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).
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Patent number: 7696514Abstract: 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: GrantFiled: June 14, 2005Date of Patent: April 13, 2010Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Chiho Kokubo, Hirokazu Yamagata, Shunpei Yamazaki
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Publication number: 20100029068Abstract: 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: ApplicationFiled: July 31, 2009Publication date: February 4, 2010Applicant: 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
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Patent number: 7652286Abstract: An insulating film having depressions and projections are formed on a substrate. A semiconductor film is formed on the insulating film. Thus, for crystallization by using laser light, a part where stress concentrates is selectively formed in the semiconductor film. More specifically, stripe or rectangular depressions and projections are provided in the semiconductor film. Then, continuous-wave laser light is irradiated along the stripe depressions and projections formed in the semiconductor film or in a direction of a major axis or minor axis of the rectangle.Type: GrantFiled: September 29, 2006Date of Patent: January 26, 2010Assignee: 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
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Patent number: 7638377Abstract: In a crystallization process of an amorphous semiconductor film, a first polycrystalline semiconductor film, in which amorphous regions are dotted within the continuous crystal region, is obtained by performing heat treatment after introducing a metallic element which promotes crystallization on the amorphous semiconductor film. At this point, the amorphous regions are kept within a predetermined range. A laser beam having a wave length region, which can give more energy to the amorphous region than to the crystal region, is irradiated to the first polycrystalline semiconductor film, it is possible to crystallize the amorphous region without destroying the crystal region. If a TFT is manufactured based on a second polycrystalline semiconductor film, which is obtained through the above-mentioned crystallization processes, the TFT with high electric characteristics and less fluctuation can be obtained.Type: GrantFiled: February 23, 2007Date of Patent: December 29, 2009Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Koichiro Tanaka, Hideto Ohnuma, Chiho Kokubo
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Patent number: 7635883Abstract: 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: GrantFiled: September 5, 2006Date of Patent: December 22, 2009Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Munehiro Azami, Chiho Kokubo, Aiko Shiga, Atsuo Isobe, Hiroshi Shibata, Shunpei Yamazaki
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Patent number: 7582162Abstract: 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: GrantFiled: November 17, 2006Date of Patent: September 1, 2009Assignee: 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
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Patent number: 7538350Abstract: 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: GrantFiled: January 29, 2007Date of Patent: May 26, 2009Assignee: 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
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Patent number: 7524713Abstract: A manufacturing method of a semiconductor device with improved operating characteristics and reliability is provided. An amorphous semiconductor film is formed over a substrate, doped with a metal element promoting crystallization, and crystallized by first heat treatment to form a crystalline semiconductor film; a first oxide film formed over the crystalline semiconductor film is removed and a second oxide film is formed; the crystalline semiconductor film having the second oxide film formed thereover is irradiated with first laser light; a semiconductor film containing a rare gas element is formed over the second oxide film; the metal element contained in the crystalline semiconductor film is gettered to the semiconductor film containing a rare gas element by second heat treatment; the semiconductor film containing a rare gas element and the second oxide film are removed; and the crystalline semiconductor film is irradiated with second laser light in an atmosphere containing oxygen.Type: GrantFiled: October 27, 2006Date of Patent: April 28, 2009Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Hidekazu Miyairi, Chiho Kokubo, Koki Inoue
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Patent number: 7503975Abstract: 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: GrantFiled: June 25, 2001Date of Patent: March 17, 2009Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Toru Mitsuki, Kenji Kasahara, Taketomi Asami, Tamae Takano, Takeshi Shichi, Chiho Kokubo
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Patent number: 7459379Abstract: When a semiconductor film is irradiated with laser light, the semiconductor film is instantaneously melted and expand locally. In order to reduce internal stress generated by this expansion, strain is locally generated in the semiconductor film. Accordingly, a variation is caused among portions with strain and portions without strain, and a variation is caused also by a difference in extent of strain. According to the present invention, after laser light irradiation, an oxide film (referred to as a chemical oxide) is formed by using a solution containing ozone (typically, ozone water) to form an oxide film of 1 to 10 nm in total, and further, a heat treatment for reducing strain of a semiconductor film (a heat treatment of heating the semiconductor film instantaneously to approximately 400 to 1000° C.) is performed.Type: GrantFiled: March 25, 2005Date of Patent: December 2, 2008Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Chiho Kokubo, Shunpei Yamazaki, Tamae Takano, Hiroaki Irie
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Patent number: 7368335Abstract: 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: GrantFiled: April 25, 2006Date of Patent: May 6, 2008Assignee: 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
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Patent number: 7319055Abstract: 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: GrantFiled: September 16, 2004Date of Patent: January 15, 2008Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Chiho Kokubo, Aiko Shiga, Yoshifumi Tanada, Shunpei Yamazaki
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Patent number: 7307282Abstract: 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: GrantFiled: December 5, 2003Date of Patent: December 11, 2007Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Toru Mitsuki, Kenji Kasahara, Taketomi Asami, Tamae Takano, Takeshi Shichi, Chiho Kokubo, Yasuyuki Arai
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Publication number: 20070184593Abstract: In a crystallization process of an amorphous semiconductor film, a first polycrystalline semiconductor film, in which amorphous regions are dotted within the continuous crystal region, is obtained by performing heat treatment after introducing a metallic element which promotes crystallization on the amorphous semiconductor film. At this point, the amorphous regions are kept within a predetermined range. A laser beam having a wave length region, which can give more energy to the amorphous region than to the crystal region, is irradiated to the first polycrystalline semiconductor film, it is possible to crystallize the amorphous region without destroying the crystal region. If a TFT is manufactured based on a second polycrystalline semiconductor film, which is obtained through the above-mentioned crystallization processes, the TFT with high electric characteristics and less fluctuation can be obtained.Type: ApplicationFiled: February 23, 2007Publication date: August 9, 2007Inventors: Koichiro Tanaka, Hideto Ohnuma, Chiho Kokubo
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Publication number: 20070120127Abstract: 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: ApplicationFiled: January 29, 2007Publication date: May 31, 2007Applicant: 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
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Publication number: 20070105288Abstract: A manufacturing method of a semiconductor device with improved operating characteristics and reliability is provided. An amorphous semiconductor film is formed over a substrate, doped with a metal element promoting crystallization, and crystallized by first heat treatment to form a crystalline semiconductor film; a first oxide film formed over the crystalline semiconductor film is removed and a second oxide film is formed; the crystalline semiconductor film having the second oxide film formed thereover is irradiated with first laser light; a semiconductor film containing a rare gas element is formed over the second oxide film; the metal element contained in the crystalline semiconductor film is gettered to the semiconductor film containing a rare gas element by second heat treatment; the semiconductor film containing a rare gas element and the second oxide film are removed; and the crystalline semiconductor film is irradiated with second laser light in an atmosphere containing oxygen.Type: ApplicationFiled: October 27, 2006Publication date: May 10, 2007Applicant: Semiconductor Energy Laboratory Co., Ltd.Inventors: Hidekazu Miyairi, Chiho Kokubo, Koki Inoue
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Publication number: 20070085080Abstract: To provide a semiconductor device composed of a semiconductor element or a group of semiconductor elements, in which a crystalline semiconductor film having as few grain boundaries as possible in a channel formation region is formed on an insulating surface, which can operate at high speed, which have high current drive performance, and which are less fluctuated between elements.Type: ApplicationFiled: December 11, 2006Publication date: April 19, 2007Applicant: Semiconductor Energy Laboratory Co., Ltd.Inventors: Atsuo Isobe, Shunpei Yamazaki, Chiho Kokubo, Koichiro Tanaka, Akihisa Shimomura, Tatsuya Arao, Hidekazu Miyairi
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Publication number: 20070070346Abstract: 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: ApplicationFiled: November 17, 2006Publication date: March 29, 2007Applicant: 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
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Patent number: 7183145Abstract: In a crystallization process of an amorphous semiconductor film, a first polycrystalline semiconductor film, in which amorphous regions are dotted within the continuous crystal region, is obtained by performing heat treatment after introducing a metallic element which promotes crystallization on the amorphous semiconductor film. At this point, the amorphous regions are kept within a predetermined range. A laser beam having a wave length region, which can give more energy to the amorphous region than to the crystal region, is irradiated to the first polycrystalline semiconductor film, it is possible to crystallize the amorphous region without destroying the crystal region. If a TFT is manufactured based on a second polycrystalline semiconductor film, which is obtained through the above-mentioned crystallization processes, the TFT with high electric characteristics and less fluctuation can be obtained.Type: GrantFiled: June 8, 2005Date of Patent: February 27, 2007Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Koichiro Tanaka, Hideto Ohnuma, Chiho Kokubo
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Publication number: 20070034877Abstract: An insulating film having depressions and projections are formed on a substrate. A semiconductor film is formed on the insulating film. Thus, for crystallization by using laser light, a part where stress concentrates is selectively formed in the semiconductor film. More specifically, stripe or rectangular depressions and projections are provided in the semiconductor film. Then, continuous-wave laser light is irradiated along the stripe depressions and projections formed in the semiconductor film or in a direction of a major axis or minor axis of the rectangle.Type: ApplicationFiled: September 29, 2006Publication date: February 15, 2007Applicant: 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