Patents by Inventor Takafumi Shimotori
Takafumi Shimotori 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: 9099180Abstract: According to one embodiment, a semiconductor memory device includes a plurality of cell array blocks and a control circuit. The control circuit sets a selected bit line to have 0 volt, applies a first electric potential which is higher than 0 volt to a selected word line, applies a second electric potential which is higher than 0 volt and lower than the first electric potential to non-selected word lines other than the selected word line, applies a third electric potential which is 0 volt or more and lower than the second electric potential to a non-selected bit line adjacent to the selected bit line in an adjacent cell array block, applies the second electric potential to non-selected bit lines other than the non-selected bit line to which the third electric potential is applied, and changes a resistance status of the resistance variable film of the selected memory cell.Type: GrantFiled: August 30, 2012Date of Patent: August 4, 2015Assignee: Kabushiki Kaisha ToshibaInventors: Yoichi Minemura, Takayuki Tsukamoto, Takafumi Shimotori, Hiroshi Kanno, Tomonori Kurosawa, Mizuki Kaneko
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Patent number: 9076525Abstract: A semiconductor storage device includes a memory cell array, and a control circuit. The memory cell array has memory cells including variable resistive elements disposed at intersections of a plurality of first lines and a plurality of second lines. The control circuit performs a set pulse applying operation, and a cure pulse applying operation. The set pulse applying operation applies a set pulse to a variable resistive element so as to cause the variable resistive element to transition from a high resistance state to a low resistance state. The cure pulse applying operation applies a cure pulse to the variable resistive element. The cure pulse has a polarity that is opposite of a polarity of the set pulse, and is larger than the set pulse.Type: GrantFiled: August 29, 2012Date of Patent: July 7, 2015Assignee: KABUSHIKI KAISHA TOSHIBAInventors: Mizuki Kaneko, Tomonori Kurosawa, Yoichi Minemura, Hiroshi Kanno, Takafumi Shimotori, Takayuki Tsukamoto
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Patent number: 8971090Abstract: A semiconductor memory device according to an embodiment comprises: a memory cell array including memory cells, each of the memory cells disposed at each of intersections of first lines and second lines and including a variable resistor; and a control circuit configured to apply a first voltage to a selected first line and to apply a second voltage having a voltage value which is smaller than that of the first voltage to a selected second line, such that a selected memory cell is applied with a first potential difference required in an operation of the selected memory cell. The control circuit is configured such that when the first potential difference is applied a plurality of times to a plurality of the selected memory cells to execute the operation, the number of selected memory cells simultaneously applied with the first potential difference can be changed.Type: GrantFiled: February 22, 2013Date of Patent: March 3, 2015Assignee: Kabushiki Kaisha ToshibaInventors: Takayuki Tsukamoto, Jun Nishimura, Masahiro Une, Takafumi Shimotori, Yoichi Minemura, Hiroshi Kanno
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Patent number: 8861265Abstract: In a memory cell array, memory cells each including a variable resistance element are arranged at crossing portions between a plurality of first wiring and a plurality of second wirings. A control circuit executes a set operation, a reset operation, and a training operation. In the set operation, a set pulse is applied to the variable resistance element to change the variable resistance element from a high resistance state to a low resistance state. In the reset operation, a reset pulse having an opposite polarity to the polarity of the set pulse is applied to the variable resistance element to change the variable resistance element from the low resistance state to the high resistance state. In the training operation, the set pulse and the reset pulse are continuously applied to the variable resistance element.Type: GrantFiled: August 29, 2012Date of Patent: October 14, 2014Assignee: Kabushiki Kaisha ToshibaInventors: Tomonori Kurosawa, Mizuki Kaneko, Takafumi Shimotori, Takayuki Tsukamoto, Yoichi Minemura, Hiroshi Kanno
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Patent number: 8837199Abstract: According to one embodiment, a semiconductor memory device includes a semiconductor substrate, a plurality of memory cells, a plurality of wires, and a control circuit. The control circuit allows a first current to change a state to flow on a selected cell by applying a first potential difference between a pair of wires that sandwich the selected cell selected from the plurality of memory cells with respect to the semiconductor substrate vertically, and allows a second current lower than the first current to flow on an non-selected cell in the same direction as the direction of the first current by applying a second potential difference between a pair of wires that sandwich the non-selected cell connected to a wire shared with the selected cell on a different layer from the selected cell.Type: GrantFiled: August 30, 2012Date of Patent: September 16, 2014Assignee: Kabushiki Kaisha ToshibaInventors: Hiroshi Kanno, Yoichi Minemura, Mizuki Kaneko, Tomonori Kurosawa, Takafumi Shimotori, Takayuki Tsukamoto
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Patent number: 8675388Abstract: A nonvolatile semiconductor memory device includes: a memory cell array including plural first lines, plural second lines, and plural memory cells each including a variable resistance element; a first decoder connected to at least one ends of the plurality of first lines and configured to select at least one of the first lines; at least one pair of second decoders connected to both ends of the plurality of second lines and configured such that one of the pair of second decoders is selected for selecting the second lines according to a distance between the one of the first lines selected by the first decoder and the both ends of the second lines; and a voltage application circuit configured to apply a certain voltage between the first line and the second line selected by the first decoder and the second decoder.Type: GrantFiled: September 15, 2011Date of Patent: March 18, 2014Assignee: Kabushiki Kaisha ToshibaInventors: Yoichi Minemura, Takayuki Tsukamoto, Takafumi Shimotori, Hiroshi Kanno, Natsuki Kikuchi, Mitsuru Sato
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Publication number: 20140063908Abstract: A semiconductor memory device according to an embodiment comprises: a memory cell array including memory cells, each of the memory cells disposed at each of intersections of first lines and second lines and including a variable resistor; and a control circuit configured to apply a first voltage to a selected first line and to apply a second voltage having a voltage value which is smaller than that of the first voltage to a selected second line, such that a selected memory cell is applied with a first potential difference required in an operation of the selected memory cell. The control circuit is configured such that when the first potential difference is applied a plurality of times to a plurality of the selected memory cells to execute the operation, the number of selected memory cells simultaneously applied with the first potential difference can be changed.Type: ApplicationFiled: February 22, 2013Publication date: March 6, 2014Applicant: Kabushiki Kaisha ToshibaInventors: Takayuki Tsukamoto, Jun Nishimura, Masahiro Une, Takafumi Shimotori, Yoichi Minemura, Hiroshi Kanno
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Patent number: 8605485Abstract: According to one embodiment, a control unit multiple-selects a first line for every N lines from a plurality of first lines. N is an integer greater than or equal to one. The control unit sets the multiple-selected first lines to a selection potential, and fixes potentials of non-selected first lines at least adjacent to the multiple-selected first lines at a first timing. The control unit causes the multiple-selected first lines to be in a floating state at a second timing after the first timing. The control unit selects one second line from the plurality of second lines and sets the one second line to a forming potential at a third timing after the second timing.Type: GrantFiled: January 13, 2012Date of Patent: December 10, 2013Assignee: Kabushiki Kaisha ToshibaInventors: Hiroshi Kanno, Takafumi Shimotori, Yoichi Minemura, Takahiko Sasaki, Takayuki Tsukamoto
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Publication number: 20130229852Abstract: According to one embodiment, a semiconductor memory device includes a semiconductor substrate, a plurality of memory cells, a plurality of wires, and a control circuit. The control circuit allows a first current to change a state to flow on a selected cell by applying a first potential difference between a pair of wires that sandwich the selected cell selected from the plurality of memory cells with respect to the semiconductor substrate vertically, and allows a second current lower than the first current to flow on an non-selected cell in the same direction as the direction of the first current by applying a second potential difference between a pair of wires that sandwich the non-selected cell connected to a wire shared with the selected cell on a different layer from the selected cell.Type: ApplicationFiled: August 30, 2012Publication date: September 5, 2013Applicant: Kabushiki Kaisha ToshibaInventors: Hiroshi KANNO, Yoichi Minemura, Mizuki Kaneko, Tomonori Kurosawa, Takafumi Shimotori, Takayuki Tsukamoto
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Publication number: 20130229850Abstract: A semiconductor storage device includes a memory cell array, and a control circuit. The memory cell array has memory cells including variable resistive elements disposed at intersections of a plurality of first lines and a plurality of second lines. The control circuit performs a set pulse applying operation, and a cure pulse applying operation. The set pulse applying operation applies a set pulse to a variable resistive element so as to cause the variable resistive element to transition from a high resistance state to a low resistance state. The cure pulse applying operation applies a cure pulse to the variable resistive element. The cure pulse has a polarity that is opposite of a polarity of the set pulse, and is larger than the set pulse.Type: ApplicationFiled: August 29, 2012Publication date: September 5, 2013Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Mizuki Kaneko, Tomonori Kurosawa, Yoichi Minemura, Hiroshi Kanno, Takafumi Shimotori, Takayuki Tsukamoto
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Publication number: 20130229851Abstract: In a memory cell array, memory cells each including a variable resistance element are arranged at crossing portions between a plurality of first wiring and a plurality of second wirings. A control circuit executes a set operation, a reset operation, and a training operation. In the set operation, a set pulse is applied to the variable resistance element to change the variable resistance element from a high resistance state to a low resistance state. In the reset operation, a reset pulse having an opposite polarity to the polarity of the set pulse is applied to the variable resistance element to change the variable resistance element from the low resistance state to the high resistance state. In the training operation, the set pulse and the reset pulse are continuously applied to the variable resistance element.Type: ApplicationFiled: August 29, 2012Publication date: September 5, 2013Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Tomonori KUROSAWA, Mizuki Kaneko, Takafumi Shimotori, Takayuki Tsukamoto, Yoichi Minemura, Hiroshi Kanno
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Publication number: 20130229853Abstract: According to one embodiment, a semiconductor memory device includes a plurality of cell array blocks and a control circuit. The control circuit sets a selected bit line to have 0 volt, applies a first electric potential which is higher than 0 volt to a selected word line, applies a second electric potential which is higher than 0 volt and lower than the first electric potential to non-selected word lines other than the selected word line, applies a third electric potential which is 0 volt or more and lower than the second electric potential to a non-selected bit line adjacent to the selected bit line in an adjacent cell array block, applies the second electric potential to non-selected bit lines other than the non-selected bit line to which the third electric potential is applied, and changes a resistance status of the resistance variable film of the selected memory cell.Type: ApplicationFiled: August 30, 2012Publication date: September 5, 2013Applicant: Kabushiki Kaisha ToshibaInventors: Yoichi MINEMURA, Takayuki Tsukamoto, Takafumi Shimotori, Hiroshi Kanno, Tomonori Kurosawa, Mizuki Kaneko
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Patent number: 8488367Abstract: According to one embodiment, a method for controlling a semiconductor device comprises determining a select bit number for a group of memory cells each includes a variable-resistance element, setting a first voltage corresponding to the select bit number, applying the set first voltage to the memory cell group, and performing verify read on the memory cell group to which the first voltage has been applied and determining whether or not the memory cell group passes the verify read. If the memory cell group is determined not to pass the verify read, the number of bits corresponding to passed memory cells is subtracted from the select bit number, and the first voltage corresponding to the decreased select bit number is set again.Type: GrantFiled: March 21, 2011Date of Patent: July 16, 2013Assignee: Kabushiki Kaisha ToshibaInventors: Takafumi Shimotori, Yoichi Minemura, Hiroshi Kanno, Takayuki Tsukamoto, Jun Nishimura, Masahiro Une
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Patent number: 8363448Abstract: According to one embodiment, a semiconductor memory device includes a memory cell, a power supply circuit, an interconnection and a discharging circuit. The memory cell includes a variable resistance element whose resistance varies by application of a voltage. The power supply circuit outputs the voltage to be applied to the memory cell. The interconnection is formed between the power supply circuit and the memory cell and supplies the voltage output from the power supply circuit to the memory cell. The discharging circuit is connected to the interconnection. The discharging circuit discharges electric charge accumulated in the interconnection after a first operation of applying the voltage to the memory cell is ended and before a second operation of applying the voltage to the memory cell next is started.Type: GrantFiled: September 1, 2010Date of Patent: January 29, 2013Assignee: Kabushiki Kaisha ToshibaInventor: Takafumi Shimotori
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Patent number: 8279655Abstract: According to an embodiment, there are provided a non-volatile semiconductor memory device includes: a memory cell array; a control circuit performing a series of operations to each memory cell and determining, as a defective memory cell, a memory cell whose data retention property does not satisfy a criteria, the series of operations including an operation applying a first bias to the memory cell in a forward direction, and including an operation thereafter applying a second bias to the memory cell in a reverse direction; a storage unit storing an address of the defective memory cell; and an address control unit performing a control to avoid storing data in the defective memory cell whose address is stored in the storage unit.Type: GrantFiled: September 17, 2010Date of Patent: October 2, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Hiroshi Kanno, Takayuki Tsukamoto, Takahiko Sasaki, Takafumi Shimotori
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Patent number: 8274822Abstract: According to one embodiment, a nonvolatile memory device includes a memory unit and a control unit. The memory unit includes first and second interconnects, and a memory cell. The second interconnect is non-parallel to the first interconnect. The memory cell includes a resistance change layer provided at an intersection between the first and second interconnects. The control unit is connected to the first and second interconnects to supply voltage and current to the resistance change layer. The control unit increases an upper limit of a current supplied to the first interconnect based on a change of a potential of the first interconnect when applying a set operation voltage to the first interconnect in a set operation of changing the resistance change layer from a first state with a first resistance value to a second state with a second resistance value being less than the first resistance value.Type: GrantFiled: February 1, 2011Date of Patent: September 25, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Takayuki Tsukamoto, Yoichi Minemura, Natsuki Kikuchi, Mitsuru Sato, Hiroshi Kanno, Takafumi Shimotori
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Publication number: 20120224411Abstract: According to one embodiment, a control unit multiple-selects a first line for every N lines from a plurality of first lines. N is an integer greater than or equal to one. The control unit sets the multiple-selected first lines to a selection potential, and fixes potentials of non-selected first lines at least adjacent to the multiple-selected first lines at a first timing. The control unit causes the multiple-selected first lines to be in a floating state at a second timing after the first timing. The control unit selects one second line from the plurality of second lines and sets the one second line to a forming potential at a third timing after the second timing.Type: ApplicationFiled: January 13, 2012Publication date: September 6, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Hiroshi KANNO, Takafumi Shimotori, Yoichi Minemura, Takahiko Sasaki, Takayuki Tsukamoto
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Publication number: 20120069627Abstract: A nonvolatile semiconductor memory device includes: a memory cell array including plural first lines, plural second lines, and plural memory cells each including a variable resistance element; a first decoder connected to at least one ends of the plurality of first lines and configured to select at least one of the first lines; at least one pair of second decoders connected to both ends of the plurality of second lines and configured such that one of the pair of second decoders is selected for selecting the second lines according to a distance between the one of the first lines selected by the first decoder and the both ends of the second lines; and a voltage application circuit configured to apply a certain voltage between the first line and the second line selected by the first decoder and the second decoder.Type: ApplicationFiled: September 15, 2011Publication date: March 22, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Yoichi MINEMURA, Takayuki TSUKAMOTO, Takafumi SHIMOTORI, Hiroshi KANNO, Natsuki KIKUCHI, Mitsuru SATO
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Publication number: 20110286260Abstract: According to one embodiment, a nonvolatile memory device includes a memory unit and a control unit. The memory unit includes first and second interconnects, and a memory cell. The second interconnect is non-parallel to the first interconnect. The memory cell includes a resistance change layer provided at an intersection between the first and second interconnects. The control unit is connected to the first and second interconnects to supply voltage and current to the resistance change layer. The control unit increases an upper limit of a current supplied to the first interconnect based on a change of a potential of the first interconnect when applying a set operation voltage to the first interconnect in a set operation of changing the resistance change layer from a first state with a first resistance value to a second state with a second resistance value being less than the first resistance value.Type: ApplicationFiled: February 1, 2011Publication date: November 24, 2011Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Takayuki TSUKAMOTO, Yoichi Minemura, Natsuki Kikuchi, Mitsuru Sato, Hiroshi Kanno, Takafumi Shimotori
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Publication number: 20110235400Abstract: According to one embodiment, a method for controlling a semiconductor device comprises determining a select bit number for a group of memory cells each includes a variable-resistance element, setting a first voltage corresponding to the select bit number, applying the set first voltage to the memory cell group, and performing verify read on the memory cell group to which the first voltage has been applied and determining whether or not the memory cell group passes the verify read. If the memory cell group is determined not to pass the verify read, the number of bits corresponding to passed memory cells is subtracted from the select bit number, and the first voltage corresponding to the decreased select bit number is set again.Type: ApplicationFiled: March 21, 2011Publication date: September 29, 2011Inventors: Takafumi Shimotori, Yoichi Minemura, Hiroshi Kanno, Takayuki Tsukamoto, Jun Nishimura, Masahiro Une