekazu Miyairi, Akihisa Shimomura, Koichiro Tanaka, Mai Akiba
  • Patent number: 6828587
    Abstract: Crystal orientation planes exist randomly in a crystalline silicon film manufactured by a conventional method, and the orientation ratio is low with respect to a specific crystal orientation. A semiconductor film having a high orientation ratio for the {101} lattice plane is obtained if crystallization of an amorphous semiconductor film, which has silicon as its main constituent and contains from 0.1 to 10 atom % germanium, is performed after introduction of a metal element. A TFT is manufactured utilizing the semiconductor film.
    Type: Grant
    Filed: June 14, 2001
    Date of Patent: December 7, 2004
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Toru Mitsuki, Kenji Kasahara, Taketomi Asami, Tamae Takano, Takeshi Shichi, Chiho Kokubo
  • Publication number: 20040201022
    Abstract: The orientation of a crystalline semiconductor film obtained by crystallizing an amorphous semiconductor film is improved and a TFT formed from this crystalline semiconductor film is provided. In a semiconductor device whose TFT is formed from a semiconductor layer mainly containing silicon, the semiconductor layer has a channel formation region and an impurity region doped with an impurity of one type of conductivity.
    Type: Application
    Filed: April 29, 2004
    Publication date: October 14, 2004
    Applicant: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Toru Mitsuki, Kenji Kasahara, Taketomi Asami, Tamae Takano, Takeshi Shichi, Chiho Kokubo
  • Patent number: 6797550
    Abstract: To provide a method of efficiently configuring a circuit requiring high inter-device consistency by using thin-film transistors. A semiconductor layer is formed on a substrate and is patterned into desired shapes to form first semiconductor islands. The first semiconductor islands are uniformly crystallized by laser irradiation within the surface areas thereof. Thereafter, the semiconductor layers are patterned into desired shapes to become active layers of the thin-film transistors layer. Active layers of all of thin-film transistors constituting one unitary circuit are formed of one of the first semiconductor islands in this case. Thus, the TFTs mutually realize high consistency.
    Type: Grant
    Filed: December 18, 2002
    Date of Patent: September 28, 2004
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Chiho Kokubo, Aiko Shiga, Yoshifumi Tanada, Shunpei Yamazaki
  • Patent number: 6787807
    Abstract: The orientation of a crystalline semiconductor film obtained by crystallizing an amorphous semiconductor film is improved and a TFT formed from this crystalline semiconductor film is provided. In a semiconductor device whose TFT is formed from a semiconductor layer mainly containing silicon, the semiconductor layer has a channel formation region and an impurity region doped with an impurity of one type of conductivity.
    Type: Grant
    Filed: June 18, 2001
    Date of Patent: September 7, 2004
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Toru Mitsuki, Kenji Kasahara, Taketomi Asami, Tamae Takano, Takeshi Shichi, Chiho Kokubo
  • Publication number: 20040169177
    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: Application
    Filed: March 4, 2004
    Publication date: September 2, 2004
    Applicant: Semiconductor Energy Laboratory Co., Ltd. a Japan corporation
    Inventors: Taketomi Asami, Mitsuhiro Ichijo, Satoshi Toriumi, Takashi Ohtsuki, Toru Mitsuki, Kenji Kasahara, Tamae Takano, Chiho Kokubo, Shunpei Yamazaki, Takeshi Shichi
  • Publication number: 20040108576
    Abstract: The TFT has a channel-forming region formed of a crystalline semiconductor film obtained by heat-treating and crystallizing an amorphous semiconductor film containing silicon as a main component and germanium in an amount of not smaller than 0.1 atomic % but not larger than 10 atomic % while adding a metal element thereto, wherein not smaller than 20% of the lattice plane {101} has an angle of not larger than 10 degrees with respect to the surface of the semiconductor film, not larger than 3% of the lattice plane {001} has an angle of not larger than 10 degrees with respect to the surface of the semiconductor film, and not larger than 5% of the lattice plane {111} has an angle of not larger than 10 degrees with respect to the surface of the semiconductor film as detected by the electron backscatter diffraction pattern method.
    Type: Application
    Filed: December 5, 2003
    Publication date: June 10, 2004
    Applicant: Semiconductor Energy Laboratory, Co., Ltd., a Japan corporation
    Inventors: Shunpei Yamazaki, Toru Mitsuki, Kenji Kasahara, Taketomi Asami, Tamae Takano, Takeshi Shichi, Chiho Kokubo, Yasuyuki Arai
  • Publication number: 20040072411
    Abstract: A method for manufacturing a semiconductor device having steps of forming an amorphous semiconductor on a substrate having an insulating surface; patterning the amorphous semiconductor to form plural first island-like semiconductors; irradiating a linearly condensed laser beam on the plural first island-like semiconductors while relatively scanning the substrate, thus crystallizing the plural first island-like semiconductors; patterning the plural first island-like semiconductors that have been crystallized into to form plural second island-like semiconductors; forming plural transistors using the plural second island-like semiconductors; and forming a unit circuit using a predetermined number of the transistors, where the second island-like semiconductors used for the predetermined number of the transistors are formed from the first island-like semiconductors that are different from each other.
    Type: Application
    Filed: December 27, 2002
    Publication date: April 15, 2004
    Inventors: Munehiro Azami, Chiho Kokubo, Aiko Shiga, Atsuo Isobe, Hiroshi Shibata, Shunpei Yamazaki
  • Publication number: 20040058486
    Abstract: To effectively crystallize an amorphous semiconductor film comprising silicon by utilizing nickel element and remove nickel element contributed to the crystallization, a mask 103 is provided on an amorphous silicon film 102, oxide film patterns 107 and 108 including nickel are formed, phosphorus is doped in a region 109, thereafter, heating is performed, nickel element is diffused via paths 110 and 111 and nickel element diffuses in the amorphous silicon film and gettered by phosphorus at the region 109 by which crystallization of diffusion of nickel and gettering of nickel can be carried out simultaneously.
    Type: Application
    Filed: September 8, 2003
    Publication date: March 25, 2004
    Applicant: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Hisashi Ohtani, Tamae Takano, Chiho Kokubo
  • Patent number: 6703265
    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: August 1, 2001
    Date of Patent: March 9, 2004
    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: 6690068
    Abstract: The TFT has a channel-forming region formed of a crystalline semiconductor film obtained by heat-treating and crystallizing an amorphous semiconductor film containing silicon as a main component and germanium in an amount of not smaller than 0.
    Type: Grant
    Filed: June 6, 2001
    Date of Patent: February 10, 2004
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Toru Mitsuki, Kenji Kasahara, Taketomi Asami, Tamae Takano, Takeshi Shichi, Chiho Kokubo, Yasuyuki Arai
  • Patent number: 6680487
    Abstract: There is disclosed a semiconductor device and a method of fabricating the semiconductor device in which a heat time required for crystal growth is shortened and a process is simplified. Two catalytic element introduction regions are arranged at both sides of one active layer and crystallization is made. A boundary portion where crystal growth from one catalytic element introduction region meets crystal growth from the other catalytic element introduction region is formed in a region which becomes a source region or drain region.
    Type: Grant
    Filed: May 8, 2000
    Date of Patent: January 20, 2004
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Chiho Kokubo, Hirokazu Yamagata, Shunpei Yamazaki
  • Publication number: 20030234395
    Abstract: In a conventional method of crystallization using a laser beam, variance (or dispersion) in a TFT characteristic becomes large, which causes various functions of a semiconductor device comprising TFTs as components of its electronic circuit to be restrained.
    Type: Application
    Filed: December 18, 2002
    Publication date: December 25, 2003
    Applicant: SEMICONDUCTOR ENERGY LABORATORY CO., LTD
    Inventors: Chiho Kokubo, Aiko Shiga, Shunpei Yamazaki, Hidekazu Miyairi, Koji Dairiki, Koichiro Tanaka