Patents by Inventor Hirohisa Iizuka
Hirohisa Iizuka 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: 7795667Abstract: A semiconductor device comprises a non-volatile memory including a memory cell array, element isolating regions, a second trench and a word line. The memory cell array is constituted by memory cells which have floating electrodes and are arranged in the shape of a matrix on a semiconductor substrate. Each of the element isolating regions has a first trench formed in the semiconductor substrate and between memory cells adjacent to each other along a gate width direction, and an isolating filler filled in the first trench. The second trench is formed in the isolating filler and between the floating electrodes of the memory cells adjacent to each other along the gate width direction, and is narrow at the bottom thereof. The word line is connected to the memory cells, buried in the second trenches and extending along the gate width direction.Type: GrantFiled: July 3, 2003Date of Patent: September 14, 2010Assignee: Kabushiki Kaisha ToshibaInventors: Tadashi Iguchi, Katsuhiro Ishida, Hiroaki Tsunoda, Hirohisa Iizuka, Hiroaki Hazama, Seiichi Mori
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Patent number: 7782671Abstract: A semiconductor device includes a plurality of a word lines. The word lines have a set of odd word lines and a set of even word lines. The odd and the even word lines are located from a first end region to a second end region through the cell region located between the first and the second end regions. The odd word lines are divided in the first end region and the even word lines are divided in the second end region to form dummy word line portions.Type: GrantFiled: August 7, 2008Date of Patent: August 24, 2010Assignee: Kabushiki Kaisha ToshibaInventor: Hirohisa Iizuka
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Publication number: 20090040824Abstract: A semiconductor device includes a plurality of a word lines. The word lines have a set of odd word lines and a set of even word lines. The odd and the even word lines are located from a first end region to a second end region through the cell region located between the first and the second end regions. The odd word lines are divided in the first end region and the even word lines are divided in the second end region to form dummy word line portions.Type: ApplicationFiled: August 7, 2008Publication date: February 12, 2009Applicant: Kabushiki Kaisha ToshibaInventor: Hirohisa IIZUKA
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Patent number: 7364951Abstract: A method for manufacturing a nonvolatile semiconductor memory device having a step of forming a first gate electrode on a peripheral circuit portion and a second gate electrode on a memory cell portion, a step of introducing impurity into the peripheral circuit portion and memory cell portion, a step of forming a first insulating film above at least the memory cell portion, and a step of annealing the semiconductor substrate into which the impurity has been introduced. The first gate electrode has a first gate length. The second gate electrode has a second gate length shorter than the first gate length.Type: GrantFiled: December 14, 2005Date of Patent: April 29, 2008Assignee: Kabushiki Kaisha ToshibaInventors: Akira Goda, Riichiro Shirota, Kazuhiro Shimizu, Hiroaki Hazama, Hirohisa Iizuka, Seiichi Aritome, Wakako Moriyama
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Patent number: 7297599Abstract: A method of fabricating a semiconductor device includes forming on a semiconductor substrate a gate electrode with a gate insulating film being interposed between the substrate and the electrode, forming an insulating film for element isolation protruding from a surface of the semiconductor substrate, forming an oxide film on the surface of the semiconductor substrate with the gate electrode and the element isolation insulating film having been formed, removing the oxide film in a region in which a self-aligned contact hole is to be formed while using a resist pattern for removing the oxide film formed in a region in which the self-aligned contact hole is formed, and etching a part of the element isolation insulating film protruding from the surface of the semiconductor substrate so that said part is substantially on a level with the surface of the semiconductor substrate, while using the resist pattern for removing the oxide film formed in the region in which the self-aligned contact hole is formed.Type: GrantFiled: September 7, 2005Date of Patent: November 20, 2007Assignee: Kabushiki Kaisha ToshibaInventors: Norio Ohtani, Hirohisa Iizuka, Hiroaki Hazama, Kazuhito Narita, Eiji Kamiya
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Publication number: 20070190727Abstract: A method of manufacturing a nonvolatile semiconductor memory device including at least one MOS transistor in a peripheral circuit and also including forming a first well for a memory cell and a second well for the MOS transistor in a semiconductor substrate.Type: ApplicationFiled: April 9, 2007Publication date: August 16, 2007Inventors: Hiroaki Hazama, Seiichi Mori, Hirohisa Iizuka, Norio Ootani, Kazuhito Narita
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Patent number: 7238975Abstract: A nonvolatile semiconductor memory device including at least one MOS transistor in a peripheral circuit comprises a semiconductor substrate, isolation insulating films for defining a plurality of element formation regions, each of the isolation insulating films being buried in an isolation trench provided in the semiconductor substrate, a floating gate provided in each of the element formation regions via a first gate insulating film, a control gate provided on the floating gate via a second gate insulating film, and source and drain regions provided in the semiconductor substrate in self-alignment with the control gate, wherein the floating gate is self-aligned at an isolation end in a direction of a channel width, and comprises a plurality of polysilicon films.Type: GrantFiled: June 4, 2004Date of Patent: July 3, 2007Assignee: Kabushiki Kaisha ToshibaInventors: Hiroaki Hazama, Seiichi Mori, Hirohisa Iizuka, Norio Ootani, Kazuhito Narita
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Patent number: 7227781Abstract: A non-volatile semiconductor memory device includes a plurality of bit lines, a bit line contact corresponding to the bit lines, a first NAND string and a second NAND string, a first string selective transistor and a second string selective transistor, and a third string selective transistor and a fourth string selective transistor. The first and third string selective transistors are connected to each other, whereas the second and fourth string selective transistors are connected to each other. Each of the first and fourth string selective transistors has a first gate length and each of the second and third string selective transistors has a second gate length differing from the first gate length.Type: GrantFiled: July 27, 2005Date of Patent: June 5, 2007Assignee: Kabushiki Kaisha ToshibaInventor: Hirohisa Iizuka
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Patent number: 7195968Abstract: A method of fabricating a semiconductor device includes forming a resist pattern so that an opening between select gates of a select gate transistor is formed in a memory cell region, implanting threshold-adjusting ions under the select gate with the resist pattern serving as a mask and removing an oxide film, forming a nitride film and an interlayer insulation film after the resist pattern has been removed, forming a resist pattern used to form a contact hole between the select gates and a contact hole for a transistor to be formed in the peripheral circuit region, the transistor having a higher breakdown voltage than a memory cell transistor and etching the interlayer insulation film, the nitride film and the gate insulation film individually with the resist pattern serving as a mask.Type: GrantFiled: May 11, 2005Date of Patent: March 27, 2007Assignee: Kabushiki Kaisha ToshibaInventors: Eiji Kamiya, Hirohisa Iizuka, Hiroaki Hazama, Kazuhito Narita, Norio Ohtani
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Patent number: 7196370Abstract: A nonvolatile semiconductor memory device includes a memory cell array region including a plurality of NAND cells, each NAND cell having a plurality of memory cell transistors, and which are arranged in series, and a plurality of select transistors. A trench-type isolation region is formed between columns in the array of the NAND columns. The trench-type isolation region is formed in self-alignment with end portions of the channel region and a floating gate of the memory cell transistor, formed in self-alignment with the end portion of a channel region of the select transistor, and has a recess formed in at least the upper surface between the floating gates of the memory cell transistors.Type: GrantFiled: August 26, 2004Date of Patent: March 27, 2007Assignee: Kabushiki Kaisha ToshibaInventors: Naoki Kai, Hiroaki Hazama, Hirohisa Iizuka
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Patent number: 7095085Abstract: A nonvolatile semiconductor memory device includes erasable and programmable memory cell transistors, a selection transistor, a peripheral transistor, first post-oxidation films each provided on a gate electrode of all of the plurality of erasable and programmable memory cell transistors, a second post-oxidation film provided on a gate electrode of the selection transistor, a third post-oxidation film provided on a gate electrode of the peripheral transistor, and an insulating film covering the memory cell transistors, the selection transistor, and the peripheral transistor. The insulating film is harder for an oxidizing agent to pass through than a silicon oxide film. The insulating film has an oxidized region. The insulating film includes a silicon nitride film. The oxidized region is provided in a surface of the silicon nitride film.Type: GrantFiled: March 12, 2004Date of Patent: August 22, 2006Assignee: Kabushiki Kaisha ToshibaInventors: Akira Goda, Riichiro Shirota, Kazuhiro Shimizu, Hiroaki Hazama, Hirohisa Iizuka, Seiichi Aritome, Wakako Moriyama
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Publication number: 20060157801Abstract: A method for manufacturing a nonvolatile semiconductor memory device having a step of forming a first gate electrode on a peripheral circuit portion and a second gate electrode on a memory cell portion, a step of introducing impurity into the peripheral circuit portion and memory cell portion, a step of forming a first insulating film above at least the memory cell portion, and a step of annealing the semiconductor substrate into which the impurity has been introduced. The first gate electrode has a first gate length. The second gate electrode has a second gate length shorter than the first gate length.Type: ApplicationFiled: December 14, 2005Publication date: July 20, 2006Inventors: Akira Goda, Riichiro Shirota, Kazuhiro Shimizu, Hiroaki Hazama, Hirohisa Iizuka, Seiichi Aritome, Wakako Moriyama
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Publication number: 20060051908Abstract: A method of fabricating a semiconductor device includes forming on a semiconductor substrate a gate electrode with a gate insulating film being interposed between the substrate and the electrode, forming an insulating film for element isolation protruding from a surface of the semiconductor substrate, forming an oxide film on the surface of the semiconductor substrate with the gate electrode and the element isolation insulating film having been formed, removing the oxide film in a region in which a self-aligned contact hole is to be formed while using a resist pattern for removing the oxide film formed in a region in which the self-aligned contact hole is formed, and etching a part of the element isolation insulating film protruding from the surface of the semiconductor substrate so that said part is substantially on a level with the surface of the semiconductor substrate, while using the resist pattern for removing the oxide film formed in the region in which the self-aligned contact hole is formed.Type: ApplicationFiled: September 7, 2005Publication date: March 9, 2006Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Norio Ohtani, Hirohisa Iizuka, Hiroaki Hazama, Kazuhito Narita, Eiji Kamiya
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Publication number: 20060023505Abstract: A non-volatile semiconductor memory device includes a bit line, a plurality of rows of NAND strings provided so as to correspond to the bit line, a plurality of series connected selective gate transistors arranged between the rows of NAND strings in a direction of column, the selective gate transistors including one selective gate transistor having a gate length differing from gate lengths of the other selective gate transistors, the selective gate transistors arranged in the direction of column including one selective gate transistor having a gate length differing from gate lengths of the other selective gate transistors.Type: ApplicationFiled: July 27, 2005Publication date: February 2, 2006Applicant: KABUSHIKI KAISHA TOSHIBAInventor: Hirohisa Iizuka
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Publication number: 20050253202Abstract: A semiconductor device includes a semiconductor substrate, a plurality of memory cell transistors and select gate transistors both formed in a memory cell region of the semiconductor substrate, and a transistor formed in a peripheral circuit region of the substrate and having a high breakdown voltage. Each select gate transistor of the memory cell region has a gate electrode under which an ion implanted layer is formed for adjustment of a threshold. The transistor having the high breakdown voltage includes a contact region around which a gate insulation film remains.Type: ApplicationFiled: May 11, 2005Publication date: November 17, 2005Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Eiji Kamiya, Hirohisa Iizuka, Hiroaki Hazama, Kazuhito Narita, Norio Ohtani
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Publication number: 20050073008Abstract: A semiconductor device exhibits a stable driving force and high performance reliability. The semiconductor device has at least one transistor having a gate insulating film formed on a element region in a semiconductor substrate, a gate electrode formed on the gate insulating film, and a diffused layer in element regions on both sides of the gate electrode. The device also has a barrier insulating film formed so as to cover the transistor and the diffused layer. The height from a surface of the semiconductor substrate to the barrier insulating film is greater than the height from the surface, of the interface between the gate insulating film and the gate electrode.Type: ApplicationFiled: November 22, 2004Publication date: April 7, 2005Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Akira Goda, Kazuhiro Shimizu, Riichiro Shirota, Norihisa Arai, Naoki Koido, Seiichi Aritome, Tohru Maruyama, Hiroaki Hazama, Hirohisa Iizuka
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Publication number: 20050047261Abstract: A nonvolatile semiconductor memory device includes a memory cell array region including a plurality of NAND cells, each NAND cell having a plurality of memory cell transistors, and which are arranged in series, and a plurality of select transistors. A trench-type isolation region is formed between columns in the array of the NAND columns. The trench-type isolation region is formed in self-alignment with end portions of the channel region and a floating gate of the memory cell transistor, formed in self-alignment with the end portion of a channel region of the select transistor, and has a recess formed in at least the upper surface between the floating gates of the memory cell transistors.Type: ApplicationFiled: August 26, 2004Publication date: March 3, 2005Inventors: Naoki Kai, Hiroaki Hazama, Hirohisa Iizuka
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Publication number: 20050012142Abstract: A nonvolatile semiconductor memory device including at least one MOS transistor in a peripheral circuit comprises a semiconductor substrate, isolation insulating films for defining a plurality of element formation regions, each of the isolation insulating films being buried in an isolation trench provided in the semiconductor substrate, a floating gate provided in each of the element formation regions via a first gate insulating film, a control gate provided on the floating gate via a second gate insulating film, and source and drain regions provided in the semiconductor substrate in self-alignment with the control gate, wherein the floating gate is self-aligned at an isolation end in a direction of a channel width, and comprises a plurality of polysilicon films.Type: ApplicationFiled: June 4, 2004Publication date: January 20, 2005Inventors: Hiroaki Hazama, Seiichi Mori, Hirohisa Iizuka, Norio Ootani, Kazuhito Narita
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Patent number: 6828624Abstract: A nonvolatile semiconductor memory device includes comprises: an element isolation region being in contact with a first element region, an insulating film covering a memory cell, a peripheral transistor and the element isolation region, an inter-level insulating film provided on the surface of the insulating film, and a contact hole provided in the inter-level insulating film and the insulating film. The inter-level insulating film contains an insulator different from the insulating film. The contact hole reaches at least one of source and drain diffusion layers of the memory cell and overlaps the element isolation region. The insulating film contains an insulator different from the element isolation region and the insulating film is harder for an oxidizing agent to pass therethrough than a silicon oxide film. A surface of the insulating film is oxidized.Type: GrantFiled: April 25, 2000Date of Patent: December 7, 2004Assignee: Kabushiki Kaisha ToshibaInventors: Akira Goda, Riichiro Shirota, Kazuhiro Shimizu, Hiroaki Hazama, Hirohisa Iizuka, Seiichi Aritome, Wakako Moriyama
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Patent number: 6828648Abstract: In a method of manufacturing a semiconductor device of STI structure, a semiconductor structure in which an insulating material layer is formed on a conductive layer which becomes a gate electrode, is prepared. Etching is conducted to the semiconductor structure to form a trench extending from the insulating material layer into the semiconductor substrate in accordance with a pattern of a resist film (not shown) covering an element region. Then, the insulating material layer is backed off by wet etching or the like and the gate electrode is processed while using the insulating material layer as a mask. As a result, it is possible to make the gate electrode smaller in size than the element region and to form a trench upper portion to be wider than the trench lower portion in the depth direction of the trench, thereby providing a good shape of the insulator embedded in the trench by depositing the insulator.Type: GrantFiled: September 4, 2003Date of Patent: December 7, 2004Assignee: Kabushiki Kaisha ToshibaInventors: Naoki Koido, Riichiro Shirota, Hirohisa Iizuka