Patents by Inventor Takeshi Takagi

Takeshi Takagi 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: 8345465
    Abstract: A method of driving a variable resistance element includes: a writing step performed by applying a writing voltage pulse having a first polarity to a variable resistance layer to change a resistance state of the layer from high to low; and an erasing step performed by applying an erasing voltage pulse having a second polarity to the layer to change the state from low to high. Here, |Vw1|>|Vw2| where Vw1 represents a voltage value of the writing voltage pulse for first to N-th writing steps (N?1) and Vw2 represents a voltage value of the writing voltage pulse for (N+1)-th and subsequent writing steps, and |Ve1|>|Ve2| where Ve1 represents a voltage value of the erasing voltage pulse for first to M-th erasing steps (M?1) and Ve2 represents a voltage value of the erasing voltage pulse for (M+1)-th and subsequent erasing steps. The (N+1)-th writing step follows the M-th erasing step.
    Type: Grant
    Filed: September 30, 2009
    Date of Patent: January 1, 2013
    Assignee: Panasonic Corporation
    Inventors: Shunsaku Muraoka, Takeshi Takagi, Satoru Mitani, Koji Katayama
  • Publication number: 20120327702
    Abstract: A nonvolatile memory element includes: a first electrode layer; a second electrode layer; and a variable resistance layer which is placed between the electrode layers, and whose resistance state reversibly changes between a high resistance state and a low resistance state based on a polarity of a voltage applied between the electrode layers. The variable resistance layer is formed by stacking a first oxide layer including an oxide of a first transition metal and a second oxide layer including an oxide of a second transition metal which is different from the first transition metal. At least one of the following conditions is satisfied: (1) a dielectric constant of the second oxide layer is larger than a dielectric constant of the first oxide layer; and (2) a band gap of the second oxide layer is smaller than a band gap of the first oxide layer.
    Type: Application
    Filed: August 30, 2012
    Publication date: December 27, 2012
    Inventors: Takeshi Takagi, Zhiqiang Wei, Takeki Ninomiya, Shunsaku Muraoka, Yoshihiko Kanzawa
  • Patent number: 8339835
    Abstract: A nonvolatile memory element includes a current controlling element having a non-linear current-voltage characteristic, a resistance variable element which changes reversibly between a low-resistance state and a high-resistance state in which a resistance value of the resistance variable element is higher than a resistance value of the resistance variable element in the low-resistance state, in response to voltage pulses applied, and a fuse. The current controlling element, the resistance variable element and the fuse are connected in series, and the fuse is configured to be blown when the current controlling element is substantially short-circuited.
    Type: Grant
    Filed: April 22, 2010
    Date of Patent: December 25, 2012
    Assignee: Panasonic Corporation
    Inventors: Zhiqiang Wei, Takeshi Takagi, Mitsuteru Iijima
  • Patent number: 8338816
    Abstract: A nonvolatile memory element of the present invention comprises a first electrode (503); a second electrode (505); and a resistance variable layer (504) which is disposed between the first electrode (503) and the second electrode (505), a resistance value of the resistance variable layer being changeable in response to electric signals which are applied between the first electrode (503) and the second electrode (505), wherein the first electrode and the second electrode comprise materials which are made of different elements.
    Type: Grant
    Filed: March 31, 2008
    Date of Patent: December 25, 2012
    Assignee: Panasonic Corporation
    Inventors: Yoshihiko Kanzawa, Shunsaku Muraoka, Satoru Mitani, Zhiqiang Wei, Takeshi Takagi
  • Publication number: 20120320661
    Abstract: A method includes applying a first polarity writing voltage pulse to a metal oxide layer to change its resistance state from high to low into a write state, applying a second polarity erasing voltage pulse different from the first polarity to the metal oxide layer to change its resistance state from low to high into an erase state, and applying an initial voltage pulse having the second polarity to the metal oxide layer before first application of the writing voltage pulse, to change an initial resistance value of the metal oxide layer. R0>RH>RL and |V0|>|Ve|?|Vw| are satisfied where R0, RL, and RH are the resistance values of the initial, write, and erase states, respectively, of the metal oxide layer, and V0, Vw, and Ve are voltage values of the initial, writing, and erasing voltage pulses, respectively.
    Type: Application
    Filed: August 28, 2012
    Publication date: December 20, 2012
    Inventors: Shunsaku MURAOKA, Takeshi Takagi, Satoru Mitani, Koji Katayama
  • Publication number: 20120319072
    Abstract: A manufacturing method for manufacturing, with a simple process, a non-volatile memory apparatus having a stable memory performance includes: (a) forming a stacking-structure body above a substrate by alternately stacking conductive layers comprising a transition metal and interlayer insulating films comprising an insulating material; (b) forming a contact hole penetrating through the stacking-structure body to expose part of each of the conductive layers; (c) forming variable resistance layers by oxidizing the part of each of the conductive layers, the part being exposed in the contact hole, and each of the variable resistance layers having a resistance value that reversibly changes according to an application of an electric signal; and (d) forming a pillar electrode in the contact hole by embedding a conductive material in the contact hole, the pillar electrode being connected to each of the variable resistance layers.
    Type: Application
    Filed: February 23, 2011
    Publication date: December 20, 2012
    Inventors: Zhiqiang Wei, Takeshi Takagi, Mitsuteru Iijima
  • Patent number: 8320159
    Abstract: Each of memory cells (MC) includes one transistor and one resistance variable element. The transistor includes a first main terminal, a second main terminal and a control terminal. The resistance variable element includes a first electrode, a second electrode and a resistance variable layer provided between the first electrode and the second electrode. A first main terminal of one of two adjacent memory cells is connected to a second main terminal of the other memory cell, to form a series path (SP) sequentially connecting main terminals of the plurality of memory cells in series.
    Type: Grant
    Filed: March 15, 2010
    Date of Patent: November 27, 2012
    Assignee: Panasonic Corporation
    Inventors: Zhiqiang Wei, Ryotaro Azuma, Takeshi Takagi, Mitsuteru Iijima, Yoshihiko Kanzawa
  • Patent number: 8309946
    Abstract: A resistance variable element of the present invention comprises a first electrode (103), a second electrode (107), and a resistance variable layer which is interposed between the first electrode (103) and the second electrode (107) to contact the first electrode (103) and the second electrode (107), the resistance variable layer being configured to change in response to electric signals with different polarities which are applied between the first electrode (103) and the second electrode (107), the resistance variable layer comprising an oxygen-deficient transition metal oxide layer, and the second electrode (107) comprising platinum having minute hillocks (108).
    Type: Grant
    Filed: July 22, 2009
    Date of Patent: November 13, 2012
    Assignee: Panasonic Corporation
    Inventors: Satoru Mitani, Shunsaku Muraoka, Yoshihiko Kanzawa, Koji Katayama, Ryoko Miyanaga, Satoru Fujii, Takeshi Takagi
  • Publication number: 20120280199
    Abstract: Provided is a nonvolatile memory element achieving a stable resistance change and miniaturization, and a method of manufacturing the same. The nonvolatile memory element includes: a first electrode formed above a substrate; an interlayer insulating layer formed above the substrate including the first electrode and having a memory cell hole reaching the first electrode; a barrier layer formed in the memory cell hole and composed of a semiconductor layer or an insulating layer connected to the first electrode; a second electrode formed in the memory cell hole and connected to the barrier layer; a variable resistance layer formed on the second electrode and having a stacked structure whose resistance value changes based on electric signals; and a third electrode connected to the variable resistance layer and formed on the interlayer insulating layer to cover the memory cell hole.
    Type: Application
    Filed: November 18, 2010
    Publication date: November 8, 2012
    Inventor: Takeshi Takagi
  • Patent number: 8295123
    Abstract: In a current rectifying element (10), a barrier height ?A of a center region (14) of a barrier layer (11) in a thickness direction thereof sandwiched between a first electrode layer (12) and a second electrode layer (13) is formed to be larger than a barrier height ?B of a region in the vicinity of an interface (17) between the barrier layer (11) and the first electrode layer (12) and an interface (17) between the barrier layer (11) and the second electrode layer (13). The barrier layer (11) has, for example, a triple-layer structure of barrier layers (11a), (11b) and (11c). The barrier layers (11a), (11b) and (11c) are, for example, formed by SiN layers of SiNx2, SiNx1, and SiNx1 (X1<X2). Therefore, the barrier layer (11) has a barrier height in which the shape changes in a stepwise manner and the height of the center region 14 is large.
    Type: Grant
    Filed: July 11, 2008
    Date of Patent: October 23, 2012
    Assignee: Panasonic Corporation
    Inventors: Takeshi Takagi, Takumi Mikawa, Koji Arita, Mitsuteru Iijima, Takashi Okada
  • Patent number: 8279658
    Abstract: Applying a writing voltage pulse having a first polarity to a metal oxide layer (3) to change a resistance state of the metal oxide layer (3) from high to low so as to render the resistance state a write state, applying an erasing voltage pulse having a second polarity different from the first polarity to the metal oxide layer (3) to change the resistance state of the metal oxide layer (3) from low to high so as to render the resistance state an erase state, and applying an initial voltage pulse having the second polarity to the metal oxide layer (3) before the applying of a writing voltage pulse is performed for a first time, to change a resistance value of an initial state of the metal oxide layer (3) are included, and R0>RH>RL and |V0|>|Ve|?|Vw| are satisfied where R0, RL, and RH are the resistance values of the initial, write, and erase states, respectively, of the metal oxide layer (3), and V0, Vw, and Ve are voltage values of the initial, writing, and erasing voltage pulses, respectively.
    Type: Grant
    Filed: March 25, 2010
    Date of Patent: October 2, 2012
    Assignee: Panasonic Corporation
    Inventors: Shunsaku Muraoka, Takeshi Takagi, Satoru Mitani, Koji Katayama
  • Patent number: 8279657
    Abstract: Provided is a nonvolatile memory element which is capable of performing a stable resistance change operation at a low breakdown voltage. A nonvolatile memory element (100) includes: a first electrode layer (103); a second electrode layer (105); and a variable resistance layer (104) which is placed between the electrodes (103 and 105), and whose resistance state reversibly changes between a high resistance state and a low resistance state based on a polarity of a voltage applied between the electrodes (103 and 105). The variable resistance layer (104) is formed by stacking a first oxide layer (104a) including an oxide of a first transition metal and a second oxide layer (104b) including an oxide of a second transition metal which is different from the first transition metal.
    Type: Grant
    Filed: December 4, 2009
    Date of Patent: October 2, 2012
    Assignee: Panasonic Corporation
    Inventors: Takeshi Takagi, Zhiqiang Wei, Takeki Ninomiya, Shunsaku Muraoka, Yoshihiko Kanzawa
  • Patent number: 8264865
    Abstract: A nonvolatile memory element of the present invention comprises a first electrode (103), a second electrode (108); a resistance variable layer (107) which is interposed between the first electrode (103) and the second electrode (107) and is configured to switch a resistance value reversibly in response to an electric signal applied between the electrodes (103) and (108), and the resistance variable layer (107) has at least a multi-layer structure in which a first hafnium-containing layer having a composition expressed as HfOx (0.9?x?1.6), and a second hafnium-containing layer having a composition expressed as HfOy (1.8<y<2.0) are stacked together.
    Type: Grant
    Filed: July 1, 2009
    Date of Patent: September 11, 2012
    Assignee: Panasonic Corporation
    Inventors: Satoru Mitani, Yoshihiko Kanzawa, Koji Katayama, Takeshi Takagi
  • Patent number: 8258493
    Abstract: A nonvolatile semiconductor memory apparatus (10) of the present invention comprises a substrate (10), lower-layer electrode wires (15) provided on the substrate (11), an interlayer insulating layer (16) which is disposed on the substrate (11) including the lower-layer electrode wires (15) and is provided with contact holes at locations respectively opposite to the lower-layer electrode wires (15), resistance variable layers (18) which are respectively connected to the lower-layer electrode wires (15); and non-ohmic devices (20) which are respectively provided on the resistance variable layers (18) such that the non-ohmic devices are respectively connected to the resistance variable layers (18). The non-ohmic devices (20) each has a laminated-layer structure including plural semiconductor layers, a laminated-layer structure including a metal electrode layer and an insulator layer, or a laminated-layer structure including a metal electrode layer and a semiconductor layer.
    Type: Grant
    Filed: November 13, 2007
    Date of Patent: September 4, 2012
    Assignee: Panasonic Corporation
    Inventors: Takumi Mikawa, Takeshi Takagi
  • Patent number: 8242479
    Abstract: A nonvolatile memory device includes via holes (12) formed at cross sections where first wires (11) cross second wires (14), respectively, and current control elements (13) each including a current control layer (13b), a first electrode layer (13a) and a second electrode layer (13c) such that the current control layer (13b) is sandwiched between the first electrode layer (13a) and the second electrode layer (13c), in which resistance variable elements (15) are provided inside the via holes (12), respectively, the first electrode layer (13a) is disposed so as to cover the via hole (12), the current control layer (13b) is disposed so as to cover the first electrode layer (13a), the second electrode layer (13c) is disposed on the current control layer (13b), a wire layer (14a) of the second wire is disposed on the second electrode layer (13c), and the second wires (14) each includes the current control layer (13b), the second electrode layer (13c) and the wire layer (14a) of the second wire.
    Type: Grant
    Filed: November 14, 2008
    Date of Patent: August 14, 2012
    Assignee: Panasonic Corporation
    Inventors: Yoshio Kawashima, Takumi Mikawa, Ryoko Miyanaga, Takeshi Takagi
  • Patent number: 8227786
    Abstract: A nonvolatile memory element comprising: a first electrode 2; a second electrode 6 formed above the first electrode 2; a variable resistance film 4 formed between the first electrode 2 and the second electrode 6, a resistance value of the variable resistance film 4 being increased or decreased by an electric pulse applied between the first and second electrodes 2, 6; and an interlayer dielectric film 3 provided between the first and second electrodes 2, 6, wherein the interlayer dielectric film 3 is provided with an opening extending from a surface thereof to the first electrode 2; the variable resistance film 4 is formed at an inner wall face of the opening; and an interior region of the opening which is defined by the variable resistance film 4 is filled with an embedded insulating film 5.
    Type: Grant
    Filed: December 14, 2010
    Date of Patent: July 24, 2012
    Assignee: Panasonic Corporation
    Inventors: Takumi Mikawa, Takeshi Takagi
  • Publication number: 20120170353
    Abstract: A method for programming a nonvolatile memory device according to the present invention includes a step of detecting an excessively low resistance cell from among a plurality of memory cells (11) (S101); a step of changing the resistance value of a load resistor (121) to a second resistance value smaller than a first resistance value (S103); and a step of causing, by applying a voltage pulse to a series circuit including the excessively low resistance cell and the load resistor (121) having the second resistance value, a variable resistance element (105) included in the excessively low resistance cell to shift to a second high resistance state having a resistance value greater than that of the first low resistance state (S104).
    Type: Application
    Filed: June 28, 2011
    Publication date: July 5, 2012
    Inventors: Mitsuteru Iijima, Takeshi Takagi, Koji Katayama
  • Publication number: 20120158314
    Abstract: A measuring apparatus for measuring a predetermined physical property of a liquid measuring sample comprises a preparing unit in which a plurality of materials including at least a liquid material are mixed; a supply route which supplies the liquid material to the preparing unit; a withdrawing unit which withdraws the measuring sample from the preparing unit into the supply route, the measuring sample being prepared to contain the liquid material supplied to the preparing unit via the supply route; and a measuring unit which measures the predetermined physical property of the measuring sample withdrawn into the supply route by the withdrawing unit.
    Type: Application
    Filed: June 23, 2011
    Publication date: June 21, 2012
    Applicant: ARKRAY, INC.
    Inventors: Takeshi TAKAGI, Koji OKUMURA, Tatsuo KAMATA
  • Patent number: 8179713
    Abstract: A nonvolatile memory element comprises a first electrode (103), a second electrode (105), and a resistance variable layer (104) which is provided between the first electrode and the second electrode, and is configured to reversibly switch an interelectrode resistance value which is a resistance value between the first electrode and the second electrode, in response to an interelectrode voltage which is an electric potential of the second electrode on the basis of the first electrode, the resistance variable layer includes an oxygen-deficient transition metal oxide, the first electrode side and the second electrode side have an asymmetric structure, a portion of the resistance variable layer which is located at the first electrode side and a portion of the resistance variable layer which is located at the second electrode side are each configured to be selectively placed into one of a low-resistance state and a high-resistance state, so as to attain a stable state in three or more different interelectrode resi
    Type: Grant
    Filed: May 18, 2009
    Date of Patent: May 15, 2012
    Assignee: Panasonic Corporation
    Inventors: Yoshihiko Kanzawa, Satoru Mitani, Zhiqiang Wei, Takeshi Takagi
  • Patent number: 8179714
    Abstract: Provided is a nonvolatile storage device (200) capable of stably operating without increasing a size of a selection transistor included in each of memory cells. The nonvolatile storage device (200) includes: a semiconductor substrate (301) which has a P-type well (301a) of a first conductivity type; a memory cell array (202) which includes memory cells (M11) or the like each of which includes a variable resistance element (R11) and a transistor (N11) that are formed above the semiconductor substrate (301) and connected in series; and a substrate bias circuit (220) which applies, to the P-type well (301a), a bias voltage in a forward direction with respect to a source and a drain of the transistor (N11), when a voltage pulse for writing is applied to the variable resistance element (R11) included in the selected memory cell (M11) or the like.
    Type: Grant
    Filed: October 16, 2009
    Date of Patent: May 15, 2012
    Assignee: Panasonic Corporation
    Inventors: Takeshi Takagi, Shunsaku Muraoka, Mitsuteru Iijima, Ken Kawai, Kazuhiko Shimakawa