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).

  • Patent number: 9153775
    Abstract: Disclosed are a semiconductor storage device and a method for manufacturing the semiconductor storage device, whereby the bit cost of memory using a variable resistance material is reduced.
    Type: Grant
    Filed: August 26, 2014
    Date of Patent: October 6, 2015
    Assignee: Hitachi, Ltd.
    Inventors: Yoshitaka Sasago, Akio Shima, Satoru Hanzawa, Takashi Kobayashi, Masaharu Kinoshita, Norikatsu Takaura
  • Patent number: 9153774
    Abstract: When a thin channel semiconductor layer formed on a side wall of a stacked film in which insulating films and gate electrodes are alternately stacked together is removed on the stacked film, a contact resistance between a vertical transistor including the channel semiconductor layer and the gate electrode, and a bit line formed on the stacked film is prevented from rising. As its means, a conductive layer electrically connected to the channel semiconductor layer is disposed immediately above the stacked film.
    Type: Grant
    Filed: December 6, 2010
    Date of Patent: October 6, 2015
    Assignee: Hitachi, Ltd.
    Inventors: Yoshitaka Sasago, Masaharu Kinoshita, Mitsuharu Tai, Akio Shima, Kenzo Kurotsuchi, Takashi Kobayashi
  • Patent number: 9099177
    Abstract: With the aim of providing a semiconductor memory device being suitable for miniaturization and allowing a contact resistance to lower, the wiring structure of a memory array (MA) is formed as follows. That is, word lines (2) and bit lines (3) are extended in parallel to each other, each of the word lines is bundled with another word line, each of the bit lines is bundled with another bit line, and two bit lines formed vertically over respective bundled two word lines are separated electrically. Such a configuration makes it possible to: form a larger contact at a bundling section (MLC) of wires; and lower a contact resistance in the memory array suitable for miniaturization.
    Type: Grant
    Filed: June 10, 2011
    Date of Patent: August 4, 2015
    Assignee: Hitachi, Ltd.
    Inventors: Yoshitaka Sasago, Masaharu Kinoshita, Akira Kotabe, Takashi Kobayashi
  • Patent number: 9070621
    Abstract: In a nonvolatile semiconductor memory device, there is provided a technique which promotes microfabrication by reducing a thickness of the device as suppressing an OFF current of a polysilicon diode which is a selective element. A polysilicon layer to which an impurity is doped at low concentration and which becomes an electric-field relaxation layer of the polysilicon diode which is a selective element of a resistance variable memory is formed so as to be divided into two or more layers such as polysilicon layers. In this manner, it is suppressed to form the crystal grain boundaries thoroughly penetrating between an n-type polysilicon layer and a p-type polysilicon layer in the electric-field relaxation layer, and therefore, it is prevented to generate a leakage current flowing through the crystal grain boundaries in application of a reverse-bias voltage without increasing a height of the polysilicon diode.
    Type: Grant
    Filed: November 10, 2013
    Date of Patent: June 30, 2015
    Assignee: Hitachi, Ltd.
    Inventors: Yoshitaka Sasago, Masaharu Kinoshita, Mitsuharu Tai, Takashi Kobayashi
  • Publication number: 20150155479
    Abstract: The purpose of the present invention is to provide a semiconductor storage device, which has small resistance in the ON state, and a small leak current in the OFF state, and which has a small-sized select transistor used therein. In this semiconductor storage device, a channel of a first select transistor that selects a memory cell array is electrically connected to each of the adjacent memory cell arrays (see FIG. 1).
    Type: Application
    Filed: June 4, 2012
    Publication date: June 4, 2015
    Inventor: Yoshitaka Sasago
  • Publication number: 20150118804
    Abstract: A vertical chain memory includes two-layer select transistors having first select transistors which are vertical transistors arranged in a matrix, and second select transistors which are vertical transistors formed on the respective first select transistors, and a plurality of memory cells connected in series on the two-layer select transistors. With this configuration, the adjacent select transistors are prevented from being selected by respective shared gates, the plurality of two-layer select transistors can be selected, independently, and a storage capacity of a non-volatile storage device is prevented from being reduced.
    Type: Application
    Filed: October 5, 2014
    Publication date: April 30, 2015
    Inventors: Yoshitaka SASAGO, Masaharu KINOSHITA, Takahiro MORIKAWA, Akio SHIMA, Takashi KOBAYASHI
  • Publication number: 20140361241
    Abstract: Disclosed are a semiconductor storage device and a method for manufacturing the semiconductor storage device, whereby the bit cost of memory using a variable resistance material is reduced.
    Type: Application
    Filed: August 26, 2014
    Publication date: December 11, 2014
    Inventors: Yoshitaka Sasago, Akio Shima, Satoru Hanzawa, Takashi Kobayashi, Masaharu Kinoshita, Norikatsu Takaura
  • Patent number: 8901712
    Abstract: The technical problem to be solved is to achieve high density with simple manufacturing process to decrease bit costs of memory. A semiconductor memory device according to a first aspect of the present invention includes a variable resistance material layer and a channel layer that are connected in series between a first diffusion layer and a metal wire, thereby separating the metal wire and a channel semiconductor layer. A semiconductor memory device according to a second aspect of the present invention includes a variable resistance material layer electrically connecting channel semiconductor layers opposed to each other in a first direction and electrically connecting channel semiconductor layers adjacent to each other in a second direction, wherein a plurality of the channel semiconductor layers is disposed in the second direction.
    Type: Grant
    Filed: March 13, 2013
    Date of Patent: December 2, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Yoshitaka Sasago, Akira Kotabe
  • Patent number: 8866123
    Abstract: A vertical chain memory includes two-layer select transistors having first select transistors which are vertical transistors arranged in a matrix, and second select transistors which are vertical transistors formed on the respective first select transistors, and a plurality of memory cells connected in series on the two-layer select transistors. With this configuration, the adjacent select transistors are prevented from being selected by respective shared gates, the plurality of two-layer select transistors can be selected, independently, and a storage capacity of a non-volatile storage device is prevented from being reduced.
    Type: Grant
    Filed: November 22, 2010
    Date of Patent: October 21, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Yoshitaka Sasago, Masaharu Kinoshita, Takahiro Morikawa, Akio Shima, Takashi Kobayashi
  • Patent number: 8841646
    Abstract: Disclosed are a semiconductor storage device and a manufacturing method. The storage device has: a substrate; a first word line above the substrate; a first laminated body above the first word line and having N+1 first inter-gate insulating layers and N first semiconductor layers alternately laminated; a first bit line above the laminated body and extending in a direction that intersects the first word line; a first gate insulating layer on side surfaces of the first inter-gate insulating layers and the first semiconductor layers; a first channel layer on the side surface of the first gate insulating layer; and a first variable resistance material layer on the side surface of the first channel layer. The first variable resistance material layer is in a region where the first word line and the first bit line intersect. A polysilicon diode is used as a selection element.
    Type: Grant
    Filed: October 6, 2013
    Date of Patent: September 23, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Yoshitaka Sasago, Akio Shima, Satoru Hanzawa, Takashi Kobayashi, Masaharu Kinoshita, Norikatsu Takaura
  • Patent number: 8830740
    Abstract: The purpose of the present invention is to improve a rewriting transmission rate and reliability of a phase change memory. To attain the purpose, a plurality of phase change memory cells (SMC or USMC) which are provided in series between a word line (2) and a bit line (3) and have a selection element and a storage element that are parallel connected with each other are entirely set, and after that, a part of the cells corresponding to a data pattern is reset. Alternatively, the reverse of the operation is carried out.
    Type: Grant
    Filed: August 26, 2011
    Date of Patent: September 9, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Yoshitaka Sasago, Hiroyuki Minemura, Takashi Kobayashi, Toshimichi Shintani, Satoru Hanzawa, Masaharu Kinoshita
  • Publication number: 20140246646
    Abstract: A memory cell array having such a structure that can be realized with a simpler process and ideal for realizing a higher density is provided. Memory cells have a structure in which channel layers (88p and 89p) are formed on the side surfaces of each of a plurality of stacked structures which extends in the Y direction and is periodically formed in the X direction with a gate insulator film layer (9) interposed, and a resistance-change material layer (7) is formed so as to be electrically connected to two adjacent channel layers of the channel layers. Due to such a structure, it is not necessary to perform such a very difficult step that processes the resistance-change material and the silicons collectively and it is possible to provide the memory cell array with a simpler process.
    Type: Application
    Filed: October 7, 2011
    Publication date: September 4, 2014
    Inventors: Yoshitaka Sasago, Masaharu Kinoshita
  • Publication number: 20140218999
    Abstract: With the aim of providing a semiconductor memory device being suitable for miniaturization and allowing a contact resistance to lower, the wiring structure of a memory array (MA) is formed as follows. That is, word lines (2) and bit lines (3) are extended in parallel to each other, each of the word lines is bundled with another word line, each of the bit lines is bundled with another bit line, and two bit lines formed vertically over respective bundled two word lines are separated electrically. Such a configuration makes it possible to: form a larger contact at a bundling section (MLC) of wires; and lower a contact resistance in the memory array suitable for miniaturization.
    Type: Application
    Filed: June 10, 2011
    Publication date: August 7, 2014
    Inventors: Yoshitaka Sasago, Masaharu Kinoshita, Akira Kotabe, Takashi Kobayashi
  • Patent number: 8772746
    Abstract: A semiconductor memory device in which the cell area can be decreased and the minimum feature size is not restricted by the thickness of the material forming the memory cell. In a semiconductor memory device, a gate insulating film, a channel extending in a direction X, and a resistance change element extending in the direction X are formed successively above multiple word lines extending in a direction Y, and a portion of the channel and a portion of the resistance change element are disposed above each of the plurality of the word lines. Such configuration can decrease the cell area and ensure the degree of design freedom.
    Type: Grant
    Filed: January 13, 2012
    Date of Patent: July 8, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Masaharu Kinoshita, Yoshitaka Sasago, Takashi Kobayashi
  • Patent number: 8735865
    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: Grant
    Filed: January 8, 2011
    Date of Patent: May 27, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Hiroyuki Minemura, Yumiko Anzai, Takahiro Morikawa, Toshimichi Shintani, Yoshitaka Sasago
  • Patent number: 8730717
    Abstract: A semiconductor device has multiple memory cell groups arranged at intersections between multiple word lines and multiple bit lines intersecting the word lines. The memory cell groups each have first and second memory cells connected in series. Each of the first and the second memory cells has a select transistor and a resistive storage device connected in parallel. The gate electrode of the select transistor in the first memory cell is connected with a first gate line, and the gate electrode of the select transistor in the second memory cell is connected to a second gate line. A first circuit block for driving the word lines (word driver group WDBK) is arranged between a second circuit block for driving the first and second gate lines (phase-change-type chain cell control circuit PCCCTL) and multiple memory cell groups (memory cell array MA).
    Type: Grant
    Filed: May 9, 2011
    Date of Patent: May 20, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Satoru Hanzawa, Yoshitaka Sasago
  • Publication number: 20140103287
    Abstract: Disclosed are a semiconductor storage device and a manufacturing method. The storage device has: a substrate; a first word line above the substrate; a first laminated body above the first word line and having N+1 first inter-gate insulating layers and N first semiconductor layers alternately laminated; a first bit line above the laminated body and extending in a direction that intersects the first word line; a first gate insulating layer on side surfaces of the first inter-gate insulating layers and the first semiconductor layers; a first channel layer on the side surface of the first gate insulating layer; and a first variable resistance material layer on the side surface of the first channel layer. The first variable resistance material layer is in a region where the first word line and the first bit line intersect. A polysilicon diode is used as a selection element.
    Type: Application
    Filed: October 6, 2013
    Publication date: April 17, 2014
    Applicant: Hitachi, Ltd.
    Inventors: Yoshitaka Sasago, Akio Shima, Satoru Hanzawa, Takashi Kobayashi, Masaharu Kinoshita, Norikatsu Takaura
  • Patent number: 8699262
    Abstract: Adverse effects of a parasitic resistance and a parasitic capacitance of a driver circuit to a memory cell causes problems of thermal disturbance to a not-selected cell, unevenness of application voltage, degradation of a memory element in reading. A capacitor (C) is provided above or beneath a memory cell (MC) that includes a memory element to which a current write memory information and a selection element connected to the memory element. A charge stored in this capacitor writes to the memory element.
    Type: Grant
    Filed: October 11, 2011
    Date of Patent: April 15, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Takao Watanabe, Satoru Hanzawa, Yoshitaka Sasago
  • Publication number: 20140065789
    Abstract: In a nonvolatile semiconductor memory device, there is provided a technique which promotes microfabrication by reducing a thickness of the device as suppressing an OFF current of a polysilicon diode which is a selective element. A polysilicon layer to which an impurity is doped at low concentration and which becomes an electric-field relaxation layer of the polysilicon diode which is a selective element of a resistance variable memory is formed so as to be divided into two or more layers such as polysilicon layers. In this manner, it is suppressed to form the crystal grain boundaries thoroughly penetrating between an n-type polysilicon layer and a p-type polysilicon layer in the electric-field relaxation layer, and therefore, it is prevented to generate a leakage current flowing through the crystal grain boundaries in application of a reverse-bias voltage without increasing a height of the polysilicon diode.
    Type: Application
    Filed: November 10, 2013
    Publication date: March 6, 2014
    Applicant: Hitachi, Ltd.
    Inventors: Yoshitaka SASAGO, Masaharu KINOSHITA, Mitsuharu TAI, Takashi KOBAYASHI
  • Patent number: 8642988
    Abstract: A non-volatile memory device includes: a first line extending along a main surface of a substrate; a stack provided above the first line; a second line formed above the stack; a select element provided where the first and second lines intersect, the select element adapted to pass current in a direction perpendicular to the main surface; a second insulator film provided along a side surface of the stack; a channel layer provided along the second insulator film; an adhesion layer provided along the channel layer; and a variable resistance material layer provided along the adhesion layer, wherein the first and second lines are electrically connected via the select element and channel layer, a contact resistance via the adhesion layer between the channel layer and variable resistance material layer is low, and a resistance of the adhesion layer is high with respect to an extending direction of the channel layer.
    Type: Grant
    Filed: August 17, 2012
    Date of Patent: February 4, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Masaharu Kinoshita, Yoshitaka Sasago, Takashi Kobayashi, Hiroyuki Minemura