Patents by Inventor Yoshitaka Sasago

Yoshitaka Sasago 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).

  • Publication number: 20110235408
    Abstract: For decreasing a recording current and suppressing a cross erase simultaneously, a three-dimensional phase-change memory for attaining higher sensitivity and higher reliability by the provision of a chalcogenide type interface layer is provided, in which an electric resistivity, a thermal conductivity, and a melting point of the material of the interface layer are selected appropriately, thereby improving the current concentration to the phase-change material and thermal and material insulation property with Si channel upon writing.
    Type: Application
    Filed: January 8, 2011
    Publication date: September 29, 2011
    Inventors: Hiroyuki MINEMURA, Yumiko Anzai, Takahiro Morikawa, Toshimichi Shintani, Yoshitaka Sasago
  • Publication number: 20110235386
    Abstract: The invention provides a voltage applying structure having a reduced area penalty with respect to a data line. A wiring forming a global data line and a local data line formed in a p-type well region are connected via a select transistor. Two select lines are formed on a gate electrode of the select transistor. One select line is electrically connected to the gate electrode of the select transistor, however, the other select line is not connected to the select transistor. That is, an insulator film is formed between the select line and the gate electrode. As mentioned above, two select lines shorter than a gate length are provided on one select transistor. The select line is structured such as to be connected to the other select transistor.
    Type: Application
    Filed: June 6, 2011
    Publication date: September 29, 2011
    Inventors: Tomoyuki Ishii, Yoshitaka Sasago, Hideaki Kurata, Toshiyuki Mine
  • Patent number: 7996735
    Abstract: To realize a fast and highly reliable phase-change memory system of low power consumption, a semiconductor device includes: a memory device which includes a first memory array having a first area including a plurality of first memory cells and a second area including a plurality of second memory cells; a controller coupled to the memory device to issue a command to the memory device; and a condition table for storing a plurality of trial writing conditions. The controller performs trial writing in the plurality of second memory cells a plurality of times based on the plurality of trial writing conditions stored in the condition table, and determines writing conditions in the plurality of first memory cells based on a result of the trial writing. The memory device performs writing in the plurality of first memory cells based on the writing conditions instructed from the controller.
    Type: Grant
    Filed: May 21, 2009
    Date of Patent: August 9, 2011
    Assignee: Hitachi, Ltd.
    Inventors: Motoyasu Terao, Satoru Hanzawa, Hitoshi Kume, Minoru Ogushi, Yoshitaka Sasago, Masaharu Kinoshita, Norikatsu Takaura
  • Patent number: 7969760
    Abstract: The invention provides a voltage applying structure having a reduced area penalty with respect to a data line. A wiring forming a global data line and a local data line formed in a p-type well region are connected via a select transistor. Two select lines are formed on a gate electrode of the select transistor. One select line is electrically connected to the gate electrode of the select transistor, however, the other select line is not connected to the select transistor. That is, an insulator film is formed between the select line and the gate electrode. As mentioned above, two select lines shorter than a gate length are provided on one select transistor. The select line is structured such as to be connected to the other select transistor.
    Type: Grant
    Filed: April 26, 2007
    Date of Patent: June 28, 2011
    Assignee: Renesas Electronics Corporation
    Inventors: Tomoyuki Ishii, Yoshitaka Sasago, Hideaki Kurata, Toshiyuki Mine
  • Publication number: 20110049454
    Abstract: In a phase-change memory, an interface layer is inserted between a chalcogenide material layer and a plug. The interface layer is arranged so as not to cover the entire interface of a plug-like electrode. When the plug is formed at an upper part than the chalcogenide layer, the degree of integration is increased. The interface layer is formed by carrying out sputtering using an oxide target, or, by forming a metal film by carrying out sputtering using a metal target followed by oxidizing the metal film in an oxidation atmosphere such as oxygen radical, oxygen plasma, etc.
    Type: Application
    Filed: June 23, 2006
    Publication date: March 3, 2011
    Inventors: Motoyasu Terao, Yuichi Matsui, Tsuyoshi Koga, Nozomu Matsuzaki, Norikatsu Takaura, Yoshihisa Fujisaki, Kenzo Kurotsuchi, Takahiro Morikawa, Yoshitaka Sasago, Junko Ushiyama, Akemi Hirotsune
  • Patent number: 7838379
    Abstract: In a phase change memory, electric property of a diode used as a selection device is extremely important. However, since crystal grain boundaries are present in the film of a diode using polysilicon, it involves a problem that the off leak property varies greatly making it difficult to prevent erroneous reading. For overcoming the problem, the present invention provides a method of controlling the temperature profile of an amorphous silicon in the laser annealing for crystallizing and activating the amorphous silicon thereby controlling the crystal grain boundaries. According to the invention, variation in the electric property of the diode can be decreased and the yield of the phase-change memory can be improved.
    Type: Grant
    Filed: January 29, 2009
    Date of Patent: November 23, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Masaharu Kinoshita, Motoyasu Terao, Hideyuki Matsuoka, Yoshitaka Sasago, Yoshinobu Kimura, Akio Shima, Mitsuharu Tai, Norikatsu Takaura
  • Patent number: 7829930
    Abstract: A technique that can realize high integration even for multilayered three-dimensional structures at low costs by improving the performance of the semiconductor device having recording or switching functions by employing a device structure that enables high precision controlling of the movement of ions in the solid electrolyte. The semiconductor element of the device is formed as follows; two or more layers are deposited with different components respectively between a pair of electrodes disposed separately in the vertical (z-axis) direction, then a pulse voltage is applied between those electrodes to form a conductive path. The resistance value of the path changes according to an information signal. Furthermore, a region is formed at a middle part of the conductive path. The region is used to accumulate a component that improves the conductivity of the path, thereby enabling the resistance value (rate) to response currently to the information signal.
    Type: Grant
    Filed: July 9, 2008
    Date of Patent: November 9, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Motoyasu Terao, Hideyuki Matsuoka, Naohiko Irie, Yoshitaka Sasago, Riichiro Takemura, Norikatsu Takaura
  • Patent number: 7767997
    Abstract: A nonvolatile, sophisticated semiconductor device with a small surface area and a simple structure capable of switching connections between three or more electrodes. In a semiconductor device at least one of the electrodes contains atoms such as copper or silver in the solid electrolyte capable of easily moving within the solid electrolyte, and those electrodes face each other and applying a voltage switches the voltage on and off by generating or annihilating the conductive path between the electrodes. Moreover applying a voltage to a separate third electrode can annihilate the conductive path formed between two electrodes without applying a voltage to the two electrode joined by the conductive path.
    Type: Grant
    Filed: July 9, 2008
    Date of Patent: August 3, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Yoshitaka Sasago, Motoyasu Terao, Norikatsu Takaura, Yoshihisa Fujisaki, Tomoyuki Kodama, Nobuyuki Arasawa
  • Publication number: 20100182828
    Abstract: There is provided a semiconductor storage device which is capable of further reducing a size of a memory cell, and increasing a storage capacity. Plural memory cells each including a transistor formed on a semiconductor substrate, and a variable resistive device having a resistance value changed by voltage supply and connected between source and drain terminals of the transistor are arranged longitudinally and in an array to configure a three-dimensional memory cell array. A memory cell structure has a double channel structure in which an inside of a switching transistor is filled with a variable resistance element, particularly, a phase change material. The switching transistor is turned off by application of a voltage to increase a channel resistance so that a current flows in the internal phase change material to operate the memory.
    Type: Application
    Filed: January 17, 2010
    Publication date: July 22, 2010
    Inventors: Akio SHIMA, Yoshitaka Sasago, Masaharu Kinoshita, Toshiyuki Mine, Norikatsu Takaura, Takahiro Morikawa, Kenzo Kurotsuchi, Satoru Hanzawa
  • Publication number: 20100058127
    Abstract: To realize a fast and highly reliable phase-change memory system of low power consumption, a semiconductor device includes: a memory device which includes a first memory array having a first area including a plurality of first memory cells and a second area including a plurality of second memory cells; a controller coupled to the memory device to issue a command to the memory device; and a condition table for storing a plurality of trial writing conditions. The controller performs trial writing in the plurality of second memory cells a plurality of times based on the plurality of trial writing conditions stored in the condition table, and determines writing conditions in the plurality of first memory cells based on a result of the trial writing. The memory device performs writing in the plurality of first memory cells based on the writing conditions instructed from the controller.
    Type: Application
    Filed: May 21, 2009
    Publication date: March 4, 2010
    Inventors: Motoyasu TERAO, Satoru HANZAWA, Hitoshi KUME, Minoru OGUSHI, Yoshitaka SASAGO, Masaharu KINOSHITA, Norikatsu TAKAURA
  • Publication number: 20100032637
    Abstract: Provided is a nonvolatile memory device including a phase-change memory configured with cross-point memory cells in which memory elements formed of a phase-change material and selection elements formed with a diode are combined. A memory cell is configured with a memory element formed of a phase-change material and a selection element formed with a diode having a stacked structure of a first polycrystalline silicon film, a second polycrystalline silicon film, and a third polycrystalline silicon film. The memory cells are arranged at intersection points of a plurality of first metal wirings extending along a first direction with a plurality of third metal wirings extending along a second direction orthogonal to the first direction. An interlayer film is formed between adjacent selection elements and between adjacent memory elements, and voids are formed in the interlayer film provided between the adjacent memory elements.
    Type: Application
    Filed: May 2, 2009
    Publication date: February 11, 2010
    Inventors: Masaharu Kinoshita, Yoshitaka Sasago, Norikatsu Takaura
  • Publication number: 20100010365
    Abstract: To increase intensity of the brain wave signal for detection. Provided is an apparatus for analyzing a brain wave which is installed on a vehicle comprising: a detection unit for detecting the brain wave signal, and separating and analyzing the detected brain wave signal; a discrimination unit for generating a control signal according to an intensity of the brain wave signal analyzed by the detection unit; a processing control unit for controlling subsequent processing according to a type of each of the plurality of control signals produced by the discrimination unit; at least one brain wave signal induction unit for generating a graphic inducing a predetermined type of the brain wave; and a display for displaying the generated graphic according to the received signal from the brain wave signal induction unit.
    Type: Application
    Filed: May 5, 2009
    Publication date: January 14, 2010
    Inventors: Motoyasu Terao, Shigeru Oho, Yoshitaka Sasago
  • Publication number: 20090267047
    Abstract: The present invention can promote the large capacity, high performance and high reliability of a semiconductor memory device by realizing high-performance of both the semiconductor device and a memory device when the semiconductor memory device is manufactured by stacking a memory device such as ReRAM or the phase change memory and the semiconductor device. After a polysilicon forming a selection device is deposited in an amorphous state at a low temperature, the crystallization of the polysilicon and the activation of impurities are briefly performed with heat treatment by laser annealing. When laser annealing is performed, the recording material located below the silicon subjected to the crystallization is completely covered with a metal film or with the metal film and an insulating film, thereby making it possible to suppress a temperature increase at the time of performing the annealing and to reduce the thermal load of the recording material.
    Type: Application
    Filed: April 27, 2009
    Publication date: October 29, 2009
    Inventors: Yoshitaka SASAGO, Riichiro TAKEMURA, Masaharu KINOSHITA, Toshiyuki MINE, Akio SHIMA, Hideyuki MATSUOKA, Mutsuko HATANO, Norikatsu TAKAURA
  • Publication number: 20090251964
    Abstract: A nonvolatile semiconductor memory device according to the present invention is a NAND-type flash memory which is electrically capable of programming/erasing. The nonvolatile semiconductor memory device has at least 3 or more memory cell columns in which a plurality of memory cells are connected in series, and these memory cell columns are adjacent to each other via a shallow trench isolation. And, a programming operation is performed individually to each of these memory cell columns. In this manner, a programming-prevent voltage is surely provided at on at least one side of both surfaces of the semiconductor substrate which are adjacent via a shallow trench isolation to the surface of the semiconductor substrate under the programming-prevented memory cell. Therefore, a miss-programming to an unselected memory cell can be largely reduced.
    Type: Application
    Filed: March 30, 2009
    Publication date: October 8, 2009
    Inventors: Yoshitaka Sasago, Hitoshi Kume
  • Publication number: 20090242868
    Abstract: A solid electrolyte memory involves a problem that stable rewriting is difficult since the amount of ions in the solid electrolyte and the shape of the electrode are changed by repeating rewriting. In a semiconductor device in which information is stored or the circuit connection is changed by the change of resistance of the solid electrolyte layer, the solid electrolyte layer includes a composition, for example, of Cu—Ta—S and an ion supply layer in adjacent or close therewith as Cu—Ta—O, in which ions supplied from the ion supply layer form a conduction path in the solid electrolyte layer thereby making it possible to store information by the level of the resistance and applying the electric pulse to change the resistance, in which the ion supply layer includes crystals having, for example, a compositional ratio of: Cu—Ta—O=1:2:6 and rewriting operation can be performed stably.
    Type: Application
    Filed: February 12, 2009
    Publication date: October 1, 2009
    Inventors: Kenzo KUROTSUCHI, Motoyasu TERAO, Norikatsu TAKAURA, Yoshihisa FUJISAKI, Kazuo ONO, Yoshitaka SASAGO
  • Patent number: 7585726
    Abstract: The present invention enables to avoid a reduction in coupling ratio in a nonvolatile semiconductor memory device. The reduction is coupling ratio is caused due to difficulties in batch forming of a control gate material, an interpoly dielectric film material, and a floating gate material, the difficulties accompanying a reduction in word line width. Further, the invention enables to avoid damage caused in the batch forming on a gate oxide film. Before forming floating gates of memory cells of a nonvolatile memory, a space enclosed by insulating layers is formed for each of the floating gates of the memory cells, so that the floating gate is buried in the space. This structure is realized by processing the floating gates in a self alignment manner after depositing the floating gate material.
    Type: Grant
    Filed: February 9, 2006
    Date of Patent: September 8, 2009
    Assignee: Renesas Technology Corp.
    Inventors: Yoshitaka Sasago, Takashi Kobayashi
  • Publication number: 20090189137
    Abstract: In a phase change memory, electric property of a diode used as a selection device is extremely important. However, since crystal grain boundaries are present in the film of a diode using polysilicon, it involves a problem that the off leak property varies greatly making it difficult to prevent erroneous reading. For overcoming the problem, the present invention provides a method of controlling the temperature profile of an amorphous silicon in the laser annealing for crystallizing and activating the amorphous silicon thereby controlling the crystal grain boundaries. According to the invention, variation in the electric property of the diode can be decreased and the yield of the phase-change memory can be improved.
    Type: Application
    Filed: January 29, 2009
    Publication date: July 30, 2009
    Inventors: Masaharu Kinoshita, Motoyasu Terao, Hideyuki Matsuoka, Yoshitaka Sasago, Yoshinobu Kimura, Akio Shima, Mitsuharu Tai, Norikatsu Takaura
  • Publication number: 20090140233
    Abstract: A nonvolatile semiconductor memory device having a large storage capacity and stabilized rewriting conditions in which a memory cell includes a nonvolatile recording material layer, a selector element and a semiconductor layer provided between the nonvolatile recording material layer and the selector element and having a thickness ranging from 5 to 200 nm.
    Type: Application
    Filed: November 10, 2008
    Publication date: June 4, 2009
    Inventors: Masaharu KINOSHITA, Motoyasu Terao, Hideyuki Matsuoka, Yoshitaka Sasago, Yoshinobu Kimura, Akio Shima, Mitsuharu Tai, Norikatsu Takaura
  • Publication number: 20090039336
    Abstract: The performance of a semiconductor device capable of storing information is improved. A memory layer of a memory element is formed by a first layer at a bottom electrode side and a second layer at a top electrode side. The first layer contains 20-70 atom % of at least one element of a first element group of Cu, Ag, Au, Al, Zn, and Cd, contains 3-40 atom % of at least one element of a second element group of V, Nb, Ta, Cr, Mo, W, Ti, Zr, Hf, Fe, Co, Ni, Pt, Pd, Rh, Ir, Ru, Os, and lanthanoid elements, and contains 20-60 atom % of at least one element of a third element group of S, Se, and Te. The second layer contains 5-50 atom % of at least one element of the first element group, 10-50 atom % of at least one element of the second element group, and 30-70 atom % of oxygen.
    Type: Application
    Filed: July 21, 2008
    Publication date: February 12, 2009
    Inventors: Motoyasu Terao, Yoshitaka Sasago, Kenzo Kurotsuchi, Kazuo Ono, Yoshihisa Fujisaki, Norikatsu Takaura, Riichiro Takemura
  • Publication number: 20090014770
    Abstract: A technique that can realize high integration even for multilayered three-dimensional structures at low costs by improving the performance of the semiconductor device having recording or switching functions by employing a device structure that enables high precision controlling of the movement of ions in the solid electrolyte. The semiconductor element of the device is formed as follows; two or more layers are deposited with different components respectively between a pair of electrodes disposed separately in the vertical (z-axis) direction, then a pulse voltage is applied between those electrodes to form a conductive path. The resistance value of the path changes according to an information signal. Furthermore, a region is formed at a middle part of the conductive path. The region is used to accumulate a component that improves the conductivity of the path, thereby enabling the resistance value (rate) to response currently to the information signal.
    Type: Application
    Filed: July 9, 2008
    Publication date: January 15, 2009
    Inventors: Motoyasu Terao, Hideyuki Matsuoka, Naohiko Irie, Yoshitaka Sasago, Riichiro Takemura, Norikatsu Takaura